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解决RecyclerView无法onItemClick问题

导读:对于RecyclerView的使用,大家可以查看将替代ListView的RecyclerView 的使用(一),单单从代码结构来说RecyclerView确实比ListView优化了很多,也简化了我们编写代码量,但是有一个问题会导致开发者不会去用它,更比说替换ListView了,我不知道使用过RecyclerView的人有没有进一步查看,RecyclerView没有提供Item的点击事件,我们使用...。。。

对于RecyclerView的使用,大家可以查看将替代ListView的RecyclerView 的使用(一),单单从代码结构来说RecyclerView确实比ListView优化了很多,也简化了我们编写代码量,但是有一个问题会导致开发者不会去用它,更比说替换ListView了,我不知道使用过RecyclerView的人有没有进一步查看,RecyclerView没有提供Item的点击事件,我们使用列表不仅仅为了显示数据,同时也可以能会交互,所以RecyclerView这个问题导致基本没有人用它,我清楚谷歌是怎么想的,不过RecyclerView也并没有把所有的路给堵死,需要我们写代码来实现Item的点击事件,我们都知道RecyclerView里面新加了ViewHolder这个静态抽象类,这个类里面有一个方法getPosition()可以返回当前ViewHolder实例的位置,实现onItemClick就是使用它来做的,下面有两种方法来实现:

第一种:不修改源码

这种方法不修改源码,问题是只能在RecyclerView.Adapter中实现ItemClick事件

public static class ViewHolder extends RecyclerView.ViewHolder {  public ViewHolder(View itemView) {   super(itemView);   itemView.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View v) {     Log.e("jwzhangjie", "当前点击的位置:"+getPosition());    }   });     } }

这种方式直观上看起来不太好,不过也可以实现ItemClick事件。

第二种方法:修改RecyclerView源码

1、把在RecyClerView类里面定义OnItemClickListener接口

/**     * Interface definition for a callback to be invoked when an item in this     * RecyclerView.Adapter has been clicked.     */    public interface OnItemClickListener {        /**         * Callback method to be invoked when an item in this RecyclerView.Adapter has         * been clicked.         * 

* Implementers can call getPosition(position) if they need * to access the data associated with the selected item. * * @param view The view within the RecyclerView.Adapter that was clicked (this * will be a view provided by the adapter) * @param position The position of the view in the adapter. */ void onItemClick(View view, int position); } public static OnItemClickListener mOnItemClickListener = null; /** * Register a callback to be invoked when an item in this AdapterView has * been clicked. * * @param listener The callback that will be invoked. */ public void setOnItemClickListener(OnItemClickListener listener) { mOnItemClickListener = listener; } /** * @return The callback to be invoked with an item in this AdapterView has * been clicked, or null id no callback has been set. */ public final OnItemClickListener getOnItemClickListener() { return mOnItemClickListener; }


2、在RecyclerView中的抽象类ViewHolder中添加View的点击事件

public static abstract class ViewHolder implements OnClickListener{        public final View itemView;        int mPosition = NO_POSITION;        int mOldPosition = NO_POSITION;        long mItemId = NO_ID;        int mItemViewType = INVALID_TYPE;        /**         * This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType         * are all valid.         */        static final int FLAG_BOUND = 1 << 0;        /**         * The data this ViewHolder's view reflects is stale and needs to be rebound         * by the adapter. mPosition and mItemId are consistent.         */        static final int FLAG_UPDATE = 1 << 1;        /**         * This ViewHolder's data is invalid. The identity implied by mPosition and mItemId         * are not to be trusted and may no longer match the item view type.         * This ViewHolder must be fully rebound to different data.         */        static final int FLAG_INVALID = 1 << 2;        /**         * This ViewHolder points at data that represents an item previously removed from the         * data set. Its view may still be used for things like outgoing animations.         */        static final int FLAG_REMOVED = 1 << 3;        /**         * This ViewHolder should not be recycled. This flag is set via setIsRecyclable()         * and is intended to keep views around during animations.         */        static final int FLAG_NOT_RECYCLABLE = 1 << 4;        private int mFlags;        private int mIsRecyclableCount = 0;        // If non-null, view is currently considered scrap and may be reused for other data by the        // scrap container.        private Recycler mScrapContainer = null;                @Override  public void onClick(View v) {         if (mOnItemClickListener != null) {          mOnItemClickListener.onItemClick(itemView, getPosition());   }  }  public ViewHolder(View itemView) {            if (itemView == null) {                throw new IllegalArgumentException("itemView may not be null");            }            this.itemView = itemView;            this.itemView.setOnClickListener(this);        }        void offsetPosition(int offset) {            if (mOldPosition == NO_POSITION) {                mOldPosition = mPosition;            }            mPosition += offset;        }        void clearOldPosition() {            mOldPosition = NO_POSITION;        }        public final int getPosition() {            return mOldPosition == NO_POSITION ? mPosition : mOldPosition;        }        public final long getItemId() {            return mItemId;        }        public final int getItemViewType() {            return mItemViewType;        }        boolean isScrap() {            return mScrapContainer != null;        }        void unScrap() {            mScrapContainer.unscrapView(this);            mScrapContainer = null;        }        void setScrapContainer(Recycler recycler) {            mScrapContainer = recycler;        }        boolean isInvalid() {            return (mFlags & FLAG_INVALID) != 0;        }        boolean needsUpdate() {            return (mFlags & FLAG_UPDATE) != 0;        }        boolean isBound() {            return (mFlags & FLAG_BOUND) != 0;        }        boolean isRemoved() {            return (mFlags & FLAG_REMOVED) != 0;        }        void setFlags(int flags, int mask) {            mFlags = (mFlags & ~mask) | (flags & mask);        }        void addFlags(int flags) {            mFlags |= flags;        }        void clearFlagsForSharedPool() {            mFlags = 0;        }        @Override        public String toString() {            final StringBuilder sb = new StringBuilder("ViewHolder{" +                    Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId);            if (isScrap()) sb.append(" scrap");            if (isInvalid()) sb.append(" invalid");            if (!isBound()) sb.append(" unbound");            if (needsUpdate()) sb.append(" update");            if (isRemoved()) sb.append(" removed");            sb.append("}");            return sb.toString();        }

3、完成上面的步骤,就可以使用RecyclerView来完成itemClick事件了

cashAccountList.setOnItemClickListener(new OnItemClickListener() {      @Override   public void onItemClick(View view, int position) {    AppLog.e("position: "+position);   }  });

下面是完整的RecyclerView源码:

/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.support.v7.widget;import android.content.Context;import android.database.Observable;import android.graphics.Canvas;import android.graphics.PointF;import android.graphics.Rect;import android.os.Build;import android.os.Parcel;import android.os.Parcelable;import android.support.annotation.Nullable;import android.support.v4.util.ArrayMap;import android.support.v4.util.Pools;import android.support.v4.view.MotionEventCompat;import android.support.v4.view.VelocityTrackerCompat;import android.support.v4.view.ViewCompat;import android.support.v4.widget.EdgeEffectCompat;import android.support.v4.widget.ScrollerCompat;import android.util.AttributeSet;import android.util.Log;import android.util.SparseArray;import android.util.SparseIntArray;import android.view.FocusFinder;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.view.ViewGroup;import android.view.ViewParent;import android.view.animation.Interpolator;import java.util.ArrayList;import java.util.Collections;import java.util.List;/** * A flexible view for providing a limited window into a large data set. * * 

Glossary of terms:

* *
    *
  • Adapter: A subclass of {@link Adapter} responsible for providing views * that represent items in a data set.
  • *
  • Position: The position of a data item within an Adapter.
  • *
  • Index: The index of an attached child view as used in a call to * {@link ViewGroup#getChildAt}. Contrast with Position.
  • *
  • Binding: The process of preparing a child view to display data corresponding * to a position within the adapter.
  • *
  • Recycle (view): A view previously used to display data for a specific adapter * position may be placed in a cache for later reuse to display the same type of data again * later. This can drastically improve performance by skipping initial layout inflation * or construction.
  • *
  • Scrap (view): A child view that has entered into a temporarily detached * state during layout. Scrap views may be reused without becoming fully detached * from the parent RecyclerView, either unmodified if no rebinding is required or modified * by the adapter if the view was considered dirty.
  • *
  • Dirty (view): A child view that must be rebound by the adapter before * being displayed.
  • *
*/public class RecyclerView extends ViewGroup { private static final String TAG = "RecyclerView"; private static final boolean DEBUG = false; private static final boolean ENABLE_PREDICTIVE_ANIMATIONS = false; private static final boolean DISPATCH_TEMP_DETACH = false; public static final int HORIZONTAL = 0; public static final int VERTICAL = 1; public static final int NO_POSITION = -1; public static final long NO_ID = -1; public static final int INVALID_TYPE = -1; private static final int MAX_SCROLL_DURATION = 2000; private final RecyclerViewDataObserver mObserver = new RecyclerViewDataObserver(); private final Recycler mRecycler = new Recycler(); private SavedState mPendingSavedState; /** * Note: this Runnable is only ever posted if: * 1) We've been through first layout * 2) We know we have a fixed size (mHasFixedSize) * 3) We're attached */ private final Runnable mUpdateChildViewsRunnable = new Runnable() { public void run() { if (mPendingUpdates.isEmpty()) { return; } eatRequestLayout(); updateChildViews(); resumeRequestLayout(true); } }; private final Rect mTempRect = new Rect(); private final ArrayList mPendingUpdates = new ArrayList(); private final ArrayList mPendingLayoutUpdates = new ArrayList(); private Pools.Pool mUpdateOpPool = new Pools.SimplePool(UpdateOp.POOL_SIZE); private Adapter mAdapter; private LayoutManager mLayout; private RecyclerListener mRecyclerListener; private final ArrayList mItemDecorations = new ArrayList(); private final ArrayList mOnItemTouchListeners = new ArrayList(); private OnItemTouchListener mActiveOnItemTouchListener; private boolean mIsAttached; private boolean mHasFixedSize; private boolean mFirstLayoutComplete; private boolean mEatRequestLayout; private boolean mLayoutRequestEaten; private boolean mAdapterUpdateDuringMeasure; private final boolean mPostUpdatesOnAnimation; private EdgeEffectCompat mLeftGlow, mTopGlow, mRightGlow, mBottomGlow; ItemAnimator mItemAnimator = new DefaultItemAnimator(); private static final int INVALID_POINTER = -1; /** * The RecyclerView is not currently scrolling. * @see #getScrollState() */ public static final int SCROLL_STATE_IDLE = 0; /** * The RecyclerView is currently being dragged by outside input such as user touch input. * @see #getScrollState() */ public static final int SCROLL_STATE_DRAGGING = 1; /** * The RecyclerView is currently animating to a final position while not under * outside control. * @see #getScrollState() */ public static final int SCROLL_STATE_SETTLING = 2; // Touch/scrolling handling private int mScrollState = SCROLL_STATE_IDLE; private int mScrollPointerId = INVALID_POINTER; private VelocityTracker mVelocityTracker; private int mInitialTouchX; private int mInitialTouchY; private int mLastTouchX; private int mLastTouchY; private final int mTouchSlop; private final int mMinFlingVelocity; private final int mMaxFlingVelocity; private final ViewFlinger mViewFlinger = new ViewFlinger(); private final State mState = new State(); private OnScrollListener mScrollListener; // For use in item animations boolean mItemsAddedOrRemoved = false; boolean mItemsChanged = false; int mAnimatingViewIndex = -1; int mNumAnimatingViews = 0; boolean mInPreLayout = false; private ItemAnimator.ItemAnimatorListener mItemAnimatorListener = new ItemAnimatorRestoreListener(); private boolean mPostedAnimatorRunner = false; private Runnable mItemAnimatorRunner = new Runnable() { @Override public void run() { if (mItemAnimator != null) { mItemAnimator.runPendingAnimations(); } mPostedAnimatorRunner = false; } }; private static final Interpolator sQuinticInterpolator = new Interpolator() { public float getInterpolation(float t) { t -= 1.0f; return t * t * t * t * t + 1.0f; } }; public RecyclerView(Context context) { this(context, null); } public RecyclerView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public RecyclerView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); final int version = Build.VERSION.SDK_INT; mPostUpdatesOnAnimation = version >= 16; final ViewConfiguration vc = ViewConfiguration.get(context); mTouchSlop = vc.getScaledTouchSlop(); mMinFlingVelocity = vc.getScaledMinimumFlingVelocity(); mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity(); setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); mItemAnimator.setListener(mItemAnimatorListener); } /** * RecyclerView can perform several optimizations if it can know in advance that changes in * adapter content cannot change the size of the RecyclerView itself. * If your use of RecyclerView falls into this category, set this to true. * * @param hasFixedSize true if adapter changes cannot affect the size of the RecyclerView. */ public void setHasFixedSize(boolean hasFixedSize) { mHasFixedSize = hasFixedSize; } /** * @return true if the app has specified that changes in adapter content cannot change * the size of the RecyclerView itself. */ public boolean hasFixedSize() { return mHasFixedSize; } /** * Set a new adapter to provide child views on demand. * * @param adapter The new adapter to set, or null to set no adapter. */ public void setAdapter(Adapter adapter) { if (mAdapter != null) { mAdapter.unregisterAdapterDataObserver(mObserver); } // end all running animations if (mItemAnimator != null) { mItemAnimator.endAnimations(); } // Since animations are ended, mLayout.children should be equal to recyclerView.children. // This may not be true if item animator's end does not work as expected. (e.g. not release // children instantly). It is safer to use mLayout's child count. if (mLayout != null) { mLayout.removeAndRecycleAllViews(mRecycler); mLayout.removeAndRecycleScrapInt(mRecycler, true); } final Adapter oldAdapter = mAdapter; mAdapter = adapter; if (adapter != null) { adapter.registerAdapterDataObserver(mObserver); } if (mLayout != null) { mLayout.onAdapterChanged(oldAdapter, mAdapter); } mRecycler.onAdapterChanged(oldAdapter, mAdapter); mState.mStructureChanged = true; markKnownViewsInvalid(); requestLayout(); } /** * Retrieves the previously set adapter or null if no adapter is set. * * @return The previously set adapter * @see #setAdapter(Adapter) */ public Adapter getAdapter() { return mAdapter; } /** * Register a listener that will be notified whenever a child view is recycled. * *

This listener will be called when a LayoutManager or the RecyclerView decides * that a child view is no longer needed. If an application associates expensive * or heavyweight data with item views, this may be a good place to release * or free those resources.

* * @param listener Listener to register, or null to clear */ public void setRecyclerListener(RecyclerListener listener) { mRecyclerListener = listener; } /** * Set the {@link LayoutManager} that this RecyclerView will use. * *

In contrast to other adapter-backed views such as {@link android.widget.ListView} * or {@link android.widget.GridView}, RecyclerView allows client code to provide custom * layout arrangements for child views. These arrangements are controlled by the * {@link LayoutManager}. A LayoutManager must be provided for RecyclerView to function.

* *

Several default strategies are provided for common uses such as lists and grids.

* * @param layout LayoutManager to use */ public void setLayoutManager(LayoutManager layout) { if (layout == mLayout) { return; } mRecycler.clear(); removeAllViews(); if (mLayout != null) { if (mIsAttached) { mLayout.onDetachedFromWindow(this); } mLayout.mRecyclerView = null; } mLayout = layout; if (layout != null) { if (layout.mRecyclerView != null) { throw new IllegalArgumentException("LayoutManager " + layout + " is already attached to a RecyclerView: " + layout.mRecyclerView); } layout.mRecyclerView = this; if (mIsAttached) { mLayout.onAttachedToWindow(this); } } requestLayout(); } @Override protected Parcelable onSaveInstanceState() { SavedState state = new SavedState(super.onSaveInstanceState()); if (mPendingSavedState != null) { state.copyFrom(mPendingSavedState); } else if (mLayout != null) { state.mLayoutState = mLayout.onSaveInstanceState(); } else { state.mLayoutState = null; } return state; } @Override protected void onRestoreInstanceState(Parcelable state) { mPendingSavedState = (SavedState) state; super.onRestoreInstanceState(mPendingSavedState.getSuperState()); if (mLayout != null && mPendingSavedState.mLayoutState != null) { mLayout.onRestoreInstanceState(mPendingSavedState.mLayoutState); } } /** * Adds a view to the animatingViews list. * mAnimatingViews holds the child views that are currently being kept around * purely for the purpose of being animated out of view. They are drawn as a regular * part of the child list of the RecyclerView, but they are invisible to the LayoutManager * as they are managed separately from the regular child views. * @param view The view to be removed */ private void addAnimatingView(View view) { boolean alreadyAdded = false; if (mNumAnimatingViews > 0) { for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { if (getChildAt(i) == view) { alreadyAdded = true; break; } } } if (!alreadyAdded) { if (mNumAnimatingViews == 0) { mAnimatingViewIndex = getChildCount(); } ++mNumAnimatingViews; addView(view); } mRecycler.unscrapView(getChildViewHolder(view)); } /** * Removes a view from the animatingViews list. * @param view The view to be removed * @see #addAnimatingView(View) */ private void removeAnimatingView(View view) { if (mNumAnimatingViews > 0) { for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { if (getChildAt(i) == view) { removeViewAt(i); --mNumAnimatingViews; if (mNumAnimatingViews == 0) { mAnimatingViewIndex = -1; } mRecycler.recycleView(view); return; } } } } private View getAnimatingView(int position, int type) { if (mNumAnimatingViews > 0) { for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) { final View view = getChildAt(i); ViewHolder holder = getChildViewHolder(view); if (holder.getPosition() == position && ( type == INVALID_TYPE || holder.getItemViewType() == type)) { return view; } } } return null; } /** * Return the {@link LayoutManager} currently responsible for * layout policy for this RecyclerView. * * @return The currently bound LayoutManager */ public LayoutManager getLayoutManager() { return mLayout; } /** * Retrieve this RecyclerView's {@link RecycledViewPool}. This method will never return null; * if no pool is set for this view a new one will be created. See * {@link #setRecycledViewPool(RecycledViewPool) setRecycledViewPool} for more information. * * @return The pool used to store recycled item views for reuse. * @see #setRecycledViewPool(RecycledViewPool) */ public RecycledViewPool getRecycledViewPool() { return mRecycler.getRecycledViewPool(); } /** * Recycled view pools allow multiple RecyclerViews to share a common pool of scrap views. * This can be useful if you have multiple RecyclerViews with adapters that use the same * view types, for example if you have several data sets with the same kinds of item views * displayed by a {@link android.support.v4.view.ViewPager ViewPager}. * * @param pool Pool to set. If this parameter is null a new pool will be created and used. */ public void setRecycledViewPool(RecycledViewPool pool) { mRecycler.setRecycledViewPool(pool); } /** * Set the number of offscreen views to retain before adding them to the potentially shared * {@link #getRecycledViewPool() recycled view pool}. * *

The offscreen view cache stays aware of changes in the attached adapter, allowing * a LayoutManager to reuse those views unmodified without needing to return to the adapter * to rebind them.

* * @param size Number of views to cache offscreen before returning them to the general * recycled view pool */ public void setItemViewCacheSize(int size) { mRecycler.setViewCacheSize(size); } /** * Return the current scrolling state of the RecyclerView. * * @return {@link #SCROLL_STATE_IDLE}, {@link #SCROLL_STATE_DRAGGING} or * {@link #SCROLL_STATE_SETTLING} */ public int getScrollState() { return mScrollState; } private void setScrollState(int state) { if (state == mScrollState) { return; } mScrollState = state; if (state != SCROLL_STATE_SETTLING) { stopScroll(); } if (mScrollListener != null) { mScrollListener.onScrollStateChanged(state); } } /** * Add an {@link ItemDecoration} to this RecyclerView. Item decorations can * affect both measurement and drawing of individual item views. * *

Item decorations are ordered. Decorations placed earlier in the list will * be run/queried/drawn first for their effects on item views. Padding added to views * will be nested; a padding added by an earlier decoration will mean further * item decorations in the list will be asked to draw/pad within the previous decoration's * given area.

