I have a SurfaceView that I use as Display for MediaPlayer. I also need to alternatively draw on the same Surface manually by locking/unlocking the Canvas. This never happens at the same time though!
The problem is that as soon I have once locked and unlocked the Surface, it will be unusable for MediaPlayer. The other way round is no problem. I can play a video on the Surface, reset the player and then manually draw on the Surface as I like.
This works:
- Play a video on the Surface using MediaPlayer.
- Reset MediaPlayer and draw on the surface manually by locking/unlocking the canvas.
This fails:
- Lock the surface, draw on it, and unlock it again.
- Play a video on the Surface with MediaPlayer.
It will fail with an IllegalStateException when MediaPlayer.prepare() is called. Strangely, the message of the exception is "null".
The same happens with a Surface that is used in a SurfaceTexture (e.g. in a GL context).
I wonder what happens with the Surface after locking/unlocking it, that MediaPlayer does not like it anymore.
I might need to end up using multiple Surfaces and switching between them. But I'd like to avoid that since I have a setup with a mix of multiple SurfaceViews and also GlSurfaceViews using SurfaceTextures.
Here is some code to reproduce the phenomenon. Make sure that VIDEO_FILE points to a valid video.
MainActivity.java:
import android.app.Activity;
import android.graphics.Canvas;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
// Make sure this points to a valid video
private String VIDEO_FILE = "/sdcard/Movies/some-video.mp4";
private MediaPlayer mediaPlayer;
private SurfaceView surfaceView;
private SurfaceHolder surfaceHolder;
private Button playButton;
private Button stopButton;
private Button drawButton;
private boolean alternate;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mediaPlayer = new MediaPlayer();
surfaceView = (SurfaceView)findViewById(R.id.video_surfaceview);
surfaceHolder = surfaceView.getHolder();
playButton = (Button)findViewById(R.id.play_button);
stopButton = (Button)findViewById(R.id.stop_button);
drawButton = (Button)findViewById(R.id.draw_button);
surfaceHolder.addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
mediaPlayer.setSurface(surfaceHolder.getSurface());
// Make sure we only do things when surface is ready
playButton.setEnabled(true);
stopButton.setEnabled(true);
drawButton.setEnabled(true);
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
}
});
playButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mediaPlayer.setDisplay(surfaceHolder);
try {
mediaPlayer.setDataSource(VIDEO_FILE);
mediaPlayer.prepare();
mediaPlayer.start();
} catch (Exception e) {
Log.e("Main", "Play failed: " + e.getMessage(), e);
}
}
});
stopButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mediaPlayer.reset();
}
});
drawButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Surface surface = surfaceHolder.getSurface();
Canvas canvas = surfaceHolder.lockCanvas(null);
// Toggle between green and red
if (alternate) {
canvas.drawARGB(255, 255, 0, 0);
} else {
canvas.drawARGB(255, 0, 255, 0);
}
alternate = !alternate;
surfaceHolder.unlockCanvasAndPost(canvas);
}
});
}
}
layout/main_activity.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<SurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/video_surfaceview"
android:layout_width="fill_parent"
android:layout_height="300dp" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/play_button"
android:enabled="false"
android:text="Play"></Button>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/stop_button"
android:enabled="false"
android:text="Stop"></Button>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/draw_button"
android:enabled="false"
android:text="Draw"></Button>
</LinearLayout>
There is three buttons: "Play", "Stop", "Draw". You may press "Play" and "Stop" several times (which should work as expected). Then press "Draw" multiple times (this should draw alternating red and green). Now press "Play" again (this will fail).
If you start with "Draw" in the beginning, then "Play" will never work.
Make sure to press "Stop" before pressing "Draw" when a video is playing. Otherwise it will crash (for a valid reason).
