Fix video player crash

Sometimes the video player will crash if you rotate the device
while a video is playing, because we aren't waiting for video
playback to stop before returning from onPause().  This causes the
TextureView to get torn down, which makes the MediaCodec unhappy
the next time it tries to decode a frame.

Now we wait for the playback thread to stop.

AndroidManifest.xml

@@ -17,7 +17,7 @@
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.android.grafika"
-    android:versionCode="32"
+    android:versionCode="33"
     android:versionName="1.0" >
 
     <uses-sdk

src/com/android/grafika/MoviePlayer.java

@@ -422,6 +422,9 @@ public static class PlayTask implements Runnable {
         private Thread mThread;
         private LocalHandler mLocalHandler;
 
+        private final Object mStopLock = new Object();
+        private boolean mStopped = false;
+
         /**
          * Prepares new PlayTask.
          *
@@ -460,13 +463,36 @@ public void requestStop() {
             mPlayer.requestStop();
         }
 
+        /**
+         * Wait for the player to stop.
+         * <p>
+         * Called from any thread other than the PlayTask thread.
+         */
+        public void waitForStop() {
+            synchronized (mStopLock) {
+                while (!mStopped) {
+                    try {
+                        mStopLock.wait();
+                    } catch (InterruptedException ie) {
+                        // discard
+                    }
+                }
+            }
+        }
+
         @Override
         public void run() {
             try {
                 mPlayer.play();
             } catch (IOException ioe) {
                 throw new RuntimeException(ioe);
             } finally {
+                // tell anybody waiting on us that we're done
+                synchronized (mStopLock) {
+                    mStopped = true;
+                    mStopLock.notifyAll();
+                }
+
                 // Send message through Handler so it runs on the right thread.
                 mLocalHandler.sendMessage(
                         mLocalHandler.obtainMessage(MSG_PLAY_STOPPED, mFeedback));

src/com/android/grafika/PlayMovieActivity.java

@@ -57,6 +57,8 @@ public class PlayMovieActivity extends Activity implements OnItemSelectedListene
     private MoviePlayer.PlayTask mPlayTask;
     private boolean mSurfaceTextureReady = false;
 
+    private final Object mStopper = new Object();   // used to signal stop
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -93,7 +95,13 @@ protected void onPause() {
         // We're not keeping track of the state in static fields, so we need to shut the
         // playback down.  Ideally we'd preserve the state so that the player would continue
         // after a device rotation.
-        stopPlayback();
+        //
+        // We want to be sure that the player won't continue to send frames after we pause,
+        // because we're tearing the view down.  So we wait for it to stop here.
+        if (mPlayTask != null) {
+            stopPlayback();
+            mPlayTask.waitForStop();
+        }
     }
 
     @Override
@@ -184,12 +192,11 @@ public void clickPlayStop(@SuppressWarnings("unused") View unused) {
     }
 
     /**
-     * Requests stoppage if a movie is currently playing.
+     * Requests stoppage if a movie is currently playing.  Does not wait for it to stop.
      */
     private void stopPlayback() {
         if (mPlayTask != null) {
             mPlayTask.requestStop();
-            mPlayTask = null;
         }
     }
 

src/com/android/grafika/PlayMovieSurfaceActivity.java

@@ -115,7 +115,13 @@ protected void onPause() {
         // We're not keeping track of the state in static fields, so we need to shut the
         // playback down.  Ideally we'd preserve the state so that the player would continue
         // after a device rotation.
-        stopPlayback();
+        //
+        // We want to be sure that the player won't continue to send frames after we pause,
+        // because we're tearing the view down.  So we wait for it to stop here.
+        if (mPlayTask != null) {
+            stopPlayback();
+            mPlayTask.waitForStop();
+        }
     }
 
     @Override
@@ -210,7 +216,6 @@ public void clickPlayStop(@SuppressWarnings("unused") View unused) {
     private void stopPlayback() {
         if (mPlayTask != null) {
             mPlayTask.requestStop();
-            mPlayTask = null;
         }
     }