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 WM_MOUSEMOVE

The WM_MOUSEMOVE message is posted to a window when the cursor moves. If the mouse is not captured, the message is posted to the window that contains the cursor. Otherwise, the message is posted to the window that has captured the mouse.

A window receives this message through its WindowProc function.

    LRESULT CALLBACK WindowProc(
      HWND hwnd,       // handle to window
      UINT uMsg,       // WM_MOUSEMOVE
      WPARAM wParam,   // key indicators
      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 down. MK_LBUTTON The left mouse button is down. MK_MBUTTON The middle mouse button is down. MK_RBUTTON The right mouse button is down. MK_SHIFT The SHIFT key is down. 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

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 3.1 or later.
  Windows 95/98/Me: Requires Windows 95 or later.
  Header: Declared in Winuser.h; include Windows.h.

//
//  Process WM_MOUSEMOVE message for window/dialog: 
//
void _OnMouseMove(HWND hwnd, int x, int y, UINT keyFlags)
{
	// TODO: Add your message processing code here...
}

windowsx.h:#define HANDLE_WM_MOUSEMOVE(hwnd,wParam,lParam,fn) ((fn)((hwnd),(int)(short)LOWORD(lParam
),(int)(short)HIWORD(lParam),(UINT)(wParam)),0)

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