Pinch - zoom feature

[AbubakerMustafa]

Hi ! Can you add pinch-zoom functionality in the project. I tried to implement pinch-zoom functionality by placing MjpegSurfaceView inside Relative layout and try to zoom layout.But Every Time I zoom in Instead of zoom it's size shortened. Please help me to implement this functionality. Thanks

[AbubakerMustafa]

Here is ZoomLayout Code that I used to zoom MjpegSurfaceView container layout

`public class ZoomLayout extends RelativeLayout implements ScaleGestureDetector.OnScaleGestureListener { private enum Mode { NONE, DRAG, ZOOM }

private static final String TAG = "ZoomLayout";
private static final float MIN_ZOOM = 1.0f;
private static final float MAX_ZOOM = 4.0f;

private Mode mode = Mode.NONE;
private float scale = 1.0f;
private float lastScaleFactor = 0f;

// Where the finger first  touches the screen
private float startX = 0f;
private float startY = 0f;

// How much to translate the canvas
private float dx = 0f;
private float dy = 0f;
private float prevDx = 0f;
private float prevDy = 0f;

public ZoomLayout(Context context) {
    super(context);
    init(context);
}

public ZoomLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context);
}

public ZoomLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init(context);
}

public void init(Context context) {
    final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(context, this);
    this.setOnTouchListener(new OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {
            switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    Log.i(TAG, "DOWN");
                    if (scale > MIN_ZOOM) {
                        mode = Mode.DRAG;
                        startX = motionEvent.getX() - prevDx;
                        startY = motionEvent.getY() - prevDy;
                    }
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == Mode.DRAG) {
                        dx = motionEvent.getX() - startX;
                        dy = motionEvent.getY() - startY;
                    }
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    mode = Mode.ZOOM;
                    break;
                case MotionEvent.ACTION_POINTER_UP:
                    mode = Mode.DRAG;
                    break;
                case MotionEvent.ACTION_UP:
                    Log.i(TAG, "UP");
                    mode = Mode.NONE;
                    prevDx = dx;
                    prevDy = dy;
                    break;
            }
            scaleDetector.onTouchEvent(motionEvent);

            if ((mode == Mode.DRAG && scale >= MIN_ZOOM) || mode == Mode.ZOOM) {
                getParent().requestDisallowInterceptTouchEvent(true);
                float maxDx = (child().getWidth() - (child().getWidth() / scale)) / 2 * scale;
                float maxDy = (child().getHeight() - (child().getHeight() / scale))/ 2 * scale;
                dx = Math.min(Math.max(dx, -maxDx), maxDx);
                dy = Math.min(Math.max(dy, -maxDy), maxDy);
                Log.i(TAG, "Width: " + child().getWidth() + ", scale " + scale + ", dx " + dx
                        + ", max " + maxDx);
                applyScaleAndTranslation();
            }

            return true;
        }
    });
}

// ScaleGestureDetector

@Override
public boolean onScaleBegin(ScaleGestureDetector scaleDetector) {
    Log.i(TAG, "onScaleBegin");
    return true;
}

@Override
public boolean onScale(ScaleGestureDetector scaleDetector) {
    float scaleFactor = scaleDetector.getScaleFactor();
    Log.i(TAG, "onScale" + scaleFactor);
    if (lastScaleFactor == 0 || (Math.signum(scaleFactor) == Math.signum(lastScaleFactor))) {
        scale *= scaleFactor;
        scale = Math.max(MIN_ZOOM, Math.min(scale, MAX_ZOOM));
        lastScaleFactor = scaleFactor;
    } else {
        lastScaleFactor = 0;
    }
    return true;
}

@Override
public void onScaleEnd(ScaleGestureDetector scaleDetector) {
    Log.i(TAG, "onScaleEnd");
}

private void applyScaleAndTranslation() {
    child().setScaleX(scale);
    child().setScaleY(scale);
    child().setTranslationX(dx);
    child().setTranslationY(dy);
}

private View child() {
    return getChildAt(0);
}

}`

[niqdev]

Hi @AbubakerMustafa that's a nice feature! Unfortunately at the moment I'm too busy to work also on this, but if you manage to create a PR with the fully functional feature I'm more than happy to review it and release it. Thanks