Trying to setOnKeyListener on camaraX

Question

I'm trying to make an app take a picture when the volume buttons are pressed, like snapchat and the like do. This app is using the CamaraX Library for camera functionality. Now as far as I can tell the CameraXView should let me set an onKeyListener as it extends frameLayout -> ViewGroup -> View. However, everything I've tried so far does not pick up the KeyEvents.

public class CameraXFragment extends LoggingFragment implements CameraFragment {
  ...
  private CameraXView          camera;
  ...
  private void initControls() {
    ...
    // This doesn't work
    camera.setOnKeyListener((v, keyCode, event) -> {
      Log.e(TAG, "KeyEvent please: " + keyCode);
      return false;
    });
    ...
    // This does work
    camera.setOnTouchListener((v, event) -> gestureDetector.onTouchEvent(event));
  }
}

CameraXView does have a onTouchEvent so I tried adding a onKeyDown within it as well but that doesn't seem to have worked.

The camera.setOnTouchEventLister was not added by me so I don't fully understand why that is working but mine isn't.

Husayn Hakeem · Answer 1 · 2020-07-14T00:04:15.280

You can register a broadcast receiver to receive a callback every time the volume button is pressed, then trigger an image capture each time. You can take a look at how the CameraX sample implements this.

The broadcast receiver will look as follows. Make sure to register and unregister it appropriately.

private val volumeDownReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        when (intent.getIntExtra(KEY_EVENT_EXTRA, KeyEvent.KEYCODE_UNKNOWN)) {
            KeyEvent.KEYCODE_VOLUME_DOWN -> // Trigger an image capture
        }
    }
}

Since -it seems- you're using CameraX's CameraView API, you can trigger an image capture by calling one of its takePicture methods.

The image capture should only occur after the camera has been set up.

Trying to setOnKeyListener on camaraX

1 Answers1