Question

因此，我在阅读WinApi文档中的低级鼠标挂钩的回调函数时，对于传递给该函数的WPARAM参数感到困惑。

从Documentation开始，有关回调函数：

wParam [in]
Type: WPARAM

The identifier of the mouse message. This parameter can be one of the following messages: WM_LBUTTONDOWN, WM_LBUTTONUP, WM_MOUSEMOVE, WM_MOUSEWHEEL, WM_MOUSEHWHEEL, WM_RBUTTONDOWN, or WM_RBUTTONUP.

这仅提及WM_LBUTTONDOWN，WM_LBUTTONUP，WM_MOUSEMOVE，WM_MOUSEWHEEL，WM_MOUSEHWHEEL，WM_RBUTTONDOWN和WM_RBUTTONUP。

但是在关于MSLLHOOKSTRUCT结构（与低级鼠标挂钩一起使用）的Documentation中，还提到了其他消息：

mouseData

Type: DWORD

If the message is WM_MOUSEWHEEL, the high-order word of this member is the wheel delta. The low-order word is reserved. A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, toward the user. One wheel click is defined as WHEEL_DELTA, which is 120.

If the message is WM_XBUTTONDOWN, WM_XBUTTONUP, WM_XBUTTONDBLCLK, WM_NCXBUTTONDOWN, WM_NCXBUTTONUP, or WM_NCXBUTTONDBLCLK, the high-order word specifies which X button was pressed or released, and the low-order word is reserved. This value can be one or more of the following values. Otherwise, mouseData is not used.

这些消息是否也通过WPARAM参数传递？

Answer 1

这些消息是否也通过WPARAM参数传递？

是的

例如，如果要处理X按钮消息，它们将使用WM_XBUTTONDOWN和WM_XBUTTONUP发布到您的应用程序中。 wParam的低位字表示哪个X按钮处于按下状态（如果有）。

此外，请参阅Responding to Mouse Clicks

WM_XBUTTONDOWN和WM_XBUTTONUP窗口消息同时适用于 XBUTTON1和XBUTTON2。 wParam参数指示哪个按钮是点击。

UINT button = GET_XBUTTON_WPARAM(wParam);  
if (button == XBUTTON1)
{
    // XBUTTON1 was clicked.
}
else if (button == XBUTTON2)
{
    // XBUTTON2 was clicked.
}

哪些消息可以传递给低级鼠标挂钩回调函数？

1 个答案: