HOOK.C

//*********************************************************************** 
// 
// hook.c 
// 
// Source file for Keyboard Hook function and support procedures.  Defines 
// the following exported functions: 
//   
// InstallHook()       - Installs/Removes keyboard hook for app's hotkeys 
// KeyboardHook()      - Keyboard Hook Procedure 
// 
// This file should go into a DLL. 
// 
// This file, although not officially containing DIB functions, is part  
// of the DIBAPI.DLL because: 
//   1) System-wide Hook Procedures in 3.1 need to be in a DLL, and  
//   2) I didn't want the user to have 2 DLLs to worry about for WINCAP.  
// 
// 
// Written by Microsoft Product Support Services, Developer Support. 
// Copyright 1991-1998 Microsoft Corporation. All rights reserved. 
//*********************************************************************** 
 
#define     STRICT      // enable strict type checking 
 
#include <windows.h> 
#include "wincap.h" 
 
// Globals for this module 
 
extern HWND     ghWndMain;      // Handle to main window -- used to post msgs 
 
static HHOOK    hHook;          // A handle to our installed hook 
static BOOL     bHookInstalled; // TRUE if hook has been installed 
 
 
// External variables 
 
extern HANDLE ghDLLInst;   // Handle to the DLL's instance.  Set in DllMain. 
 
// Local function.  Although this function is exported from our DLL (Windows 
// needs to call it directly), no other app needs to call this, so we can 
// just prototype it here.  
 
LRESULT CALLBACK KeyboardHook (int nCode, WORD wParam, DWORD lParam ); 
 
//********************************************************************** 
// InstallHook() 
// 
// Installs/Removes Filter function for the WH_KEYBOARD hook. 
// 
// Parameters: 
// HWND hWnd      Handle to main window to receive posted messages.  See 
//                KeyboardHook() for more info on how it works. 
//  
// BOOL bCode     TRUE to hook, FALSE to unhook 
// 
// Returns: 
// 1 if successful, 0 if not. 
// 
//********************************************************************** 
 
int APIENTRY InstallHook (HWND hWnd, BOOL bCode ) 
{ 
 
    int nReturn = 1; 
 
    ghWndMain = hWnd;  // Store app's window handle in DLL global variable 
 
    // Make sure that we are installing/removing in the proper order 
 
    if (bCode == bHookInstalled) 
        return 0; 
 
    if (bCode) 
    { 
        hHook = (HHOOK)SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardHook, 
            ghDLLInst, 0); 
 
        if (!hHook) 
            return 0; 
 
        bHookInstalled = TRUE; 
    } 
    else 
    { 
        nReturn = UnhookWindowsHookEx(hHook); 
        bHookInstalled = FALSE; 
    } 
    return nReturn; 
} 
 
 
 
 
//********************************************************************** 
// 
// KeyboardHook() 
// 
// This is the Keyboard Hook function which windows will call every 
// time it gets a keyboard message.  In this function, we check to 
// see if the key pressed was Ctrl+Alt+F[8,9,10], and if it is, we post 
// the proper message to our main window which will do the right 
// thing.   
// 
// Note that the window handle that we post from was set by a call to 
// InstallHook() above. 
// 
// Parameters/return value: 
// 
// Standard 3.1 KeyboardProc.  See docs for "KeyboardProc". 
// 
//********************************************************************* 
 
LRESULT CALLBACK KeyboardHook (int nCode, WORD wParam, DWORD lParam ) 
{ 
 
    if ( nCode >= 0 ) 
    { 
 
        // Check to see if it's a key we're looking for 
 
        if (GetKeyState(VK_SHIFT) < 0 && GetKeyState(VK_CONTROL) < 0) 
        { 
            switch (wParam) 
            { 
 
//      MENUITEM    "&Active Window \aCtrl+Shift+F9",  IDM_ACTIVEWINDOW 
//      MENUITEM    "&Desktop\aCtrl+Shift+F10",       IDM_DESKTOP 
 
                case VK_F9: 
                    if (HIWORD(lParam) & 0x8000) 
                        PostMessage(ghWndMain, WM_COMMAND, IDM_ACTIVEWINDOW, 0L); 
                    return 1; 
 
                case VK_F10: 
 
                    if (HIWORD(lParam) & 0x8000) 
                        PostMessage(ghWndMain, WM_COMMAND, IDM_DESKTOP, 0L); 
                    return 1; 
            } 
        } 
   } 
 
   // 
   // If we haven't returned 1 by the time we get here, then we 
   // need to pass on the message to CallNextHookEx. 
   // 
   return (int)CallNextHookEx(hHook, nCode, wParam, lParam); 
}