如何将鼠标滚轮支持添加到TGraphicControl下的组件？ [英] How to add mouse wheel support to a component descended from TGraphicControl?

问题描述

我已经创建了一个从TGraphicControl下载的delphi组件。是否可以添加对鼠标滚轮的支持？

---编辑---

我已经暴露了MouseWheel事件，如下所示，但它们不被调用。

  TMyComponent = class（TGraphicControl）
已发布
属性OnMouseWheel; 
属性OnMouseWheelDown; 
属性OnMouseWheelUp; 
结束
  

---编辑---

如下所示，我试图捕获WM_MOUSEWHEEL和CM_MOUSEWHEEL消息，但它似乎不起作用。但是，我设法捕获CM_MOUSEENTER消息。我不明白为什么我可以捕获一种类型的消息，而不是其他消息。

解决方案

TGraphicControl 从 TControl ，它已经具有鼠标滚轮支持。请参阅 wm_MouseWheel 消息， DoMouseWheel ， DoMouseWheelDown ， DoMouseWheelUp 和 MouseWheelHandler 方法，以及 WheelAccumulator 属性。 / p>


I have created a delphi component which descends from TGraphicControl. Is it possible to add support for mouse wheels?


--- Edit ---

I've exposed the MouseWheel events as shown below but they aren't called.

TMyComponent = class(TGraphicControl)
published
  property OnMouseWheel;
  property OnMouseWheelDown;
  property OnMouseWheelUp;
end;

--- Edit ---

As suggested below, I've tried to trap the WM_MOUSEWHEEL and CM_MOUSEWHEEL messages, but it doesn't seem to work. However I've managed to trap the CM_MOUSEENTER message. I don't understand why i can trap one type of message, but not the other.

解决方案

TGraphicControl descends from TControl, which already has mouse-wheel support. See the wm_MouseWheel message, the DoMouseWheel, DoMouseWheelDown, DoMouseWheelUp, and MouseWheelHandler methods, and the WheelAccumulator property.

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