java - 如何在 Piccolo 2D 中反转鼠标滚轮缩放处理？

Question

在大多数应用中，向下旋转滚轮会减小缩放对象的尺寸，而向上旋转滚轮会增大尺寸。

在 piccolo2d 中，默认行为是相反的:

private static void showWorldNode() {
        new PFrame() {

            @Override
            public void initialize() {

                getCanvas().getLayer().addChild(worldNode);

                PMouseWheelZoomEventHandler mouseWheelZoomEventHandler = new PMouseWheelZoomEventHandler();
                mouseWheelZoomEventHandler.zoomAboutMouse();
                getCanvas().addInputEventListener(mouseWheelZoomEventHandler);
            }

        };
    }

如何恢复默认？

Answer 1

您可以提供负比例因子来反转行为，例如:

mouseWheelZoomEventHandler.setScaleFactor(-0.1d);

PMouseWheelZoomEventHandler 根据比例因子和 MouseWheelEvent.getWheelRotation() 的值计算缩放值返回:

negative values if the mouse wheel was rotated up/away from the user, and positive values if the mouse wheel was rotated down/ towards the user

这里是来自PMouseWheelZoomEventHandler的相关代码

double scale = 1.0d + event.getWheelRotation() * scaleFactor;