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 WM_MOUSEHOVER

The WM_MOUSEHOVER message is posted to a window when the cursor hovers over the client area of the window for the period of time specified in a prior call to TrackMouseEvent.

A window receives this message through its WindowProc function.

    LRESULT CALLBACK WindowProc(
      HWND hwnd,       // handle to window
      UINT uMsg,       // WM_MOUSEHOVER
      WPARAM wParam,   // key indicator
      LPARAM lParam    // horizontal and vertical position
    );

Parameters

• wParam
  Indicates whether various virtual keys are down. This parameter can be one or more of the following values. Value Description
  • MK_CONTROL The CTRL key is depressed.
  • MK_LBUTTON The left mouse button is depressed.
  • MK_MBUTTON The middle mouse button is depressed.
  • MK_RBUTTON The right mouse button is depressed.
  • MK_SHIFT The SHIFT key is depressed.
  • MK_XBUTTON1 Windows 2000 or later: The first X button is down.
  • MK_XBUTTON2 Windows 2000 or later: The second X button is down.
• lParam
  The low-order word specifies the x-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area. The high-order word specifies the y-coordinate of the cursor. The coordinate is relative to the upper-left corner of the client area.

Return Values

If an application processes this message, it should return zero.

Remarks

Hover tracking stops when WM_MOUSEHOVER is generated. The application must call TrackMouseEvent again if it requires further tracking of mouse hover behavior.

Use the following code to obtain the horizontal and vertical position:

xPos = GET_X_LPARAM(lParam); yPos = GET_Y_LPARAM(lParam);

You can also use the MAKEPOINTS macro to convert the lParam parameter to a POINTS structure.

Requirements

• Windows NT/2000 or later: Requires Windows NT 4.0 or later.
• Windows 95/98/Me: Requires Windows 98 or later.
• Header: Declared in Winuser.h; include Windows.h.

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Notebook exported on Monday, 7 July 2008, 18:56:50 PM Eastern Daylight Time