Add BackgroundManager release.

Change-Id: I5a4af31a214f2db26a399db39cf73d578dcbc71c

samples/SupportLeanbackDemos/src/com/example/android/leanback/BackgroundHelper.java

@@ -100,6 +100,7 @@ public class BackgroundHelper {
         private Bitmap loadBitmap(Activity activity, Object imageToken) {
             if (imageToken instanceof Integer) {
                 final int resourceId = (Integer) imageToken;
+                if (DEBUG) Log.v(TAG, "load resourceId " + resourceId);
                 Drawable drawable = ContextCompat.getDrawable(activity, resourceId);
                 if (drawable instanceof BitmapDrawable) {
                     return ((BitmapDrawable) drawable).getBitmap();
@@ -110,7 +111,7 @@ public class BackgroundHelper {
 
         private void applyBackground(Activity activity, Bitmap bitmap) {
             BackgroundManager backgroundManager = BackgroundManager.getInstance(activity);
-            if (bitmap == null || backgroundManager == null || !backgroundManager.isAttached()) {
+            if (backgroundManager == null || !backgroundManager.isAttached()) {
                 return;
             }
             backgroundManager.setBitmap(bitmap);
@@ -120,22 +121,34 @@ public class BackgroundHelper {
     private LoadBackgroundRunnable mRunnable;
     private LoadBitmapTask mTask;
 
-    public void attach(Activity activity) {
+    // Allocate a dedicated handler because there may be no view available
-        if (!ENABLED) {
+    // when setBackground is invoked.
-            return;
+    private Handler mHandler = new Handler();
-        }
-        BackgroundManager.getInstance(activity).attach(activity.getWindow());
-    }
 
     public void setBackground(Activity activity, Object imageToken) {
         if (!ENABLED) {
             return;
         }
-        Handler handler = activity.getWindow().getDecorView().getHandler();
         if (mRunnable != null) {
-            handler.removeCallbacks(mRunnable);
+            mHandler.removeCallbacks(mRunnable);
         }
         mRunnable = new LoadBackgroundRunnable(activity, imageToken);
-        handler.postDelayed(mRunnable, SET_BACKGROUND_DELAY_MS);
+        mHandler.postDelayed(mRunnable, SET_BACKGROUND_DELAY_MS);
+    }
+
+    static public void attach(Activity activity) {
+        if (!ENABLED) {
+            return;
+        }
+        if (DEBUG) Log.v(TAG, "attach to activity " + activity);
+        BackgroundManager.getInstance(activity).attach(activity.getWindow());
+    }
+
+    static public void release(Activity activity) {
+        if (!ENABLED) {
+            return;
+        }
+        if (DEBUG) Log.v(TAG, "release from activity " + activity);
+        BackgroundManager.getInstance(activity).release();
     }
 }

samples/SupportLeanbackDemos/src/com/example/android/leanback/BrowseActivity.java

@@ -23,4 +23,16 @@ public class BrowseActivity extends Activity {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.browse);
     }
+
+    @Override
+    public void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        BackgroundHelper.attach(this);
+    }
+
+    @Override
+    public void onStop() {
+        BackgroundHelper.release(this);
+        super.onStop();
+    }
 }

samples/SupportLeanbackDemos/src/com/example/android/leanback/BrowseFragment.java

@@ -67,7 +67,10 @@ public class BrowseFragment extends android.support.v17.leanback.app.BrowseFragm
                     RowPresenter.ViewHolder rowViewHolder, Row row) {
                 Log.i(TAG, "onItemSelected: " + item + " row " + row);
 
-                if (item instanceof PhotoItem) {
+                if (isShowingHeaders()) {
+                    mBackgroundHelper.setBackground(getActivity(), null);
+                }
+                else if (item instanceof PhotoItem) {
                     mBackgroundHelper.setBackground(
                             getActivity(), ((PhotoItem) item).getImageResourceId());
                 }
@@ -85,8 +88,6 @@ public class BrowseFragment extends android.support.v17.leanback.app.BrowseFragm
                 }
             }, 2000);
         }
-
-        mBackgroundHelper.attach(getActivity());
     }
 
     private void setupRows() {
@@ -112,7 +113,7 @@ public class BrowseFragment extends android.support.v17.leanback.app.BrowseFragm
             listRowAdapter.add(new PhotoItem("Hello world", R.drawable.gallery_photo_5));
             listRowAdapter.add(new PhotoItem("This is a test", "Only a test", R.drawable.gallery_photo_6));
             listRowAdapter.add(new PhotoItem("Android TV", "open RowsActivity", R.drawable.gallery_photo_7));
-            listRowAdapter.add(new PhotoItem("Leanback", "open MainActivity", R.drawable.gallery_photo_8));
+            listRowAdapter.add(new PhotoItem("Leanback", "open BrowseActivity", R.drawable.gallery_photo_8));
             HeaderItem header = new HeaderItem(i, "Row " + i);
             mRowsAdapter.add(new ListRow(header, listRowAdapter));
         }
@@ -128,7 +129,7 @@ public class BrowseFragment extends android.support.v17.leanback.app.BrowseFragm
             Intent intent;
             Bundle bundle;
             if ( ((PhotoItem) item).getImageResourceId() == R.drawable.gallery_photo_8) {
-                intent = new Intent(getActivity(), MainActivity.class);
+                intent = new Intent(getActivity(), BrowseActivity.class);
                 bundle = ActivityOptionsCompat.makeSceneTransitionAnimation(getActivity())
                         .toBundle();
             } else if ( ((PhotoItem) item).getImageResourceId() == R.drawable.gallery_photo_7) {

samples/SupportLeanbackDemos/src/com/example/android/leanback/DetailsActivity.java

@@ -35,4 +35,15 @@ public class DetailsActivity extends Activity
         }
     }
 
+    @Override
+    public void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        BackgroundHelper.attach(this);
+    }
+
+    @Override
+    public void onStop() {
+        BackgroundHelper.release(this);
+        super.onStop();
+    }
 }

samples/SupportLeanbackDemos/src/com/example/android/leanback/DetailsFragment.java

@@ -159,8 +159,6 @@ public class DetailsFragment extends android.support.v17.leanback.app.DetailsFra
                 prepareEntranceTransition();
             }
         }
-
-        mBackgroundHelper.attach(getActivity());
     }
 
     @Override
@@ -206,4 +204,13 @@ public class DetailsFragment extends android.support.v17.leanback.app.DetailsFra
         setAdapter(mRowsAdapter);
     }
 
+    @Override
+    public void onStart() {
+        super.onStart();
+        if (mPhotoItem != null) {
+            mBackgroundHelper.setBackground(
+                    getActivity(), mPhotoItem.getImageResourceId());
+        }
+    }
+
 }

samples/SupportLeanbackDemos/src/com/example/android/leanback/MainActivity.java

@@ -88,5 +88,4 @@ public class MainActivity extends Activity {
         }
 
     }
-
 }