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
Indicates whether various virtual keys are down. This parameter can be one or more of the following values.
The CTRL key is depressed.
The left mouse button is depressed.
The middle mouse button is depressed.
The right mouse button is depressed.
The SHIFT key is depressed.
The first X button is down.
The second X button is down.
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.
If an application processes this message, it should return zero.
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.
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.
|Minimum supported client
||Windows 2000 Professional [desktop apps only]
|Minimum supported server
||Windows 2000 Server [desktop apps only]