| HHOOK SetWindowsHookEx(idHook, hkprc, hMod, dwThreadID) | |||||
| int idHook; | /* type of hook to install | */ | |||
| HOOKPROC hkprc; | /* address of hook procedure | */ | |||
| HANDLE hMod; | /* handle of application instance | */ | |||
| DWORD dwThreadID; | /* thread to install hook for | */ | |||
The SetWindowsHookEx function installs an application-defined hook procedure into a hook chain. An application installs a hook procedure to monitor the system for certain types of events. A hook procedure can monitor events associated with either a specific thread or with all threads in the system.
idHook
Specifies the type of hook procedure to be installed. This parameter can be one of the following values:
| Value | Meaning |
| WH_CALLWNDPROC | ||
| Installs a window-procedure filter. For more information, see the description of the CallWndProc callback function. | ||
| WH_CBT | ||
| Installs a computer-based training (CBT) filter. For more information, see the description of the CBTProc callback function. | ||
| WH_DEBUG | ||
| Installs a debugging filter. For more information, see the description of the DebugProc callback function. | ||
| WH_GETMESSAGE | ||
| Installs a message filter. For more information, see the description of the GetMsgProc callback function. | ||
| WH_JOURNALPLAYBACK | ||
| Installs a journaling playback filter. For more information, see the description of the JournalPlaybackProc callback function. | ||
| WH_JOURNALRECORD | ||
| Installs a journaling record filter. For more information, see the description of the JournalRecordProc callback function. | ||
| WH_KEYBOARD | ||
| Installs a keyboard filter. For more information, see the description of the KeyboardProc callback function. | ||
| WH_MOUSE | ||
| Installs a mouse-message filter. For more information, see the description of the MouseProc callback function. | ||
| WH_MSGFILTER | ||
| Installs a message filter. For more information, see the description of the MessageProc callback function. | ||
| WH_SHELL | ||
| Installs a shell-application filter. For more information, see the description of the ShellProc callback function. | ||
| WH_SYSMSGFILTER | ||
| Installs a system-wide message filter. For more information, see the description of the SysMsgProc callback function. | ||
hkprc
Points to the hook procedure. If the dwThreadID parameter is 0 or specifies the identifier of a thread created by a different process, the hkprc parameter must point to a hook procedure in a dynamic-link library (DLL). Otherwise, the hkprc parameter can point to a hook procedure in the code associated with the current process.
hMod
Identifies the DLL containing the hook procedure pointed to by the hkprc parameter. The hMod parameter should be set to NULL if the dwThreadID parameter specifies a thread created by the current process and the the hook procedure is within the code associated with the current process.
dwThreadID
Specifies the identifier of the thread with which the hook procedure is to be associated. If this parameter is 0, the hook procedure is associated with all existing threads.
The return value is the handle of the hook procedure if the function is successful. Otherwise, the return value is NULL.
An error may occur if the hMod parameter is NULL and the dwThreadId parameter is 0 or specifies the identifier of a thread created by another process.
CallNextHookEx, SetWindowsHook, UnhookWindowsHookEx