Api 2 Android Camera Manual Focus with Touch Control

Question

I want to make an application for a camera with touch focus, but I'm a little confused with the api 2 camera. I read about LENS_FOCUS_DISTANCE, but I don’t understand how to use it. Can you help?

Thank you in advance and wish you a pleasant weekend!

Answer 1

The API2 camera looks weird to start with, but then you'll see that it's pretty simple.

The 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();
    }
}