* * @param decor Decoration to add * @param index Position in the decoration chain to insert this decoration at. If this value * is negative the decoration will be added at the end. */ public void addItemDecoration(ItemDecoration decor, int index) { if (mItemDecorations.isEmpty()) { setWillNotDraw(false); } if (index < 0) { mItemDecorations.add(decor); } else { mItemDecorations.add(index, decor); } markItemDecorInsetsDirty(); requestLayout(); } /** * Add an {@link ItemDecoration} to this RecyclerView. Item decorations can * affect both measurement and drawing of individual item views. * *

Item decorations are ordered. Decorations placed earlier in the list will * be run/queried/drawn first for their effects on item views. Padding added to views * will be nested; a padding added by an earlier decoration will mean further * item decorations in the list will be asked to draw/pad within the previous decoration's * given area.

* * @param decor Decoration to add */ public void addItemDecoration(ItemDecoration decor) { addItemDecoration(decor, -1); } /** * Remove an {@link ItemDecoration} from this RecyclerView. * *

The given decoration will no longer impact the measurement and drawing of * item views.

* * @param decor Decoration to remove * @see #addItemDecoration(ItemDecoration) */ public void removeItemDecoration(ItemDecoration decor) { mItemDecorations.remove(decor); if (mItemDecorations.isEmpty()) { setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER); } markItemDecorInsetsDirty(); requestLayout(); } /** * Set a listener that will be notified of any changes in scroll state or position. * * @param listener Listener to set or null to clear */ public void setOnScrollListener(OnScrollListener listener) { mScrollListener = listener; } /** * Convenience method to scroll to a certain position. * * RecyclerView does not implement scrolling logic, rather forwards the call to * {@link android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)} * @param position Scroll to this adapter position * @see android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int) */ public void scrollToPosition(int position) { stopScroll(); mLayout.scrollToPosition(position); awakenScrollBars(); } /** * Starts a smooth scroll to an adapter position. *

* To support smooth scrolling, you must override * {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} and create a * {@link SmoothScroller}. *

* {@link LayoutManager} is responsible for creating the actual scroll action. If you want to * provide a custom smooth scroll logic, override * {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} in your * LayoutManager. * * @param position The adapter position to scroll to * @see LayoutManager#smoothScrollToPosition(RecyclerView, State, int) */ public void smoothScrollToPosition(int position) { mLayout.smoothScrollToPosition(this, mState, position); } @Override public void scrollTo(int x, int y) { throw new UnsupportedOperationException( "RecyclerView does not support scrolling to an absolute position."); } @Override public void scrollBy(int x, int y) { if (mLayout == null) { throw new IllegalStateException("Cannot scroll without a LayoutManager set. " + "Call setLayoutManager with a non-null argument."); } final boolean canScrollHorizontal = mLayout.canScrollHorizontally(); final boolean canScrollVertical = mLayout.canScrollVertically(); if (canScrollHorizontal || canScrollVertical) { scrollByInternal(canScrollHorizontal ? x : 0, canScrollVertical ? y : 0); } } /** * Helper method reflect data changes to the state. *

* Adapter changes during a scroll may trigger a crash because scroll assumes no data change * but data actually changed. *

* This method consumes all deferred changes to avoid that case. *

* This also ends all pending animations. It will be changed once we can support * animations during scroll. */ private void consumePendingUpdateOperations() { if (mItemAnimator != null) { mItemAnimator.endAnimations(); } if (mPendingUpdates.size() > 0) { mUpdateChildViewsRunnable.run(); } } /** * Does not perform bounds checking. Used by internal methods that have already validated input. */ void scrollByInternal(int x, int y) { int overscrollX = 0, overscrollY = 0; consumePendingUpdateOperations(); if (mAdapter != null) { eatRequestLayout(); if (x != 0) { final int hresult = mLayout.scrollHorizontallyBy(x, mRecycler, mState); overscrollX = x - hresult; } if (y != 0) { final int vresult = mLayout.scrollVerticallyBy(y, mRecycler, mState); overscrollY = y - vresult; } resumeRequestLayout(false); } if (!mItemDecorations.isEmpty()) { invalidate(); } if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { pullGlows(overscrollX, overscrollY); } if (mScrollListener != null && (x != 0 || y != 0)) { mScrollListener.onScrolled(x, y); } if (!awakenScrollBars()) { invalidate(); } } /** *

Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal * range. This value is used to compute the length of the thumb within the scrollbar's track. *

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollExtent()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollOffset(RecyclerView.State)} in your * LayoutManager.

* * @return The horizontal offset of the scrollbar's thumb * @see android.support.v7.widget.RecyclerView.LayoutManager#computeHorizontalScrollOffset * (RecyclerView.Adapter) */ @Override protected int computeHorizontalScrollOffset() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollOffset(mState) : 0; } /** *

Compute the horizontal extent of the horizontal scrollbar's thumb within the * horizontal range. This value is used to compute the length of the thumb within the * scrollbar's track.

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollOffset()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)} in your * LayoutManager.

* * @return The horizontal extent of the scrollbar's thumb * @see RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State) */ @Override protected int computeHorizontalScrollExtent() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollExtent(mState) : 0; } /** *

Compute the horizontal range that the horizontal scrollbar represents.

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeHorizontalScrollExtent()} and {@link #computeHorizontalScrollOffset()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)} in your * LayoutManager.

* * @return The total horizontal range represented by the vertical scrollbar * @see RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State) */ @Override protected int computeHorizontalScrollRange() { return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollRange(mState) : 0; } /** *

Compute the vertical offset of the vertical scrollbar's thumb within the vertical range. * This value is used to compute the length of the thumb within the scrollbar's track.

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollExtent()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollOffset(RecyclerView.State)} in your * LayoutManager.

* * @return The vertical offset of the scrollbar's thumb * @see android.support.v7.widget.RecyclerView.LayoutManager#computeVerticalScrollOffset * (RecyclerView.Adapter) */ @Override protected int computeVerticalScrollOffset() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollOffset(mState) : 0; } /** *

Compute the vertical extent of the vertical scrollbar's thumb within the vertical range. * This value is used to compute the length of the thumb within the scrollbar's track.

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollOffset()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)} in your * LayoutManager.

* * @return The vertical extent of the scrollbar's thumb * @see RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State) */ @Override protected int computeVerticalScrollExtent() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollExtent(mState) : 0; } /** *

Compute the vertical range that the vertical scrollbar represents.

* *

The range is expressed in arbitrary units that must be the same as the units used by * {@link #computeVerticalScrollExtent()} and {@link #computeVerticalScrollOffset()}.

* *

Default implementation returns 0.

* *

If you want to support scroll bars, override * {@link RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)} in your * LayoutManager.

* * @return The total vertical range represented by the vertical scrollbar * @see RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State) */ @Override protected int computeVerticalScrollRange() { return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0; } void eatRequestLayout() { if (!mEatRequestLayout) { mEatRequestLayout = true; mLayoutRequestEaten = false; } } void resumeRequestLayout(boolean performLayoutChildren) { if (mEatRequestLayout) { if (performLayoutChildren && mLayoutRequestEaten && mLayout != null && mAdapter != null) { dispatchLayout(); } mEatRequestLayout = false; mLayoutRequestEaten = false; } } /** * Animate a scroll by the given amount of pixels along either axis. * * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically */ public void smoothScrollBy(int dx, int dy) { if (dx != 0 || dy != 0) { mViewFlinger.smoothScrollBy(dx, dy); } } /** * Begin a standard fling with an initial velocity along each axis in pixels per second. * If the velocity given is below the system-defined minimum this method will return false * and no fling will occur. * * @param velocityX Initial horizontal velocity in pixels per second * @param velocityY Initial vertical velocity in pixels per second * @return true if the fling was started, false if the velocity was too low to fling */ public boolean fling(int velocityX, int velocityY) { if (Math.abs(velocityX) < mMinFlingVelocity) { velocityX = 0; } if (Math.abs(velocityY) < mMinFlingVelocity) { velocityY = 0; } velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity)); velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity)); if (velocityX != 0 || velocityY != 0) { mViewFlinger.fling(velocityX, velocityY); return true; } return false; } /** * Stop any current scroll in progress, such as one started by * {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling. */ public void stopScroll() { mViewFlinger.stop(); mLayout.stopSmoothScroller(); } /** * Apply a pull to relevant overscroll glow effects */ private void pullGlows(int overscrollX, int overscrollY) { if (overscrollX < 0) { if (mLeftGlow == null) { mLeftGlow = new EdgeEffectCompat(getContext()); mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } mLeftGlow.onPull(-overscrollX / (float) getWidth()); } else if (overscrollX > 0) { if (mRightGlow == null) { mRightGlow = new EdgeEffectCompat(getContext()); mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } mRightGlow.onPull(overscrollX / (float) getWidth()); } if (overscrollY < 0) { if (mTopGlow == null) { mTopGlow = new EdgeEffectCompat(getContext()); mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } mTopGlow.onPull(-overscrollY / (float) getHeight()); } else if (overscrollY > 0) { if (mBottomGlow == null) { mBottomGlow = new EdgeEffectCompat(getContext()); mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } mBottomGlow.onPull(overscrollY / (float) getHeight()); } if (overscrollX != 0 || overscrollY != 0) { ViewCompat.postInvalidateOnAnimation(this); } } private void releaseGlows() { boolean needsInvalidate = false; if (mLeftGlow != null) needsInvalidate = mLeftGlow.onRelease(); if (mTopGlow != null) needsInvalidate |= mTopGlow.onRelease(); if (mRightGlow != null) needsInvalidate |= mRightGlow.onRelease(); if (mBottomGlow != null) needsInvalidate |= mBottomGlow.onRelease(); if (needsInvalidate) { ViewCompat.postInvalidateOnAnimation(this); } } void absorbGlows(int velocityX, int velocityY) { if (velocityX < 0) { if (mLeftGlow == null) { mLeftGlow = new EdgeEffectCompat(getContext()); mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } mLeftGlow.onAbsorb(-velocityX); } else if (velocityX > 0) { if (mRightGlow == null) { mRightGlow = new EdgeEffectCompat(getContext()); mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), getMeasuredWidth() - getPaddingLeft() - getPaddingRight()); } mRightGlow.onAbsorb(velocityX); } if (velocityY < 0) { if (mTopGlow == null) { mTopGlow = new EdgeEffectCompat(getContext()); mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } mTopGlow.onAbsorb(-velocityY); } else if (velocityY > 0) { if (mBottomGlow == null) { mBottomGlow = new EdgeEffectCompat(getContext()); mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), getMeasuredHeight() - getPaddingTop() - getPaddingBottom()); } mBottomGlow.onAbsorb(velocityY); } if (velocityX != 0 || velocityY != 0) { ViewCompat.postInvalidateOnAnimation(this); } } // Focus handling @Override public View focusSearch(View focused, int direction) { View result = mLayout.onInterceptFocusSearch(focused, direction); if (result != null) { return result; } final FocusFinder ff = FocusFinder.getInstance(); result = ff.findNextFocus(this, focused, direction); if (result == null && mAdapter != null) { eatRequestLayout(); result = mLayout.onFocusSearchFailed(focused, direction, mRecycler, mState); resumeRequestLayout(false); } return result != null ? result : super.focusSearch(focused, direction); } @Override public void requestChildFocus(View child, View focused) { if (!mLayout.onRequestChildFocus(this, child, focused)) { mTempRect.set(0, 0, focused.getWidth(), focused.getHeight()); offsetDescendantRectToMyCoords(focused, mTempRect); offsetRectIntoDescendantCoords(child, mTempRect); requestChildRectangleOnScreen(child, mTempRect, !mFirstLayoutComplete); } super.requestChildFocus(child, focused); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) { return mLayout.requestChildRectangleOnScreen(this, child, rect, immediate); } @Override public void addFocusables(ArrayList views, int direction, int focusableMode) { if (!mLayout.onAddFocusables(this, views, direction, focusableMode)) { super.addFocusables(views, direction, focusableMode); } } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); mIsAttached = true; mFirstLayoutComplete = false; if (mLayout != null) { mLayout.onAttachedToWindow(this); } mPostedAnimatorRunner = false; } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mFirstLayoutComplete = false; stopScroll(); // TODO Mark what our target position was if relevant, then we can jump there // on reattach. mIsAttached = false; if (mLayout != null) { mLayout.onDetachedFromWindow(this); } removeCallbacks(mItemAnimatorRunner); } /** * Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched * to child views or this view's standard scrolling behavior. * *

Client code may use listeners to implement item manipulation behavior. Once a listener * returns true from * {@link OnItemTouchListener#onInterceptTouchEvent(RecyclerView, MotionEvent)} its * {@link OnItemTouchListener#onTouchEvent(RecyclerView, MotionEvent)} method will be called * for each incoming MotionEvent until the end of the gesture.

