Zoom Camera2 Preview using TextureView

Question

i have a Problem with my Preview Zoom for the Camera2 API. I am using a TextureView.

I want to zoom only the preview Stream that was showed in the TextureView.

I want to zoom the Area where i use the Zoom Gesture.

I use the SimpleOnScaleGestureListener!

I added following Code. The zoomingFactor and the x and y Position are right.

 private void updateTextureViewSize(float xPosi,float yPosi, float scale){
        float scaleX = 1.0f;
        float scaleY = 1.0f;




        float mVideoWidth = mCamcontrol.getmPreviewSize().getWidth();
        float mVideoHeight = mCamcontrol.getmPreviewSize().getHeight();

        int rotation = getWindowManager().getDefaultDisplay().getRotation();
        RectF viewRect = new RectF(0, 0, 1440, 2560);
        RectF bufferRect = new RectF(0, 0, mVideoHeight, mVideoWidth);

        bufferRect.offset(xPosi - bufferRect.centerX(), yPosi -    bufferRect.centerY());

         //16:9 faktor
        scaleX = ((mScale * scale) / 9f) * 16f;
        scaleY = ((mScale * scale) / 16f) * 9f;

        Matrix matrix = new Matrix();

        matrix.setRectToRect(bufferRect, viewRect, Matrix.ScaleToFit.FILL);
        scalefactorView.setText(String.valueOf(xPosi) + "  " + String.valueOf(yPosi));

        matrix.setScale(scaleY, scaleX, xPosi, yPosi);
        matrix.postRotate(90 * (rotation - 2), xPosi, yPosi);

        mTextureView.setTransform(matrix);


}

Zooming is Right, but not the Position where i Zoom. For Example! When i zoom on the position right/middle i see only the left/top rectangle of the Stream.

I added the following pictures to unterstand the problem.

Answer 1

Thanks to @arin 's answer, I made an improved version.

His code is basically working, but there are 2 problems:
1) Readability - actually I don't know what is going on calculating the Rect zoom
2) In my Android 7.1.1 device, the preview will freeze if the zoom is big to a certain extent. Since I solved this problem with the code below, I am pretty sure it is because the original code allowed over-zooming beyond camera's maximum zoom ratio.
(In fact, I don't know why he needs to apply *10 on the ratio returned by CameraCharacteristics)

Below are my codes: (I do this all inside my custom TextureView, which also stores my Camera2 objects and logics):

Related Member variables:

protected CameraCharacteristics cameraCharacteristics;
protected CameraCaptureSession captureSession;
protected CaptureRequest.Builder previewRequestBuilder;

//Zooming
protected float fingerSpacing = 0;
protected float zoomLevel = 1f;
protected float maximumZoomLevel;
protected Rect zoom;

Right after you get CameraCharacteristics from CameraManager, probably in some initial setup:

maximumZoomLevel = cameraCharacteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM);

override onTouchEvent:

@Override
public boolean onTouchEvent(MotionEvent event) {
    try {
        Rect rect = cameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);
        if (rect == null) return false;
        float currentFingerSpacing;

        if (event.getPointerCount() == 2) { //Multi touch.
            currentFingerSpacing = getFingerSpacing(event);
            float delta = 0.05f; //Control this value to control the zooming sensibility
            if (fingerSpacing != 0) {
                if (currentFingerSpacing > fingerSpacing) { //Don't over zoom-in
                    if ((maximumZoomLevel - zoomLevel) <= delta) {
                        delta = maximumZoomLevel - zoomLevel;
                    }
                    zoomLevel = zoomLevel + delta;
                } else if (currentFingerSpacing < fingerSpacing){ //Don't over zoom-out
                    if ((zoomLevel - delta) < 1f) {
                        delta = zoomLevel - 1f;
                    }
                    zoomLevel = zoomLevel - delta;
                }
                float ratio = (float) 1 / zoomLevel; //This ratio is the ratio of cropped Rect to Camera's original(Maximum) Rect
                //croppedWidth and croppedHeight are the pixels cropped away, not pixels after cropped
                int croppedWidth = rect.width() - Math.round((float)rect.width() * ratio);
                int croppedHeight = rect.height() - Math.round((float)rect.height() * ratio);
                //Finally, zoom represents the zoomed visible area
                zoom = new Rect(croppedWidth/2, croppedHeight/2,
                        rect.width() - croppedWidth/2, rect.height() - croppedHeight/2);
                previewRequestBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
            }
            fingerSpacing = currentFingerSpacing;
        } else { //Single touch point, needs to return true in order to detect one more touch point
            return true;
        }
        captureSession.setRepeatingRequest(previewRequestBuilder.build(), captureCallback, null);
        return true;
    } catch (final Exception e) {
        //Error handling up to you
        return true;
    }
}

And the getFingerSpacing method:

private float getFingerSpacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return (float) Math.sqrt(x * x + y * y);
}

Finally don't forget to set the crop region when you actually take the photo. My code is base on this Camera2Basic, I do this inside the captureStillPicture() method:

        //Zoom
        if (zoom != null) {
            captureBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
        }

Answer 2

Android Camera2 api : Pinch Zoom In/Out

Use this sample code for Camera2Basic from google developers. https://github.com/googlesamples/android-Camera2Basic

Now declare two class variables –

public float finger_spacing = 0;
public int zoom_level = 1;

and update the given onTouch() method.

public boolean onTouch(View v, MotionEvent event) {
    try {
        Activity activity = getActivity();
        CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
        CameraCharacteristics characteristics = manager.getCameraCharacteristics(mCameraId);
        float maxzoom = (characteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM))*10;

        Rect m = characteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);
        int action = event.getAction();
        float current_finger_spacing;

        if (event.getPointerCount() > 1) {
            // Multi touch logic
            current_finger_spacing = getFingerSpacing(event);
            if(finger_spacing != 0){
                if(current_finger_spacing > finger_spacing && maxzoom > zoom_level){
                    zoom_level++;
                } else if (current_finger_spacing < finger_spacing && zoom_level > 1){
                    zoom_level--;
                }
                int minW = (int) (m.width() / maxzoom);
                int minH = (int) (m.height() / maxzoom);
                int difW = m.width() - minW;
                int difH = m.height() - minH;
                int cropW = difW /100 *(int)zoom_level;
                int cropH = difH /100 *(int)zoom_level;
                cropW -= cropW & 3;
                cropH -= cropH & 3;
                Rect zoom = new Rect(cropW, cropH, m.width() - cropW, m.height() - cropH);
                mPreviewRequestBuilder.set(CaptureRequest.SCALER_CROP_REGION, zoom);
            }
            finger_spacing = current_finger_spacing;
        } else{
            if (action == MotionEvent.ACTION_UP) {
                //single touch logic
            }
        }

        try {
            mCaptureSession
                .setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        }
    } catch (CameraAccessException e) {
        throw new RuntimeException("can not access camera.", e);
    }
    return true;
}


//Determine the space between the first two fingers
@SuppressWarnings("deprecation")
private float getFingerSpacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return (float) Math.sqrt(x * x + y * y);
}

Answer 3

@arin Answer is working thank @arin just one thing zoom sensitivity too high.

To control this i make some changes in might be useful to you.

Change zoom_level data type to double

public int zoom_level = 1; to public double zoom_level = 1;

Then increase or decrease zoom_level with low value i use 0.4

if (current_finger_spacing > finger_spacing && maxzoom > zoom_level) {
        zoom_level = zoom_level + .4;
        //zoom_level++;
    } else if (current_finger_spacing < finger_spacing && zoom_level > 1) {
        zoom_level = zoom_level - .4;
        //zoom_level--;
      }