Что такое SetWindowsHookEx CallNextHookEx ?

Public Declare Function SetWindowsHookEx Lib 'user32' Alias 'SetWindowsHookExA' (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Public Declare Function CallNextHookEx Lib 'user32' (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Ктонибудь знает что означают эти параметры в этих функциях:
idHook
lpfn
hmod
dwThreadId
hHook
nCode
wParam
lParam
Если у вас есть msdn кинте пожалуйста чтонибуть по этому поводу от туда.

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Описание:

The SetWindowsHookEx function installs an application-defined hook procedure into a hook chain. You would install a hook procedure to monitor the system for certain types of events. These events are associated either with a specific thread or with all threads in the system.

Параметры:

· idHook
Specifies the type of hook procedure to be installed. This parameter can be one of the following values:
WH_CALLWNDPROC
Installs a hook procedure that monitors messages before the system sends them to the destination window procedure. For more information, see the CallWndProc hook procedure.
WH_CALLWNDPROCRET
Installs a hook procedure that monitors messages after they have been processed by the destination window procedure. For more information, see the CallWndRetProc hook procedure.
WH_CBT
Installs a hook procedure that receives notifications useful to a computer-based training (CBT) application. For more information, see the CBTProc hook procedure.
WH_DEBUG
Installs a hook procedure useful for debugging other hook procedures. For more information, see the DebugProc hook procedure.
WH_GETMESSAGE
Installs a hook procedure that monitors messages posted to a message queue. For more information, see the GetMsgProc hook procedure.
WH_JOURNALPLAYBACK
Installs a hook procedure that posts messages previously recorded by a WH_JOURNALRECORD hook procedure. For more information, see the JournalPlaybackProc hook procedure.
WH_JOURNALRECORD
Installs a hook procedure that records input messages posted to the system message queue. This hook is useful for recording macros. For more information, see the JournalRecordProc hook procedure.
WH_KEYBOARD
Installs a hook procedure that monitors keystroke messages. For more information, see the KeyboardProc hook procedure.
WH_MOUSE
Installs a hook procedure that monitors mouse messages. For more information, see the MouseProc hook procedure.
WH_MSGFILTER
Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or scroll bar. For more information, see the MessageProc hook procedure.
WH_SHELL
Installs a hook procedure that receives notifications useful to shell applications. For more information, see the ShellProc hook procedure.
WH_SYSMSGFILTER
Installs a hook procedure that monitors messages generated as a result of an input event in a dialog box, message box, menu, or scroll bar. The hook procedure monitors these messages for all applications in the system. For more information, see the SysMsgProc hook procedure.

· lpfn
Points to the hook procedure. If the dwThreadId parameter is zero or specifies the identifier of a thread created by a different process, the lpfn parameter must point to a hook procedure in a dynamic-link library (DLL). Otherwise, lpfn 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 lpfn parameter. The hMod parameter must be set to NULL if the dwThreadId parameter specifies a thread created by the current process and if 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 zero, the hook procedure is associated with all existing threads.

Пример:

'In a module
Public Const WH_KEYBOARD = 2
Public Const VK_SHIFT = &H10
Declare Function CallNextHookEx Lib 'user32' (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long
Declare Function GetKeyState Lib 'user32' (ByVal nVirtKey As Long) As