* * @param listener Listener to add */ public void addOnItemTouchListener(OnItemTouchListener listener) { mOnItemTouchListeners.add(listener); } /** * Remove an {@link OnItemTouchListener}. It will no longer be able to intercept touch events. * * @param listener Listener to remove */ public void removeOnItemTouchListener(OnItemTouchListener listener) { mOnItemTouchListeners.remove(listener); if (mActiveOnItemTouchListener == listener) { mActiveOnItemTouchListener = null; } } private boolean dispatchOnItemTouchIntercept(MotionEvent e) { final int action = e.getAction(); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_DOWN) { mActiveOnItemTouchListener = null; } final int listenerCount = mOnItemTouchListeners.size(); for (int i = 0; i < listenerCount; i++) { final OnItemTouchListener listener = mOnItemTouchListeners.get(i); if (listener.onInterceptTouchEvent(this, e) && action != MotionEvent.ACTION_CANCEL) { mActiveOnItemTouchListener = listener; return true; } } return false; } private boolean dispatchOnItemTouch(MotionEvent e) { final int action = e.getAction(); if (mActiveOnItemTouchListener != null) { if (action == MotionEvent.ACTION_DOWN) { // Stale state from a previous gesture, we're starting a new one. Clear it. mActiveOnItemTouchListener = null; } else { mActiveOnItemTouchListener.onTouchEvent(this, e); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { // Clean up for the next gesture. mActiveOnItemTouchListener = null; } return true; } } // Listeners will have already received the ACTION_DOWN via dispatchOnItemTouchIntercept // as called from onInterceptTouchEvent; skip it. if (action != MotionEvent.ACTION_DOWN) { final int listenerCount = mOnItemTouchListeners.size(); for (int i = 0; i < listenerCount; i++) { final OnItemTouchListener listener = mOnItemTouchListeners.get(i); if (listener.onInterceptTouchEvent(this, e)) { mActiveOnItemTouchListener = listener; return true; } } } return false; } @Override public boolean onInterceptTouchEvent(MotionEvent e) { if (dispatchOnItemTouchIntercept(e)) { cancelTouch(); return true; } final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); final boolean canScrollVertically = mLayout.canScrollVertically(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(e); final int action = MotionEventCompat.getActionMasked(e); final int actionIndex = MotionEventCompat.getActionIndex(e); switch (action) { case MotionEvent.ACTION_DOWN: mScrollPointerId = MotionEventCompat.getPointerId(e, 0); mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); if (mScrollState == SCROLL_STATE_SETTLING) { getParent().requestDisallowInterceptTouchEvent(true); setScrollState(SCROLL_STATE_DRAGGING); } break; case MotionEventCompat.ACTION_POINTER_DOWN: mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); break; case MotionEvent.ACTION_MOVE: { final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); if (index < 0) { Log.e(TAG, "Error processing scroll; pointer index for id " + mScrollPointerId + " not found. Did any MotionEvents get skipped?"); return false; } final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); if (mScrollState != SCROLL_STATE_DRAGGING) { final int dx = x - mInitialTouchX; final int dy = y - mInitialTouchY; boolean startScroll = false; if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); startScroll = true; } if (canScrollVertically && Math.abs(dy) > mTouchSlop) { mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); startScroll = true; } if (startScroll) { getParent().requestDisallowInterceptTouchEvent(true); setScrollState(SCROLL_STATE_DRAGGING); } } } break; case MotionEventCompat.ACTION_POINTER_UP: { onPointerUp(e); } break; case MotionEvent.ACTION_UP: { mVelocityTracker.clear(); } break; case MotionEvent.ACTION_CANCEL: { cancelTouch(); } } return mScrollState == SCROLL_STATE_DRAGGING; } @Override public boolean onTouchEvent(MotionEvent e) { if (dispatchOnItemTouch(e)) { cancelTouch(); return true; } final boolean canScrollHorizontally = mLayout.canScrollHorizontally(); final boolean canScrollVertically = mLayout.canScrollVertically(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(e); final int action = MotionEventCompat.getActionMasked(e); final int actionIndex = MotionEventCompat.getActionIndex(e); switch (action) { case MotionEvent.ACTION_DOWN: { mScrollPointerId = MotionEventCompat.getPointerId(e, 0); mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f); mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f); } break; case MotionEventCompat.ACTION_POINTER_DOWN: { mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f); } break; case MotionEvent.ACTION_MOVE: { final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId); if (index < 0) { Log.e(TAG, "Error processing scroll; pointer index for id " + mScrollPointerId + " not found. Did any MotionEvents get skipped?"); return false; } final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f); final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f); if (mScrollState != SCROLL_STATE_DRAGGING) { final int dx = x - mInitialTouchX; final int dy = y - mInitialTouchY; boolean startScroll = false; if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) { mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1); startScroll = true; } if (canScrollVertically && Math.abs(dy) > mTouchSlop) { mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1); startScroll = true; } if (startScroll) { getParent().requestDisallowInterceptTouchEvent(true); setScrollState(SCROLL_STATE_DRAGGING); } } if (mScrollState == SCROLL_STATE_DRAGGING) { final int dx = x - mLastTouchX; final int dy = y - mLastTouchY; scrollByInternal(canScrollHorizontally ? -dx : 0, canScrollVertically ? -dy : 0); } mLastTouchX = x; mLastTouchY = y; } break; case MotionEventCompat.ACTION_POINTER_UP: { onPointerUp(e); } break; case MotionEvent.ACTION_UP: { mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity); final float xvel = canScrollHorizontally ? -VelocityTrackerCompat.getXVelocity(mVelocityTracker, mScrollPointerId) : 0; final float yvel = canScrollVertically ? -VelocityTrackerCompat.getYVelocity(mVelocityTracker, mScrollPointerId) : 0; if (!((xvel != 0 || yvel != 0) && fling((int) xvel, (int) yvel))) { setScrollState(SCROLL_STATE_IDLE); } mVelocityTracker.clear(); releaseGlows(); } break; case MotionEvent.ACTION_CANCEL: { cancelTouch(); } break; } return true; } private void cancelTouch() { mVelocityTracker.clear(); releaseGlows(); setScrollState(SCROLL_STATE_IDLE); } private void onPointerUp(MotionEvent e) { final int actionIndex = MotionEventCompat.getActionIndex(e); if (MotionEventCompat.getPointerId(e, actionIndex) == mScrollPointerId) { // Pick a new pointer to pick up the slack. final int newIndex = actionIndex == 0 ? 1 : 0; mScrollPointerId = MotionEventCompat.getPointerId(e, newIndex); mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, newIndex) + 0.5f); mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, newIndex) + 0.5f); } } @Override protected void onMeasure(int widthSpec, int heightSpec) { if (mAdapterUpdateDuringMeasure) { eatRequestLayout(); updateChildViews(); mAdapterUpdateDuringMeasure = false; resumeRequestLayout(false); } if (mAdapter != null) { mState.mItemCount = mAdapter.getItemCount(); } mLayout.onMeasure(mRecycler, mState, widthSpec, heightSpec); final int widthSize = getMeasuredWidth(); final int heightSize = getMeasuredHeight(); if (mLeftGlow != null) mLeftGlow.setSize(heightSize, widthSize); if (mTopGlow != null) mTopGlow.setSize(widthSize, heightSize); if (mRightGlow != null) mRightGlow.setSize(heightSize, widthSize); if (mBottomGlow != null) mBottomGlow.setSize(widthSize, heightSize); } /** * Sets the {@link ItemAnimator} that will handle animations involving changes * to the items in this RecyclerView. By default, RecyclerView instantiates and * uses an instance of {@link DefaultItemAnimator}. Whether item animations are * enabled for the RecyclerView depends on the ItemAnimator and whether * the LayoutManager {@link LayoutManager#supportsPredictiveItemAnimations() * supports item animations}. * * @param animator The ItemAnimator being set. If null, no animations will occur * when changes occur to the items in this RecyclerView. */ public void setItemAnimator(ItemAnimator animator) { if (mItemAnimator != null) { mItemAnimator.setListener(null); } mItemAnimator = animator; if (mItemAnimator != null) { mItemAnimator.setListener(mItemAnimatorListener); } } /** * Gets the current ItemAnimator for this RecyclerView. A null return value * indicates that there is no animator and that item changes will happen without * any animations. By default, RecyclerView instantiates and * uses an instance of {@link DefaultItemAnimator}. * * @return ItemAnimator The current ItemAnimator. If null, no animations will occur * when changes occur to the items in this RecyclerView. */ public ItemAnimator getItemAnimator() { return mItemAnimator; } /** * Post a runnable to the next frame to run pending item animations. Only the first such * request will be posted, governed by the mPostedAnimatorRunner flag. */ private void postAnimationRunner() { if (!mPostedAnimatorRunner && mIsAttached) { ViewCompat.postOnAnimation(this, mItemAnimatorRunner); mPostedAnimatorRunner = true; } } private boolean predictiveItemAnimationsEnabled() { return (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations()); } /** * Wrapper around layoutChildren() that handles animating changes caused by layout. * Animations work on the assumption that there are five different kinds of items * in play: * PERSISTENT: items are visible before and after layout * REMOVED: items were visible before layout and were removed by the app * ADDED: items did not exist before layout and were added by the app * DISAPPEARING: items exist in the data set before/after, but changed from * visible to non-visible in the process of layout (they were moved off * screen as a side-effect of other changes) * APPEARING: items exist in the data set before/after, but changed from * non-visible to visible in the process of layout (they were moved on * screen as a side-effect of other changes) * The overall approach figures out what items exist before/after layout and * infers one of the five above states for each of the items. Then the animations * are set up accordingly: * PERSISTENT views are moved ({@link ItemAnimator#animateMove(ViewHolder, int, int, int, int)}) * REMOVED views are removed ({@link ItemAnimator#animateRemove(ViewHolder)}) * ADDED views are added ({@link ItemAnimator#animateAdd(ViewHolder)}) * DISAPPEARING views are moved off screen * APPEARING views are moved on screen */ void dispatchLayout() { if (mAdapter == null) { Log.e(TAG, "No adapter attached; skipping layout"); return; } eatRequestLayout(); // simple animations are a subset of advanced animations (which will cause a // prelayout step) boolean animateChangesSimple = mItemAnimator != null && mItemsAddedOrRemoved && !mItemsChanged; final boolean animateChangesAdvanced = ENABLE_PREDICTIVE_ANIMATIONS && animateChangesSimple && predictiveItemAnimationsEnabled(); mItemsAddedOrRemoved = mItemsChanged = false; ArrayMap appearingViewInitialBounds = null; mState.mInPreLayout = animateChangesAdvanced; mState.mItemCount = mAdapter.getItemCount(); if (animateChangesSimple) { // Step 0: Find out where all non-removed items are, pre-layout mState.mPreLayoutHolderMap.clear(); mState.mPostLayoutHolderMap.clear(); int count = getChildCount(); for (int i = 0; i < count; ++i) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); final View view = holder.itemView; mState.mPreLayoutHolderMap.put(holder, new ItemHolderInfo(holder, view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), holder.mPosition)); } } if (animateChangesAdvanced) { // Step 1: run prelayout: This will use the old positions of items. The layout manager // is expected to layout everything, even removed items (though not to add removed // items back to the container). This gives the pre-layout position of APPEARING views // which come into existence as part of the real layout. mInPreLayout = true; final boolean didStructureChange = mState.mStructureChanged; mState.mStructureChanged = false; // temporarily disable flag because we are asking for previous layout mLayout.onLayoutChildren(mRecycler, mState); mState.mStructureChanged = didStructureChange; mInPreLayout = false; appearingViewInitialBounds = new ArrayMap(); for (int i = 0; i < getChildCount(); ++i) { boolean found = false; View child = getChildAt(i); for (int j = 0; j < mState.mPreLayoutHolderMap.size(); ++j) { ViewHolder holder = mState.mPreLayoutHolderMap.keyAt(j); if (holder.itemView == child) { found = true; continue; } } if (!found) { appearingViewInitialBounds.put(child, new Rect(child.getLeft(), child.getTop(), child.getRight(), child.getBottom())); } } } clearOldPositions(); dispatchLayoutUpdates(); mState.mItemCount = mAdapter.getItemCount(); // Step 2: Run layout mState.mInPreLayout = false; mLayout.onLayoutChildren(mRecycler, mState); mState.mStructureChanged = false; mPendingSavedState = null; // onLayoutChildren may have caused client code to disable item animations; re-check animateChangesSimple = animateChangesSimple && mItemAnimator != null; if (animateChangesSimple) { // Step 3: Find out where things are now, post-layout int count = getChildCount(); for (int i = 0; i < count; ++i) { ViewHolder holder = getChildViewHolderInt(getChildAt(i)); final View view = holder.itemView; mState.mPostLayoutHolderMap.put(holder, new ItemHolderInfo(holder, view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), holder.mPosition)); } // Step 4: Animate DISAPPEARING and REMOVED items int preLayoutCount = mState.mPreLayoutHolderMap.size(); for (int i = preLayoutCount - 1; i >= 0; i--) { ViewHolder itemHolder = mState.mPreLayoutHolderMap.keyAt(i); if (!mState.mPostLayoutHolderMap.containsKey(itemHolder)) { ItemHolderInfo disappearingItem = mState.mPreLayoutHolderMap.valueAt(i); mState.mPreLayoutHolderMap.removeAt(i); View disappearingItemView = disappearingItem.holder.itemView; removeDetachedView(disappearingItemView, false); mRecycler.unscrapView(disappearingItem.holder); animateDisappearance(disappearingItem); } } // Step 5: Animate APPEARING and ADDED items int postLayoutCount = mState.mPostLayoutHolderMap.size(); if (postLayoutCount > 0) { for (int i = postLayoutCount - 1; i >= 0; i--) { ViewHolder itemHolder = mState.mPostLayoutHolderMap.keyAt(i); ItemHolderInfo info = mState.mPostLayoutHolderMap.valueAt(i); if ((mState.mPreLayoutHolderMap.isEmpty() || !mState.mPreLayoutHolderMap.containsKey(itemHolder))) { mState.mPostLayoutHolderMap.removeAt(i); Rect initialBounds = (appearingViewInitialBounds != null) ? appearingViewInitialBounds.get(itemHolder.itemView) : null; animateAppearance(itemHolder, initialBounds, info.left, info.top); } } } // Step 6: Animate PERSISTENT items count = mState.mPostLayoutHolderMap.size(); for (int i = 0; i < count; ++i) { ViewHolder postHolder = mState.mPostLayoutHolderMap.keyAt(i); ItemHolderInfo postInfo = mState.mPostLayoutHolderMap.valueAt(i); ItemHolderInfo preInfo = mState.mPreLayoutHolderMap.get(postHolder); if (preInfo != null && postInfo != null) { if (preInfo.left != postInfo.left || preInfo.top != postInfo.top) { postHolder.setIsRecyclable(false); if (DEBUG) { Log.d(TAG, "PERSISTENT: " + postHolder + " with view " + postHolder.itemView); } if (mItemAnimator.animateMove(postHolder, preInfo.left, preInfo.top, postInfo.left, postInfo.top)) { postAnimationRunner(); } } } } } resumeRequestLayout(false); mLayout.removeAndRecycleScrapInt(mRecycler, !animateChangesAdvanced); mState.mPreviousLayoutItemCount = mState.mItemCount; mState.mDeletedInvisibleItemCountSincePreviousLayout = 0; } private void animateAppearance(ViewHolder itemHolder, Rect beforeBounds, int afterLeft, int afterTop) { View newItemView = itemHolder.itemView; if (beforeBounds != null && (beforeBounds.left != afterLeft || beforeBounds.top != afterTop)) { // slide items in if before/after locations differ itemHolder.setIsRecyclable(false); if (DEBUG) { Log.d(TAG, "APPEARING: " + itemHolder + " with view " + newItemView); } if (mItemAnimator.animateMove(itemHolder, beforeBounds.left, beforeBounds.top, afterLeft, afterTop)) { postAnimationRunner(); } } else { if (DEBUG) { Log.d(TAG, "ADDED: " + itemHolder + " with view " + newItemView); } itemHolder.setIsRecyclable(false); if (mItemAnimator.animateAdd(itemHolder)) { postAnimationRunner(); } } } private void animateDisappearance(ItemHolderInfo disappearingItem) { View disappearingItemView = disappearingItem.holder.itemView; addAnimatingView(disappearingItemView); int oldLeft = disappearingItem.left; int oldTop = disappearingItem.top; int newLeft = disappearingItemView.getLeft(); int newTop = disappearingItemView.getTop(); if (oldLeft != newLeft || oldTop != newTop) { disappearingItem.holder.setIsRecyclable(false); disappearingItemView.layout(newLeft, newTop, newLeft + disappearingItemView.getWidth(), newTop + disappearingItemView.getHeight()); if (DEBUG) { Log.d(TAG, "DISAPPEARING: " + disappearingItem.holder + " with view " + disappearingItemView); } if (mItemAnimator.animateMove(disappearingItem.holder, oldLeft, oldTop, newLeft, newTop)) { postAnimationRunner(); } } else { if (DEBUG) { Log.d(TAG, "REMOVED: " + disappearingItem.holder + " with view " + disappearingItemView); } disappearingItem.holder.setIsRecyclable(false); if (mItemAnimator.animateRemove(disappearingItem.holder)) { postAnimationRunner(); } } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { eatRequestLayout(); dispatchLayout(); resumeRequestLayout(false); mFirstLayoutComplete = true; } @Override public void requestLayout() { if (!mEatRequestLayout) { super.requestLayout(); } else { mLayoutRequestEaten = true; } } void markItemDecorInsetsDirty() { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final View child = getChildAt(i); ((LayoutParams) child.getLayoutParams()).mInsetsDirty = true; } } @Override public void draw(Canvas c) { super.draw(c); final int count = mItemDecorations.size(); for (int i = 0; i < count; i++) { mItemDecorations.get(i).onDrawOver(c, this); } boolean needsInvalidate = false; if (mLeftGlow != null && !mLeftGlow.isFinished()) { final int restore = c.save(); c.rotate(270); c.translate(-getHeight() + getPaddingTop(), 0); needsInvalidate = mLeftGlow != null && mLeftGlow.draw(c); c.restoreToCount(restore); } if (mTopGlow != null && !mTopGlow.isFinished()) { c.translate(getPaddingLeft(), getPaddingTop()); needsInvalidate |= mTopGlow != null && mTopGlow.draw(c); } if (mRightGlow != null && !mRightGlow.isFinished()) { final int restore = c.save(); final int width = getWidth(); c.rotate(90); c.translate(-getPaddingTop(), -width); needsInvalidate |= mRightGlow != null && mRightGlow.draw(c); c.restoreToCount(restore); } if (mBottomGlow != null && !mBottomGlow.isFinished()) { final int restore = c.save(); c.rotate(180); c.translate(-getWidth() + getPaddingLeft(), -getHeight() + getPaddingTop()); needsInvalidate |= mBottomGlow != null && mBottomGlow.draw(c); c.restoreToCount(restore); } if (needsInvalidate) { ViewCompat.postInvalidateOnAnimation(this); } } @Override public void onDraw(Canvas c) { super.onDraw(c); final int count = mItemDecorations.size(); for (int i = 0; i < count; i++) { mItemDecorations.get(i).onDraw(c, this); } } @Override protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { return p instanceof LayoutParams && mLayout.checkLayoutParams((LayoutParams) p); } @Override protected ViewGroup.LayoutParams generateDefaultLayoutParams() { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateDefaultLayoutParams(); } @Override public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateLayoutParams(getContext(), attrs); } @Override protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { if (mLayout == null) { throw new IllegalStateException("RecyclerView has no LayoutManager"); } return mLayout.generateLayoutParams(p); } private int findPositionOffset(int position) { int offset = 0; int count = mPendingLayoutUpdates.size(); for (int i = 0; i < count; ++i) { UpdateOp op = mPendingLayoutUpdates.get(i); if (op.positionStart <= position) { if (op.cmd == UpdateOp.REMOVE) { offset -= op.itemCount; } else if (op.cmd == UpdateOp.ADD) { offset += op.itemCount; } } } return position + offset; } void dispatchLayoutUpdates() { final int opCount = mPendingLayoutUpdates.size(); for (int i = 0; i < opCount; i++) { final UpdateOp op = mPendingLayoutUpdates.get(i); switch (op.cmd) { case UpdateOp.ADD: mLayout.onItemsAdded(this, op.positionStart, op.itemCount); break; case UpdateOp.REMOVE: mLayout.onItemsRemoved(this, op.positionStart, op.itemCount); break; case UpdateOp.UPDATE: // TODO: tell the layout manager break; } recycleUpdateOp(op); } mPendingLayoutUpdates.clear(); } void updateChildViews() { final int opCount = mPendingUpdates.size(); for (int i = 0; i < opCount; i++) { final UpdateOp op = mPendingUpdates.get(i); switch (op.cmd) { case UpdateOp.ADD: if (DEBUG) { Log.d(TAG, "UpdateOp.ADD start=" + op.positionStart + " count=" + op.itemCount); } offsetPositionRecordsForInsert(op.positionStart, op.itemCount); mItemsAddedOrRemoved = true; break; case UpdateOp.REMOVE: if (DEBUG) { Log.d(TAG, "UpdateOp.REMOVE start=" + op.positionStart + " count=" + op.itemCount); } for (int j = 0; j < op.itemCount; ++j) { ViewHolder holder = findViewHolderForPosition(op.positionStart + j, true); if (holder != null) { holder.setIsRecyclable(false); } else { mState.mDeletedInvisibleItemCountSincePreviousLayout ++; } } offsetPositionRecordsForRemove(op.positionStart, op.itemCount); mItemsAddedOrRemoved = true; break; case UpdateOp.UPDATE: if (DEBUG) { Log.d(TAG, "UpdateOp.UPDATE start=" + op.positionStart + " count=" + op.itemCount); } viewRangeUpdate(op.positionStart, op.itemCount); mItemsChanged = true; break; } mPendingLayoutUpdates.add(op); // TODO: recycle the op if no animator (also don't bother stashing in pending layout updates?) } mPendingUpdates.clear(); } void clearOldPositions() { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); holder.clearOldPosition(); } mRecycler.clearOldPositions(); } void offsetPositionRecordsForInsert(int positionStart, int itemCount) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder != null && holder.mPosition >= positionStart) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForInsert attached child " + i + " holder " + holder + " now at position " + (holder.mPosition + itemCount)); } holder.offsetPosition(itemCount); mState.mStructureChanged = true; } } mRecycler.offsetPositionRecordsForInsert(positionStart, itemCount); requestLayout(); } void offsetPositionRecordsForRemove(int positionStart, int itemCount) { final int positionEnd = positionStart + itemCount; final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder != null) { if (holder.mPosition >= positionEnd) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i + " holder " + holder + " now at position " + (holder.mPosition - itemCount)); } holder.offsetPosition(-itemCount); mState.mStructureChanged = true; } else if (holder.mPosition >= positionStart) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i + " holder " + holder + " now REMOVED"); } holder.addFlags(ViewHolder.FLAG_REMOVED); mState.mStructureChanged = true; } } } mRecycler.offsetPositionRecordsForRemove(positionStart, itemCount); requestLayout(); } /** * Rebind existing views for the given range, or create as needed. * * @param positionStart Adapter position to start at * @param itemCount Number of views that must explicitly be rebound */ void viewRangeUpdate(int positionStart, int itemCount) { final int childCount = getChildCount(); final int positionEnd = positionStart + itemCount; for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder == null) { continue; } final int position = holder.getPosition(); if (position >= positionStart && position < positionEnd) { holder.addFlags(ViewHolder.FLAG_UPDATE); // Binding an attached view will request a layout if needed. mAdapter.bindViewHolder(holder, holder.getPosition()); } } mRecycler.viewRangeUpdate(positionStart, itemCount); } /** * Mark all known views as invalid. Used in response to a, "the whole world might have changed" * data change event. */ void markKnownViewsInvalid() { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder != null) { holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID); } } mRecycler.markKnownViewsInvalid(); } /** * Schedule an update of data from the adapter to occur on the next frame. * On newer platform versions this happens via the postOnAnimation mechanism and RecyclerView * attempts to avoid relayouts if possible. * On older platform versions the RecyclerView requests a layout the same way ListView does. */ void postAdapterUpdate(UpdateOp op) { mPendingUpdates.add(op); if (mPendingUpdates.size() == 1) { if (mPostUpdatesOnAnimation && mHasFixedSize && mIsAttached) { ViewCompat.postOnAnimation(this, mUpdateChildViewsRunnable); } else { mAdapterUpdateDuringMeasure = true; requestLayout(); } } } /** * Retrieve the {@link ViewHolder} for the given child view. * * @param child Child of this RecyclerView to query for its ViewHolder * @return The child view's ViewHolder */ public ViewHolder getChildViewHolder(View child) { final ViewParent parent = child.getParent(); if (parent != null && parent != this) { throw new IllegalArgumentException("View " + child + " is not a direct child of " + this); } return getChildViewHolderInt(child); } static ViewHolder getChildViewHolderInt(View child) { if (child == null) { return null; } return ((LayoutParams) child.getLayoutParams()).mViewHolder; } /** * Return the adapter position that the given child view corresponds to. * * @param child Child View to query * @return Adapter position corresponding to the given view or {@link #NO_POSITION} */ public int getChildPosition(View child) { final ViewHolder holder = getChildViewHolderInt(child); return holder != null ? holder.getPosition() : NO_POSITION; } /** * Return the stable item id that the given child view corresponds to. * * @param child Child View to query * @return Item id corresponding to the given view or {@link #NO_ID} */ public long getChildItemId(View child) { if (mAdapter == null || !mAdapter.hasStableIds()) { return NO_ID; } final ViewHolder holder = getChildViewHolderInt(child); return holder != null ? holder.getItemId() : NO_ID; } /** * Return the ViewHolder for the item in the given position of the data set. * * @param position The position of the item in the data set of the adapter * @return The ViewHolder at position */ public ViewHolder findViewHolderForPosition(int position) { return findViewHolderForPosition(position, false); } ViewHolder findViewHolderForPosition(int position, boolean checkNewPosition) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder != null) { if (checkNewPosition) { if (holder.mPosition == position) { return holder; } } else if(holder.getPosition() == position) { return holder; } } } return mRecycler.findViewHolderForPosition(position); } /** * Return the ViewHolder for the item with the given id. The RecyclerView must * use an Adapter with {@link Adapter#setHasStableIds(boolean) stableIds} to * return a non-null value. * * @param id The id for the requested item * @return The ViewHolder with the given id, of null if there * is no such item. */ public ViewHolder findViewHolderForItemId(long id) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final ViewHolder holder = getChildViewHolderInt(getChildAt(i)); if (holder != null && holder.getItemId() == id) { return holder; } } return mRecycler.findViewHolderForItemId(id); } /** * Find the topmost view under the given point. * * @param x Horizontal position in pixels to search * @param y Vertical position in pixels to search * @return The child view under (x, y) or null if no matching child is found */ public View findChildViewUnder(float x, float y) { final int count = getChildCount(); for (int i = count - 1; i >= 0; i--) { final View child = getChildAt(i); final float translationX = ViewCompat.getTranslationX(child); final float translationY = ViewCompat.getTranslationY(child); if (x >= child.getLeft() + translationX && x <= child.getRight() + translationX && y >= child.getTop() + translationY && y <= child.getBottom() + translationY) { return child; } } return null; } /** * Offset the bounds of all child views by dy pixels. * Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}. * * @param dy Vertical pixel offset to apply to the bounds of all child views */ public void offsetChildrenVertical(int dy) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { getChildAt(i).offsetTopAndBottom(dy); } } /** * Called when an item view is attached to this RecyclerView. * *

Subclasses of RecyclerView may want to perform extra bookkeeping or modifications * of child views as they become attached. This will be called before a * {@link LayoutManager} measures or lays out the view and is a good time to perform these * changes.

* * @param child Child view that is now attached to this RecyclerView and its associated window */ public void onChildAttachedToWindow(View child) { } /** * Called when an item view is detached from this RecyclerView. * *

Subclasses of RecyclerView may want to perform extra bookkeeping or modifications * of child views as they become detached. This will be called as a * {@link LayoutManager} fully detaches the child view from the parent and its window.

* * @param child Child view that is now detached from this RecyclerView and its associated window */ public void onChildDetachedFromWindow(View child) { } /** * Offset the bounds of all child views by dx pixels. * Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}. * * @param dx Horizontal pixel offset to apply to the bounds of all child views */ public void offsetChildrenHorizontal(int dx) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { getChildAt(i).offsetLeftAndRight(dx); } } Rect getItemDecorInsetsForChild(View child) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); if (!lp.mInsetsDirty) { return lp.mDecorInsets; } final Rect insets = lp.mDecorInsets; insets.set(0, 0, 0, 0); final int decorCount = mItemDecorations.size(); for (int i = 0; i < decorCount; i++) { mTempRect.set(0, 0, 0, 0); mItemDecorations.get(i).getItemOffsets(mTempRect, lp.getViewPosition(), this); insets.left += mTempRect.left; insets.top += mTempRect.top; insets.right += mTempRect.right; insets.bottom += mTempRect.bottom; } lp.mInsetsDirty = false; return insets; } private class ViewFlinger implements Runnable { private int mLastFlingX; private int mLastFlingY; private ScrollerCompat mScroller; private Interpolator mInterpolator = sQuinticInterpolator; // When set to true, postOnAnimation callbacks are delayed until the run method completes private boolean mEatRunOnAnimationRequest = false; // Tracks if postAnimationCallback should be re-attached when it is done private boolean mReSchedulePostAnimationCallback = false; public ViewFlinger() { mScroller = ScrollerCompat.create(getContext(), sQuinticInterpolator); } @Override public void run() { disableRunOnAnimationRequests(); consumePendingUpdateOperations(); // keep a local reference so that if it is changed during onAnimation method, it wont cause // unexpected behaviors final ScrollerCompat scroller = mScroller; final SmoothScroller smoothScroller = mLayout.mSmoothScroller; if (scroller.computeScrollOffset()) { final int x = scroller.getCurrX(); final int y = scroller.getCurrY(); final int dx = x - mLastFlingX; final int dy = y - mLastFlingY; mLastFlingX = x; mLastFlingY = y; int overscrollX = 0, overscrollY = 0; if (mAdapter != null) { eatRequestLayout(); if (dx != 0) { final int hresult = mLayout.scrollHorizontallyBy(dx, mRecycler, mState); overscrollX = dx - hresult; } if (dy != 0) { final int vresult = mLayout.scrollVerticallyBy(dy, mRecycler, mState); overscrollY = dy - vresult; } if (smoothScroller != null && !smoothScroller.isPendingInitialRun() && smoothScroller.isRunning()) { smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY); } resumeRequestLayout(false); } if (!mItemDecorations.isEmpty()) { invalidate(); } if (overscrollX != 0 || overscrollY != 0) { final int vel = (int) scroller.getCurrVelocity(); int velX = 0; if (overscrollX != x) { velX = overscrollX < 0 ? -vel : overscrollX > 0 ? vel : 0; } int velY = 0; if (overscrollY != y) { velY = overscrollY < 0 ? -vel : overscrollY > 0 ? vel : 0; } if (ViewCompat.getOverScrollMode(RecyclerView.this) != ViewCompat.OVER_SCROLL_NEVER) { absorbGlows(velX, velY); } if ((velX != 0 || overscrollX == x || scroller.getFinalX() == 0) && (velY != 0 || overscrollY == y || scroller.getFinalY() == 0)) { scroller.abortAnimation(); } } if (mScrollListener != null && (x != 0 || y != 0)) { mScrollListener.onScrolled(dx, dy); } if (!awakenScrollBars()) { invalidate(); } if (scroller.isFinished()) { setScrollState(SCROLL_STATE_IDLE); } else { postOnAnimation(); } } // call this after the onAnimation is complete not to have inconsistent callbacks etc. if (smoothScroller != null && smoothScroller.isPendingInitialRun()) { smoothScroller.onAnimation(0, 0); } enableRunOnAnimationRequests(); } private void disableRunOnAnimationRequests() { mReSchedulePostAnimationCallback = false; mEatRunOnAnimationRequest = true; } private void enableRunOnAnimationRequests() { mEatRunOnAnimationRequest = false; if (mReSchedulePostAnimationCallback) { postOnAnimation(); } } void postOnAnimation() { if (mEatRunOnAnimationRequest) { mReSchedulePostAnimationCallback = true; } else { ViewCompat.postOnAnimation(RecyclerView.this, this); } } public void fling(int velocityX, int velocityY) { setScrollState(SCROLL_STATE_SETTLING); mLastFlingX = mLastFlingY = 0; mScroller.fling(0, 0, velocityX, velocityY, Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE); postOnAnimation(); } public void smoothScrollBy(int dx, int dy) { smoothScrollBy(dx, dy, 0, 0); } public void smoothScrollBy(int dx, int dy, int vx, int vy) { smoothScrollBy(dx, dy, computeScrollDuration(dx, dy, vx, vy)); } private float distanceInfluenceForSnapDuration(float f) { f -= 0.5f; // center the values about 0. f *= 0.3f * Math.PI / 2.0f; return (float) Math.sin(f); } private int computeScrollDuration(int dx, int dy, int vx, int vy) { final int absDx = Math.abs(dx); final int absDy = Math.abs(dy); final boolean horizontal = absDx > absDy; final int velocity = (int) Math.sqrt(vx * vx + vy * vy); final int delta = (int) Math.sqrt(dx * dx + dy * dy); final int containerSize = horizontal ? getWidth() : getHeight(); final int halfContainerSize = containerSize / 2; final float distanceRatio = Math.min(1.f, 1.f * delta / containerSize); final float distance = halfContainerSize + halfContainerSize * distanceInfluenceForSnapDuration(distanceRatio); final int duration; if (velocity > 0) { duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); } else { float absDelta = (float) (horizontal ? absDx : absDy); duration = (int) (((absDelta / containerSize) + 1) * 300); } return Math.min(duration, MAX_SCROLL_DURATION); } public void smoothScrollBy(int dx, int dy, int duration) { smoothScrollBy(dx, dy, duration, sQuinticInterpolator); } public void smoothScrollBy(int dx, int dy, int duration, Interpolator interpolator) { if (mInterpolator != interpolator) { mInterpolator = interpolator; mScroller = ScrollerCompat.create(getContext(), interpolator); } setScrollState(SCROLL_STATE_SETTLING); mLastFlingX = mLastFlingY = 0; mScroller.startScroll(0, 0, dx, dy, duration); postOnAnimation(); } public void stop() { removeCallbacks(this); mScroller.abortAnimation(); } } private class RecyclerViewDataObserver extends AdapterDataObserver { @Override public void onChanged() { if (mAdapter.hasStableIds()) { // TODO Determine what actually changed markKnownViewsInvalid(); mState.mStructureChanged = true; requestLayout(); } else { markKnownViewsInvalid(); mState.mStructureChanged = true; requestLayout(); } } @Override public void onItemRangeChanged(int positionStart, int itemCount) { postAdapterUpdate(obtainUpdateOp(UpdateOp.UPDATE, positionStart, itemCount)); } @Override public void onItemRangeInserted(int positionStart, int itemCount) { postAdapterUpdate(obtainUpdateOp(UpdateOp.ADD, positionStart, itemCount)); } @Override public void onItemRangeRemoved(int positionStart, int itemCount) { postAdapterUpdate(obtainUpdateOp(UpdateOp.REMOVE, positionStart, itemCount)); } } public static class RecycledViewPool { private SparseArray> mScrap = new SparseArray>(); private SparseIntArray mMaxScrap = new SparseIntArray(); private int mAttachCount = 0; private static final int DEFAULT_MAX_SCRAP = 5; public void clear() { mScrap.clear(); } public void setMaxRecycledViews(int viewType, int max) { mMaxScrap.put(viewType, max); final ArrayList scrapHeap = mScrap.get(viewType); if (scrapHeap != null) { while (scrapHeap.size() > max) { scrapHeap.remove(scrapHeap.size() - 1); } } } public ViewHolder getRecycledView(int viewType) { final ArrayList scrapHeap = mScrap.get(viewType); if (scrapHeap != null && !scrapHeap.isEmpty()) { final int index = scrapHeap.size() - 1; final ViewHolder scrap = scrapHeap.get(index); scrapHeap.remove(index); return scrap; } return null; } public void putRecycledView(ViewHolder scrap) { final int viewType = scrap.getItemViewType(); final ArrayList scrapHeap = getScrapHeapForType(viewType); if (mMaxScrap.get(viewType) <= scrapHeap.size()) { return; } scrap.mPosition = NO_POSITION; scrap.mOldPosition = NO_POSITION; scrap.mItemId = NO_ID; scrap.clearFlagsForSharedPool(); scrapHeap.add(scrap); } void attach(Adapter adapter) { mAttachCount++; } void detach() { mAttachCount--; } void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) { if (mAttachCount == 1) { clear(); } } private ArrayList getScrapHeapForType(int viewType) { ArrayList scrap = mScrap.get(viewType); if (scrap == null) { scrap = new ArrayList(); mScrap.put(viewType, scrap); if (mMaxScrap.indexOfKey(viewType) < 0) { mMaxScrap.put(viewType, DEFAULT_MAX_SCRAP); } } return scrap; } } /** * A Recycler is responsible for managing scrapped or detached item views for reuse. * *

A "scrapped" view is a view that is still attached to its parent RecyclerView but * that has been marked for removal or reuse.

* *

Typical use of a Recycler by a {@link LayoutManager} will be to obtain views for * an adapter's data set representing the data at a given position or item ID. * If the view to be reused is considered "dirty" the adapter will be asked to rebind it. * If not, the view can be quickly reused by the LayoutManager with no further work. * Clean views that have not {@link android.view.View#isLayoutRequested() requested layout} * may be repositioned by a LayoutManager without remeasurement.

*/ public final class Recycler { private final ArrayList mAttachedScrap = new ArrayList(); private final ArrayList mCachedViews = new ArrayList(); private final List mUnmodifiableAttachedScrap = Collections.unmodifiableList(mAttachedScrap); private int mViewCacheMax = DEFAULT_CACHE_SIZE; private RecycledViewPool mRecyclerPool; private static final int DEFAULT_CACHE_SIZE = 2; /** * Clear scrap views out of this recycler. Detached views contained within a * recycled view pool will remain. */ public void clear() { mAttachedScrap.clear(); recycleCachedViews(); } /** * Set the maximum number of detached, valid views we should retain for later use. * * @param viewCount Number of views to keep before sending views to the shared pool */ public void setViewCacheSize(int viewCount) { mViewCacheMax = viewCount; while (mCachedViews.size() > viewCount) { mCachedViews.remove(mCachedViews.size() - 1); } } /** * Returns an unmodifiable list of ViewHolders that are currently in the scrap list. * * @return List of ViewHolders in the scrap list. */ public List getScrapList() { return mUnmodifiableAttachedScrap; } /** * Helper method for getViewForPosition. *

* Checks whether a given view holder can be used for the provided position. * * @param holder ViewHolder * @param offsetPosition The position which is updated by UPDATE_OP changes on the adapter * @return true if ViewHolder matches the provided position, false otherwise */ boolean validateViewHolderForOffsetPosition(ViewHolder holder, int offsetPosition) { // if it is a removed holder, nothing to verify since we cannot ask adapter anymore // if it is not removed, verify the type and id. if (holder.isRemoved()) { return true; } if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) { if (DEBUG) { Log.d(TAG, "validateViewHolderForOffsetPosition: invalid position, returning " + "false"); } return false; } final int type = mAdapter.getItemViewType(offsetPosition); if (type != holder.getItemViewType()) { return false; } if (mAdapter.hasStableIds()) { return holder.getItemId() == mAdapter.getItemId(offsetPosition); } return true; } /** * Obtain a view initialized for the given position. * *

This method should be used by {@link LayoutManager} implementations to obtain * views to represent data from an {@link Adapter}.

* *

The Recycler may reuse a scrap or detached view from a shared pool if one is * available for the correct view type. If the adapter has not indicated that the * data at the given position has changed, the Recycler will attempt to hand back * a scrap view that was previously initialized for that data without rebinding.

* * @param position Position to obtain a view for * @return A view representing the data at position from adapter */ public View getViewForPosition(int position) { ViewHolder holder; holder = getScrapViewForPosition(position, INVALID_TYPE); final int offsetPosition = findPositionOffset(position); if (holder != null) { if (!validateViewHolderForOffsetPosition(holder, offsetPosition)) { // recycle this scrap removeDetachedView(holder.itemView, false); quickRecycleScrapView(holder.itemView); // if validate fails, we can query scrap again w/ type. that may return a // different view holder from cache. final int type = mAdapter.getItemViewType(offsetPosition); if (mAdapter.hasStableIds()) { final long id = mAdapter.getItemId(offsetPosition); holder = getScrapViewForId(id, type); } else { holder = getScrapViewForPosition(offsetPosition, type); } } } else { // try recycler. holder = getRecycledViewPool() .getRecycledView(mAdapter.getItemViewType(offsetPosition)); } if (holder == null) { if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) { throw new IndexOutOfBoundsException("Invalid item position " + position + "(" + offsetPosition + ")"); } else { holder = mAdapter.createViewHolder(RecyclerView.this, mAdapter.getItemViewType(offsetPosition)); if (DEBUG) { Log.d(TAG, "getViewForPosition created new ViewHolder"); } } } if (!holder.isRemoved() && (!holder.isBound() || holder.needsUpdate())) { if (DEBUG) { Log.d(TAG, "getViewForPosition unbound holder or needs update; updating..."); } // TODO: think through when getOffsetPosition() is called. I use it here because // existing views have already been offset appropriately through the mOldOffset // mechanism, but new views do not have this mechanism. mAdapter.bindViewHolder(holder, offsetPosition); } ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams(); if (lp == null) { lp = generateDefaultLayoutParams(); holder.itemView.setLayoutParams(lp); } else if (!checkLayoutParams(lp)) { lp = generateLayoutParams(lp); holder.itemView.setLayoutParams(lp); } ((LayoutParams) lp).mViewHolder = holder; return holder.itemView; } /** * Recycle a detached view. The specified view will be added to a pool of views * for later rebinding and reuse. * *

A view must be fully detached before it may be recycled.

* * @param view Removed view for recycling */ public void recycleView(View view) { recycleViewHolder(getChildViewHolderInt(view)); } void recycleCachedViews() { final int count = mCachedViews.size(); for (int i = count - 1; i >= 0; i--) { final ViewHolder cachedView = mCachedViews.get(i); if (cachedView.isRecyclable()) { getRecycledViewPool().putRecycledView(cachedView); dispatchViewRecycled(cachedView); } mCachedViews.remove(i); } } void recycleViewHolder(ViewHolder holder) { if (holder.isScrap() || holder.itemView.getParent() != null) { throw new IllegalArgumentException( "Scrapped or attached views may not be recycled."); } boolean cached = false; if (!holder.isInvalid() && (mInPreLayout || !holder.isRemoved())) { // Retire oldest cached views first if (mCachedViews.size() == mViewCacheMax && !mCachedViews.isEmpty()) { for (int i = 0; i < mCachedViews.size(); i++) { final ViewHolder cachedView = mCachedViews.get(i); if (cachedView.isRecyclable()) { mCachedViews.remove(i); getRecycledViewPool().putRecycledView(cachedView); dispatchViewRecycled(cachedView); break; } } } if (mCachedViews.size() < mViewCacheMax) { mCachedViews.add(holder); cached = true; } } if (!cached && holder.isRecyclable()) { getRecycledViewPool().putRecycledView(holder); dispatchViewRecycled(holder); } // Remove from pre/post maps that are used to animate items; a recycled holder // should not be animated mState.mPreLayoutHolderMap.remove(holder); mState.mPostLayoutHolderMap.remove(holder); } /** * Used as a fast path for unscrapping and recycling a view during a bulk operation. * The caller must call {@link #clearScrap()} when it's done to update the recycler's * internal bookkeeping. */ void quickRecycleScrapView(View view) { final ViewHolder holder = getChildViewHolderInt(view); holder.mScrapContainer = null; recycleViewHolder(holder); } /** * Mark an attached view as scrap. * *

"Scrap" views are still attached to their parent RecyclerView but are eligible * for rebinding and reuse. Requests for a view for a given position may return a * reused or rebound scrap view instance.

* * @param view View to scrap */ void scrapView(View view) { final ViewHolder holder = getChildViewHolderInt(view); holder.setScrapContainer(this); mAttachedScrap.add(holder); } /** * Remove a previously scrapped view from the pool of eligible scrap. * *

This view will no longer be eligible for reuse until re-scrapped or * until it is explicitly removed and recycled.

*/ void unscrapView(ViewHolder holder) { mAttachedScrap.remove(holder); holder.mScrapContainer = null; } int getScrapCount() { return mAttachedScrap.size(); } View getScrapViewAt(int index) { return mAttachedScrap.get(index).itemView; } void clearScrap() { mAttachedScrap.clear(); } /** * Returns a scrap view for the position. If type is not INVALID_TYPE, it also checks if * ViewHolder's type matches the provided type. * * @param position Item position * @param type View type * @return a ViewHolder that can be re-used for this position. */ ViewHolder getScrapViewForPosition(int position, int type) { final int scrapCount = mAttachedScrap.size(); // Try first for an exact, non-invalid match from scrap. for (int i = 0; i < scrapCount; i++) { final ViewHolder holder = mAttachedScrap.get(i); if (holder.getPosition() == position && !holder.isInvalid() && (mInPreLayout || !holder.isRemoved())) { if (type != INVALID_TYPE && holder.getItemViewType() != type) { Log.e(TAG, "Scrap view for position " + position + " isn't dirty but has" + " wrong view type! (found " + holder.getItemViewType() + " but expected " + type + ")"); break; } mAttachedScrap.remove(i); holder.setScrapContainer(null); if (DEBUG) { Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type + ") found exact match in scrap: " + holder); } return holder; } } if (mNumAnimatingViews != 0) { View view = getAnimatingView(position, type); if (view != null) { // ending the animation should cause it to get recycled before we reuse it mItemAnimator.endAnimation(getChildViewHolder(view)); } } // Search in our first-level recycled view cache. final int cacheSize = mCachedViews.size(); for (int i = 0; i < cacheSize; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder.getPosition() == position) { mCachedViews.remove(i); if (holder.isInvalid() && (type != INVALID_TYPE && holder.getItemViewType() != type)) { // Can't use it. We don't know where it's been. if (DEBUG) { Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type + ") found position match, but holder is invalid with type " + holder.getItemViewType()); } if (holder.isRecyclable()) { getRecycledViewPool().putRecycledView(holder); } // Even if the holder wasn't officially recycleable, dispatch that it // was recycled anyway in case there are resources to unbind. dispatchViewRecycled(holder); // Drop out of the cache search and try something else instead, // we won't find another match here. break; } if (DEBUG) { Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type + ") found match in cache: " + holder); } return holder; } } // Give up. Head to the shared pool. if (DEBUG) { Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type + ") fetching from shared pool"); } return type == INVALID_TYPE ? null : getRecycledViewPool().getRecycledView(type); } ViewHolder getScrapViewForId(long id, int type) { // Look in our attached views first final int count = mAttachedScrap.size(); for (int i = 0; i < count; i++) { final ViewHolder holder = mAttachedScrap.get(i); if (holder.getItemId() == id) { if (type == holder.getItemViewType()) { mAttachedScrap.remove(i); holder.setScrapContainer(null); return holder; } else { break; } } } // Search the first-level cache final int cacheSize = mCachedViews.size(); for (int i = 0; i < cacheSize; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder.getItemId() == id) { mCachedViews.remove(i); return holder; } } // That didn't work, look for an unordered view of the right type instead. // The holder's position won't match so the calling code will need to have // the adapter rebind it. return getRecycledViewPool().getRecycledView(type); } void dispatchViewRecycled(ViewHolder holder) { if (mRecyclerListener != null) { mRecyclerListener.onViewRecycled(holder); } if (mAdapter != null) { mAdapter.onViewRecycled(holder); } if (DEBUG) Log.d(TAG, "dispatchViewRecycled: " + holder); } void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) { clear(); getRecycledViewPool().onAdapterChanged(oldAdapter, newAdapter); } void offsetPositionRecordsForInsert(int insertedAt, int count) { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null && holder.getPosition() >= insertedAt) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForInsert cached " + i + " holder " + holder + " now at position " + (holder.mPosition + count)); } holder.offsetPosition(count); } } } void offsetPositionRecordsForRemove(int removedFrom, int count) { final int removedEnd = removedFrom + count; final int cachedCount = mCachedViews.size(); for (int i = cachedCount - 1; i >= 0; i--) { final ViewHolder holder = mCachedViews.get(i); if (holder != null) { if (holder.getPosition() >= removedEnd) { if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove cached " + i + " holder " + holder + " now at position " + (holder.mPosition - count)); } holder.offsetPosition(-count); } else if (holder.getPosition() >= removedFrom) { // Item for this view was removed. Dump it from the cache. if (DEBUG) { Log.d(TAG, "offsetPositionRecordsForRemove cached " + i + " holder " + holder + " now placed in pool"); } mCachedViews.remove(i); getRecycledViewPool().putRecycledView(holder); dispatchViewRecycled(holder); } } } } void setRecycledViewPool(RecycledViewPool pool) { if (mRecyclerPool != null) { mRecyclerPool.detach(); } mRecyclerPool = pool; if (pool != null) { mRecyclerPool.attach(getAdapter()); } } RecycledViewPool getRecycledViewPool() { if (mRecyclerPool == null) { mRecyclerPool = new RecycledViewPool(); } return mRecyclerPool; } ViewHolder findViewHolderForPosition(int position) { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null && holder.getPosition() == position) { mCachedViews.remove(i); return holder; } } return null; } ViewHolder findViewHolderForItemId(long id) { if (!mAdapter.hasStableIds()) { return null; } final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null && holder.getItemId() == id) { mCachedViews.remove(i); return holder; } } return null; } void viewRangeUpdate(int positionStart, int itemCount) { final int positionEnd = positionStart + itemCount; final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder == null) { continue; } final int pos = holder.getPosition(); if (pos >= positionStart && pos < positionEnd) { holder.addFlags(ViewHolder.FLAG_UPDATE); } } } void markKnownViewsInvalid() { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); if (holder != null) { holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID); } } } void clearOldPositions() { final int cachedCount = mCachedViews.size(); for (int i = 0; i < cachedCount; i++) { final ViewHolder holder = mCachedViews.get(i); holder.clearOldPosition(); } } } /** * Base class for an Adapter * *

Adapters provide a binding from an app-specific data set to views that are displayed * within a {@link RecyclerView}.

