Merge "Cache display lists for Drawables"
diff --git a/api/current.txt b/api/current.txt
index 241c540..2c22472 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -10338,7 +10338,6 @@
     ctor public BitmapDrawable(android.content.res.Resources, java.lang.String);
     ctor public deprecated BitmapDrawable(java.io.InputStream);
     ctor public BitmapDrawable(android.content.res.Resources, java.io.InputStream);
-    method public void draw(android.graphics.Canvas);
     method public final android.graphics.Bitmap getBitmap();
     method public final android.graphics.drawable.Drawable.ConstantState getConstantState();
     method public int getGravity();
@@ -10364,7 +10363,6 @@
 
   public class ClipDrawable extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public ClipDrawable(android.graphics.drawable.Drawable, int, int);
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public void invalidateDrawable(android.graphics.drawable.Drawable);
     method public void scheduleDrawable(android.graphics.drawable.Drawable, java.lang.Runnable, long);
@@ -10378,7 +10376,6 @@
   public class ColorDrawable extends android.graphics.drawable.Drawable {
     ctor public ColorDrawable();
     ctor public ColorDrawable(int);
-    method public void draw(android.graphics.Canvas);
     method public int getColor();
     method public int getOpacity();
     method public void setAlpha(int);
@@ -10397,7 +10394,7 @@
     method public static android.graphics.drawable.Drawable createFromStream(java.io.InputStream, java.lang.String);
     method public static android.graphics.drawable.Drawable createFromXml(android.content.res.Resources, org.xmlpull.v1.XmlPullParser) throws java.io.IOException, org.xmlpull.v1.XmlPullParserException;
     method public static android.graphics.drawable.Drawable createFromXmlInner(android.content.res.Resources, org.xmlpull.v1.XmlPullParser, android.util.AttributeSet) throws java.io.IOException, org.xmlpull.v1.XmlPullParserException;
-    method public abstract void draw(android.graphics.Canvas);
+    method public void draw(android.graphics.Canvas);
     method public int getAlpha();
     method public final android.graphics.Rect getBounds();
     method public android.graphics.drawable.Drawable.Callback getCallback();
@@ -10421,6 +10418,7 @@
     method public void jumpToCurrentState();
     method public android.graphics.drawable.Drawable mutate();
     method protected void onBoundsChange(android.graphics.Rect);
+    method protected void onDraw(android.graphics.Canvas);
     method protected boolean onLevelChange(int);
     method protected boolean onStateChange(int[]);
     method public static int resolveOpacity(int, int);
@@ -10456,7 +10454,6 @@
 
   public class DrawableContainer extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public DrawableContainer();
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public void invalidateDrawable(android.graphics.drawable.Drawable);
     method public void scheduleDrawable(android.graphics.drawable.Drawable, java.lang.Runnable, long);
@@ -10497,7 +10494,6 @@
   public class GradientDrawable extends android.graphics.drawable.Drawable {
     ctor public GradientDrawable();
     ctor public GradientDrawable(android.graphics.drawable.GradientDrawable.Orientation, int[]);
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public android.graphics.drawable.GradientDrawable.Orientation getOrientation();
     method public boolean onStateChange(int[]);
@@ -10544,7 +10540,6 @@
   public class InsetDrawable extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public InsetDrawable(android.graphics.drawable.Drawable, int);
     ctor public InsetDrawable(android.graphics.drawable.Drawable, int, int, int, int);
-    method public void draw(android.graphics.Canvas);
     method public android.graphics.drawable.Drawable getDrawable();
     method public int getOpacity();
     method public void invalidateDrawable(android.graphics.drawable.Drawable);
@@ -10556,7 +10551,6 @@
 
   public class LayerDrawable extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public LayerDrawable(android.graphics.drawable.Drawable[]);
-    method public void draw(android.graphics.Canvas);
     method public android.graphics.drawable.Drawable findDrawableByLayerId(int);
     method public android.graphics.drawable.Drawable getDrawable(int);
     method public int getId(int);
@@ -10587,7 +10581,6 @@
     ctor public NinePatchDrawable(android.content.res.Resources, android.graphics.Bitmap, byte[], android.graphics.Rect, java.lang.String);
     ctor public deprecated NinePatchDrawable(android.graphics.NinePatch);
     ctor public NinePatchDrawable(android.content.res.Resources, android.graphics.NinePatch);
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public android.graphics.Paint getPaint();
     method public void setAlpha(int);
@@ -10606,7 +10599,6 @@
 
   public class PictureDrawable extends android.graphics.drawable.Drawable {
     ctor public PictureDrawable(android.graphics.Picture);
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public android.graphics.Picture getPicture();
     method public void setAlpha(int);
@@ -10620,7 +10612,6 @@
 
