Watch Trigger + for Pebble: Initial Release


After the success of the first Watch Trigger, and a good deal of requests, I spent another two weeks to build upon and improve the experience. The result of all this work is Watch Trigger + (or Plus), and boasts this list of improvements:

  • Remote triggering of video capture, as well as photo capture
  • New landing screen for mode selection and a single access point to the Settings menu
  • Settings menu has been re-vamped to enable expansion with new settings in the future using PreferenceHeaders.
  • Included Gingerbread devices in the Media Gallery scanning functionality, as there were problems previously. Gingerbread devices will use Intent driven media scanning instead of Honeycomb + devices using a MediaScanner connection and callback method.
  • File names are now based on the time and date they were taken.
  • Removed watch-app autostart when entering either of the viewfinder Activities. This approach led to some AppSync difficulties with the improvements in the next bullet point;
  • Enhanced Watch App that adapts its layout depending on which shooting mode the Android app is currently in.
  • More stability fixes, including slightly faster Photo Viewfinder startup time.


The new landing screen for mode selection:

shot1This Activity is fitted with some smooth and subtle animations to make it feel a lot nicer to use. Also note the single access point to the Settings menu on the ActionBar at the top right.

The new Video Viewfinder:

shot3Mostly similar to the Photo Viewfinder, but lacking the timer UI, as it is rendered pretty much moot by definition, as the video captured can be of any length.

The new enhanced adapting watch app:

WTP watchappExcuse the state of my screen protector! So far it’s done its duty perfectly. I haven’t found any function to assign the UP and DOWN buttons on the Pebble Action Bar so far, so if you can think of one, let me know!

Notes on Android

First, the process for capturing video on Android is very different from photo capture. There are two methods I can think of for capturing photos/videos on Android:

  1. Start an Intent to launch the device’s built-in Camera app, which then waits for the user to press the capture button and then go back, which hands the resulting image data back to the previous Activity. Useless for this purpose, since once the Intent is launched, the Watch Trigger app and hence Pebble cannot control the built-in Camera app, which leaves us with the alternative;
  2. Re-implement the Camera app as a custom Activity to enable access to all stages of preview, capture, write and gallery scan. This involves creating a new SurfaceView subclass that opens the Camera and displays the preview images. Once the basic layout is complete, and the Camera.Parameters API probed to expose the requires settings to the user, this isn’t too much work.
The problems start to appear if you want to do approach #2 above with video capture. Whereas the Camera API has the takePicture() method, which calls the supplied callbacks to get and save the image data to internal storage, the capturing of video data requires continuous storage functionality, which is managed with the MediaRecorder class.
On paper (in the API documentation), the video capture process is simple enough, if you tread with caution. Even following this admittedly precision orientated procedure, I spent at least two days wrestling with ‘setParameters failed’ and ‘start failed -19’ errors. One thing I like about the Java language is with a suitable debugger the stack trace is nearly always informative enough to show you exactly what failed and why. But these errors were near meaningless, and according to sites such as Stack Overflow, could occur due to a wide variety of reasons.
Eventually I managed to get video capture to work after making assumptions about camera hardware, encoder options and file formats, which when considering to release to a device-fragmented ecosystem such as Android, is scary enough. A few more days work enabled me to eliminate most of these assumptions which should provide the best compatibility. In case you were led here by struggles re-creating the Camera app for video recording, here is my code which works (at least for a CM10.1 Galaxy S, stock HTC One, stock 2.3.3 Galaxy Ace and stock Galaxy Y (I still pity Galaxy Y users):
	 * @return true if successful
	private boolean prepareMediaRecorder() {
		try {
			mRecorder = new MediaRecorder();

			//Select camera
				Log.d(TAG, "Camera instance is: " + camera.toString());

			//Setup audio/video sources

			//Set quality
			CamcorderProfile profile = CamcorderProfile.get(0, CamcorderProfile.QUALITY_HIGH);

			//Get next name
			nextName = getTimeStampName() + ".mp4";

			//Output file
				Log.d(TAG, "Opening media file...");
			File dir = new File (prefPath + "/");
			currentFile = new File(dir, nextName);

				Log.d(TAG, "Media file is: " + currentFile.getAbsolutePath().toString());

			//Setup Surface

				Log.d(TAG, "Preparing MediaRecorder...");

				Log.d(TAG, "MediaRecorder preparations complete!");
			Globals.addToDebugLog(TAG, "MediaRecorder preparations complete!");
			return true;
		} catch (Exception e) {
			Log.e(TAG, "Error preparing MediaRecorder: " + e.getLocalizedMessage());
			Globals.addToDebugLog(TAG, "Error preparing MediaRecorder: " + e.getLocalizedMessage());
			return false;

	private void releaseMediaRecorder() {
		mRecorder = null;

			Log.d(TAG, "MediaRecorder released successfully.");
		Globals.addToDebugLog(TAG, "MediaRecorder released successfully");

If you are working in this area of Android app development heed my warning and ALWAYS USE TRY/CATCH TO RELEASE THE CAMERA LOCK AND MEDIARECORDER LOCK IF ANY CODE SEGMENT INVOLVING THEM FAILS! Failure to do this means if your app FCs or ANRs and you have to kill it, you will be unable to access the Camera in ANY app until you restart your device!