*/ public static abstract class Adapter { private final AdapterDataObservable mObservable = new AdapterDataObservable(); private boolean mHasStableIds = false; public abstract VH onCreateViewHolder(ViewGroup parent, int viewType); public abstract void onBindViewHolder(VH holder, int position); public final VH createViewHolder(ViewGroup parent, int viewType) { final VH holder = onCreateViewHolder(parent, viewType); holder.mItemViewType = viewType; return holder; } public final void bindViewHolder(VH holder, int position) { holder.mPosition = position; if (hasStableIds()) { holder.mItemId = getItemId(position); } onBindViewHolder(holder, position); holder.setFlags(ViewHolder.FLAG_BOUND, ViewHolder.FLAG_BOUND | ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID); } /** * Return the view type of the item at position for the purposes * of view recycling. * *

The default implementation of this method returns 0, making the assumption of * a single view type for the adapter. Unlike ListView adapters, types need not * be contiguous. Consider using id resources to uniquely identify item view types. * * @param position position to query * @return integer value identifying the type of the view needed to represent the item at * position. Type codes need not be contiguous. */ public int getItemViewType(int position) { return 0; } public void setHasStableIds(boolean hasStableIds) { if (hasObservers()) { throw new IllegalStateException("Cannot change whether this adapter has " + "stable IDs while the adapter has registered observers."); } mHasStableIds = hasStableIds; } /** * Return the stable ID for the item at position. If {@link #hasStableIds()} * would return false this method should return {@link #NO_ID}. The default implementation * of this method returns {@link #NO_ID}. * * @param position Adapter position to query * @return the stable ID of the item at position */ public long getItemId(int position) { return NO_ID; } public abstract int getItemCount(); /** * Returns true if this adapter publishes a unique long value that can * act as a key for the item at a given position in the data set. If that item is relocated * in the data set, the ID returned for that item should be the same. * * @return true if this adapter's items have stable IDs */ public final boolean hasStableIds() { return mHasStableIds; } /** * Called when a view created by this adapter has been recycled. * *

A view is recycled when a {@link LayoutManager} decides that it no longer * needs to be attached to its parent {@link RecyclerView}. This can be because it has * fallen out of visibility or a set of cached views represented by views still * attached to the parent RecyclerView. If an item view has large or expensive data * bound to it such as large bitmaps, this may be a good place to release those * resources.

* * @param holder The ViewHolder for the view being recycled */ public void onViewRecycled(VH holder) { } /** * Called when a view created by this adapter has been attached to a window. * *

This can be used as a reasonable signal that the view is about to be seen * by the user. If the adapter previously freed any resources in * {@link #onViewDetachedFromWindow(RecyclerView.ViewHolder) onViewDetachedFromWindow} * those resources should be restored here.

* * @param holder Holder of the view being attached */ public void onViewAttachedToWindow(VH holder) { } /** * Called when a view created by this adapter has been detached from its window. * *

Becoming detached from the window is not necessarily a permanent condition; * the consumer of an Adapter's views may choose to cache views offscreen while they * are not visible, attaching an detaching them as appropriate.

* * @param holder Holder of the view being detached */ public void onViewDetachedFromWindow(VH holder) { } /** * Returns true if one or more observers are attached to this adapter. * @return true if this adapter has observers */ public final boolean hasObservers() { return mObservable.hasObservers(); } /** * Register a new observer to listen for data changes. * *

The adapter may publish a variety of events describing specific changes. * Not all adapters may support all change types and some may fall back to a generic * {@link android.support.v7.widget.RecyclerView.AdapterDataObserver#onChanged() * "something changed"} event if more specific data is not available.

* *

Components registering observers with an adapter are responsible for * {@link #unregisterAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver) * unregistering} those observers when finished.

* * @param observer Observer to register * * @see #unregisterAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver) */ public void registerAdapterDataObserver(AdapterDataObserver observer) { mObservable.registerObserver(observer); } /** * Unregister an observer currently listening for data changes. * *

The unregistered observer will no longer receive events about changes * to the adapter.

* * @param observer Observer to unregister * * @see #registerAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver) */ public void unregisterAdapterDataObserver(AdapterDataObserver observer) { mObservable.unregisterObserver(observer); } /** * Notify any registered observers that the data set has changed. * *

There are two different classes of data change events, item changes and structural * changes. Item changes are when a single item has its data updated but no positional * changes have occurred. Structural changes are when items are inserted, removed or moved * within the data set.

* *

This event does not specify what about the data set has changed, forcing * any observers to assume that all existing items and structure may no longer be valid. * LayoutManagers will be forced to fully rebind and relayout all visible views.

* *

RecyclerView will attempt to synthesize visible structural change events * for adapters that report that they have {@link #hasStableIds() stable IDs} when * this method is used. This can help for the purposes of animation and visual * object persistence but individual item views will still need to be rebound * and relaid out.

* *

If you are writing an adapter it will always be more efficient to use the more * specific change events if you can. Rely on notifyDataSetChanged() * as a last resort.

* * @see #notifyItemChanged(int) * @see #notifyItemInserted(int) * @see #notifyItemRemoved(int) * @see #notifyItemRangeChanged(int, int) * @see #notifyItemRangeInserted(int, int) * @see #notifyItemRangeRemoved(int, int) */ public final void notifyDataSetChanged() { mObservable.notifyChanged(); } /** * Notify any registered observers that the item at position has changed. * *

This is an item change event, not a structural change event. It indicates that any * reflection of the data at position is out of date and should be updated. * The item at position retains the same identity.

* * @param position Position of the item that has changed * * @see #notifyItemRangeChanged(int, int) */ public final void notifyItemChanged(int position) { mObservable.notifyItemRangeChanged(position, 1); } /** * Notify any registered observers that the itemCount items starting at * position positionStart have changed. * *

This is an item change event, not a structural change event. It indicates that * any reflection of the data in the given position range is out of date and should * be updated. The items in the given range retain the same identity.

* * @param positionStart Position of the first item that has changed * @param itemCount Number of items that have changed * * @see #notifyItemChanged(int) */ public final void notifyItemRangeChanged(int positionStart, int itemCount) { mObservable.notifyItemRangeChanged(positionStart, itemCount); } /** * Notify any registered observers that the item reflected at position * has been newly inserted. The item previously at position is now at * position position + 1. * *

This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their * positions may be altered.

* * @param position Position of the newly inserted item in the data set * * @see #notifyItemRangeInserted(int, int) */ public final void notifyItemInserted(int position) { mObservable.notifyItemRangeInserted(position, 1); } /** * Notify any registered observers that the currently reflected itemCount * items starting at positionStart have been newly inserted. The items * previously located at positionStart and beyond can now be found starting * at position positionStart + itemCount. * *

This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their positions * may be altered.

* * @param positionStart Position of the first item that was inserted * @param itemCount Number of items inserted * * @see #notifyItemInserted(int) */ public final void notifyItemRangeInserted(int positionStart, int itemCount) { mObservable.notifyItemRangeInserted(positionStart, itemCount); } /** * Notify any registered observers that the item previously located at position * has been removed from the data set. The items previously located at and after * position may now be found at oldPosition - 1. * *

This is a structural change event. Representations of other existing items in the * data set are still considered up to date and will not be rebound, though their positions * may be altered.

* * @param position Position of the item that has now been removed * * @see #notifyItemRangeRemoved(int, int) */ public final void notifyItemRemoved(int position) { mObservable.notifyItemRangeRemoved(position, 1); } /** * Notify any registered observers that the itemCount items previously * located at positionStart have been removed from the data set. The items * previously located at and after positionStart + itemCount may now be found * at oldPosition - itemCount. * *

This is a structural change event. Representations of other existing items in the data * set are still considered up to date and will not be rebound, though their positions * may be altered.

* * @param positionStart Previous position of the first item that was removed * @param itemCount Number of items removed from the data set */ public final void notifyItemRangeRemoved(int positionStart, int itemCount) { mObservable.notifyItemRangeRemoved(positionStart, itemCount); } } /** * A LayoutManager is responsible for measuring and positioning item views * within a RecyclerView as well as determining the policy for when to recycle * item views that are no longer visible to the user. By changing the LayoutManager * a RecyclerView can be used to implement a standard vertically scrolling list, * a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock * layout managers are provided for general use. */ public static abstract class LayoutManager { RecyclerView mRecyclerView; @Nullable SmoothScroller mSmoothScroller; /** * Calls {@code RecyclerView#requestLayout} on the underlying RecyclerView */ public void requestLayout() { if(mRecyclerView != null) { mRecyclerView.requestLayout(); } } /** * Returns whether this LayoutManager supports automatic item animations. * A LayoutManager wishing to support item animations should obey certain * rules as outlined in {@link #onLayoutChildren(Recycler, State)}. * The default return value is false, so subclasses of LayoutManager * will not get predictive item animations by default. * *

Whether item animations are enabled in a RecyclerView is determined both * by the return value from this method and the * {@link RecyclerView#setItemAnimator(ItemAnimator) ItemAnimator} set on the * RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this * method returns false, then simple item animations will be enabled, in which * views that are moving onto or off of the screen are simply faded in/out. If * the RecyclerView has a non-null ItemAnimator and this method returns true, * then there will be two calls to {@link #onLayoutChildren(Recycler, State)} to * setup up the information needed to more intelligently predict where appearing * and disappearing views should be animated from/to.

* * @return true if predictive item animations should be enabled, false otherwise */ public boolean supportsPredictiveItemAnimations() { return false; } /** * Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView * is attached to a window. * *

Subclass implementations should always call through to the superclass implementation. *

* * @param view The RecyclerView this LayoutManager is bound to */ public void onAttachedToWindow(RecyclerView view) { } /** * Called when this LayoutManager is detached from its parent RecyclerView or when * its parent RecyclerView is detached from its window. * *

Subclass implementations should always call through to the superclass implementation. *

* * @param view The RecyclerView this LayoutManager is bound to */ public void onDetachedFromWindow(RecyclerView view) { } /** * Lay out all relevant child views from the given adapter. * * The LayoutManager is in charge of the behavior of item animations. By default, * RecyclerView has a non-null {@link #getItemAnimator() ItemAnimator}, and simple * item animations are enabled. This means that add/remove operations on the * adapter will result in animations to add new or appearing items, removed or * disappearing items, and moved items. If a LayoutManager returns false from * {@link #supportsPredictiveItemAnimations()}, which is the default, and runs a * normal layout operation during {@link #onLayoutChildren(Recycler, State)}, the * RecyclerView will have enough information to run those animations in a simple * way. For example, the default ItemAnimator, {@link DefaultItemAnimator}, will * simple fade views in and out, whether they are actuall added/removed or whether * they are moved on or off the screen due to other add/remove operations. * *

A LayoutManager wanting a better item animation experience, where items can be * animated onto and off of the screen according to where the items exist when they * are not on screen, then the LayoutManager should return true from * {@link #supportsPredictiveItemAnimations()} and add additional logic to * {@link #onLayoutChildren(Recycler, State)}. Supporting predictive animations * means that {@link #onLayoutChildren(Recycler, State)} will be called twice; * once as a "pre" layout step to determine where items would have been prior to * a real layout, and again to do the "real" layout. In the pre-layout phase, * items will remember their pre-layout positions to allow them to be laid out * appropriately. Also, {@link LayoutParams#isItemRemoved() removed} items will * be returned from the scrap to help determine correct placement of other items. * These removed items should not be added to the child list, but should be used * to help calculate correct positioning of other views, including views that * were not previously onscreen (referred to as APPEARING views), but whose * pre-layout offscreen position can be determined given the extra * information about the pre-layout removed views.

* *

The second layout pass is the real layout in which only non-removed views * will be used. The only additional requirement during this pass is, if * {@link #supportsPredictiveItemAnimations()} returns true, to note which * views exist in the child list prior to layout and which are not there after * layout (referred to as DISAPPEARING views), and to position/layout those views * appropriately, without regard to the actual bounds of the RecyclerView. This allows * the animation system to know the location to which to animate these disappearing * views.

* *

The default LayoutManager implementations for RecyclerView handle all of these * requirements for animations already. Clients of RecyclerView can either use one * of these layout managers directly or look at their implementations of * onLayoutChildren() to see how they account for the APPEARING and * DISAPPEARING views.

* * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView */ public void onLayoutChildren(Recycler recycler, State state) { Log.e(TAG, "You must override onLayoutChildren(Recycler recycler, State state) "); } /** * Create a default LayoutParams object for a child of the RecyclerView. * *

LayoutManagers will often want to use a custom LayoutParams type * to store extra information specific to the layout. Client code should subclass * {@link RecyclerView.LayoutParams} for this purpose.

* *

Important: if you use your own custom LayoutParams type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.

* * @return A new LayoutParams for a child view */ public abstract LayoutParams generateDefaultLayoutParams(); /** * Determines the validity of the supplied LayoutParams object. * *

This should check to make sure that the object is of the correct type * and all values are within acceptable ranges. The default implementation * returns true for non-null params.

* * @param lp LayoutParams object to check * @return true if this LayoutParams object is valid, false otherwise */ public boolean checkLayoutParams(LayoutParams lp) { return lp != null; } /** * Create a LayoutParams object suitable for this LayoutManager, copying relevant * values from the supplied LayoutParams object if possible. * *

Important: if you use your own custom LayoutParams type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.

* * @param lp Source LayoutParams object to copy values from * @return a new LayoutParams object */ public LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) { if (lp instanceof LayoutParams) { return new LayoutParams((LayoutParams) lp); } else if (lp instanceof MarginLayoutParams) { return new LayoutParams((MarginLayoutParams) lp); } else { return new LayoutParams(lp); } } /** * Create a LayoutParams object suitable for this LayoutManager from * an inflated layout resource. * *

Important: if you use your own custom LayoutParams type * you must also override * {@link #checkLayoutParams(LayoutParams)}, * {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and * {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.

* * @param c Context for obtaining styled attributes * @param attrs AttributeSet describing the supplied arguments * @return a new LayoutParams object */ public LayoutParams generateLayoutParams(Context c, AttributeSet attrs) { return new LayoutParams(c, attrs); } /** * Scroll horizontally by dx pixels in screen coordinates and return the distance traveled. * The default implementation does nothing and returns 0. * * @param dx distance to scroll by in pixels. X increases as scroll position * approaches the right. * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView * @return The actual distance scrolled. The return value will be negative if dx was * negative and scrolling proceeeded in that direction. * Math.abs(result) may be less than dx if a boundary was reached. */ public int scrollHorizontallyBy(int dx, Recycler recycler, State state) { return 0; } /** * Scroll vertically by dy pixels in screen coordinates and return the distance traveled. * The default implementation does nothing and returns 0. * * @param dy distance to scroll in pixels. Y increases as scroll position * approaches the bottom. * @param recycler Recycler to use for fetching potentially cached views for a * position * @param state Transient state of RecyclerView * @return The actual distance scrolled. The return value will be negative if dy was * negative and scrolling proceeeded in that direction. * Math.abs(result) may be less than dy if a boundary was reached. */ public int scrollVerticallyBy(int dy, Recycler recycler, State state) { return 0; } /** * Query if horizontal scrolling is currently supported. The default implementation * returns false. * * @return True if this LayoutManager can scroll the current contents horizontally */ public boolean canScrollHorizontally() { return false; } /** * Query if vertical scrolling is currently supported. The default implementation * returns false. * * @return True if this LayoutManager can scroll the current contents vertically */ public boolean canScrollVertically() { return false; } /** * Scroll to the specified adapter position. * * Actual position of the item on the screen depends on the LayoutManager implementation. * @param position Scroll to this adapter position. */ public void scrollToPosition(int position) { if (DEBUG) { Log.e(TAG, "You MUST implement scrollToPosition. It will soon become abstract"); } } /** *

Smooth scroll to the specified adapter position.

*

To support smooth scrolling, override this method, create your {@link SmoothScroller} * instance and call {@link #startSmoothScroll(SmoothScroller)}. *

* @param recyclerView The RecyclerView to which this layout manager is attached * @param state Current State of RecyclerView * @param position Scroll to this adapter position. */ public void smoothScrollToPosition(RecyclerView recyclerView, State state, int position) { Log.e(TAG, "You must override smoothScrollToPosition to support smooth scrolling"); } /** *

Starts a smooth scroll using the provided SmoothScroller.

*

Calling this method will cancel any previous smooth scroll request.

