boolean isMoved=true;
    Matrix matrix=new Matrix();
    Matrix savedMatrix=new Matrix();
    PointF startPoint=new PointF();
    PointF midPoint=new PointF();
    float oldDist = 1f;
    int NONE = 0;
    int DRAG = 1;
    int ZOOM = 2;
    int mode = NONE;
public boolean onTouch(View v, MotionEvent event) {

        ImageView imageView = (ImageView) v;
        imageView.setScaleType(ScaleType.MATRIX);

        switch (event.getAction() & MotionEvent.ACTION_MASK) {

        case MotionEvent.ACTION_DOWN:
            matrix.set(imageView.getImageMatrix());
            isMoved = false;
            startPoint.set(event.getX(), event.getY());
            savedMatrix.set(matrix);
            mode = DRAG;
            break;

        case MotionEvent.ACTION_UP:
            if (!isMoved) {
                v.performClick();
            }
            break;

        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            savedMatrix.set(matrix);
            break;

        case MotionEvent.ACTION_MOVE:

            if (mode == DRAG) {
                matrix.set(savedMatrix);
                matrix.postTranslate(event.getX() - startPoint.x, event.getY()
                        - startPoint.y);
            } else if (mode == ZOOM) {

                float newDist = spacing(event);
                if (newDist > 10f) {
                    matrix.set(savedMatrix);
                    float scale = newDist / oldDist;
                    matrix.postScale(scale, scale, midPoint.x, midPoint.y);
                }
            }
            isMoved = true;
            break;

        case MotionEvent.ACTION_POINTER_DOWN:

            oldDist = spacing(event);

            if (oldDist > 10f) {
                savedMatrix.set(matrix);
                midPoint(midPoint, event);
                mode = ZOOM;
                isMoved = false;
            }
            break;
        }

        imageView.setImageMatrix(matrix);
        return true;
    }
@SuppressLint("FloatMath")
    private float spacing(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);
    }

    private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }