From 3b3ab0e040ecbeee2f916b969b1044a2b9e222bd Mon Sep 17 00:00:00 2001
From: Chet Haase <chet@google.com>
Date: Mon, 27 Jan 2014 12:39:48 -0800
Subject: [PATCH] Add demo for animating RecyclerView actions

Change-Id: Ie076db6646cf734706fe2ea8659ee57f3a7742e9
---
 samples/Support7Demos/AndroidManifest.xml     |  13 +-
 .../res/layout/animated_recycler_view.xml     |  59 +++
 .../res/layout/selectable_item.xml            |  19 +
 samples/Support7Demos/res/values/strings.xml  |  10 +-
 .../widget/AnimatedRecyclerView.java          | 457 ++++++++++++++++++
 .../widget/RecyclerViewActivity.java          |   6 +
 6 files changed, 561 insertions(+), 3 deletions(-)
 create mode 100644 samples/Support7Demos/res/layout/animated_recycler_view.xml
 create mode 100644 samples/Support7Demos/res/layout/selectable_item.xml
 create mode 100644 samples/Support7Demos/src/com/example/android/supportv7/widget/AnimatedRecyclerView.java

diff --git a/samples/Support7Demos/AndroidManifest.xml b/samples/Support7Demos/AndroidManifest.xml
index 0e9ed0b93..6f9b2373e 100644
--- a/samples/Support7Demos/AndroidManifest.xml
+++ b/samples/Support7Demos/AndroidManifest.xml
@@ -175,8 +175,17 @@
 
         <!-- RecyclerView samples -->
         <activity android:name=".widget.RecyclerViewActivity"
-                android:label="@string/recycler_view"
-                android:theme="@style/Theme.AppCompat">
+                  android:label="@string/recycler_view"
+                  android:theme="@style/Theme.AppCompat">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="com.example.android.supportv7.SAMPLE_CODE" />
+            </intent-filter>
+        </activity>
+
+        <activity android:name=".widget.AnimatedRecyclerView"
+                  android:label="@string/animated_recycler_view"
+                  android:theme="@style/Theme.AppCompat">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="com.example.android.supportv7.SAMPLE_CODE" />
diff --git a/samples/Support7Demos/res/layout/animated_recycler_view.xml b/samples/Support7Demos/res/layout/animated_recycler_view.xml
new file mode 100644
index 000000000..188a1548b
--- /dev/null
+++ b/samples/Support7Demos/res/layout/animated_recycler_view.xml
@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="vertical"
+              android:id="@+id/container"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <CheckBox
+            android:id="@+id/enableAnimations"
+            android:checked="true"
+            android:text="@string/enableAnimations"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"/>
+
+    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+                  android:orientation="horizontal"
+                  android:layout_width="match_parent"
+                  android:layout_height="wrap_content">
+
+        <Button
+                android:id="@+id/deleteButton"
+                android:layout_weight=".5"
+                android:layout_width="0dip"
+                android:layout_height="wrap_content"
+                android:onClick="deleteItem"
+                android:text="@string/delete_item"/>
+
+        <Button
+                android:layout_weight=".5"
+                android:layout_width="0dip"
+                android:layout_height="wrap_content"
+                android:onClick="addItem"
+                android:text="@string/add_item"/>
+
+        <Button
+                android:layout_weight=".5"
+                android:layout_width="0dip"
+                android:layout_height="wrap_content"
+                android:onClick="addDeleteItem"
+                android:text="@string/add_delete_item"/>
+
+        <Button
+                android:layout_weight=".5"
+                android:layout_width="0dip"
+                android:layout_height="wrap_content"
+                android:onClick="deleteAddItem"
+                android:text="@string/delete_add_item"/>
+
+        <Button
+                android:layout_weight=".5"
+                android:layout_width="0dip"
+                android:layout_height="wrap_content"
+                android:onClick="d1a2d3"
+                android:text="@string/d1a2d3"/>
+
+    </LinearLayout>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/samples/Support7Demos/res/layout/selectable_item.xml b/samples/Support7Demos/res/layout/selectable_item.xml
new file mode 100644
index 000000000..65a23ccc4
--- /dev/null
+++ b/samples/Support7Demos/res/layout/selectable_item.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="horizontal"
+              android:layout_width="match_parent"
+              android:layout_height="match_parent">
+
+    <CheckBox
+            android:id="@+id/selected"
+            android:onClick="checkboxClicked"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"/>
+
+    <TextView
+            android:id="@+id/text"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"/>
+
+</LinearLayout>
\ No newline at end of file
diff --git a/samples/Support7Demos/res/values/strings.xml b/samples/Support7Demos/res/values/strings.xml
index 5852d0a71..7e4e03c1a 100644
--- a/samples/Support7Demos/res/values/strings.xml
+++ b/samples/Support7Demos/res/values/strings.xml
@@ -95,10 +95,18 @@
     <string name="sample_media_route_activity_local">Local Playback</string>
