@Override
    public boolean handleTouchEvent(MotionEvent event) {
        boolean needInvalidate = super.handleTouchEvent(event);

        if (isRotationEnabled) {
            needInvalidate = gestureDetector.onTouchEvent(event) || needInvalidate;
        }
        return needInvalidate;
    }
Reference to PieChartView to use some methods specific for that kind of chart.
hellocharts-library/src/lecho/lib/hellocharts/gesture/PieChartTouchHandler.java