   public class RotateDrawable extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public RotateDrawable();
-    method public void draw(android.graphics.Canvas);
     method public android.graphics.drawable.Drawable getDrawable();
     method public int getOpacity();
     method public void invalidateDrawable(android.graphics.drawable.Drawable);
@@ -10632,7 +10623,6 @@
 
   public class ScaleDrawable extends android.graphics.drawable.Drawable implements android.graphics.drawable.Drawable.Callback {
     ctor public ScaleDrawable(android.graphics.drawable.Drawable, int, float, float);
-    method public void draw(android.graphics.Canvas);
     method public android.graphics.drawable.Drawable getDrawable();
     method public int getOpacity();
     method public void invalidateDrawable(android.graphics.drawable.Drawable);
@@ -10645,7 +10635,6 @@
   public class ShapeDrawable extends android.graphics.drawable.Drawable {
     ctor public ShapeDrawable();
     ctor public ShapeDrawable(android.graphics.drawable.shapes.Shape);
-    method public void draw(android.graphics.Canvas);
     method public int getOpacity();
     method public android.graphics.Paint getPaint();
     method public android.graphics.drawable.ShapeDrawable.ShaderFactory getShaderFactory();
diff --git a/graphics/java/android/graphics/drawable/BitmapDrawable.java b/graphics/java/android/graphics/drawable/BitmapDrawable.java
index 9360558..52e5b5b 100644
--- a/graphics/java/android/graphics/drawable/BitmapDrawable.java
+++ b/graphics/java/android/graphics/drawable/BitmapDrawable.java
@@ -456,7 +456,7 @@
     }
 
     @Override
-    public void draw(Canvas canvas) {
+    protected void onDraw(Canvas canvas) {
         Bitmap bitmap = mBitmap;
         if (bitmap != null) {
             final BitmapState state = mBitmapState;
diff --git a/graphics/java/android/graphics/drawable/Drawable.java b/graphics/java/android/graphics/drawable/Drawable.java
index b8365aa..cfb1983 100644
--- a/graphics/java/android/graphics/drawable/Drawable.java
+++ b/graphics/java/android/graphics/drawable/Drawable.java
@@ -39,6 +39,9 @@
 import android.util.StateSet;
 import android.util.TypedValue;
 import android.util.Xml;
+import android.view.DisplayList;
+import android.view.HardwareCanvas;
+import android.view.HardwareRenderer;
 import android.view.View;
 
 import java.io.IOException;
@@ -139,16 +142,96 @@
     private Rect mBounds = ZERO_BOUNDS_RECT;  // lazily becomes a new Rect()
     private WeakReference<Callback> mCallback = null;
     private boolean mVisible = true;
+    private DisplayList mDisplayList;
 
     private int mLayoutDirection;
 
     /**
      * Draw in its bounds (set via setBounds) respecting optional effects such
      * as alpha (set via setAlpha) and color filter (set via setColorFilter).
+     * <p>
+     * Overriding this method will prevent caching optimizations. To enable
+     * optimizations, override {@link #onDraw} instead.
      *
      * @param canvas The canvas to draw into
      */
-    public abstract void draw(Canvas canvas);
+    public void draw(Canvas canvas) {
+        if (canvas != null && canvas.isHardwareAccelerated()) {
+            final HardwareCanvas hardwareCanvas = (HardwareCanvas) canvas;
+            final DisplayList displayList = getDisplayList(hardwareCanvas);
+            if (displayList != null) {
+                final int restoreCount = hardwareCanvas.save(Canvas.MATRIX_SAVE_FLAG);
+                hardwareCanvas.translate(mBounds.left, mBounds.top);
+                hardwareCanvas.drawDisplayList(displayList);
+                hardwareCanvas.restoreToCount(restoreCount);
+                return;
+            }
+        }
+
+        onDraw(canvas);
+    }
+
+    /**
+     * Draw in its bounds (set via setBounds) respecting optional effects such
+     * as alpha (set via setAlpha) and color filter (set via setColorFilter).
+     * <p>
+     * Overriding this method, rather than {@link #draw}, enables caching
+     * optimizations that avoid re-drawing when unnecessary.
+     *
+     * @param canvas The canvas to draw into
+     */
+    protected void onDraw(Canvas canvas) {
+        throw new UnsupportedOperationException(
+                "Drawable subclasses must implement either draw or onDraw");
+    }
+
+    /**
+     * Gets a display list that can be used to draw this drawable again without
+     * invoking its draw method.
+     *
+     * @param hardwareCanvas The hardware canvas.
+     * @return A DisplayList ready to replay, or null if caching is not enabled.
+     * @hide
+     */
+    private DisplayList getDisplayList(HardwareCanvas hardwareCanvas) {
+        DisplayList displayList = mDisplayList;
+        if (displayList != null && displayList.isValid()) {
+            // Note: This code assumes that the display list previously generated
+            // is compatible with the given hardware canvas.  That might not be true
+            // if we start using multiple different types of hardware canvas
+            // in the system someday.
+            return displayList;
+        }
+
+        displayList = DisplayList.create(getClass().getName());
+        mDisplayList = displayList;
+
+        final Rect bounds = mBounds;
+        final int width = bounds.width();
+        final int height = bounds.height();
+        final HardwareCanvas canvas = displayList.start(width, height);
+        canvas.onPreDraw(null);
+
+        // Draw the display list with origin (0,0) so that if the position
+        // changes then we can translate without recreating the display list.
+        final int restoreCount = canvas.save();
+        try {
+            canvas.translate(-bounds.left, -bounds.top);
+            onDraw(canvas);
+        } finally {
+            canvas.restoreToCount(restoreCount);
+            canvas.onPostDraw();
+            displayList.end();
+        }
+
+        displayList.setLeftTopRightBottom(0, 0, width, height);
+        displayList.setClipToBounds(false);
+        return displayList;
+    }
+
+    private void invalidateDisplayList() {
+        mDisplayList = null;
+    }
 
