Stop GifDrawable in onFrameReady if all callbacks are Drawables.

When we use TransitionDrawable, the GifDrawable’s callback is always
non-null and always the TransitionDrawable, even if the
TransitionDrawable was removed from the view hierarchy. Checking up
the callback chain allows us to ensure that there’s a non-Drawable 
callback eventually.

library/src/main/java/com/bumptech/glide/load/resource/gif/GifDrawable.java

@@ -327,9 +327,18 @@ public int getOpacity() {
     return PixelFormat.TRANSPARENT;
   }
 
+  // See #1087.
+  private Callback findCallback() {
+    Callback callback = getCallback();
+    while (callback instanceof Drawable) {
+      callback = ((Drawable) callback).getCallback();
+    }
+    return callback;
+  }
+
   @Override
   public void onFrameReady() {
-    if (getCallback() == null) {
+    if (findCallback() == null) {
       stop();
       invalidateSelf();
       return;

library/src/test/java/com/bumptech/glide/load/resource/gif/GifDrawableTest.java

@@ -14,6 +14,7 @@
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import android.app.Application;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
@@ -24,10 +25,11 @@
 import android.graphics.PorterDuffColorFilter;
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
+import android.graphics.drawable.TransitionDrawable;
 import android.os.Build;
+import android.view.View;
 import com.bumptech.glide.gifdecoder.GifDecoder;
 import com.bumptech.glide.load.Transformation;
-import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
 import com.bumptech.glide.load.resource.gif.GifDrawableTest.BitmapTrackingShadowCanvas;
 import com.bumptech.glide.tests.GlideShadowLooper;
 import com.bumptech.glide.tests.Util;
@@ -59,10 +61,10 @@ public class GifDrawableTest {
   private int initialSdkVersion;
 
   @Mock private Drawable.Callback cb;
-  @Mock private BitmapPool bitmapPool;
   @Mock private GifFrameLoader frameLoader;
   @Mock private Paint paint;
   @Mock private Transformation<Bitmap> transformation;
+  private Application context;
 
   private static Paint isAPaint() {
     return isA(Paint.class);
@@ -75,6 +77,7 @@ private static Rect isARect() {
   @Before
   public void setUp() {
     MockitoAnnotations.initMocks(this);
+    context = RuntimeEnvironment.application;
     frameWidth = 120;
     frameHeight = 450;
     firstFrame = Bitmap.createBitmap(frameWidth, frameHeight, Bitmap.Config.RGB_565);
@@ -574,6 +577,30 @@ public void testThrowsIfCreatedWithNullState() {
     new GifDrawable(null);
   }
 
+  @Test
+  public void onFrameReady_whenAttachedToDrawableCallbackButNotViewCallback_stops() {
+    TransitionDrawable topLevel = new TransitionDrawable(new Drawable[] { drawable });
+    drawable.setCallback(topLevel);
+    topLevel.setCallback(null);
+
+    drawable.start();
+    drawable.onFrameReady();
+
+    assertThat(drawable.isRunning()).isFalse();
+  }
+
+  @Test
+  public void onFrameReady_whenAttachedtoDrawableCallbackWithViewCallbackParent_doesNotStop() {
+      TransitionDrawable topLevel = new TransitionDrawable(new Drawable[] { drawable });
+    drawable.setCallback(topLevel);
+    topLevel.setCallback(new View(context));
+
+    drawable.start();
+    drawable.onFrameReady();
+
+    assertThat(drawable.isRunning()).isTrue();
+  }
+
   private void verifyRanLoops(int loopCount, int frameCount) {
     // 1 for invalidate in start().
     verify(cb, times(1 + loopCount * frameCount)).invalidateDrawable(eq(drawable));