Bug in Android samples [includes fix]. (Patch #2366)

Added by Rui Marques over 12 years ago. Updated about 12 years ago.

Status:	Done	Start date:
Priority:	Normal	Due date:
Assignee:	Alexander Smorkalov	% Done:	0%
Category:	android
Target version:	2.4.3
Affected version:		Operating System:
Difficulty:		HW Platform:
Pull request:

Description

I came up with a bug with the Android samples, in particular the "Tutorial 1 - Add Opencv" but it should be the same for similar samples.
It happens when the sample activity goes to the background, for example when a call is received.
It does not happen when the home button is pressed.

What happens is that, when the activity gets focus again, the camera is frozen in the last frame.
This was tested with opencv 2.4.1 but I think it remains like this in 2.4.2.

The activity cycle when the home button is pressed is the following.

Cycle down:
onPause > releaseCamera > Surface destroyed > releaseCamera > onStop

Cycle up:
onRestart > onResume > openCamera > releaseCamera > surface created > surface changed > setup camera > "starting processing thread"

The activity cycle when it goes to the background is the following.

Cycle down:
onPause > releaseCamera

Cycle up:
onResume > openCamera > releaseCamera

Somehow the thread is not running properly and/or the camera is not setup properly.
I was able to fix it like this, it is not very elegant I think someone might came up with a better solution =)

Sample file DemoJava.java:

onResume() {
   // Add this at the end:
   // I have defined processingThread from DemoViewBase.java as protected so I access it here.
   if(null != mView && null != mView.processingThread) {
      //if(!mView.processingThread.isAlive()) // I tried to check this but it also freezes when thread isAlive, so I removed it.
      Log.d(TAG, "onResume: thread state: "+mView.processingThread.getState()); // outputs either WAITING or TERMINATED
      mView.forceThreadRestart(); 
      mView.setupCamera(mView.surfaceWidth, mView.surfaceHeight);
   }
}

Associated revisions

Revision b7659c62
Added by Roman Donchenko about 11 years ago

Merge pull request #2366 from yashdv:mat_copyto_doc_bug

History

#1
Updated by Rui Marques over 12 years ago

I forgot to mention the forceThreadRestart code:


    protected void forceThreadRestart() {
        if(processingThread!=null) {
            processingThread.interrupt(); //Seems to be the only non-deprecated way to somehow stop a thread.
            processingThread = null;
        }

        processingThread = new Thread(this);
        processingThread.start();
    }