Example of Android application to publish device screen
The example shows how to share device screen. Device microphone or (in Android 10 or above) system audio may also be captured.
Work with example code
To analyze the code let's take the class ScreenSharingActivity.java of the screen-sharing example, which can be downloaded with build 1.1.0.64.
1. Initialization of the API.
Flashphoner.init() code
Context object is passed to method init() for initialization.
Flashphoner.init(this);
2. Display or hide a system sound capture button depending on Android version
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
mAudioRadioGroup.setVisibility(View.VISIBLE);
} else {
mAudioRadioGroup.setVisibility(View.GONE);
}
3. Request the permission to capture audio
mUseAudioCheckBox.setOnClickListener(v -> {
if (mUseAudioCheckBox.isChecked()) {
ActivityCompat.requestPermissions(ScreenSharingActivity.this,
new String[]{Manifest.permission.RECORD_AUDIO},
PUBLISH_REQUEST_CODE);
}
});
4. Choose the microphone
mMicSpinner = (Spinner) findViewById(R.id.spinner_mic);
ArrayAdapter<MediaDevice> arrayAdapter = new ArrayAdapter<MediaDevice>(this, android.R.layout.simple_spinner_item, Flashphoner.getMediaDevices().getAudioList());
arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mMicSpinner.setAdapter(arrayAdapter);
5. Session creation
Flashphoner.createSession() code
SessionOptions is passed to the method with the following parameters
- WCS server URL
- SurfaceViewRenderer localRenderer to display local video
- SurfaceViewRenderer remoteRenderer to display video published
SessionOptions sessionOptions = new SessionOptions(url);
sessionOptions.setLocalRenderer(localRender);
sessionOptions.setRemoteRenderer(remoteRender);
/**
* Session for connection to WCS server is created with method createSession().
*/
session = Flashphoner.createSession(sessionOptions);
6. Connection to the server
Session.connect() code
session.connect(new Connection());
7. Receiving the event confirming successful connection.
session.onConnected() code
@Override
public void onConnected(final Connection connection) {
runOnUiThread(() -> {
mStartButton.setText(R.string.action_stop);
mStartButton.setTag(R.string.action_stop);
mStatusView.setText(connection.getStatus());
});
...
}
8. Video stream creation
session.createStream() code
StreamOptions streamOptions = new StreamOptions(streamName);
VideoConstraints videoConstraints = new VideoConstraints();
DisplayMetrics metrics = getResources().getDisplayMetrics();
videoConstraints.setResolution(metrics.widthPixels, metrics.heightPixels);
videoConstraints.setVideoFps(metrics.densityDpi);
streamOptions.getConstraints().setVideoConstraints(videoConstraints);
streamOptions.getConstraints().updateAudio(mUseAudioCheckBox.isChecked());
/**
* Stream is created with method Session.createStream().
*/
publishStream = session.createStream(streamOptions);
...
startScreenCapture();
9. Prepare to capture device screen
private void startScreenCapture() {
mMediaProjectionManager = (MediaProjectionManager) getSystemService(
Context.MEDIA_PROJECTION_SERVICE);
Intent permissionIntent = mMediaProjectionManager.createScreenCaptureIntent();
startActivityForResult(permissionIntent, REQUEST_CODE_CAPTURE_PERM);
}
10. Start foreground service
context.startForegroundService() code
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (REQUEST_CODE_CAPTURE_PERM == requestCode && resultCode == RESULT_OK) {
this.mediaProjectionData = data;
Context context = getApplicationContext();
this.serviceIntent = new Intent(context, ScreenSharingService.class);
context.startForegroundService(serviceIntent);
} else {
runOnUiThread(() -> mStartButton.setEnabled(false));
stop();
Log.i(TAG, "Permission has been denied by user");
}
}
11. Capture device screen and publish a stream
ScreenCapturerAndroid(), Stream.publish() code
private final BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (intent != null) {
if (ScreenSharingService.ACTION_START.equals(intent.getAction())) {
MediaProjection mediaProjection = null;
if (mUseAudioCheckBox.isChecked() && !mUseMicRadioButton.isChecked() && Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
mediaProjection = mediaProjectionManager.getMediaProjection(Activity.RESULT_OK, mediaProjectionData);
}
WebRTCMediaProvider.getInstance().setMediaProjection(mediaProjection);
videoCapturer = new ScreenCapturerAndroid(mediaProjection, mediaProjectionData, new MediaProjection.Callback() {
@Override
public void onStop() {
super.onStop();
handler.post(ScreenSharingActivity.this::stop);
}
});
WebRTCMediaProvider.getInstance().setVideoCapturer(videoCapturer);
publishStream.publish();
} else if (ScreenSharingService.ACTION_STOP.equals(intent.getAction())) {
handler.post(ScreenSharingActivity.this::stop);
}
}
}
};
12. Receiving the event confirming the successful stream publishing
StreamStatus.PUBLISHING code
On receiving this event preview stream is created with Session.createStream() and Stream.play() is invoked to play it.
publishStream.on(new StreamStatusEvent() {
@Override
public void onStreamStatus(final Stream stream, final StreamStatus streamStatus) {
runOnUiThread(new Runnable() {
@Override
public void run() {
if (StreamStatus.PUBLISHING.equals(streamStatus)) {
/**
* The options for the stream to play are set.
* The stream name is passed when StreamOptions object is created.
*/
StreamOptions streamOptions = new StreamOptions(streamName);
streamOptions.getConstraints().updateAudio(mUseAudioCheckBox.isChecked());
/**
* Stream is created with method Session.createStream().
*/
playStream = session.createStream(streamOptions);
...
playStream.play();
} else {
Log.e(TAG, "Can not publish stream " + stream.getName() + " " + streamStatus);
}
mStatusView.setText(streamStatus.toString());
}
});
}
});
13. Session disconnection.
Session.disconnect() code
private synchronized void stop() {
if (session != null) {
session.disconnect();
session = null;
}
WebRTCMediaProvider.getInstance().releaseLocalMediaAccess();
if (serviceIntent != null) {
stopService(serviceIntent);
this.serviceIntent = null;
}
...
}
14. Foreground service creation
Service.onCreate(), startForeground() code
@Override
public void onCreate() {
super.onCreate();
NotificationChannel chan = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_NONE);
chan.setImportance(NotificationManager.IMPORTANCE_MIN);
NotificationManager manager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
manager.createNotificationChannel(chan);
final int notificationId = (int) System.currentTimeMillis();
Notification.Builder notificationBuilder = new Notification.Builder(this, CHANNEL_ID);
Notification notification =
notificationBuilder
.setSmallIcon(R.drawable.service_icon)
.setOngoing(true)
.setShowWhen(true)
.setContentTitle("ScreenSharingService is running in the foreground")
.setCategory(Notification.CATEGORY_SERVICE)
.addAction(createStopAction())
.build();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
startForeground(notificationId, notification, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION);
} else {
startForeground(notificationId, notification);
}
}
15. Stopping foreground service
Service.onDestroy(), stopForeground() code
@Override
public void onDestroy() {
stopForeground(true);
super.onDestroy();
}