     <string name="sample_media_route_activity_presentation">Local Playback on Presentation Display</string>
 
-    <string name="recycler_view">RecyclerView</string>
+    <string name="recycler_view">RecyclerView/RecyclerViewActivity</string>
+    <string name="animated_recycler_view">RecyclerView/AnimatedRecyclerView</string>
     <string name="linear_layout_manager">Linear Layout Manager</string>
     <string name="checkbox_orientation">Horz.</string>
     <string name="checkbox_reverse">Rev.</string>
     <string name="checkbox_layout_dir">Layout Dir</string>
     <string name="checkbox_stack_from_end">Stack From End</string>
+    <string name="enableAnimations">Animate Changes</string>
+    <string name="add_item">Add</string>
+    <string name="delete_item">Delete</string>
+    <string name="add_delete_item">A+D</string>
+    <string name="delete_add_item">D+A</string>
+    <string name="d1a2d3">d1a2d3</string>
+
 </resources>
diff --git a/samples/Support7Demos/src/com/example/android/supportv7/widget/AnimatedRecyclerView.java b/samples/Support7Demos/src/com/example/android/supportv7/widget/AnimatedRecyclerView.java
new file mode 100644
index 000000000..a6f346a7f
--- /dev/null
+++ b/samples/Support7Demos/src/com/example/android/supportv7/widget/AnimatedRecyclerView.java
@@ -0,0 +1,457 @@
+/*
+ * Copyright (C) 2014 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 com.example.android.supportv7.widget;
+
+import android.widget.CompoundButton;
+import com.example.android.supportv7.R;
+import android.app.Activity;
+import android.content.Context;
+import android.os.Bundle;
+import android.support.v4.view.MenuItemCompat;
+import android.support.v7.widget.RecyclerView;
+import android.util.DisplayMetrics;
+import android.util.TypedValue;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.CheckBox;
+import android.widget.TextView;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+public class AnimatedRecyclerView extends Activity {
+
+    private static final int SCROLL_DISTANCE = 80; // dp
+
+    private RecyclerView mRecyclerView;
+
+    private int mNumItemsAdded = 0;
+    ArrayList<String> mItems = new ArrayList<String>();
+    MyAdapter mAdapter;
+
+    static final boolean USE_CUSTOM_ANIMATIONS = false;
+
+    boolean mAnimationsEnabled = true;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.animated_recycler_view);
+
+        ViewGroup container = (ViewGroup) findViewById(R.id.container);
+        mRecyclerView = new RecyclerView(this);
+        mRecyclerView.setLayoutManager(new MyLayoutManager(this));
+        mRecyclerView.setHasFixedSize(true);
+        mRecyclerView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
+                ViewGroup.LayoutParams.MATCH_PARENT));
+        for (int i = 0; i < 6; ++i) {
+            mItems.add("Item #" + i);
+        }
+        mAdapter = new MyAdapter(mItems);
+        mRecyclerView.setAdapter(mAdapter);
+        container.addView(mRecyclerView);
+
+        CheckBox enableAnimations = (CheckBox) findViewById(R.id.enableAnimations);
+        enableAnimations.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                mAnimationsEnabled = isChecked;
+            }
+        });
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        super.onCreateOptionsMenu(menu);
+        MenuItemCompat.setShowAsAction(menu.add("Layout"), MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        mRecyclerView.requestLayout();
+        return super.onOptionsItemSelected(item);
+    }
+
+    public void checkboxClicked(View view) {
+        ViewGroup parent = (ViewGroup) view.getParent();
+        boolean selected = ((CheckBox) view).isChecked();
+        int index = mRecyclerView.indexOfChild(parent);
+        MyViewHolder holder = (MyViewHolder) mRecyclerView.getViewHolderForChildAt(index);
+        mAdapter.selectItem(holder, selected);
+    }
+
+    public void deleteItem(View view) {
+        int numItems = mItems.size();
+        if (numItems > 0) {
+            for (int i = numItems - 1; i >= 0; --i) {
+                final String itemText = mItems.get(i);
+                boolean selected = mAdapter.mSelected.get(itemText);
+                if (selected) {
+                    removeAtPosition(i);
+                }
+            }
+        }
+    }
+
+    private String generateNewText() {
+        return "Added Item #" + mNumItemsAdded++;
+    }
+
+    public void d1a2d3(View view) {
+        removeAtPosition(1);
+        addAtPosition(2, "Added Item #" + mNumItemsAdded++);
+        removeAtPosition(3);
+    }
+
+    private void removeAtPosition(int position) {
+        mItems.remove(position);
+        mAdapter.notifyItemRemoved(position);
+    }
+
+    private void addAtPosition(int position, String text) {
+        mItems.add(position, text);
+        mAdapter.mSelected.put(text, Boolean.FALSE);
+        mAdapter.notifyItemInserted(position);
+    }
+
+    public void addDeleteItem(View view) {
+        addItem(view);
+        deleteItem(view);
+    }
+
+    public void deleteAddItem(View view) {
+        deleteItem(view);
+        addItem(view);
+    }
+
+    public void addItem(View view) {
+        addAtPosition(3, "Added Item #" + mNumItemsAdded++);
+    }
+
+    /**
+     * A basic ListView-style LayoutManager.