Finally in this section, notes on supporting Android 2.3.3 Gingerbread and upwards. In Android 3.0 Honeycomb and upwards, there are a lot of nice features and conveniences I originally took for granted when building this app. Examples include:

  • The ActionBar API
  • The newer Media Scanner API functions
  • Some methods involved with the Camera API

After a few requests and accepting that I should support all the devices that Pebble do themselves, I worked to include those older devices into the Watch Trigger fold. In doing so, I had to write replacement imitation ActionBar layout items and buttons to provide the closest possible similarity between device versions. Originally I had great difficulties with implementing media scanning (to add the captures media files to the system Gallery so they can be viewed immediately) on Gingerbread, but no problems with Honeycomb upwards. I got round this like so:

	//Check Android version
	public static boolean isHoneycombPlus() {
		return android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.HONEYCOMB;


	if(Globals.isHoneycombPlus()) {
		MediaScannerConnection.scanFile(getContext(), paths, mimes, new MediaScannerConnection.OnScanCompletedListener() {

			public void onScanCompleted(String path, Uri uri) {
					Log.d(TAG, "Finished scanning " + path + " to gallery");
				Globals.addToDebugLog(TAG, "Finished scanning video into Gallery");
				VideoViewfinder.overlayNotify("Media scan complete.");

				readyToCapture = true;

	} else {
		//Media scan intent?
		Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);

		VideoViewfinder.overlayNotify("Media scan requested.");

		readyToCapture = true;

Thus, in many other places including the one shown above, the app takes a different path depending on the device platform version.

So, that’s the big upgrade! All that’s left now is to provide a link to get your teeth into taking loony videos of yourself. Hopefully nothing like this.


Get it on Google Play

    • bonsitm said:

      Unfortunately not, this is an Android app. Have a look on the Watch App Directory for an iPhone alternative.

    • bonsitm said:

      Hi Aaron, after multiple requests I am currently working on this. I may have more success than my last attempt at implementing portrait a few months ago. If I’m successful, I will post another blog entry. Stay tuned!

  1. Aaron Nabil said:

    If you can get Portrait mode work either automatically or via a toggle, I’ll send you one of these:

      • Aaron Nabil said:

        In a portrait orientation you are holding the phone & sensor such that the long axis is vertical, so you would want the 2nd but with the sky on top and the lake on the bottom. I would expect that (as would most people) that if you were detecting orientation with the accelerometer (OrientationEventListener) taking the second picture would be impossible, the long axis of the picture would be perpendicular with the horizon (just like you are holding the phone), not parallel with it as you have in you mock-ups.

      • bonsitm said:

        Noted. I did say the mockups were crude 😉

  2. Aaron Nabil said:

    I just updated WT+, it seems to support auto portrait/landscape switching now even though I don’t see it mentioned in the release notes. Was this fix intentional or a side-effect? Either way, do you want to claim your widebody strap?

    I’m looking forward to working through your SDK 2.0 tutorial, thanks for putting it up.

    • bonsitm said:

      Hi Aaron, yes please!

      I believe it was in the 2.1.0 notes, superseded by the patch. It was an intentional design effort in the redesign.

  3. Aaron Nabil said:

    There is something funny going on in that the orientation of the photo isn’t getting recorded properly. As an example, using the default camera app if you take 1 photo of the horizon in the portrait orientation and 1 after rotating the camera to the landscape orientation, viewing the photos in the gallery will show the horizon correctly horizontal in all the photos (no matter how you hold the phone), but half will be wide or narrow (depending on which way you hold the phone when viewing in gallery). But when viewing pictures taken by WT+ in both orientation, the horizon will only be horizontal for 1/2 the pictures and all will either be full frame or narrow (depending on how you hold the phone when viewing the photos in gallery).

    Since I wanted portrait I’m happy, but now the landscape people are going to be miffed.

    • bonsitm said:

      Hi Aaron.

      This is strange, as the orientation appears correct in my device. Which device are you running the app on? Can you provide sample screenshots?


      • Aaron Nabil said:

        Samsung galaxy note 3. I can make some test photos in both orientations with both the built-in app and WT+ and email them.

      • bonsitm said:

        Ok. Yes, please send me some examples.

  4. pebbleguru said:

    Hi there…..looks good!

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