The TrackMouseEvent function posts messages when the mouse pointer leaves a window or hovers over a window for a specified amount of time.
BOOL TrackMouseEvent(
LPTRACKMOUSEEVENT lpEventTrack // pointer to a TRACKMOUSEEVENT
// structure
);
If the function succeeds, the return value is nonzero .
If the function fails, return value is zero. To get extended error information, call GetLastError.
The messages that the function can post are the following:
| Message | Meaning |
|---|---|
| WM_MOUSEHOVER | The mouse hovered over the client area of the window for the period of time specified in a prior call to TrackMouseEvent. Hover tracking stops when this message is generated. The application must call TrackMouseEvent again if it requires further tracking of mouse hover behavior. |
| WM_MOUSELEAVE | The mouse left the client area of the window specified in a prior call to TrackMouseEvent. All tracking requested by TrackMouseEvent is canceled when this message is generated. The application must call TrackMouseEvent when the mouse re-enters its window if it requires further tracking of mouse hover behavior. |
The mouse pointer is considered to be hovering when it stays within a specified rectangle for a specified period of time. Call SystemParametersInfo and use the values SPI_GETMOUSEHOVERWIDTH, SPI_GETMOUSEHOVERHEIGHT, and SPI_GETMOUSEHOVERTIME to retrieve the size of the rectangle and the time.
Windows NT: Requires version 4.0 or later.
Windows: Requires Windows 98.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Import Library: Use user32.lib.
Mouse Input Overview, Mouse Input Functions, SystemParametersInfo, TRACKMOUSEEVENT