HELP.C

/************************************************************************** 
 * 
 *  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY 
 *  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE 
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR 
 *  PURPOSE. 
 * 
 *  Copyright 1992 - 1998 Microsoft Corporation.  All Rights Reserved. 
 * 
 **************************************************************************/ 
/**************************************************************************** 
 * 
 *   help.c: Help system interface 
 * 
 *   Vidcap32 Source code 
 * 
 ***************************************************************************/ 
 
/* 
 * supports F1 key help in app and in dialog by installing a hook, 
 * 
 * Keep track of which dialog is currently displayed in a global: 
 * dialog ids are also topic ids in the help file. 
 */ 
 
 
#include <windows.h> 
#include <windowsx.h> 
#include <string.h> 
 
#include "help.h" 
 
int CurrentDialogID = 0; 
 
 
// app info passed to helpinit 
HINSTANCE hInstance; 
char HelpFile[MAX_PATH]; 
HWND hwndApp; 
 
//hook proc and old msg filter 
#ifdef _WIN32 
HHOOK hOurHook; 
#else 
FARPROC fnOldMsgFilter = NULL; 
FARPROC fnMsgHook = NULL; 
#endif 
 
 
// call DialogBoxParam, but ensuring correct help processing: 
// assumes that each Dialog Box ID is a context number in the help file. 
// calls MakeProcInstance as necessary. Uses instance data passed to 
// HelpInit(). 
int 
DoDialog( 
   HWND hwndParent,     // parent window 
   int DialogID,        // dialog resource id 
   DLGPROC fnDialog,    // dialog proc 
   long lParam          // passed as lparam in WM_INITDIALOG 
) 
{ 
    int olddialog; 
    DLGPROC fn; 
    int result; 
 
    // remember current id (for nested dialogs) 
    olddialog = CurrentDialogID; 
 
    // save the current id so the hook proc knows what help to display 
    CurrentDialogID = DialogID; 
 
    fn = (DLGPROC) MakeProcInstance(fnDialog, hInstance); 
    result = DialogBoxParam( 
                hInstance, 
                MAKEINTRESOURCE(CurrentDialogID), 
                hwndParent, 
                fn, 
                lParam); 
    FreeProcInstance(fn); 
    CurrentDialogID = olddialog; 
 
    return result; 
} 
 
 
// set the help context id for a dialog displayed other than by DoDialog 
// (eg by GetOpenFileName). Returns the old help context that you must 
// restore by a further call to this function 
int 
SetCurrentHelpContext(int DialogID) 
{ 
    int oldid = CurrentDialogID; 
    CurrentDialogID = DialogID; 
    return(oldid); 
} 
 
 
 
// return TRUE if lpMsg is a non-repeat F1 key message 
BOOL 
IsHelpKey(LPMSG lpMsg) 
{ 
    return lpMsg->message == WM_KEYDOWN && 
               lpMsg->wParam == VK_F1 && 
               !(HIWORD(lpMsg->lParam) & KF_REPEAT) && 
               GetKeyState(VK_SHIFT) >= 0 && 
               GetKeyState(VK_CONTROL) >= 0 && 
               GetKeyState(VK_MENU) >= 0; 
} 
 
 
 
LRESULT CALLBACK 
HelpMsgHook(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
    if (nCode >= 0) { 
        if (IsHelpKey((LPMSG)lParam)) { 
            if (CurrentDialogID != 0) { 
                WinHelp(hwndApp, HelpFile, HELP_CONTEXT, CurrentDialogID); 
            } else { 
                WinHelp(hwndApp, HelpFile, HELP_CONTENTS, 0); 
            } 
        } 
    } 
#ifdef _WIN32 
    return CallNextHookEx(hOurHook, nCode, wParam, lParam); 
#else 
    return DefHookProc(nCode, wParam, lParam, fnOldMsgFilter); 
#endif 
 
} 
 
 
 
 
 
// help init - initialise the support for the F1 key help 
BOOL 
HelpInit(HINSTANCE hinstance, LPSTR helpfilepath, HWND hwnd) 
{ 
    LPSTR pch; 
 
    // save app details 
    hwndApp = hwnd; 
    hInstance = hinstance; 
 
    // assume that the help file is in the same directory as the executable- 
    // get the executable path, and replace the filename with the help 
    // file name. 
    GetModuleFileName(hinstance, HelpFile, sizeof(HelpFile)); 
 
    // find the final backslash, and append the help file name there 
    pch = _fstrrchr(HelpFile, '\\'); 
    pch++; 
    lstrcpy(pch, helpfilepath); 
 
    // install a hook for msgs and save old one 
#ifdef _WIN32 
    hOurHook = SetWindowsHookEx( 
                        WH_MSGFILTER, 
                        (HOOKPROC) HelpMsgHook, 
                        NULL, GetCurrentThreadId()); 
#else 
    fnMsgHook = (FARPROC) MakeProcInstance(HelpMsgHook, hInstance); 
    fnOldMsgFilter = SetWindowsHook(WH_MSGFILTER, (HOOKPROC) fnMsgHook); 
#endif 
 
    return(TRUE); 
} 
 
 
 
// shutdown the help system 
void 
HelpShutdown(void) 
{ 
#ifdef _WIN32 
    UnhookWindowsHookEx(hOurHook); 
#else 
    if (fnOldMsgFilter) { 
        UnhookWindowsHook(WH_MSGFILTER, fnMsgHook); 
        FreeProcInstance(fnMsgHook); 
    } 
#endif 
 
    WinHelp(hwndApp, HelpFile, HELP_QUIT, 0); 
} 
 
 
// start help at the contents page 
void 
HelpContents(void) 
{ 
    WinHelp(hwndApp, HelpFile, HELP_CONTENTS, 0); 
}