Decouple parallaxSpeedMultiplier from setDecodeDimensions().

Expose decode vertical center through ExtendedOptions.

Genericize BitmapDrawableImageView#getTypedDrawable().

Bug: 11691744
Change-Id: I62e05ab2136cf031eaf1752dba728156c97c87a6

5 files changed, 70 insertions, 33 deletions

diff --git a/sample/src/com/example/bitmapsample/BitmapView.java b/sample/src/com/example/bitmapsample/BitmapView.java
index 0613168..dc676dd 100644
--- a/sample/src/com/example/bitmapsample/BitmapView.java
+++ b/sample/src/com/example/bitmapsample/BitmapView.java
@@ -21,7 +21,6 @@ import android.graphics.Canvas;
 import android.util.AttributeSet;
 import android.widget.ListView;
 
-import com.android.bitmap.drawable.BasicBitmapDrawable;
 import com.android.bitmap.drawable.ExtendedBitmapDrawable;
 import com.android.bitmap.view.BitmapDrawableImageView;
 
@@ -29,7 +28,6 @@ public class BitmapView extends BitmapDrawableImageView {
     private final float mDensity;
 
     private ListView mListView;
-    private float mParallaxSpeedMultiplier;
 
     public BitmapView(Context c) {
         this(c, null);
@@ -47,8 +45,8 @@ public class BitmapView extends BitmapDrawableImageView {
 
     @Override
     protected void onSizeChanged(final int w, final int h, int oldw, int oldh) {
-        ExtendedBitmapDrawable drawable = (ExtendedBitmapDrawable) getBasicBitmapDrawable();
-        drawable.setDecodeDimensions(w, (int) (h * mParallaxSpeedMultiplier));
+        ExtendedBitmapDrawable drawable = getTypedDrawable();
+        drawable.setDecodeDimensions(w, h);
     }
 
     public void setListView(final ListView listView) {
@@ -57,14 +55,10 @@ public class BitmapView extends BitmapDrawableImageView {
 
     @Override
     protected void onDraw(final Canvas canvas) {
-        ExtendedBitmapDrawable drawable = (ExtendedBitmapDrawable) getBasicBitmapDrawable();
+        ExtendedBitmapDrawable drawable = getTypedDrawable();
         float fraction = (float) getBottom() / (mListView.getHeight() + getHeight());
         drawable.setParallaxFraction(fraction);
 
         super.onDraw(canvas);
     }
-
-    public void setParallaxSpeedMultiplier(final float parallaxSpeedMultiplier) {
-        mParallaxSpeedMultiplier = parallaxSpeedMultiplier;
-    }
 }
\ No newline at end of file
diff --git a/sample/src/com/example/bitmapsample/MainActivity.java b/sample/src/com/example/bitmapsample/MainActivity.java
index cd8f6ac..5a2ac3a 100644
--- a/sample/src/com/example/bitmapsample/MainActivity.java
+++ b/sample/src/com/example/bitmapsample/MainActivity.java
@@ -118,11 +118,10 @@ public class MainActivity extends Activity {
                 final ExtendedBitmapDrawable drawable = new ExtendedBitmapDrawable(getResources(),
                         mCache, true /* limit density */, opts);
 
-                v.setBasicBitmapDrawable(drawable);
+                v.setTypedDrawable(drawable);
                 v.setListView(mListView);
-                v.setParallaxSpeedMultiplier(NORMAL_PARALLAX_MULTIPLIER);
             }
-            v.getBasicBitmapDrawable().bind(new BitmapRequestKeyImpl(mItems[position]));
+            v.getTypedDrawable().bind(new BitmapRequestKeyImpl(mItems[position]));
             return v;
         }
     }
diff --git a/src/com/android/bitmap/drawable/BasicBitmapDrawable.java b/src/com/android/bitmap/drawable/BasicBitmapDrawable.java
index 684d322..a09daad 100644
--- a/src/com/android/bitmap/drawable/BasicBitmapDrawable.java
+++ b/src/com/android/bitmap/drawable/BasicBitmapDrawable.java
@@ -119,10 +119,12 @@ public class BasicBitmapDrawable extends Drawable implements DecodeCallback,
      *
      * All UI operations should be called from the UI thread.
      */
-    public final void setDecodeDimensions(int w, int h) {
-        mDecodeWidth = w;
-        mDecodeHeight = h;
-        bind(mCurrKey);
+    public void setDecodeDimensions(int width, int height) {
+        if (mDecodeWidth == 0 || mDecodeHeight == 0) {
+            mDecodeWidth = width;
+            mDecodeHeight = height;
+            setImage(mCurrKey);
+        }
     }
 
     /**
@@ -133,6 +135,9 @@ public class BasicBitmapDrawable extends Drawable implements DecodeCallback,
      */
     public void bind(RequestKey key) {
         Trace.beginSection("bind");
+        if (mCurrKey != null && mCurrKey.equals(key)) {
+            return;
+        }
         setImage(key);
         Trace.endSection();
     }
@@ -153,10 +158,6 @@ public class BasicBitmapDrawable extends Drawable implements DecodeCallback,
      * Should only be overriden, not called.
      */
     protected void setImage(final RequestKey key) {
-        if (mCurrKey != null && mCurrKey.equals(key)) {
-            return;
-        }
-
         Trace.beginSection("set image");
         Trace.beginSection("release reference");
         if (mBitmap != null) {
@@ -282,6 +283,10 @@ public class BasicBitmapDrawable extends Drawable implements DecodeCallback,
         return NO_MULTIPLIER;
     }
 
