class PanZoom implements View.OnTouchListener {

    protected RectF fingerDistance(float firstFingerX, float firstFingerY, float secondFingerX, float secondFingerY) {
        final float left = firstFingerX > secondFingerX ? secondFingerX : firstFingerX;
        final float right = firstFingerX > secondFingerX ? firstFingerX : secondFingerX;
        final float top = firstFingerY > secondFingerY ? secondFingerY : firstFingerY;
        final float bottom = firstFingerY > secondFingerY ? firstFingerY : secondFingerY;
        return new RectF(left, top, right, bottom);
    }

    protected  PanZoom(@NonNull XYPlot plot, Pan pan, Zoom zoom);
    protected  PanZoom(@NonNull XYPlot plot, Pan pan, Zoom zoom, ZoomLimit limit);

}