How to detect Is it Rotation Gesture or Zoom Gesture in android

Question

I am new to android. I am working on Gesture part. I got stuck i could not find the way to detect either its Zoom or Rotation Gesture (Two Finger) in android.

case MotionEvent.ACTION_MOVE:
    if(event.getPointerCount() == 2) {
        float currentX = event.getX();
        Log.v(GlobalVars.TAG, (currentX - lastX) + "");
        lastX = currentX;
        double currentAngle = getAngle(event.getX(), event.getY());
        Log.v(GlobalVars.TAG, "Rotation Y::" + (startAngle - currentAngle));

        if((startAngle - currentAngle) > 0 && mRotate.y > (-1 * 45) && )  {
                mRotate.y -= 1.0;
            } else if((startAngle - currentAngle) < 0 && mRotate.y < 45) {
                mRotate.y += 1.0; 
            }
        startAngle = currentAngle;
    }



private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        mOrigin.z *= detector.getScaleFactor(); // scale change since previous event
        mOrigin.z = Math.max(MIN_ZOOM, Math.min(mOrigin.z, MAX_ZOOM)); //Max Zoom Value.
        return true;
    }
}

Refer following link http://www.codeproject.com/Articles/319401/Simple-Gestures-on-Android — Yogesh Tatwal, Aug 12 '13 at 12:45

score 1 · Answer 1 · answered Jun 26 '14 at 05:52

You detect it from pointer movement direction like , left, right or top, down. If fist pointer move on left direction or down and second pointer move on right or up direction that means user is trying to rotate the image. so disable scale event that time. my code for detect rotation and scale is like this. I hope it will helpful to you.

private boolean isRotate(MotionEvent event){
    int dx1 = (int) (event.getX(0) - lastEvent[0]);
    int dy1 = (int) (event.getY(0) - lastEvent[2]);
    int dx2 = (int) (event.getX(1) - lastEvent[1]);
    int dy2 = (int) (event.getY(1) - lastEvent[3]);
    Log.d("dx1 ", ""+ dx1);
    Log.d("dx2 ", "" + dx2);
    Log.d("dy1 ", "" + dy1);
    Log.d("dy2 ", "" + dy2);
    //pointer 1
    if(Math.abs(dx1) > Math.abs(dy1) && Math.abs(dx2) > Math.abs(dy2)) {
        if(dx1 >= 2.0 && dx2 <=  -2.0){
            Log.d("first pointer ", "right");
            return true;
        }
        else if(dx1 <= -2.0 && dx2 >= 2.0){
            Log.d("first pointer ", "left");
            return true;
        }
    }
    else {
         if(dy1 >= 2.0 && dy2 <=  -2.0){
                Log.d("seccond pointer ", "top");
                return true;
            }
            else if(dy1 <= -2.0 && dy2 >= 2.0){
                Log.d("second pointer ", "bottom");
                return true; 
            }

    }

    return false;
}

then after you can check it on ACTION_MOVE like

if (mode == DRAG && !isZoomAndRotate) {
                isZoomAndRotate = false;
                view.setTranslationX((event.getX() - start.x) + view.getTranslationX());
                view.setTranslationY((event.getY() - start.y) + view.getTranslationY());
            } else if (mode == ZOOM && event.getPointerCount() == 2) {
                isZoomAndRotate = true;
                boolean isZoom = false;
                if(!isRotate(event)){
                    float newDist = spacing(event);
                    if (newDist > 10f) {
                        float scale = newDist / oldDist * view.getScaleX();
                        view.setScaleX(scale);
                        view.setScaleY(scale);
                        isZoom = true;
                    }
                }
                else if(!isZoom){
                    newRot = rotation(event);
                    view.setRotation((float)(view.getRotation() + (newRot - d)));
                }
            }

How to detect Is it Rotation Gesture or Zoom Gesture in android

1 Answers1