+     */
+    class MyLayoutManager extends RecyclerView.LayoutManager {
+        private static final String TAG = "MyLayoutManager";
+        private int mFirstPosition;
+        private final int mScrollDistance;
+
+        public MyLayoutManager(Context c) {
+            final DisplayMetrics dm = c.getResources().getDisplayMetrics();
+            mScrollDistance = (int) (SCROLL_DISTANCE * dm.density + 0.5f);
+        }
+
+        @Override
+        public boolean supportsItemAnimations() {
+            return mAnimationsEnabled;
+        }
+
+        @Override
+        public void onLayoutChildren(RecyclerView.Adapter adapter, RecyclerView.Recycler recycler,
+                boolean structureChanged, RecyclerView.State state) {
+            int parentBottom = getHeight() - getPaddingBottom();
+
+            final View oldTopView = getChildCount() > 0 ? getChildAt(0) : null;
+            int oldTop = getPaddingTop();
+            if (oldTopView != null) {
+                oldTop = Math.min(oldTopView.getTop(), oldTop);
+            }
+
+            // Note that we add everything to the scrap, but we do not clean it up;
+            // that is handled by the RecyclerView after this method returns
+            detachAndScrapAttachedViews(recycler);
+
+            int top = oldTop;
+            int bottom = top;
+            final int left = getPaddingLeft();
+            final int right = getWidth() - getPaddingRight();
+
+            int count = state.getItemCount();
+            for (int i = 0; mFirstPosition + i < count && top < parentBottom; i++, top = bottom) {
+                View v = recycler.getViewForPosition(adapter, mFirstPosition + i);
+
+                RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) v.getLayoutParams();
+                if (!params.isItemRemoved()) {
+                    addView(v);
+                }
+                measureChild(v, 0, 0);
+                bottom = top + v.getMeasuredHeight();
+                v.layout(left, top, right, bottom);
+                if (params.isItemRemoved()) {
+                    parentBottom += v.getHeight();
+                }
+            }
+
+            // Now that we've run a full layout, figure out which views were not used
+            // (cached in previousViews). For each of these views, position it where
+            // it would go, according to its position relative to the visible
+            // positions in the list. This information will be used by RecyclerView to
+            // record post-layout positions of these items for the purposes of animating them
+            // out of view
+
+            View lastVisibleView = getChildAt(getChildCount() - 1);
+            if (lastVisibleView != null) {
+                RecyclerView.LayoutParams lastParams =
+                        (RecyclerView.LayoutParams) lastVisibleView.getLayoutParams();
+                int lastPosition = lastParams.getViewPosition();
+                final List<RecyclerView.ViewHolder> previousViews = recycler.getScrapList();
+                count = previousViews.size();
+                for (int i = 0; i < count; ++i) {
+                    View view = previousViews.get(i).itemView;
+                    RecyclerView.LayoutParams params =
+                            (RecyclerView.LayoutParams) view.getLayoutParams();
+                    int position = params.getViewPosition();
+                    int newTop;
+                    if (position < mFirstPosition) {
+                        newTop = view.getHeight() * (position - mFirstPosition);
+                    } else {
+                        newTop = lastVisibleView.getTop() + view.getHeight() *
+                                (position - lastPosition);
+                    }
+                    view.offsetTopAndBottom(newTop - view.getTop());
