TrackMouseEvent Function ()

TrackMouseEvent Function

The TrackMouseEvent function posts messages when the mouse pointer leaves a window or hovers over a window for a specified amount of time.

Syntax

BOOL TrackMouseEvent(      
    LPTRACKMOUSEEVENT lpEventTrack
);

Parameters

lpEventTrack
[in, out] Pointer to a TRACKMOUSEEVENT structure that contains tracking information.

Return Value

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 function can post the following messages.
Message Meaning
WM_NCMOUSEHOVER Windows 98/Me, Windows 2000/XP: The same meaning as WM_MOUSEHOVER except this is for the nonclient area of the window.
WM_NCMOUSELEAVE Windows 98/Me, Windows 2000/XP: The same meaning as WM_MOUSELEAVE except this is for the nonclient area of the window.
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 reenters its window if it requires further tracking of mouse hover behavior.

Remarks

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.
Note The _TrackMouseEvent function calls TrackMouseEvent if it exists, otherwise _TrackMouseEvent emulates TrackMouseEvent. The _TrackMouseEvent function is in commctrl.h and is exported by COMCTRL32.DLL.

Function Information

Minimum DLL Version user32.dll
Header Declared in Winuser.h, include Windows.h
Import library User32.lib
Minimum operating systems Windows 98, Windows NT 4.0
Unicode Implemented as Unicode version.

Minimum DLL Version	user32.dll
Header	Declared in Winuser.h, include Windows.h
Import library	User32.lib
Minimum operating systems	Windows 98, Windows NT 4.0
Unicode	Implemented as Unicode version.

See Also

Mouse Input, SystemParametersInfo, _TrackMouseEvent, TRACKMOUSEEVENT

Message	Meaning
WM_NCMOUSEHOVER	Windows 98/Me, Windows 2000/XP: The same meaning as WM_MOUSEHOVER except this is for the nonclient area of the window.
WM_NCMOUSELEAVE	Windows 98/Me, Windows 2000/XP: The same meaning as WM_MOUSELEAVE except this is for the nonclient area of the window.
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 reenters its window if it requires further tracking of mouse hover behavior.