* @param smoothScroller Unstance which defines how smooth scroll should be animated */ public void startSmoothScroll(SmoothScroller smoothScroller) { if (mSmoothScroller != null && smoothScroller != mSmoothScroller && mSmoothScroller.isRunning()) { mSmoothScroller.stop(); } mSmoothScroller = smoothScroller; mSmoothScroller.start(mRecyclerView, this); } /** * @return true if RecycylerView is currently in the state of smooth scrolling. */ public boolean isSmoothScrolling() { return mSmoothScroller != null && mSmoothScroller.isRunning(); } /** * Returns the resolved layout direction for this RecyclerView. * * @return {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_RTL} if the layout * direction is RTL or returns * {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_LTR} if the layout direction * is not RTL. */ public int getLayoutDirection() { return ViewCompat.getLayoutDirection(mRecyclerView); } /** * Add a view to the currently attached RecyclerView if needed. LayoutManagers should * use this method to add views obtained from a {@link Recycler} using * {@link Recycler#getViewForPosition(int)}. * * @param child View to add * @param index Index to add child at */ public void addView(View child, int index) { if (mRecyclerView.mAnimatingViewIndex >= 0) { if (index > mRecyclerView.mAnimatingViewIndex) { throw new IndexOutOfBoundsException("index=" + index + " count=" + mRecyclerView.mAnimatingViewIndex); } mRecyclerView.mAnimatingViewIndex++; } final ViewHolder holder = getChildViewHolderInt(child); if (holder.isScrap()) { holder.unScrap(); mRecyclerView.attachViewToParent(child, index, child.getLayoutParams()); if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchFinishTemporaryDetach(child); } } else { mRecyclerView.addView(child, index); final LayoutParams lp = (LayoutParams) child.getLayoutParams(); lp.mInsetsDirty = true; final Adapter adapter = mRecyclerView.getAdapter(); if (adapter != null) { adapter.onViewAttachedToWindow(getChildViewHolderInt(child)); } mRecyclerView.onChildAttachedToWindow(child); if (mSmoothScroller != null && mSmoothScroller.isRunning()) { mSmoothScroller.onChildAttachedToWindow(child); } } } /** * Add a view to the currently attached RecyclerView if needed. LayoutManagers should * use this method to add views obtained from a {@link Recycler} using * {@link Recycler#getViewForPosition(int)}. * * @param child View to add */ public void addView(View child) { if (mRecyclerView.mAnimatingViewIndex >= 0) { addView(child, mRecyclerView.mAnimatingViewIndex); } else { addView(child, -1); } } /** * Remove a view from the currently attached RecyclerView if needed. LayoutManagers should * use this method to completely remove a child view that is no longer needed. * LayoutManagers should strongly consider recycling removed views using * {@link Recycler#recycleView(android.view.View)}. * * @param child View to remove */ public void removeView(View child) { final Adapter adapter = mRecyclerView.getAdapter(); if (adapter != null) { adapter.onViewDetachedFromWindow(getChildViewHolderInt(child)); } mRecyclerView.onChildDetachedFromWindow(child); mRecyclerView.removeView(child); if (mRecyclerView.mAnimatingViewIndex >= 0) { mRecyclerView.mAnimatingViewIndex--; } } /** * Remove a view from the currently attached RecyclerView if needed. LayoutManagers should * use this method to completely remove a child view that is no longer needed. * LayoutManagers should strongly consider recycling removed views using * {@link Recycler#recycleView(android.view.View)}. * * @param index Index of the child view to remove */ public void removeViewAt(int index) { final View child = mRecyclerView.getChildAt(index); if (child != null) { final Adapter adapter = mRecyclerView.getAdapter(); if (adapter != null) { adapter.onViewDetachedFromWindow(getChildViewHolderInt(child)); } mRecyclerView.onChildDetachedFromWindow(child); mRecyclerView.removeViewAt(index); if (mRecyclerView.mAnimatingViewIndex >= 0) { mRecyclerView.mAnimatingViewIndex--; } } } /** * Remove all views from the currently attached RecyclerView. This will not recycle * any of the affected views; the LayoutManager is responsible for doing so if desired. */ public void removeAllViews() { final Adapter adapter = mRecyclerView.getAdapter(); // Only remove non-animating views final int childCount = mRecyclerView.getChildCount() - mRecyclerView.mNumAnimatingViews; for (int i = 0; i < childCount; i++) { final View child = mRecyclerView.getChildAt(i); if (adapter != null) { adapter.onViewDetachedFromWindow(getChildViewHolderInt(child)); } mRecyclerView.onChildDetachedFromWindow(child); } for (int i = childCount - 1; i >= 0; i--) { mRecyclerView.removeViewAt(i); if (mRecyclerView.mAnimatingViewIndex >= 0) { mRecyclerView.mAnimatingViewIndex--; } } } /** * Returns the adapter position of the item represented by the given View. * * @param view The view to query * @return The adapter position of the item which is rendered by this View. */ public int getPosition(View view) { return ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewPosition(); } /** *

Finds the view which represents the given adapter position.

*

This method traverses each child since it has no information about child order. * Override this method to improve performance if your LayoutManager keeps data about * child views.

* * @param position Position of the item in adapter * @return The child view that represents the given position or null if the position is not * visible */ public View findViewByPosition(int position) { final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { View child = getChildAt(i); if (getPosition(child) == position) { return child; } } return null; } /** * Temporarily detach a child view. * *

LayoutManagers may want to perform a lightweight detach operation to rearrange * views currently attached to the RecyclerView. Generally LayoutManager implementations * will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} * so that the detached view may be rebound and reused.

* *

If a LayoutManager uses this method to detach a view, it must * {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach} * or {@link #removeDetachedView(android.view.View) fully remove} the detached view * before the LayoutManager entry point method called by RecyclerView returns.

* * @param child Child to detach */ public void detachView(View child) { if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchStartTemporaryDetach(child); } mRecyclerView.detachViewFromParent(child); } /** * Temporarily detach a child view. * *

LayoutManagers may want to perform a lightweight detach operation to rearrange * views currently attached to the RecyclerView. Generally LayoutManager implementations * will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} * so that the detached view may be rebound and reused.

* *

If a LayoutManager uses this method to detach a view, it must * {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach} * or {@link #removeDetachedView(android.view.View) fully remove} the detached view * before the LayoutManager entry point method called by RecyclerView returns.

* * @param index Index of the child to detach */ public void detachViewAt(int index) { if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchStartTemporaryDetach(mRecyclerView.getChildAt(index)); } mRecyclerView.detachViewFromParent(index); if (mRecyclerView.mAnimatingViewIndex >= 0) { --mRecyclerView.mAnimatingViewIndex; } } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach * @param index Intended child index for child * @param lp LayoutParams for child */ public void attachView(View child, int index, LayoutParams lp) { mRecyclerView.attachViewToParent(child, index, lp); if (mRecyclerView.mAnimatingViewIndex >= 0) { ++mRecyclerView.mAnimatingViewIndex; } if (DISPATCH_TEMP_DETACH) { ViewCompat.dispatchFinishTemporaryDetach(child); } } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach * @param index Intended child index for child */ public void attachView(View child, int index) { attachView(child, index, (LayoutParams) child.getLayoutParams()); } /** * Reattach a previously {@link #detachView(android.view.View) detached} view. * This method should not be used to reattach views that were previously * {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}. * * @param child Child to reattach */ public void attachView(View child) { attachView(child, -1); } /** * Finish removing a view that was previously temporarily * {@link #detachView(android.view.View) detached}. * * @param child Detached child to remove */ public void removeDetachedView(View child) { mRecyclerView.removeDetachedView(child, false); } /** * Detach a child view and add it to a {@link Recycler Recycler's} scrap heap. * *

Scrapping a view allows it to be rebound and reused to show updated or * different data.

* * @param child Child to detach and scrap * @param recycler Recycler to deposit the new scrap view into */ public void detachAndScrapView(View child, Recycler recycler) { detachView(child); recycler.scrapView(child); } /** * Detach a child view and add it to a {@link Recycler Recycler's} scrap heap. * *

Scrapping a view allows it to be rebound and reused to show updated or * different data.

* * @param index Index of child to detach and scrap * @param recycler Recycler to deposit the new scrap view into */ public void detachAndScrapViewAt(int index, Recycler recycler) { final View child = getChildAt(index); detachViewAt(index); recycler.scrapView(child); } /** * Remove a child view and recycle it using the given Recycler. * * @param child Child to remove and recycle * @param recycler Recycler to use to recycle child */ public void removeAndRecycleView(View child, Recycler recycler) { removeView(child); recycler.recycleView(child); } /** * Remove a child view and recycle it using the given Recycler. * * @param index Index of child to remove and recycle * @param recycler Recycler to use to recycle child */ public void removeAndRecycleViewAt(int index, Recycler recycler) { final View view = getChildAt(index); removeViewAt(index); recycler.recycleView(view); } /** * Return the current number of child views attached to the parent RecyclerView. * This does not include child views that were temporarily detached and/or scrapped. * * @return Number of attached children */ public int getChildCount() { return mRecyclerView != null ? mRecyclerView.getChildCount() - mRecyclerView.mNumAnimatingViews : 0; } /** * Return the child view at the given index * @param index Index of child to return * @return Child view at index */ public View getChildAt(int index) { return mRecyclerView != null ? mRecyclerView.getChildAt(index) : null; } /** * Return the width of the parent RecyclerView * * @return Width in pixels */ public int getWidth() { return mRecyclerView != null ? mRecyclerView.getWidth() : 0; } /** * Return the height of the parent RecyclerView * * @return Height in pixels */ public int getHeight() { return mRecyclerView != null ? mRecyclerView.getHeight() : 0; } /** * Return the left padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingLeft() { return mRecyclerView != null ? mRecyclerView.getPaddingLeft() : 0; } /** * Return the top padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingTop() { return mRecyclerView != null ? mRecyclerView.getPaddingTop() : 0; } /** * Return the right padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingRight() { return mRecyclerView != null ? mRecyclerView.getPaddingRight() : 0; } /** * Return the bottom padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingBottom() { return mRecyclerView != null ? mRecyclerView.getPaddingBottom() : 0; } /** * Return the start padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingStart() { return mRecyclerView != null ? ViewCompat.getPaddingStart(mRecyclerView) : 0; } /** * Return the end padding of the parent RecyclerView * * @return Padding in pixels */ public int getPaddingEnd() { return mRecyclerView != null ? ViewCompat.getPaddingEnd(mRecyclerView) : 0; } /** * Returns true if the RecyclerView this LayoutManager is bound to has focus. * * @return True if the RecyclerView has focus, false otherwise. * @see View#isFocused() */ public boolean isFocused() { return mRecyclerView != null && mRecyclerView.isFocused(); } /** * Returns true if the RecyclerView this LayoutManager is bound to has or contains focus. * * @return true if the RecyclerView has or contains focus * @see View#hasFocus() */ public boolean hasFocus() { return mRecyclerView != null && mRecyclerView.hasFocus(); } /** * Return the number of items in the adapter bound to the parent RecyclerView * * @return Items in the bound adapter */ public int getItemCount() { final Adapter a = mRecyclerView != null ? mRecyclerView.getAdapter() : null; return a != null ? a.getItemCount() : 0; } /** * Offset all child views attached to the parent RecyclerView by dx pixels along * the horizontal axis. * * @param dx Pixels to offset by */ public void offsetChildrenHorizontal(int dx) { if (mRecyclerView != null) { mRecyclerView.offsetChildrenHorizontal(dx); } } /** * Offset all child views attached to the parent RecyclerView by dy pixels along * the vertical axis. * * @param dy Pixels to offset by */ public void offsetChildrenVertical(int dy) { if (mRecyclerView != null) { mRecyclerView.offsetChildrenVertical(dy); } } /** * Temporarily detach and scrap all currently attached child views. Views will be scrapped * into the given Recycler. The Recycler may prefer to reuse scrap views before * other views that were previously recycled. * * @param recycler Recycler to scrap views into */ public void detachAndScrapAttachedViews(Recycler recycler) { final int childCount = getChildCount(); for (int i = childCount - 1; i >= 0; i--) { final View v = getChildAt(i); detachViewAt(i); recycler.scrapView(v); } } /** * Recycles the scrapped views. *

* When a view is detached and removed, it does not trigger a ViewGroup invalidate. This is * the expected behavior if scrapped views are used for animations. Otherwise, we need to * call remove and invalidate RecyclerView to ensure UI update. * * @param recycler Recycler * @param remove Whether scrapped views should be removed from ViewGroup or not. This * method will invalidate RecyclerView if it removes any scrapped child. */ void removeAndRecycleScrapInt(Recycler recycler, boolean remove) { final int scrapCount = recycler.getScrapCount(); for (int i = 0; i < scrapCount; i++) { final View scrap = recycler.getScrapViewAt(i); if (remove) { mRecyclerView.removeDetachedView(scrap, false); } recycler.quickRecycleScrapView(scrap); } recycler.clearScrap(); if (remove && scrapCount > 0) { mRecyclerView.invalidate(); } } /** * Measure a child view using standard measurement policy, taking the padding * of the parent RecyclerView and any added item decorations into account. * *

If the RecyclerView can be scrolled in either dimension the caller may * pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

* * @param child Child view to measure * @param widthUsed Width in pixels currently consumed by other views, if relevant * @param heightUsed Height in pixels currently consumed by other views, if relevant */ public void measureChild(View child, int widthUsed, int heightUsed) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child); widthUsed += insets.left + insets.right; heightUsed += insets.top + insets.bottom; final int widthSpec = getChildMeasureSpec(getWidth(), getPaddingLeft() + getPaddingRight() + widthUsed, lp.width, canScrollHorizontally()); final int heightSpec = getChildMeasureSpec(getHeight(), getPaddingTop() + getPaddingBottom() + heightUsed, lp.height, canScrollVertically()); child.measure(widthSpec, heightSpec); } /** * Measure a child view using standard measurement policy, taking the padding * of the parent RecyclerView, any added item decorations and the child margins * into account. * *

If the RecyclerView can be scrolled in either dimension the caller may * pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.

* * @param child Child view to measure * @param widthUsed Width in pixels currently consumed by other views, if relevant * @param heightUsed Height in pixels currently consumed by other views, if relevant */ public void measureChildWithMargins(View child, int widthUsed, int heightUsed) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child); widthUsed += insets.left + insets.right; heightUsed += insets.top + insets.bottom; final int widthSpec = getChildMeasureSpec(getWidth(), getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin + widthUsed, lp.width, canScrollHorizontally()); final int heightSpec = getChildMeasureSpec(getHeight(), getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin + heightUsed, lp.height, canScrollVertically()); child.measure(widthSpec, heightSpec); } /** * Calculate a MeasureSpec value for measuring a child view in one dimension. * * @param parentSize Size of the parent view where the child will be placed * @param padding Total space currently consumed by other elements of parent * @param childDimension Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT. * Generally obtained from the child view's LayoutParams * @param canScroll true if the parent RecyclerView can scroll in this dimension * * @return a MeasureSpec value for the child view */ public static int getChildMeasureSpec(int parentSize, int padding, int childDimension, boolean canScroll) { int size = Math.max(0, parentSize - padding); int resultSize = 0; int resultMode = 0; if (canScroll) { if (childDimension >= 0) { resultSize = childDimension; resultMode = MeasureSpec.EXACTLY; } else { // MATCH_PARENT can't be applied since we can scroll in this dimension, wrap // instead using UNSPECIFIED. resultSize = 0; resultMode = MeasureSpec.UNSPECIFIED; } } else { if (childDimension >= 0) { resultSize = childDimension; resultMode = MeasureSpec.EXACTLY; } else if (childDimension == LayoutParams.FILL_PARENT) { resultSize = size; resultMode = MeasureSpec.EXACTLY; } else if (childDimension == LayoutParams.WRAP_CONTENT) { resultSize = size; resultMode = MeasureSpec.AT_MOST; } } return MeasureSpec.makeMeasureSpec(resultSize, resultMode); } /** * Returns the measured width of the given child, plus the additional size of * any insets applied by {@link ItemDecoration ItemDecorations}. * * @param child Child view to query * @return child's measured width plus ItemDecoration insets * * @see View#getMeasuredWidth() */ public int getDecoratedMeasuredWidth(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getMeasuredWidth() + insets.left + insets.right; } /** * Returns the measured height of the given child, plus the additional size of * any insets applied by {@link ItemDecoration ItemDecorations}. * * @param child Child view to query * @return child's measured height plus ItemDecoration insets * * @see View#getMeasuredHeight() */ public int getDecoratedMeasuredHeight(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getMeasuredHeight() + insets.top + insets.bottom; } /** * Lay out the given child view within the RecyclerView using coordinates that * include any current {@link ItemDecoration ItemDecorations}. * *

LayoutManagers should prefer working in sizes and coordinates that include * item decoration insets whenever possible. This allows the LayoutManager to effectively * ignore decoration insets within measurement and layout code. See the following * methods:

*
    *
  • {@link #measureChild(View, int, int)}
  • *
  • {@link #measureChildWithMargins(View, int, int)}
  • *
  • {@link #getDecoratedLeft(View)}
  • *
  • {@link #getDecoratedTop(View)}
  • *
  • {@link #getDecoratedRight(View)}
  • *
  • {@link #getDecoratedBottom(View)}
  • *
  • {@link #getDecoratedMeasuredWidth(View)}
  • *
  • {@link #getDecoratedMeasuredHeight(View)}
  • *
* * @param child Child to lay out * @param left Left edge, with item decoration insets included * @param top Top edge, with item decoration insets included * @param right Right edge, with item decoration insets included * @param bottom Bottom edge, with item decoration insets included * * @see View#layout(int, int, int, int) */ public void layoutDecorated(View child, int left, int top, int right, int bottom) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; child.layout(left + insets.left, top + insets.top, right - insets.right, bottom - insets.bottom); } /** * Returns the left edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child left edge with offsets applied */ public int getDecoratedLeft(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getLeft() - insets.left; } /** * Returns the top edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child top edge with offsets applied */ public int getDecoratedTop(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getTop() - insets.top; } /** * Returns the right edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child right edge with offsets applied */ public int getDecoratedRight(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getRight() + insets.right; } /** * Returns the bottom edge of the given child view within its parent, offset by any applied * {@link ItemDecoration ItemDecorations}. * * @param child Child to query * @return Child bottom edge with offsets applied */ public int getDecoratedBottom(View child) { final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets; return child.getBottom() + insets.bottom; } /** * Called when searching for a focusable view in the given direction has failed * for the current content of the RecyclerView. * *

This is the LayoutManager's opportunity to populate views in the given direction * to fulfill the request if it can. The LayoutManager should attach and return * the view to be focused. The default implementation returns null.

* * @param focused The currently focused view * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * or 0 for not applicable * @param recycler The recycler to use for obtaining views for currently offscreen items * @param state Transient state of RecyclerView * @return The chosen view to be focused */ public View onFocusSearchFailed(View focused, int direction, Recycler recycler, State state) { return null; } /** * This method gives a LayoutManager an opportunity to intercept the initial focus search * before the default behavior of {@link FocusFinder} is used. If this method returns * null FocusFinder will attempt to find a focusable child view. If it fails * then {@link #onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State)} * will be called to give the LayoutManager an opportunity to add new views for items * that did not have attached views representing them. The LayoutManager should not add * or remove views from this method. * * @param focused The currently focused view * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * @return A descendant view to focus or null to fall back to default behavior. * The default implementation returns null. */ public View onInterceptFocusSearch(View focused, int direction) { return null; } /** * Called when a child of the RecyclerView wants a particular rectangle to be positioned * onto the screen. See {@link ViewParent#requestChildRectangleOnScreen(android.view.View, * android.graphics.Rect, boolean)} for more details. * *

The base implementation will attempt to perform a standard programmatic scroll * to bring the given rect into view, within the padded area of the RecyclerView.

* * @param child The direct child making the request. * @param rect The rectangle in the child's coordinates the child * wishes to be on the screen. * @param immediate True to forbid animated or delayed scrolling, * false otherwise * @return Whether the group scrolled to handle the operation */ public boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect, boolean immediate) { final int parentLeft = getPaddingLeft(); final int parentTop = getPaddingTop(); final int parentRight = getWidth() - getPaddingRight(); final int parentBottom = getHeight() - getPaddingBottom(); final int childLeft = child.getLeft() + rect.left; final int childTop = child.getTop() + rect.top; final int childRight = childLeft + rect.right; final int childBottom = childTop + rect.bottom; final int offScreenLeft = Math.min(0, childLeft - parentLeft); final int offScreenTop = Math.min(0, childTop - parentTop); final int offScreenRight = Math.max(0, childRight - parentRight); final int offScreenBottom = Math.max(0, childBottom - parentBottom); // Favor the "start" layout direction over the end when bringing one side or the other // of a large rect into view. final int dx; if (ViewCompat.getLayoutDirection(parent) == ViewCompat.LAYOUT_DIRECTION_RTL) { dx = offScreenRight != 0 ? offScreenRight : offScreenLeft; } else { dx = offScreenLeft != 0 ? offScreenLeft : offScreenRight; } // Favor bringing the top into view over the bottom final int dy = offScreenTop != 0 ? offScreenTop : offScreenBottom; if (dx != 0 || dy != 0) { if (immediate) { parent.scrollBy(dx, dy); } else { parent.smoothScrollBy(dx, dy); } return true; } return false; } /** * Called when a descendant view of the RecyclerView requests focus. * *

A LayoutManager wishing to keep focused views aligned in a specific * portion of the view may implement that behavior in an override of this method.

