WININFO.C

/******************************************************************************\ 
*       This is a part of the Microsoft Source Code Samples.  
*       Copyright 1993 - 1998 Microsoft Corporation. 
*       All rights reserved.  
*       This source code is only intended as a supplement to  
*       Microsoft Development Tools and/or WinHelp documentation. 
*       See these sources for detailed information regarding the  
*       Microsoft samples programs. 
\******************************************************************************/ 
 
/*---------------------------------------------------------------------------*\ 
| WINDOW INFORMATION MODULE 
|   This module contains the routines which deal with obtaining the extra 
|   object information associated with a window.  For these to work, the 
|   window class must reserve the 0th word of the win-class object to be 
|   used to hold global-memory handle. 
\*---------------------------------------------------------------------------*/ 
 
#include <windows.h> 
#include "gdidemo.h" 
 
/*---------------------------------------------------------------------------*\ 
| ALLOC WINDOW INFO 
|   This routine allocates memory out of the application heap for storing 
|   extra memory for the window.  It is alway referenced as offset 0. 
\*---------------------------------------------------------------------------*/ 
BOOL FAR AllocWindowInfo(HWND hWnd, WORD wSize) 
{ 
    HANDLE hsd; 
 
 
    if(hsd = LocalAlloc(LHND,(WORD)wSize)) 
    { 
        SetWindowLong(hWnd,0,(LONG)hsd); 
        return(TRUE); 
    } 
    return(FALSE); 
} 
 
 
/*---------------------------------------------------------------------------*\ 
| LOCK WINDOW INFO 
|   This routine de-references the extra-memory associated with the window. 
|   it locks the object and gives the caller a pointer to the memory. 
\*---------------------------------------------------------------------------*/ 
PVOID FAR LockWindowInfo(HWND hWnd) 
{ 
    HANDLE hMem; 
    PVOID  pMem; 
 
 
    pMem = NULL; 
    if(hMem = (HANDLE)GetWindowLong(hWnd,0)) 
        pMem = (PVOID)LocalLock(hMem); 
 
    return(pMem); 
} 
 
 
/*---------------------------------------------------------------------------*\ 
| UNLOCK WINDOW INFO 
|   This routine unlocks the memory the caller has previously locked. 
\*---------------------------------------------------------------------------*/ 
BOOL FAR UnlockWindowInfo(HWND hWnd) 
{ 
    HANDLE hMem; 
 
 
    if(hMem = (HANDLE)GetWindowLong(hWnd,0)) 
        if(!LocalUnlock(hMem)) 
            return(TRUE); 
 
    return(FALSE); 
} 
 
 
/*---------------------------------------------------------------------------*\ 
| FREE WINDOW INFO 
|   This routine frees the object memory associated with the window. 
\*---------------------------------------------------------------------------*/ 
BOOL FAR FreeWindowInfo(HWND hWnd) 
{ 
    LOCALHANDLE hMem; 
 
 
    if(hMem = (HANDLE)GetWindowLong(hWnd,0)) 
        LocalFree(hMem); 
    return(TRUE); 
}