PRB: Metafiles and Palettes (98268)

MORE INFORMATION

Below is the code necessary to correct the problem. There are no rules regarding when to call FlushGDIHeap(); however, Microsoft recommends doing this after a major operation, such as after saving a file or printing. Determining whether you need to flush the GDI heap depends on how often your application selects in a palette in a metafile. Optionally, you could periodically call TOOLHELP and see if the GDI resources are greater than X%.

Sample Code

SEG       segGDI, segNil;
HANDLE    hPalSys;
int       iPal;
BOOL      fEnableFlushHeap;

/* ---------------------------------------------
   The following code is used to initialize the
   FlushGDIHeap function.
   --------------------------------------------- */ 
API VOID InitOLE(VOID)
{
  HANDLE hGDISegment;

  /* Called once during application initialization.  Sets up the
     state for FlushGDIHeap.  */ 
  /* Make sure this version of Windows has the bug. */ 
  if (wWinVer >= 0x400)
          return;

  /* This is from MSDN and it gets GDI's DS.
   * The module handle return by LoadLibrary is actually the module's DS.
   */ 
  hGDISegment = LoadLibrary("GDI.EXE");
  if (hGDISegment <= HINSTANCE_ERROR)
          return;

  FreeLibrary(hGDISegment);

  Glob(segGDI) = HIWORD(GlobalLock(hGDISegment));
  if (Glob(segGDI) != segNil)
  {
    GlobalUnlock(hGDISegment);
    Glob(hPalSys) = GetStockObject(DEFAULT_PALETTE);
    // Debug version of Windows has palette metafile list
    // heap handle in different offset than in retail Windows
    // versions greater than 3.0.
    // The offset is in WORD's.
    Glob(iPal) = (GetSystemMetrics(SM_DEBUG) != 0 &&
            FGTWinVer30()) ? 11 : 9;
    Glob(fEnableFlushHeap) = TRUE;
  }

} // end InitOLE

/*=========================================================================
=
FlushGDIHeap
===========================================================================
=*/ 
STATIC VOID NEAR FlushGDIHeap(VOID)
{
  HANDLE hPal;
  SEG segTmp;
  WORD *pPal, *pw, w2, iPal;

  /* If the flush heap operation is not enabled then return. */ 
  if (!Glob(fEnableFlushHeap))
          return;

  /* Switch to GDI's heap for Local memory functions. */ 
  segTmp = Glob(segGDI);
  hPal = Glob(hPalSys);
  /* Offset in Pal data structure to second metafile list handle.
  * This varies between debug and retail (see InitOLE).
  */ 
  iPal = Glob(iPal);
  _asm {
          push ds
          mov  ds,segTmp
       }

  /* Shrink the metafile list table down for the system palette. */ 
  if ((pPal = (WORD *)LocalLock(hPal)) != NULL)
  {
     /* First free memory from the standard object metafile list.
      * All GDI objects have this list associated with them if
      * they are selected into metafiles.
      */ 

     if (pPal[4] != hNil)
     {
        if ((pw = (WORD *)LocalLock(pPal[4])) != NULL)
        {
           w2 = *pw;
           LocalUnlock(pPal[4]);
           LocalReAlloc(pPal[4], (w2+1) * sizeof(WORD), LHND);
        }
     }

     /* Second, free memory from the secondary metafile list.
      * Only palettes have this list.
      */ 

     if (pPal[iPal] != hNil)
     {
       if ((pw = (WORD *)LocalLock(pPal[iPal])) != NULL)
       {
          w2 = *pw;
          LocalUnlock(pPal[iPal]);
          LocalReAlloc(pPal[iPal], (w2+1) * sizeof(WORD), LHND);
       }
     }

     LocalUnlock(hPal);
  }

  /* Restore application's data segment. */ 
  _asm {
         pop ds
       }
} // end FlushGDIHeap