The MouseProc hook procedure is an application-defined or library-defined callback function the system calls whenever an application calls the GetMessage or PeekMessage function and there is a mouse message to be processed.
LRESULT CALLBACK MouseProc(
| int nCode, | // hook code |
| WPARAM wParam, | // message identifier |
| LPARAM lParam | // mouse coordinates |
| ); |
Parameters
nCode
Specifies a code the hook procedure uses to determine how to process the message. This parameter can be one of the following values:
| Value | Meaning |
| HC_ACTION | The wParam and lParam parameters contain information about a mouse message. |
| HC_NOREMOVE | The wParam and lParam parameters contain information about a mouse message, and the mouse message has not been removed from the message queue. (An application called the PeekMessage function, specifying the PM_NOREMOVE flag.) |
If nCode is less than zero, the hook procedure must pass the message to the CallNextHookEx function without further processing and should return the value returned by CallNextHookEx.
wParam
Specifies the identifier of the mouse message.
lParam
Points to a MOUSEHOOKSTRUCT structure.
Return Values
To enable the system to process the message, the return value must be zero. To discard the message, the return value must be a nonzero value.
Remarks
The hook procedure must not install a JournalPlaybackProc callback function.
An application installs the hook procedure by specifying the WH_MOUSE hook type and the address of the hook procedure in a call to the SetWindowsHookEx function.
MouseProc is a placeholder for the application-defined or library-defined function name.
See Also
CallNextHookEx, GetMessage, JournalPlaybackProc, MOUSEHOOKSTRUCT, PeekMessage, SetWindowsHookEx