+    /**
+     * Clients can override this to specify which section of the source image to decode from.
+     * Possible applications include using face detection to always decode around facial features.
+     */
     protected float getDecodeVerticalCenter() {
         return VERTICAL_CENTER;
     }
diff --git a/src/com/android/bitmap/drawable/ExtendedBitmapDrawable.java b/src/com/android/bitmap/drawable/ExtendedBitmapDrawable.java
index 6d9f05f..b6093e7 100644
--- a/src/com/android/bitmap/drawable/ExtendedBitmapDrawable.java
+++ b/src/com/android/bitmap/drawable/ExtendedBitmapDrawable.java
@@ -61,7 +61,6 @@ public class ExtendedBitmapDrawable extends BasicBitmapDrawable implements
     private final ExtendedOptions mOpts;
 
     // Parallax.
-    private static final float DECODE_VERTICAL_CENTER = 1f / 3;
     private float mParallaxFraction = 1f / 2;
 
     // State changes.
@@ -157,12 +156,26 @@ public class ExtendedBitmapDrawable extends BasicBitmapDrawable implements
         setLoadState(LOAD_STATE_FAILED);
     }
 
+    /**
+     * Directly sets the decode width and height. The given height should already have had the
+     * parallaxSpeedMultiplier applied to it.
+     */
+    public void setExactDecodeDimensions(int width, int height) {
+        super.setDecodeDimensions(width, height);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * The given height should not have had the parallaxSpeedMultiplier applied to it.
+     */
     @Override
-    protected void setImage(final RequestKey key) {
-        if (mCurrKey != null && mCurrKey.equals(key)) {
-            return;
-        }
+    public void setDecodeDimensions(int width, int height) {
+        super.setDecodeDimensions(width, (int) (height * mOpts.parallaxSpeedMultiplier));
+    }
 
+    @Override
+    protected void setImage(final RequestKey key) {
         if (mCurrKey != null && getDecodeAggregator() != null) {
             getDecodeAggregator().forget(mCurrKey);
         }
@@ -212,13 +225,13 @@ public class ExtendedBitmapDrawable extends BasicBitmapDrawable implements
     }
 
     @Override
-    protected float getDrawVerticalOffsetMultiplier() {
+    protected final float getDrawVerticalOffsetMultiplier() {
         return mOpts.parallaxSpeedMultiplier;
     }
 
     @Override
     protected float getDecodeVerticalCenter() {
-        return DECODE_VERTICAL_CENTER;
+        return mOpts.decodeVerticalCenter;
     }
 
     private DecodeAggregator getDecodeAggregator() {
@@ -651,6 +664,23 @@ public class ExtendedBitmapDrawable extends BasicBitmapDrawable implements
         public final int features;
 
         /**
+         * Optional field for general decoding.
+         *
+         * This field determines which section of the source image to decode from. A value of 0
+         * indicates a preference for the very top of the source, while a value of 1 indicates a
+         * preference for the very bottom of the source. A value of .5 will result in the center
+         * of the source being decoded.
+         *
+         * This should not be confused with {@link #setParallaxFraction(float)}. This field
+         * determines the general section for decode. The parallax fraction then determines the
+         * slice from within that section for display.
+         *
+         * The default value of 1f / 3 provides a good heuristic for the subject's face in a
+         * portrait photo.
+         */
+        public float decodeVerticalCenter = 1f / 3;
+
+        /**
          * Required field if {@link #FEATURE_ORDERED_DISPLAY} is supported.
          */
         public DecodeAggregator decodeAggregator = null;
@@ -725,6 +755,10 @@ public class ExtendedBitmapDrawable extends BasicBitmapDrawable implements
          */
         private void validate()
                 throws IllegalStateException {
+            if (decodeVerticalCenter < 0 || decodeVerticalCenter > 1) {
+                throw new IllegalStateException(
+                        "ExtendedOptions: decodeVerticalCenter must be within 0 and 1, inclusive");
+            }
             if ((features & FEATURE_ORDERED_DISPLAY) != 0 && decodeAggregator == null) {
                 throw new IllegalStateException(
                         "ExtendedOptions: To support FEATURE_ORDERED_DISPLAY, "
diff --git a/src/com/android/bitmap/view/BitmapDrawableImageView.java b/src/com/android/bitmap/view/BitmapDrawableImageView.java
index b776c34..67ef3eb 100644
--- a/src/com/android/bitmap/view/BitmapDrawableImageView.java
+++ b/src/com/android/bitmap/view/BitmapDrawableImageView.java
@@ -47,18 +47,23 @@ public class BitmapDrawableImageView extends ImageView {
     }
 
     /**
-     * Get the source BasicBitmapDrawable for this BitmapDrawableImageView.
-     * @return The source drawable.
+     * Get the source drawable for this BitmapDrawableImageView.
+     * @return The source drawable casted to the given type, or null if the type does not match.
      */
-    public BasicBitmapDrawable getBasicBitmapDrawable() {
-        return mDrawable;
+    @SuppressWarnings("unchecked") // Cast to type parameter.
+    public <E extends BasicBitmapDrawable> E getTypedDrawable() {
+        try {
+            return (E) mDrawable;
+        } catch (Exception ignored) {
+            return null;
+        }
     }
 
     /**
-     * Set the given BasicBitmapDrawable as the source for this BitmapDrawableImageView.
+     * Set the given drawable as the source for this BitmapDrawableImageView.
      * @param drawable The source drawable.
      */
-    public void setBasicBitmapDrawable(BasicBitmapDrawable drawable) {
+    public <E extends BasicBitmapDrawable> void setTypedDrawable(E drawable) {
         super.setImageDrawable(drawable);
         unbindDrawable();
         mDrawable = drawable;