* *

If the LayoutManager executes different behavior that should override the default * behavior of scrolling the focused child on screen instead of running alongside it, * this method should return true.

* * @param parent The RecyclerView hosting this LayoutManager * @param child Direct child of the RecyclerView containing the newly focused view * @param focused The newly focused view. This may be the same view as child * @return true if the default scroll behavior should be suppressed */ public boolean onRequestChildFocus(RecyclerView parent, View child, View focused) { return false; } /** * Called if the RecyclerView this LayoutManager is bound to has a different adapter set. * The LayoutManager may use this opportunity to clear caches and configure state such * that it can relayout appropriately with the new data and potentially new view types. * *

The default implementation removes all currently attached views.

* * @param oldAdapter The previous adapter instance. Will be null if there was previously no * adapter. * @param newAdapter The new adapter instance. Might be null if * {@link #setAdapter(RecyclerView.Adapter)} is called with {@code null}. */ public void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) { } /** * Called to populate focusable views within the RecyclerView. * *

The LayoutManager implementation should return true if the default * behavior of {@link ViewGroup#addFocusables(java.util.ArrayList, int)} should be * suppressed.

* *

The default implementation returns false to trigger RecyclerView * to fall back to the default ViewGroup behavior.

* * @param recyclerView The RecyclerView hosting this LayoutManager * @param views List of output views. This method should add valid focusable views * to this list. * @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN}, * {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT}, * {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD} * @param focusableMode The type of focusables to be added. * * @return true to suppress the default behavior, false to add default focusables after * this method returns. * * @see #FOCUSABLES_ALL * @see #FOCUSABLES_TOUCH_MODE */ public boolean onAddFocusables(RecyclerView recyclerView, ArrayList views, int direction, int focusableMode) { return false; } /** * Called when items have been added to the adapter. The LayoutManager may choose to * requestLayout if the inserted items would require refreshing the currently visible set * of child views. (e.g. currently empty space would be filled by appended items, etc.) * * @param recyclerView * @param positionStart * @param itemCount */ public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) { } /** * Called when items have been removed from the adapter. * * @param recyclerView * @param positionStart * @param itemCount */ public void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) { } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeHorizontalScrollExtent()} for details.

* *

Default implementation returns 0.

* * @param state Current state of RecyclerView * @return The horizontal extent of the scrollbar's thumb * @see RecyclerView#computeHorizontalScrollExtent() */ public int computeHorizontalScrollExtent(State state) { return 0; } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeHorizontalScrollOffset()} for details.

* *

Default implementation returns 0.

* * @param state Current State of RecyclerView where you can find total item count * @return The horizontal offset of the scrollbar's thumb * @see RecyclerView#computeHorizontalScrollOffset() */ public int computeHorizontalScrollOffset(State state) { return 0; } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeHorizontalScrollRange()} for details.

* *

Default implementation returns 0.

* * @param state Current State of RecyclerView where you can find total item count * @return The total horizontal range represented by the vertical scrollbar * @see RecyclerView#computeHorizontalScrollRange() */ public int computeHorizontalScrollRange(State state) { return 0; } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeVerticalScrollExtent()} for details.

* *

Default implementation returns 0.

* * @param state Current state of RecyclerView * @return The vertical extent of the scrollbar's thumb * @see RecyclerView#computeVerticalScrollExtent() */ public int computeVerticalScrollExtent(State state) { return 0; } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeVerticalScrollOffset()} for details.

* *

Default implementation returns 0.

* * @param state Current State of RecyclerView where you can find total item count * @return The vertical offset of the scrollbar's thumb * @see RecyclerView#computeVerticalScrollOffset() */ public int computeVerticalScrollOffset(State state) { return 0; } /** *

Override this method if you want to support scroll bars.

* *

Read {@link RecyclerView#computeVerticalScrollRange()} for details.

* *

Default implementation returns 0.

* * @param state Current State of RecyclerView where you can find total item count * @return The total vertical range represented by the vertical scrollbar * @see RecyclerView#computeVerticalScrollRange() */ public int computeVerticalScrollRange(State state) { return 0; } /** * Measure the attached RecyclerView. Implementations must call * {@link #setMeasuredDimension(int, int)} before returning. * *

The default implementation will handle EXACTLY measurements and respect * the minimum width and height properties of the host RecyclerView if measured * as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView * will consume all available space.

* * @param recycler Recycler * @param state Transient state of RecyclerView * @param widthSpec Width {@link android.view.View.MeasureSpec} * @param heightSpec Height {@link android.view.View.MeasureSpec} */ public void onMeasure(Recycler recycler, State state, int widthSpec, int heightSpec) { final int widthMode = MeasureSpec.getMode(widthSpec); final int heightMode = MeasureSpec.getMode(heightSpec); final int widthSize = MeasureSpec.getSize(widthSpec); final int heightSize = MeasureSpec.getSize(heightSpec); int width = 0; int height = 0; switch (widthMode) { case MeasureSpec.EXACTLY: case MeasureSpec.AT_MOST: width = widthSize; break; case MeasureSpec.UNSPECIFIED: default: width = getMinimumWidth(); break; } switch (heightMode) { case MeasureSpec.EXACTLY: case MeasureSpec.AT_MOST: height = heightSize; break; case MeasureSpec.UNSPECIFIED: default: height = getMinimumHeight(); break; } setMeasuredDimension(width, height); } /** * {@link View#setMeasuredDimension(int, int) Set the measured dimensions} of the * host RecyclerView. * * @param widthSize Measured width * @param heightSize Measured height */ public void setMeasuredDimension(int widthSize, int heightSize) { mRecyclerView.setMeasuredDimension(widthSize, heightSize); } /** * @return The host RecyclerView's {@link View#getMinimumWidth()} */ public int getMinimumWidth() { return ViewCompat.getMinimumWidth(mRecyclerView); } /** * @return The host RecyclerView's {@link View#getMinimumHeight()} */ public int getMinimumHeight() { return ViewCompat.getMinimumHeight(mRecyclerView); } /** *

Called when the LayoutManager should save its state. This is a good time to save your * scroll position, configuration and anything else that may be required to restore the same * layout state if the LayoutManager is recreated.

*

RecyclerView does NOT verify if the LayoutManager has changed between state save and * restore. This will let you share information between your LayoutManagers but it is also * your responsibility to make sure they use the same parcelable class.

* * @return Necessary information for LayoutManager to be able to restore its state */ public Parcelable onSaveInstanceState() { return null; } public void onRestoreInstanceState(Parcelable state) { } void stopSmoothScroller() { if (mSmoothScroller != null) { mSmoothScroller.stop(); } } private void onSmoothScrollerStopped(SmoothScroller smoothScroller) { if (mSmoothScroller == smoothScroller) { mSmoothScroller = null; } } void removeAndRecycleAllViews(Recycler recycler) { for (int i = getChildCount() - 1; i >= 0; i--) { removeAndRecycleViewAt(i, recycler); } } } /** * An ItemDecoration allows the application to add a special drawing and layout offset * to specific item views from the adapter's data set. This can be useful for drawing dividers * between items, highlights, visual grouping boundaries and more. * *

All ItemDecorations are drawn in the order they were added, before the item * views (in {@link ItemDecoration#onDraw(Canvas, RecyclerView) onDraw()} and after the items * (in {@link ItemDecoration#onDrawOver(Canvas, RecyclerView)}.

*/ public static abstract class ItemDecoration { /** * Draw any appropriate decorations into the Canvas supplied to the RecyclerView. * Any content drawn by this method will be drawn before the item views are drawn, * and will thus appear underneath the views. * * @param c Canvas to draw into * @param parent RecyclerView this ItemDecoration is drawing into */ public void onDraw(Canvas c, RecyclerView parent) { } /** * Draw any appropriate decorations into the Canvas supplied to the RecyclerView. * Any content drawn by this method will be drawn after the item views are drawn * and will thus appear over the views. * * @param c Canvas to draw into * @param parent RecyclerView this ItemDecoration is drawing into */ public void onDrawOver(Canvas c, RecyclerView parent) { } /** * Retrieve any offsets for the given item. Each field of outRect specifies * the number of pixels that the item view should be inset by, similar to padding or margin. * The default implementation sets the bounds of outRect to 0 and returns. * *

If this ItemDecoration does not affect the positioning of item views it should set * all four fields of outRect (left, top, right, bottom) to zero * before returning.

* * @param outRect Rect to receive the output. * @param itemPosition Adapter position of the item to offset * @param parent RecyclerView this ItemDecoration is decorating */ public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) { outRect.set(0, 0, 0, 0); } } /** * An OnItemTouchListener allows the application to intercept touch events in progress at the * view hierarchy level of the RecyclerView before those touch events are considered for * RecyclerView's own scrolling behavior. * *

This can be useful for applications that wish to implement various forms of gestural * manipulation of item views within the RecyclerView. OnItemTouchListeners may intercept * a touch interaction already in progress even if the RecyclerView is already handling that * gesture stream itself for the purposes of scrolling.

*/ public interface OnItemTouchListener { /** * Silently observe and/or take over touch events sent to the RecyclerView * before they are handled by either the RecyclerView itself or its child views. * *

The onInterceptTouchEvent methods of each attached OnItemTouchListener will be run * in the order in which each listener was added, before any other touch processing * by the RecyclerView itself or child views occurs.

* * @param e MotionEvent describing the touch event. All coordinates are in * the RecyclerView's coordinate system. * @return true if this OnItemTouchListener wishes to begin intercepting touch events, false * to continue with the current behavior and continue observing future events in * the gesture. */ public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e); /** * Process a touch event as part of a gesture that was claimed by returning true from * a previous call to {@link #onInterceptTouchEvent}. * * @param e MotionEvent describing the touch event. All coordinates are in * the RecyclerView's coordinate system. */ public void onTouchEvent(RecyclerView rv, MotionEvent e); } /** * An OnScrollListener can be set on a RecyclerView to receive messages * when a scrolling event has occurred on that RecyclerView. * * @see RecyclerView#setOnScrollListener(OnScrollListener) */ public interface OnScrollListener { public void onScrollStateChanged(int newState); public void onScrolled(int dx, int dy); } /** * A RecyclerListener can be set on a RecyclerView to receive messages whenever * a view is recycled. * * @see RecyclerView#setRecyclerListener(RecyclerListener) */ public interface RecyclerListener { /** * This method is called whenever the view in the ViewHolder is recycled. * * @param holder The ViewHolder containing the view that was recycled */ public void onViewRecycled(ViewHolder holder); } /** * Interface definition for a callback to be invoked when an item in this * RecyclerView.Adapter has been clicked. */ public interface OnItemClickListener { /** * Callback method to be invoked when an item in this RecyclerView.Adapter has * been clicked. *

* Implementers can call getPosition(position) if they need * to access the data associated with the selected item. * * @param view The view within the RecyclerView.Adapter that was clicked (this * will be a view provided by the adapter) * @param position The position of the view in the adapter. */ void onItemClick(View view, int position); } public static OnItemClickListener mOnItemClickListener = null; /** * Register a callback to be invoked when an item in this AdapterView has * been clicked. * * @param listener The callback that will be invoked. */ public void setOnItemClickListener(OnItemClickListener listener) { mOnItemClickListener = listener; } /** * @return The callback to be invoked with an item in this AdapterView has * been clicked, or null id no callback has been set. */ public final OnItemClickListener getOnItemClickListener() { return mOnItemClickListener; } /** * A ViewHolder describes an item view and metadata about its place within the RecyclerView. * *

{@link Adapter} implementations should subclass ViewHolder and add fields for caching * potentially expensive {@link View#findViewById(int)} results.

* *

While {@link LayoutParams} belong to the {@link LayoutManager}, * {@link ViewHolder ViewHolders} belong to the adapter. Adapters should feel free to use * their own custom ViewHolder implementations to store data that makes binding view contents * easier. Implementations should assume that individual item views will hold strong references * to ViewHolder objects and that RecyclerView instances may hold * strong references to extra off-screen item views for caching purposes

*/ public static abstract class ViewHolder implements OnClickListener{ public final View itemView; int mPosition = NO_POSITION; int mOldPosition = NO_POSITION; long mItemId = NO_ID; int mItemViewType = INVALID_TYPE; /** * This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType * are all valid. */ static final int FLAG_BOUND = 1 << 0; /** * The data this ViewHolder's view reflects is stale and needs to be rebound * by the adapter. mPosition and mItemId are consistent. */ static final int FLAG_UPDATE = 1 << 1; /** * This ViewHolder's data is invalid. The identity implied by mPosition and mItemId * are not to be trusted and may no longer match the item view type. * This ViewHolder must be fully rebound to different data. */ static final int FLAG_INVALID = 1 << 2; /** * This ViewHolder points at data that represents an item previously removed from the * data set. Its view may still be used for things like outgoing animations. */ static final int FLAG_REMOVED = 1 << 3; /** * This ViewHolder should not be recycled. This flag is set via setIsRecyclable() * and is intended to keep views around during animations. */ static final int FLAG_NOT_RECYCLABLE = 1 << 4; private int mFlags; private int mIsRecyclableCount = 0; // If non-null, view is currently considered scrap and may be reused for other data by the // scrap container. private Recycler mScrapContainer = null; @Override public void onClick(View v) { if (mOnItemClickListener != null) { mOnItemClickListener.onItemClick(itemView, getPosition()); } } public ViewHolder(View itemView) { if (itemView == null) { throw new IllegalArgumentException("itemView may not be null"); } this.itemView = itemView; this.itemView.setOnClickListener(this); } void offsetPosition(int offset) { if (mOldPosition == NO_POSITION) { mOldPosition = mPosition; } mPosition += offset; } void clearOldPosition() { mOldPosition = NO_POSITION; } public final int getPosition() { return mOldPosition == NO_POSITION ? mPosition : mOldPosition; } public final long getItemId() { return mItemId; } public final int getItemViewType() { return mItemViewType; } boolean isScrap() { return mScrapContainer != null; } void unScrap() { mScrapContainer.unscrapView(this); mScrapContainer = null; } void setScrapContainer(Recycler recycler) { mScrapContainer = recycler; } boolean isInvalid() { return (mFlags & FLAG_INVALID) != 0; } boolean needsUpdate() { return (mFlags & FLAG_UPDATE) != 0; } boolean isBound() { return (mFlags & FLAG_BOUND) != 0; } boolean isRemoved() { return (mFlags & FLAG_REMOVED) != 0; } void setFlags(int flags, int mask) { mFlags = (mFlags & ~mask) | (flags & mask); } void addFlags(int flags) { mFlags |= flags; } void clearFlagsForSharedPool() { mFlags = 0; } @Override public String toString() { final StringBuilder sb = new StringBuilder("ViewHolder{" + Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId); if (isScrap()) sb.append(" scrap"); if (isInvalid()) sb.append(" invalid"); if (!isBound()) sb.append(" unbound"); if (needsUpdate()) sb.append(" update"); if (isRemoved()) sb.append(" removed"); sb.append("}"); return sb.toString(); } /** * Informs the recycler whether this item can be recycled. Views which are not * recyclable will not be reused for other items until setIsRecyclable() is * later set to true. Calls to setIsRecyclable() should always be paired (one * call to setIsRecyclabe(false) should always be matched with a later call to * setIsRecyclable(true)). Pairs of calls may be nested, as the state is internally * reference-counted. * * @param recyclable Whether this item is available to be recycled. Default value * is true. */ public final void setIsRecyclable(boolean recyclable) { mIsRecyclableCount = recyclable ? mIsRecyclableCount - 1 : mIsRecyclableCount + 1; if (mIsRecyclableCount < 0) { mIsRecyclableCount = 0; Log.e(VIEW_LOG_TAG, "isRecyclable decremented below 0: " + "unmatched pair of setIsRecyable() calls"); } else if (!recyclable && mIsRecyclableCount == 1) { mFlags |= FLAG_NOT_RECYCLABLE; } else if (recyclable && mIsRecyclableCount == 0) { mFlags &= ~FLAG_NOT_RECYCLABLE; } } /** * @see {@link #setIsRecyclable(boolean)} * * @return true if this item is available to be recycled, false otherwise. */ public final boolean isRecyclable() { return (mFlags & FLAG_NOT_RECYCLABLE) == 0 && !ViewCompat.hasTransientState(itemView); } } /** * Queued operation to happen when child views are updated. */ private static class UpdateOp { public static final int ADD = 0; public static final int REMOVE = 1; public static final int UPDATE = 2; static final int POOL_SIZE = 30; public int cmd; public int positionStart; public int itemCount; public UpdateOp(int cmd, int positionStart, int itemCount) { this.cmd = cmd; this.positionStart = positionStart; this.itemCount = itemCount; } } UpdateOp obtainUpdateOp(int cmd, int positionStart, int itemCount) { UpdateOp op = mUpdateOpPool.acquire(); if (op == null) { op = new UpdateOp(cmd, positionStart, itemCount); } else { op.cmd = cmd; op.positionStart = positionStart; op.itemCount = itemCount; } return op; } void recycleUpdateOp(UpdateOp op) { mUpdateOpPool.release(op); } /** * {@link android.view.ViewGroup.MarginLayoutParams LayoutParams} subclass for children of * {@link RecyclerView}. Custom {@link LayoutManager layout managers} are encouraged * to create their own subclass of this LayoutParams class * to store any additional required per-child view metadata about the layout. */ public static class LayoutParams extends MarginLayoutParams { ViewHolder mViewHolder; final Rect mDecorInsets = new Rect(); boolean mInsetsDirty = true; public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); } public LayoutParams(int width, int height) { super(width, height); } public LayoutParams(MarginLayoutParams source) { super(source); } public LayoutParams(ViewGroup.LayoutParams source) { super(source); } public LayoutParams(LayoutParams source) { super((ViewGroup.LayoutParams) source); } /** * Returns true if the view this LayoutParams is attached to needs to have its content * updated from the corresponding adapter. * * @return true if the view should have its content updated */ public boolean viewNeedsUpdate() { return mViewHolder.needsUpdate(); } /** * Returns true if the view this LayoutParams is attached to is now representing * potentially invalid data. A LayoutManager should scrap/recycle it. * * @return true if the view is invalid */ public boolean isViewInvalid() { return mViewHolder.isInvalid(); } /** * Returns true if the adapter data item corresponding to the view this LayoutParams * is attached to has been removed from the data set. A LayoutManager may choose to * treat it differently in order to animate its outgoing or disappearing state. * * @return true if the item the view corresponds to was removed from the data set */ public boolean isItemRemoved() { return mViewHolder.isRemoved(); } /** * Returns the position that the view this LayoutParams is attached to corresponds to. * * @return the adapter position this view was bound from */ public int getViewPosition() { return mViewHolder.getPosition(); } } /** * Observer base class for watching changes to an {@link Adapter}. * See {@link Adapter#registerAdapterDataObserver(AdapterDataObserver)}. */ public static abstract class AdapterDataObserver { public void onChanged() { // Do nothing } public void onItemRangeChanged(int positionStart, int itemCount) { // do nothing } public void onItemRangeInserted(int positionStart, int itemCount) { // do nothing } public void onItemRangeRemoved(int positionStart, int itemCount) { // do nothing } } /** *

Base class for smooth scrolling. Handles basic tracking of the target view position and * provides methods to trigger a programmatic scroll.

* * @see LinearSmoothScroller */ public static abstract class SmoothScroller { private int mTargetPosition = RecyclerView.NO_POSITION; private RecyclerView mRecyclerView; private LayoutManager mLayoutManager; private boolean mPendingInitialRun; private boolean mRunning; private View mTargetView; private final Action mRecyclingAction; public SmoothScroller() { mRecyclingAction = new Action(0, 0); } /** * Starts a smooth scroll for the given target position. *

In each animation step, {@link RecyclerView} will check * for the target view and call either * {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or * {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)} until * SmoothScroller is stopped.

* *

Note that if RecyclerView finds the target view, it will automatically stop the * SmoothScroller. This does not mean that scroll will stop, it only means it will * stop calling SmoothScroller in each animation step.

