Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

◄Function Group►  ◄Overview►                          ◄Up► ◄Next► ◄Previous►
────────────────────────────────────────────────────────────────────────────
 
#define INCL_WINHOOKS
 
BOOL WinSetHook(hab, hmq, iHook, pfnHook, hmod)
HAB hab;         /* handle of the anchor block                   */
HMQ hmq;         /* handle of the message queue                  */
SHORT iHook;     /* type of hook chain                           */
PFN pfnHook;     /* address of the hook procedure                */
HMODULE hmod;    /* handle of the module with the hook procedure */
 
The WinSetHook function installs an application procedure into a specified
hook chain. In this function, queue hooks are called before system hooks.
 
A call to WinSetHook installs the hook at the head of either the system or
queue chain. The most recently installed hook is called first.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
hab        Identifies an anchor block.
 
hmq        Identifies the queue to which the hook chain belongs. If this
           parameter is NULL, the hook is installed in the system hook
           chain. If it is HMQ_CURRENT, the hook is installed in the message
           queue associated with the current thread (calling thread).
 
iHook      Specifies the type of hook chain. This parameter can be one of
           the following values:
 
           Hook Type           Description
           ─────────────────────────────────────────────────────────────────
           HK_HELP             Monitors the WM_HELP message. Returns BOOL.
                               If FALSE, next hook in chain is called. If
                               TRUE, the next hook in the chain is not
                               called.
 
           HK_INPUT            Monitors messages in specified message queue.
                               Returns BOOL. If FALSE, next hook in the
                               chain is called. If TRUE, the message is not
                               passed on to the next hook in the chain.
 
           HK_JOURNALPLAYBACK  Allows applications to insert events into the
                               system input queue. Returns LONG time-out
                               value. This value is the time to wait (in
                               milliseconds) before processing the current
                               message. Never calls the next hook in the
                               chain.
 
           HK_JOURNALRECORD    Allows applications to record system input
                               queue events. Returns VOID. Next hook in
                               chain is always called.
 
           HK_MSGFILTER        Monitors input events during system modal
                               loops. Returns BOOL. If FALSE, next hook in
                               the chain is called. If TRUE, the message is
                               not passed on to the next hook in the chain.
 
           HK_SENDMSG          Monitors messages sent with WinSendMsg.
                               Returns VOID. Next hook in chain is always
                               called.
 
pfnHook    Points to an application hook procedure.
 
hmod       Identifies the module that contains the hook procedure. This
           parameter can be either the module handle returned by the
           DosLoadModule function or NULL for the application's module.
 
Return Value
 
The return value is TRUE if the function is successful or FALSE if an error
occurs.
 
Comments
 
You should use the handle returned from WinCreateMsgQueue for the hmq
parameter. If this is not available, you can use the WinQueryWindowULong
function with the index QWL_HMQ to obtain the queue handle associated with a
window handle.
 
Note: If a system hook is installed, the procedure must be contained in a
DLL; the procedure may be called from different applications, which do not
have access to code segments that are contained in a .exe file.
 
See Also
 
DosLoadModule, WinCreateMsgQueue, WinQueryWindowULong, WinReleaseHook,
WinSendMsg
 
                                      ♦