+                }
+            }
+        }
+
+        @Override
+        public RecyclerView.LayoutParams generateDefaultLayoutParams() {
+            return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
+                    ViewGroup.LayoutParams.WRAP_CONTENT);
+        }
+
+        @Override
+        public boolean canScrollVertically() {
+            return true;
+        }
+
+        @Override
+        public int scrollVerticallyBy(int dy, RecyclerView.Adapter adapter,
+                RecyclerView.Recycler recycler) {
+            if (getChildCount() == 0) {
+                return 0;
+            }
+
+            int scrolled = 0;
+            final int left = getPaddingLeft();
+            final int right = getWidth() - getPaddingRight();
+            if (dy < 0) {
+                while (scrolled > dy) {
+                    final View topView = getChildAt(0);
+                    final int hangingTop = Math.max(-topView.getTop(), 0);
+                    final int scrollBy = Math.min(scrolled - dy, hangingTop);
+                    scrolled -= scrollBy;
+                    offsetChildrenVertical(scrollBy);
+                    if (mFirstPosition > 0 && scrolled > dy) {
+                        mFirstPosition--;
+                        View v = recycler.getViewForPosition(adapter, mFirstPosition);
+                        addView(v, 0);
+                        measureChild(v, 0, 0);
+                        final int bottom = topView.getTop(); // TODO decorated top?
+                        final int top = bottom - v.getMeasuredHeight();
+                        v.layout(left, top, right, bottom);
+                    } else {
+                        break;
+                    }
+                }
+            } else if (dy > 0) {
+                final int parentHeight = getHeight();
+                while (scrolled < dy) {
+                    final View bottomView = getChildAt(getChildCount() - 1);
+                    final int hangingBottom = Math.max(bottomView.getBottom() - parentHeight, 0);
+                    final int scrollBy = -Math.min(dy - scrolled, hangingBottom);
+                    scrolled -= scrollBy;
+                    offsetChildrenVertical(scrollBy);
+                    if (scrolled < dy && getItemCount() > mFirstPosition + getChildCount()) {
+                        View v = recycler.getViewForPosition(adapter,
+                                mFirstPosition + getChildCount());
+                        final int top = getChildAt(getChildCount() - 1).getBottom();
+                        addView(v);
+                        measureChild(v, 0, 0);
+                        final int bottom = top + v.getMeasuredHeight();
+                        v.layout(left, top, right, bottom);
+                    } else {
+                        break;
+                    }
+                }
+            }
+            recycleViewsOutOfBounds(recycler);
+            return scrolled;
+        }
+
+        @Override
+        public View onFocusSearchFailed(View focused, int direction,
+                RecyclerView.Adapter adapter, RecyclerView.Recycler recycler) {
+            final int oldCount = getChildCount();
+
+            if (oldCount == 0) {
+                return null;
+            }
+
+            final int left = getPaddingLeft();
+            final int right = getWidth() - getPaddingRight();
+
+            View toFocus = null;
+            int newViewsHeight = 0;
+            if (direction == View.FOCUS_UP || direction == View.FOCUS_BACKWARD) {
+                while (mFirstPosition > 0 && newViewsHeight < mScrollDistance) {
+                    mFirstPosition--;
+                    View v = recycler.getViewForPosition(adapter, mFirstPosition);
+                    final int bottom = getChildAt(0).getTop(); // TODO decorated top?
+                    addView(v, 0);
+                    measureChild(v, 0, 0);
+                    final int top = bottom - v.getMeasuredHeight();
+                    v.layout(left, top, right, bottom);
+                    if (v.isFocusable()) {
+                        toFocus = v;
+                        break;
+                    }
+                }
+            }
+            if (direction == View.FOCUS_DOWN || direction == View.FOCUS_FORWARD) {
+                while (mFirstPosition + getChildCount() < getItemCount() &&
+                        newViewsHeight < mScrollDistance) {
+                    View v = recycler.getViewForPosition(adapter, mFirstPosition + getChildCount());
+                    final int top = getChildAt(getChildCount() - 1).getBottom();
+                    addView(v);
+                    measureChild(v, 0, 0);
+                    final int bottom = top + v.getMeasuredHeight();
+                    v.layout(left, top, right, bottom);
+                    if (v.isFocusable()) {
+                        toFocus = v;
+                        break;
+                    }
+                }
+            }
+
+            return toFocus;
+        }
+
+        public void recycleViewsOutOfBounds(RecyclerView.Recycler recycler) {
+            final int childCount = getChildCount();
+            final int parentWidth = getWidth();
+            final int parentHeight = getHeight();
+            boolean foundFirst = false;
+            int first = 0;
+            int last = 0;
+            for (int i = 0; i < childCount; i++) {
+                final View v = getChildAt(i);
+                if (v.hasFocus() || (v.getRight() >= 0 && v.getLeft() <= parentWidth &&
+                        v.getBottom() >= 0 && v.getTop() <= parentHeight)) {
+                    if (!foundFirst) {
+                        first = i;
+                        foundFirst = true;
+                    }
+                    last = i;
+                }
+            }
+            for (int i = childCount - 1; i > last; i--) {
+                removeAndRecycleViewAt(i, recycler);
+            }
+            for (int i = first - 1; i >= 0; i--) {
+                removeAndRecycleViewAt(i, recycler);
+            }
+            if (getChildCount() == 0) {
+                mFirstPosition = 0;
+            } else {
+                mFirstPosition += first;
+            }
+        }
+
+        @Override
+        public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) {
+            if (positionStart < mFirstPosition) {
+                mFirstPosition += itemCount;
+            }
+        }
+
+        @Override
+        public void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) {
+            if (positionStart < mFirstPosition) {
+                mFirstPosition -= itemCount;
+            }
+        }
+    }
+
+    class MyAdapter extends RecyclerView.Adapter {
+        private int mBackground;
+        List<String> mData;
+        HashMap<String, Boolean> mSelected = new HashMap<String, Boolean>();
+
+        public MyAdapter(List<String> data) {
+            TypedValue val = new TypedValue();
+            AnimatedRecyclerView.this.getTheme().resolveAttribute(
+                    R.attr.selectableItemBackground, val, true);
+            mBackground = val.resourceId;
+            mData = data;
+            for (String itemText : mData) {
+                mSelected.put(itemText, Boolean.FALSE);
+            }
+        }
+
+        @Override
+        public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+            MyViewHolder h = new MyViewHolder(getLayoutInflater().inflate(R.layout.selectable_item,
+                    null));
+            h.textView.setMinimumHeight(128);
+            h.textView.setFocusable(true);
+            h.textView.setBackgroundResource(mBackground);
+            return h;
+        }
+
+        @Override
+        public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
+            String itemText = mData.get(position);
+            ((MyViewHolder) holder).textView.setText(itemText);
+            boolean selected = false;
+            if (mSelected.get(itemText) != null) {
+                selected = mSelected.get(itemText);
+            }
+            ((MyViewHolder) holder).checkBox.setChecked(selected);
+        }
+
+        @Override
+        public int getItemCount() {
+            return mData.size();
+        }
+
+        public void selectItem(String itemText, boolean selected) {
+            mSelected.put(itemText, selected);
+        }
+
+        public void selectItem(MyViewHolder holder, boolean selected) {
+            mSelected.put((String) holder.textView.getText(), selected);
+        }
+    }
+
+    static class MyViewHolder extends RecyclerView.ViewHolder {
+        public TextView textView;
+        public CheckBox checkBox;
+
+        public MyViewHolder(View v) {
+            super(v);
+            textView = (TextView) v.findViewById(R.id.text);
+            checkBox = (CheckBox) v.findViewById(R.id.selected);
+        }
+
+        @Override
+        public String toString() {
+            return super.toString() + " \"" + textView.getText() + "\"";
+        }
+    }}
diff --git a/samples/Support7Demos/src/com/example/android/supportv7/widget/RecyclerViewActivity.java b/samples/Support7Demos/src/com/example/android/supportv7/widget/RecyclerViewActivity.java
index 223da652f..c5ab703e6 100644
--- a/samples/Support7Demos/src/com/example/android/supportv7/widget/RecyclerViewActivity.java
+++ b/samples/Support7Demos/src/com/example/android/supportv7/widget/RecyclerViewActivity.java
@@ -101,6 +101,12 @@ public class RecyclerViewActivity extends Activity {
             mScrollDistance = (int) (SCROLL_DISTANCE * dm.density + 0.5f);
         }
 
+        @Override
+        public void onLayoutChildren(RecyclerView.Adapter adapter, RecyclerView.Recycler recycler,
+                boolean structureChanged, RecyclerView.State state) {
+            layoutChildren(adapter, recycler, structureChanged);
+        }
+
         @Override
         public void layoutChildren(RecyclerView.Adapter adapter, RecyclerView.Recycler recycler,
                 boolean structureChanged) {