Focus gain sends focus loss through the focus stack

When a new focus owner lands on the stack, don't just make the
 previous top of the stack lose focus, propagate the loss throughout
 the stack.
Only dispatch focus loss on focus loss state change
Remove canDispatchFocus() method as it now doesn't need to be known
 (and shouldn't be known) outside of the implementation.
Fix error where the focus code for a focus gain request should
 always be a focus loss code.

Bug 8315302

Change-Id: I92c8f51fdcc090851d34d00fefed916e25da40c1

2 files changed, 42 insertions, 26 deletions

diff --git a/media/java/android/media/FocusRequester.java b/media/java/android/media/FocusRequester.java
index 6b34b5671c42..020f3e1ee941 100644
--- a/media/java/android/media/FocusRequester.java
+++ b/media/java/android/media/FocusRequester.java
@@ -37,9 +37,10 @@ class FocusRequester {
 
     // on purpose not using this classe's name, as it will only be used from MediaFocusControl
     private static final String TAG = "MediaFocusControl";
+    private static final boolean DEBUG = false;
 
     private AudioFocusDeathHandler mDeathHandler;
-    private final IAudioFocusDispatcher mFocusDispatcher;
+    private final IAudioFocusDispatcher mFocusDispatcher; // may be null
     private final IBinder mSourceRef;
     private final String mClientId;
     private final String mPackageName;
@@ -73,10 +74,6 @@ class FocusRequester {
     }
 
 
-    boolean canDispatchFocus() {
-        return (mFocusDispatcher != null);
-    }
-
     boolean hasSameClient(String otherClient) {
         try {
             return mClientId.compareTo(otherClient) == 0;
@@ -197,7 +194,7 @@ class FocusRequester {
                 switch(mFocusLossReceived) {
                     case AUDIOFOCUS_NONE:
                     case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
-                        return AudioManager.AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK;
+                        return AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK;
                     case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
                         return AudioManager.AUDIOFOCUS_LOSS_TRANSIENT;
                     case AudioManager.AUDIOFOCUS_LOSS:
@@ -210,20 +207,19 @@ class FocusRequester {
     }
 
     void handleExternalFocusGain(int focusGain) {
-        try {
-            int focusLoss = focusLossForGainRequest(focusGain);
-            if (focusLoss != mFocusLossReceived) {
-                mFocusDispatcher.dispatchAudioFocusChange(focusLoss, mClientId);
-                mFocusLossReceived = focusLoss;
-            }
-        } catch (android.os.RemoteException e) {
-            Log.e(TAG, "Failure to signal loss of focus: ", e);
-        }
+        int focusLoss = focusLossForGainRequest(focusGain);
+        handleFocusLoss(focusLoss);
     }
 
     void handleFocusGain(int focusGain) {
         try {
-            mFocusDispatcher.dispatchAudioFocusChange(focusGain, mClientId);
+            if (mFocusDispatcher != null) {
+                if (DEBUG) {
+                    Log.v(TAG, "dispatching " + focusChangeToString(focusGain) + " to "
+                        + mClientId);
+                }
+                mFocusDispatcher.dispatchAudioFocusChange(focusGain, mClientId);
+            }
             mFocusLossReceived = AUDIOFOCUS_NONE;
         } catch (android.os.RemoteException e) {
             Log.e(TAG, "Failure to signal gain of audio focus due to: ", e);
@@ -232,9 +228,16 @@ class FocusRequester {
 
     void handleFocusLoss(int focusLoss) {
         try {
-            mFocusDispatcher.dispatchAudioFocusChange(
-                    focusLoss, mClientId);
-            mFocusLossReceived = focusLoss;
+            if (focusLoss != mFocusLossReceived) {
+                if (mFocusDispatcher != null) {
+                    if (DEBUG) {
+                        Log.v(TAG, "dispatching " + focusChangeToString(focusLoss) + " to "
+                            + mClientId);
+                    }
+                    mFocusDispatcher.dispatchAudioFocusChange(focusLoss, mClientId);
+                }
+                mFocusLossReceived = focusLoss;
+            }
         } catch (android.os.RemoteException e) {
             Log.e(TAG, "Failure to signal loss of audio focus due to:", e);
         }
diff --git a/media/java/android/media/MediaFocusControl.java b/media/java/android/media/MediaFocusControl.java
index ca57b92089d7..c5b110170c3c 100644
--- a/media/java/android/media/MediaFocusControl.java
+++ b/media/java/android/media/MediaFocusControl.java
@@ -265,7 +265,7 @@ public class MediaFocusControl implements OnFinished {
      */
     protected void discardAudioFocusOwner() {
         synchronized(mAudioFocusLock) {
-            if (!mFocusStack.empty() && mFocusStack.peek().canDispatchFocus()) {
+            if (!mFocusStack.empty()) {
                 // notify the current focus owner it lost focus after removing it from stack
                 final FocusRequester exFocusOwner = mFocusStack.pop();
                 exFocusOwner.handleFocusLoss(AudioManager.AUDIOFOCUS_LOSS);
@@ -280,13 +280,26 @@ public class MediaFocusControl implements OnFinished {
 
     private void notifyTopOfAudioFocusStack() {
         // notify the top of the stack it gained focus
-        if (!mFocusStack.empty() && mFocusStack.peek().canDispatchFocus()) {
+        if (!mFocusStack.empty()) {
             if (canReassignAudioFocus()) {
                 mFocusStack.peek().handleFocusGain(AudioManager.AUDIOFOCUS_GAIN);
             }
         }
     }
 
+    /**
+     * Focus is requested, propagate the associated loss throughout the stack.
+     * @param focusGain the new focus gain that will later be added at the top of the stack
+     */
+    private void propagateFocusLossFromGain_syncAf(int focusGain) {
+        // going through the audio focus stack to signal new focus, traversing order doesn't
+        // matter as all entries respond to the same external focus gain
+        Iterator<FocusRequester> stackIterator = mFocusStack.iterator();
+        while(stackIterator.hasNext()) {
+            stackIterator.next().handleExternalFocusGain(focusGain);
+        }
+    }
+
     private final Stack<FocusRequester> mFocusStack = new Stack<FocusRequester>();
 
     /**
@@ -462,14 +475,14 @@ public class MediaFocusControl implements OnFinished {
                 fr.release();
             }
 
-            // notify current top of stack it is losing focus
-            if (!mFocusStack.empty() && mFocusStack.peek().canDispatchFocus()) {
-                mFocusStack.peek().handleExternalFocusGain(focusChangeHint);
-            }
-
             // focus requester might already be somewhere below in the stack, remove it
             removeFocusStackEntry(clientId, false /* signal */);
 
+            // propagate the focus change through the stack
+            if (!mFocusStack.empty()) {
+                propagateFocusLossFromGain_syncAf(focusChangeHint);
+            }
+
             // push focus requester at the top of the audio focus stack
             mFocusStack.push(new FocusRequester(mainStreamType, focusChangeHint, fd, cb,
                     clientId, afdh, callingPackageName, Binder.getCallingUid()));