TOPIC:

// event when double tap occurs
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            float x = e.getX();
            float y = e.getY();

            if (m_layout.vGetScale() <= 1.0){
                int vx = (int) x;
                int vy = (int) y;
                PDFLayout.PDFPos pos = m_layout.vGetPos(vx, vy);
                m_layout.vZoomSet(vx, vy, pos, 3.0f);
            } else {
                int vx = (int) x;
                int vy = (int) y;
                PDFLayout.PDFPos pos = m_layout.vGetPos(vx, vy);
                m_layout.vZoomSet(vx, vy, pos, 1.0f);
            }
            return true;
        }