     /**
      * Specify a bounding rectangle for the Drawable. This is where the drawable
@@ -163,10 +246,11 @@
 
         if (oldBounds.left != left || oldBounds.top != top ||
                 oldBounds.right != right || oldBounds.bottom != bottom) {
-            if (!oldBounds.isEmpty()) {
-                // first invalidate the previous bounds
-                invalidateSelf();
+            if (oldBounds.right - oldBounds.left != right - left
+                    || oldBounds.bottom - oldBounds.top != bottom - top) {
+                invalidateDisplayList();
             }
+
             mBounds.set(left, top, right, bottom);
             onBoundsChange(mBounds);
         }
@@ -354,6 +438,8 @@
      * @see #setCallback(android.graphics.drawable.Drawable.Callback) 
      */
     public void invalidateSelf() {
+        invalidateDisplayList();
+
         final Callback callback = getCallback();
         if (callback != null) {
             callback.invalidateDrawable(this);
diff --git a/graphics/java/android/graphics/drawable/GradientDrawable.java b/graphics/java/android/graphics/drawable/GradientDrawable.java
index 75184e0..6a9454c 100644
--- a/graphics/java/android/graphics/drawable/GradientDrawable.java
+++ b/graphics/java/android/graphics/drawable/GradientDrawable.java
@@ -472,7 +472,7 @@
     }
 
     @Override
-    public void draw(Canvas canvas) {
+    protected void onDraw(Canvas canvas) {
         if (!ensureValidRect()) {
             // nothing to draw
             return;
diff --git a/graphics/java/android/graphics/drawable/NinePatchDrawable.java b/graphics/java/android/graphics/drawable/NinePatchDrawable.java
index 515d3c1..ee64d7a 100644
--- a/graphics/java/android/graphics/drawable/NinePatchDrawable.java
+++ b/graphics/java/android/graphics/drawable/NinePatchDrawable.java
@@ -223,7 +223,7 @@
     }
 
     @Override
-    public void draw(Canvas canvas) {
+    protected void onDraw(Canvas canvas) {
         final Rect bounds = getBounds();
         final boolean needsMirroring = needsMirroring();
         if (needsMirroring) {
diff --git a/graphics/java/android/graphics/drawable/PictureDrawable.java b/graphics/java/android/graphics/drawable/PictureDrawable.java
index cb2d8f6..2118b23 100644
--- a/graphics/java/android/graphics/drawable/PictureDrawable.java
+++ b/graphics/java/android/graphics/drawable/PictureDrawable.java
@@ -60,7 +60,7 @@
     }
     
     @Override
-    public void draw(Canvas canvas) {
+    protected void onDraw(Canvas canvas) {
         if (mPicture != null) {
             Rect bounds = getBounds();
             canvas.save();
diff --git a/graphics/java/android/graphics/drawable/ShapeDrawable.java b/graphics/java/android/graphics/drawable/ShapeDrawable.java
index 93f2dc60..9ca3bbf 100644
--- a/graphics/java/android/graphics/drawable/ShapeDrawable.java
+++ b/graphics/java/android/graphics/drawable/ShapeDrawable.java
@@ -210,7 +210,7 @@
     }
 
     @Override
-    public void draw(Canvas canvas) {
+    protected void onDraw(Canvas canvas) {
         Rect r = getBounds();
         Paint paint = mShapeState.mPaint;