*/ void start(RecyclerView recyclerView, LayoutManager layoutManager) { mRecyclerView = recyclerView; mLayoutManager = layoutManager; if (mTargetPosition == RecyclerView.NO_POSITION) { throw new IllegalArgumentException("Invalid target position"); } mRecyclerView.mState.mTargetPosition = mTargetPosition; mRunning = true; mPendingInitialRun = true; mTargetView = findViewByPosition(getTargetPosition()); onStart(); mRecyclerView.mViewFlinger.postOnAnimation(); } public void setTargetPosition(int targetPosition) { mTargetPosition = targetPosition; } /** * @return The LayoutManager to which this SmoothScroller is attached */ public LayoutManager getLayoutManager() { return mLayoutManager; } /** * Stops running the SmoothScroller in each animation callback. Note that this does not * cancel any existing {@link Action} updated by * {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or * {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)}. */ final protected void stop() { if (!mRunning) { return; } onStop(); mRecyclerView.mState.mTargetPosition = RecyclerView.NO_POSITION; mTargetView = null; mTargetPosition = RecyclerView.NO_POSITION; mPendingInitialRun = false; mRunning = false; // trigger a cleanup mLayoutManager.onSmoothScrollerStopped(this); // clear references to avoid any potential leak by a custom smooth scroller mLayoutManager = null; mRecyclerView = null; } /** * Returns true if SmoothScroller has beens started but has not received the first * animation * callback yet. * * @return True if this SmoothScroller is waiting to start */ public boolean isPendingInitialRun() { return mPendingInitialRun; } /** * @return True if SmoothScroller is currently active */ public boolean isRunning() { return mRunning; } /** * Returns the adapter position of the target item * * @return Adapter position of the target item or * {@link RecyclerView#NO_POSITION} if no target view is set. */ public int getTargetPosition() { return mTargetPosition; } private void onAnimation(int dx, int dy) { if (!mRunning || mTargetPosition == RecyclerView.NO_POSITION) { stop(); } mPendingInitialRun = false; if (mTargetView != null) { // verify target position if (getChildPosition(mTargetView) == mTargetPosition) { onTargetFound(mTargetView, mRecyclerView.mState, mRecyclingAction); mRecyclingAction.runInNecessary(mRecyclerView); stop(); } else { Log.e(TAG, "Passed over target position while smooth scrolling."); mTargetView = null; } } if (mRunning) { onSeekTargetStep(dx, dy, mRecyclerView.mState, mRecyclingAction); mRecyclingAction.runInNecessary(mRecyclerView); } } /** * @see RecyclerView#getChildPosition(android.view.View) */ public int getChildPosition(View view) { return mRecyclerView.getChildPosition(view); } /** * @see RecyclerView#getChildCount() */ public int getChildCount() { return mRecyclerView.getChildCount(); } /** * @see RecyclerView.LayoutManager#findViewByPosition(int) */ public View findViewByPosition(int position) { return mRecyclerView.mLayout.findViewByPosition(position); } /** * @see RecyclerView#scrollToPosition(int) */ public void instantScrollToPosition(int position) { mRecyclerView.scrollToPosition(position); } protected void onChildAttachedToWindow(View child) { if (getChildPosition(child) == getTargetPosition()) { mTargetView = child; if (DEBUG) { Log.d(TAG, "smooth scroll target view has been attached"); } } } /** * Normalizes the vector. * @param scrollVector The vector that points to the target scroll position */ protected void normalize(PointF scrollVector) { final double magnitute = Math.sqrt(scrollVector.x * scrollVector.x + scrollVector.y * scrollVector.y); scrollVector.x /= magnitute; scrollVector.y /= magnitute; } /** * Called when smooth scroll is started. This might be a good time to do setup. */ abstract protected void onStart(); /** * Called when smooth scroller is stopped. This is a good place to cleanup your state etc. * @see #stop() */ abstract protected void onStop(); /** *

RecyclerView will call this method each time it scrolls until it can find the target * position in the layout.

*

SmoothScroller should check dx, dy and if scroll should be changed, update the * provided {@link Action} to define the next scroll.

* * @param dx Last scroll amount horizontally * @param dy Last scroll amount verticaully * @param state Transient state of RecyclerView * @param action If you want to trigger a new smooth scroll and cancel the previous one, * update this object. */ abstract protected void onSeekTargetStep(int dx, int dy, State state, Action action); /** * Called when the target position is laid out. This is the last callback SmoothScroller * will receive and it should update the provided {@link Action} to define the scroll * details towards the target view. * @param targetView The view element which render the target position. * @param state Transient state of RecyclerView * @param action Action instance that you should update to define final scroll action * towards the targetView * @return An {@link Action} to finalize the smooth scrolling */ abstract protected void onTargetFound(View targetView, State state, Action action); /** * Holds information about a smooth scroll request by a {@link SmoothScroller}. */ public static class Action { public static final int UNDEFINED_DURATION = Integer.MIN_VALUE; private int mDx; private int mDy; private int mDuration; private Interpolator mInterpolator; private boolean changed = false; // we track this variable to inform custom implementer if they are updating the action // in every animation callback private int consecutiveUpdates = 0; /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically */ public Action(int dx, int dy) { this(dx, dy, UNDEFINED_DURATION, null); } /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds */ public Action(int dx, int dy, int duration) { this(dx, dy, duration, null); } /** * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds * @param interpolator Interpolator to be used when calculating scroll position in each * animation step */ public Action(int dx, int dy, int duration, Interpolator interpolator) { mDx = dx; mDy = dy; mDuration = duration; mInterpolator = interpolator; } private void runInNecessary(RecyclerView recyclerView) { if (changed) { validate(); if (mInterpolator == null) { if (mDuration == UNDEFINED_DURATION) { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy); } else { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration); } } else { recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration, mInterpolator); } consecutiveUpdates ++; if (consecutiveUpdates > 10) { // A new action is being set in every animation step. This looks like a bad // implementation. Inform developer. Log.e(TAG, "Smooth Scroll action is being updated too frequently. Make sure" + " you are not changing it unless necessary"); } changed = false; } else { consecutiveUpdates = 0; } } private void validate() { if (mInterpolator != null && mDuration < 1) { throw new IllegalStateException("If you provide an interpolator, you must" + " set a positive duration"); } else if (mDuration < 1) { throw new IllegalStateException("Scroll duration must be a positive number"); } } public int getDx() { return mDx; } public void setDx(int dx) { changed = true; mDx = dx; } public int getDy() { return mDy; } public void setDy(int dy) { changed = true; mDy = dy; } public int getDuration() { return mDuration; } public void setDuration(int duration) { changed = true; mDuration = duration; } public Interpolator getInterpolator() { return mInterpolator; } /** * Sets the interpolator to calculate scroll steps * @param interpolator The interpolator to use. If you specify an interpolator, you must * also set the duration. * @see #setDuration(int) */ public void setInterpolator(Interpolator interpolator) { changed = true; mInterpolator = interpolator; } /** * Updates the action with given parameters. * @param dx Pixels to scroll horizontally * @param dy Pixels to scroll vertically * @param duration Duration of the animation in milliseconds * @param interpolator Interpolator to be used when calculating scroll position in each * animation step */ public void update(int dx, int dy, int duration, Interpolator interpolator) { mDx = dx; mDy = dy; mDuration = duration; mInterpolator = interpolator; changed = true; } } } static class AdapterDataObservable extends Observable { public boolean hasObservers() { return !mObservers.isEmpty(); } public void notifyChanged() { // since onChanged() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onChanged(); } } public void notifyItemRangeChanged(int positionStart, int itemCount) { // since onItemRangeChanged() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeChanged(positionStart, itemCount); } } public void notifyItemRangeInserted(int positionStart, int itemCount) { // since onItemRangeInserted() is implemented by the app, it could do anything, // including removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeInserted(positionStart, itemCount); } } public void notifyItemRangeRemoved(int positionStart, int itemCount) { // since onItemRangeRemoved() is implemented by the app, it could do anything, including // removing itself from {@link mObservers} - and that could cause problems if // an iterator is used on the ArrayList {@link mObservers}. // to avoid such problems, just march thru the list in the reverse order. for (int i = mObservers.size() - 1; i >= 0; i--) { mObservers.get(i).onItemRangeRemoved(positionStart, itemCount); } } } static class SavedState extends BaseSavedState { Parcelable mLayoutState; /** * called by CREATOR */ SavedState(Parcel in) { super(in); mLayoutState = in.readParcelable(LayoutManager.class.getClassLoader()); } /** * Called by onSaveInstanceState */ SavedState(Parcelable superState) { super(superState); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeParcelable(mLayoutState, 0); } private void copyFrom(SavedState other) { mLayoutState = other.mLayoutState; } public static final Parcelable.Creator CREATOR = new Parcelable.Creator() { @Override public SavedState createFromParcel(Parcel in) { return new SavedState(in); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }; } /** *

Contains useful information about the current RecyclerView state like target scroll * position or view focus. State object can also keep arbitrary data, identified by resource * ids.

*

Often times, RecyclerView components will need to pass information between each other. * To provide a well defined data bus between components, RecyclerView passes the same State * object to component callbacks and these components can use it to exchange data.

*

If you implement custom components, you can use State's put/get/remove methods to pass * data between your components without needing to manage their lifecycles.

*/ public static class State { private int mTargetPosition = RecyclerView.NO_POSITION; private ArrayMap mPreLayoutHolderMap = new ArrayMap(); private ArrayMap mPostLayoutHolderMap = new ArrayMap(); private SparseArray mData; /** * Number of items adapter has. */ private int mItemCount = 0; /** * Number of items adapter had in the previous layout. */ private int mPreviousLayoutItemCount = 0; /** * Number of items that were NOT laid out but has been deleted from the adapter after the * previous layout. */ private int mDeletedInvisibleItemCountSincePreviousLayout = 0; private boolean mStructureChanged = false; private boolean mInPreLayout = false; State reset() { mTargetPosition = RecyclerView.NO_POSITION; if (mData != null) { mData.clear(); } mItemCount = 0; mStructureChanged = false; return this; } public boolean isPreLayout() { return mInPreLayout; } /** * Removes the mapping from the specified id, if there was any. * @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* to * preserve cross functionality and avoid conflicts. */ public void remove(int resourceId) { if (mData == null) { return; } mData.remove(resourceId); } /** * Gets the Object mapped from the specified id, or null * if no such data exists. * * @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* * to * preserve cross functionality and avoid conflicts. */ public T get(int resourceId) { if (mData == null) { return null; } return (T) mData.get(resourceId); } /** * Adds a mapping from the specified id to the specified value, replacing the previous * mapping from the specified key if there was one. * * @param resourceId Id of the resource you want to add. It is suggested to use R.id.* to * preserve cross functionality and avoid conflicts. * @param data The data you want to associate with the resourceId. */ public void put(int resourceId, Object data) { if (mData == null) { mData = new SparseArray(); } mData.put(resourceId, data); } /** * If scroll is triggered to make a certain item visible, this value will return the * adapter index of that item. * @return Adapter index of the target item or * {@link RecyclerView#NO_POSITION} if there is no target * position. */ public int getTargetScrollPosition() { return mTargetPosition; } /** * Returns if current scroll has a target position. * @return true if scroll is being triggered to make a certain position visible * @see #getTargetScrollPosition() */ public boolean hasTargetScrollPosition() { return mTargetPosition != RecyclerView.NO_POSITION; } /** * @return true if the structure of the data set has changed since the last call to * onLayoutChildren, false otherwise */ public boolean didStructureChange() { return mStructureChanged; } /** * @return Total number of items to be laid out. Note that, this number is not necessarily * equal to the number of items in the adapter, so you should always use this number for * your position calculations and never call adapter directly. */ public int getItemCount() { return mInPreLayout ? (mPreviousLayoutItemCount - mDeletedInvisibleItemCountSincePreviousLayout) : mItemCount; } } /** * Internal listener that manages items after animations finish. This is how items are * retained (not recycled) during animations, but allowed to be recycled afterwards. * It depends on the contract with the ItemAnimator to call the appropriate dispatch*Finished() * method on the animator's listener when it is done animating any item. */ private class ItemAnimatorRestoreListener implements ItemAnimator.ItemAnimatorListener { @Override public void onRemoveFinished(ViewHolder item) { item.setIsRecyclable(true); removeAnimatingView(item.itemView); removeDetachedView(item.itemView, false); } @Override public void onAddFinished(ViewHolder item) { item.setIsRecyclable(true); removeAnimatingView(item.itemView); } @Override public void onMoveFinished(ViewHolder item) { item.setIsRecyclable(true); removeAnimatingView(item.itemView); } }; /** * This class defines the animations that take place on items as changes are made * to the adapter. * * Subclasses of ItemAnimator can be used to implement custom animations for actions on * ViewHolder items. The RecyclerView will manage retaining these items while they * are being animated, but implementors must call the appropriate "Finished" * method when each item animation is done ({@link #dispatchRemoveFinished(ViewHolder)}, * {@link #dispatchMoveFinished(ViewHolder)}, or {@link #dispatchAddFinished(ViewHolder)}). * *

By default, RecyclerView uses {@link DefaultItemAnimator}

* * @see #setItemAnimator(ItemAnimator) */ public static abstract class ItemAnimator { private ItemAnimatorListener mListener = null; private ArrayList mFinishedListeners = new ArrayList(); private long mAddDuration = 120; private long mRemoveDuration = 120; private long mMoveDuration = 250; /** * Gets the current duration for which all move animations will run. * * @return The current move duration */ public long getMoveDuration() { return mMoveDuration; } /** * Sets the current duration for which all move animations will run. * * @param moveDuration The current move duration */ public void setMoveDuration(long moveDuration) { mMoveDuration = moveDuration; } /** * Gets the current duration for which all add animations will run. * * @return The current add duration */ public long getAddDuration() { return mAddDuration; } /** * Sets the current duration for which all add animations will run. * * @param addDuration The current add duration */ public void setAddDuration(long addDuration) { mAddDuration = addDuration; } /** * Gets the current duration for which all remove animations will run. * * @return The current remove duration */ public long getRemoveDuration() { return mRemoveDuration; } /** * Sets the current duration for which all remove animations will run. * * @param removeDuration The current remove duration */ public void setRemoveDuration(long removeDuration) { mRemoveDuration = removeDuration; } /** * Internal only: * Sets the listener that must be called when the animator is finished * animating the item (or immediately if no animation happens). This is set * internally and is not intended to be set by external code. * * @param listener The listener that must be called. */ void setListener(ItemAnimatorListener listener) { mListener = listener; } /** * Called when there are pending animations waiting to be started. This state * is governed by the return values from {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and * {@link #animateRemove(ViewHolder) animateRemove()}, which inform the * RecyclerView that the ItemAnimator wants to be called later to start the * associated animations. runPendingAnimations() will be scheduled to be run * on the next frame. */ abstract public void runPendingAnimations(); /** * Called when an item is removed from the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchRemoveFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimators {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and * {@link #animateRemove(ViewHolder) animateRemove()} come in one by one, then * start the animations together in the later call to {@link #runPendingAnimations()}. * *

This method may also be called for disappearing items which continue to exist in the * RecyclerView, but for which the system does not have enough information to animate * them out of view. In that case, the default animation for removing items is run * on those items as well.

* * @param holder The item that is being removed. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateRemove(ViewHolder holder); /** * Called when an item is added to the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchAddFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimators {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and * {@link #animateRemove(ViewHolder) animateRemove()} come in one by one, then * start the animations together in the later call to {@link #runPendingAnimations()}. * *

This method may also be called for appearing items which were already in the * RecyclerView, but for which the system does not have enough information to animate * them into view. In that case, the default animation for adding items is run * on those items as well.

* * @param holder The item that is being added. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateAdd(ViewHolder holder); /** * Called when an item is moved in the RecyclerView. Implementors can choose * whether and how to animate that change, but must always call * {@link #dispatchMoveFinished(ViewHolder)} when done, either * immediately (if no animation will occur) or after the animation actually finishes. * The return value indicates whether an animation has been set up and whether the * ItemAnimators {@link #runPendingAnimations()} method should be called at the * next opportunity. This mechanism allows ItemAnimator to set up individual animations * as separate calls to {@link #animateAdd(ViewHolder) animateAdd()}, * {@link #animateMove(ViewHolder, int, int, int, int) animateMove()}, and * {@link #animateRemove(ViewHolder) animateRemove()} come in one by one, then * start the animations together in the later call to {@link #runPendingAnimations()}. * * @param holder The item that is being moved. * @return true if a later call to {@link #runPendingAnimations()} is requested, * false otherwise. */ abstract public boolean animateMove(ViewHolder holder, int fromX, int fromY, int toX, int toY); /** * Method to be called by subclasses when a remove animation is done. * * @param item The item which has been removed */ public final void dispatchRemoveFinished(ViewHolder item) { if (mListener != null) { mListener.onRemoveFinished(item); } } /** * Method to be called by subclasses when a move animation is done. * * @param item The item which has been moved */ public final void dispatchMoveFinished(ViewHolder item) { if (mListener != null) { mListener.onMoveFinished(item); } } /** * Method to be called by subclasses when an add animation is done. * * @param item The item which has been added */ public final void dispatchAddFinished(ViewHolder item) { if (mListener != null) { mListener.onAddFinished(item); } } /** * Method called when an animation on a view should be ended immediately. * This could happen when other events, like scrolling, occur, so that * animating views can be quickly put into their proper end locations. * Implementations should ensure that any animations running on the item * are canceled and affected properties are set to their end values. * Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)} * should be called since the animations are effectively done when this * method is called. * * @param item The item for which an animation should be stopped. */ abstract public void endAnimation(ViewHolder item); /** * Method called when all item animations should be ended immediately. * This could happen when other events, like scrolling, occur, so that * animating views can be quickly put into their proper end locations. * Implementations should ensure that any animations running on any items * are canceled and affected properties are set to their end values. * Also, appropriate dispatch methods (e.g., {@link #dispatchAddFinished(ViewHolder)} * should be called since the animations are effectively done when this * method is called. */ abstract public void endAnimations(); /** * Method which returns whether there are any item animations currently running. * This method can be used to determine whether to delay other actions until * animations end. * * @return true if there are any item animations currently running, false otherwise. */ abstract public boolean isRunning(); /** * Like {@link #isRunning()}, this method returns whether there are any item * animations currently running. Addtionally, the listener passed in will be called * when there are no item animations running, either immediately (before the method * returns) if no animations are currently running, or when the currently running * animations are {@link #dispatchAnimationsFinished() finished}. * *

Note that the listener is transient - it is either called immediately and not * stored at all, or stored only until it is called when running animations * are finished sometime later.

* * @param listener A listener to be called immediately if no animations are running * or later when currently-running animations have finished. A null listener is * equivalent to calling {@link #isRunning()}. * @return true if there are any item animations currently running, false otherwise. */ public final boolean isRunning(ItemAnimatorFinishedListener listener) { boolean running = isRunning(); if (listener != null) { if (!running) { listener.onAnimationsFinished(); } else { mFinishedListeners.add(listener); } } return running; } /** * The interface to be implemented by listeners to animation events from this * ItemAnimator. This is used internally and is not intended for developers to * create directly. */ private interface ItemAnimatorListener { void onRemoveFinished(ViewHolder item); void onAddFinished(ViewHolder item); void onMoveFinished(ViewHolder item); } /** * This method should be called by ItemAnimator implementations to notify * any listeners that all pending and active item animations are finished. */ public final void dispatchAnimationsFinished() { final int count = mFinishedListeners.size(); for (int i = 0; i < count; ++i) { mFinishedListeners.get(i).onAnimationsFinished(); } mFinishedListeners.clear(); } /** * This interface is used to inform listeners when all pending or running animations * in an ItemAnimator are finished. This can be used, for example, to delay an action * in a data set until currently-running animations are complete. * * @see #isRunning(ItemAnimatorFinishedListener) */ public interface ItemAnimatorFinishedListener { void onAnimationsFinished(); } } /** * Internal data structure that holds information about an item's bounds. * This information is used in calculating item animations. */ private static class ItemHolderInfo { ViewHolder holder; int left, top, right, bottom; int position; ItemHolderInfo(ViewHolder holder, int left, int top, int right, int bottom, int position) { this.holder = holder; this.left = left; this.top = top; this.right = right; this.bottom = bottom; this.position = position; } }}

(编辑: jwzhangjie)

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