Android Camera Api 2 Manual focus with touch

Question

I want to to make camera app with touch focus, but i am little confused with the camera api 2. I have read about LENS_FOCUS_DISTANCE but i don't understand how to use it. Can you please assist?

Thank you in advance and wish you nice weekend!

Answer 1

Camera API2 looks weird for begin, but then you will see that it's pretty easy.

Best answer for this question is code with comments:

private void captureImage() {
    try {
        //for do this you should have mCameraDevice and mCameraCaptureSession

        //get CaptureRequestBuilder.
        captureStillBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);

        //add target surfaces - for getting image data you should have instance on ImageReader
        //with OnImageAvailableListener that will be called when image will be captured
        //but for showing on screen you have to use SurfaceView or TextureView
        captureStillBuilder.addTarget(mImageReader.getSurface());

        //add some details for Request
        //in general: you have fields and values for it and you just set what value should be in each field
        // auto focus works only when whole control mode in auto
        captureStillBuilder.set(CaptureRequest.CONTROL_MODE, CaptureRequest.CONTROL_MODE_AUTO);
        // before capture lock focus
        captureStillBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
                CaptureRequest.CONTROL_AF_TRIGGER_START);
        // set area for focusing
        MeteringRectangle[] focusArea = new MeteringRectangle[1];            
        focusArea[0] = new MeteringRectangle(/*here set coordinates for focus on */);
        captureStillBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, focusArea);

        // create callback for this capture
        CameraCaptureSession.CaptureCallback callback = new ...
        // just run capture to make focused photo
        mCameraCaptureSession.capture(captureStillBuilder.build(), callback, null);

    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}