@Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        this.onTouchEvent(event);

        return super.dispatchTouchEvent(event);
    }

    private void onTouchEvent(MotionEvent motionEvent) {
        if (event.getActionMasked() == MotionEvent.ACTION_DOWN ||
            event.getActionMasked() == MotionEvent.ACTION_POINTER_DOWN) {
            StringBuilder builder = new StringBuilder();
            this.coordinates = new ArrayList<>();
            int count = event.getPointerCount();

            for (int i = 0; i < count; i++) {
                int x = (int) event.getX(i);
                int y = (int) event.getY(i);
                Logger.d("# X: " + x + ", y: " + y + ", PointerID: " + event.getPointerId(i));
                builder.append("(" + x + "," + y + "),");

                Coordinate coordinate = new Coordinate(x, y);
                this.coordinates.add(coordinate);
            }

            Logger.d("# 座標: " + builder.toString());
        }
    }