WM_MOUSEHOVER message

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.

#define WM_MOUSEHOVER                   0x02A1

Parameters

wParam

Indicates whether various virtual keys are down. This parameter can be one or more of the following values.

Value	Meaning
MK_CONTROL 0x0008	The CTRL key is depressed.
MK_LBUTTON 0x0001	The left mouse button is depressed.
MK_MBUTTON 0x0010	The middle mouse button is depressed.
MK_RBUTTON 0x0002	The right mouse button is depressed.
MK_SHIFT 0x0004	The SHIFT key is depressed.
MK_XBUTTON1 0x0020	The XBUTTON1 is down.
MK_XBUTTON2 0x0040	The XBUTTON2 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 value

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); 

As noted above, the x-coordinate is in the low-order short of the return value; the y-coordinate is in the high-order short (both represent signed values because they can take negative values on systems with multiple monitors). If the return value is assigned to a variable, you can use the MAKEPOINTS macro to obtain a POINTS structure from the return value. You can also use the GET_X_LPARAM or GET_Y_LPARAM macro to extract the x- or y-coordinate.

Important

Do not use the LOWORD or HIWORD macros to extract the x- and y- coordinates of the cursor position because these macros return incorrect results on systems with multiple monitors. Systems with multiple monitors can have negative x- and y- coordinates, and LOWORD and HIWORD treat the coordinates as unsigned quantities.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Winuser.h (include Windowsx.h)

See also

Reference

GET_X_LPARAM

GET_Y_LPARAM

GetCapture

SetCapture

TrackMouseEvent

TRACKMOUSEEVENT

Conceptual

Mouse Input

Other Resources

MAKEPOINTS

POINTS