Close CameraDevice in a seperate thread

Question

I am using Android camera2 to create a custom camera. The cameraDevice.close() method is slow and it makes UI freeze for 1 sec. I put it in another thread and it seems to work j

Answer 1

As Alex Cohn mentions, the recommended practice is to do all camera-related work on a separate thread from the UI.

It also takes a long time to open the camera, or create a capture session, relatively speaking, so doing those operations not on the UI thread is also a good idea.

That said, as long as you're not losing track of your own app state (so that you don't try to use a camera device you've already closed by accident, for example), there's no reason you can't mix calls to the camera device or capture session from multiple threads. The classes themselves are thread-safe.

Answer 2

As far as I know, such freeze with cameraDevice.close() happens on some unfortunate devices, and sometimes is cured by performing a normal system upgrade.

But this is a little consolation if this happens to you, on your device. Actually, you are kind of lucky that you can prepare a fix for that. The end-users of your app will benefit from your misfortune.

Your code looks OK, if it delivers desired improvements for you. As I explained, it may be hard to reproduce this problem on another device.

I would rather put all closeCamera() logic on the same background thread. If you provided a Handler to openCamera(), as in the official example,

manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);

then I would suggest posting all closeCamera() sequence to this mBackgroundHandler.