Releasing camera instance after a single image is

问题:

I am trying to call camera instance, capture an image and return to the parent activity. I am able to create and call the camera instance, capture and store the image, but the activity with the camera does not exit.

The Preview activity creates a camera instance and implements methods like onPause(), onResume() and resetCam(). The code is:

        //capture button
        buttonClick.setOnClickListener(new OnClickListener(){
                        public void onClick(View v) {
                            camera.takePicture(shutterCallback, rawCallback, pngCallback);
                       }
        }


    protected void onResume() {
            super.onResume();
            int numCams = Camera.getNumberOfCameras();
            if(numCams > 0){
                try{
                    camera = Camera.open(0);
                    camera.startPreview();
                    preview.setCamera(camera);
                } catch (RuntimeException ex){
                    Toast.makeText(ctx, getString(R.string.camera_not_found), Toast.LENGTH_LONG).show();
                }
            }
        }

        @Override
        protected void onPause() {
            if(camera != null) {
                camera.stopPreview();
                preview.setCamera(null);
                camera.release();
                camera = null;
            }
            super.onPause();
        }

        private void resetCam() {
            camera.startPreview();
            preview.setCamera(camera);
        }

ShutterCallback shutterCallback = new ShutterCallback() {
        public void onShutter() {
            }
    };

    PictureCallback rawCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            }
    };

    PictureCallback pngCallback = new PictureCallback() {
            public void onPictureTaken(byte[] data, Camera camera) {

//save the iamge here

                resetCam();

            Log.d(TAG, "onPictureTaken - png");
        }
    };

After a single capture event, the control should be returned to parent activity PhotoCapture which calls Preview by:

Intent intent = new Intent(PhotoCapture.this,Preview.class);
                startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

And performs onActivityResult() for the same.

How should I release camera instance for safe exit?

I want to return the path of image saved as well.

Thank you!

EDIT:

I tried to call finish(); this way:

    buttonClick.setOnClickListener(new OnClickListener()
            {
                public void onClick(View v) {
                    camera.takePicture(shutterCallback, rawCallback, pngCallback);
                    Log.d("Tag","4");
                    finish();
                }
            });

I put the Log.d() for getting the control flow:

ShutterCallback shutterCallback = new ShutterCallback() {
        public void onShutter() {
                Log.d("Tag","1");
        }
    };

    PictureCallback rawCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            Log.d("Tag","2");
        }
    };

    PictureCallback pngCallback = new PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            Log.d("Tag","3");
            //save image
            resetCam();
            Log.d(TAG, "onPictureTaken - png");
        }
    };

The log is:

02-19 14:00:28.046    4680-4680/preview.preview D/Tag﹕ 4
02-19 14:00:38.414    4680-4686/preview.preview W/Camera﹕ Camera server died!

There is no log for Tag:1 or Tag: 2 or Tag: 3!

So the activity is finished before the actual image is captured/stored.

Even though i set (result_code=OK) the image is not saved.

How can i resolve this?

回答1:

make a call to finish() once you are done taking a photo, it will exit you from current activity and you will be returned back to previous activity.

回答2:

When you have taken your photo and are ready to return to your calling activity, you have to call this code

setResult(RESULT_OK);

then

finish();

This will return to your calling activity with the resultCode = RESULT_OK

回答3:

For finishing the activity you have to use finish() method after starting activity or you can include flags to intent before starting activity.