wpQueryBitmapHandle - Example Code

This example is a simplified version of the code in the WPBitmap class. The example does build a color palette for the bitmap and does no scaling of the bitmap size. (In this code, vhab is a global variable that contains the handle for the HAB for the Workplace Shell and RemoveBitmapFromMem is a function that frees the specified Device Context, Presentation Space, Bitmap, and Palette.)

SOM_Scope BOOL32 bmp_wpQueryBitmapHandle(WPBitmap *somSelf,
                                         HBITMAP *phBitmap,
                                         HPAL *phPalette,
                                         ULONG ulWidth,
                                         ULONG ulHeight,
                                         ULONG ulFlags,
                                         LONG lBackgroundColor,
                                         BOOL *pbQuitEarly)
{
   HDC         hdc = NULLHANDLE;
   HPS         hps = NULLHANDLE;
   union
   {
      PBITMAPFILEHEADER  pbfh;
      PBITMAPFILEHEADER2 pbfh2;
   } pBitmapFileHeader;
   union
   {
      PBITMAPINFOHEADER  pbinfoh;
      PBITMAPINFOHEADER2 pbinfoh2;
      PBITMAPINFO2       pbinfo2;
   } pBitmapInfoHeader;
   SIZEL       sizlSource;

   /* Make sure the caller specified a place to return the bitmap handle */
   if (!phBitmap)
   {
      return FALSE;
   }

   /* Set the returned bitmap and palette handles to NULLHANDLE in case
    * this method fails  */
   *phBitmap = NULLHANDLE;
   if (phPalette)
   {
      *phPalette = NULLHANDLE;
   }

   /* Read the bitmap file   */
   if (!_wpReadImageFile(somSelf))
   {
      return FALSE;
   }

   /* Create a device context and presentation space for the bitmap  */
   hdc = DevOpenDC (vhab, OD_MEMORY, "*", 0L, NULL, NULLHANDLE);
   if (hdc == DEV_ERROR)
   {
      return FALSE;
   }

   /*
    *  Create a new Presentation Space for the bitmap  */
   sizlSource.cx = 0;
   sizlSource.cy = 0;
   hps = GpiCreatePS (vhab,
                      hdc,
                      &sizlSource,
                      PU_PELS | GPIT_NORMAL | GPIA_ASSOC);
   if(hps == GPI_ERROR)
   {
      RemoveBitmapFromMem(&hdc,NULL,NULL,NULL);
      return FALSE;
   }

   /* Make sure there is no palette selected in the PS   */
   GpiSelectPalette(hps,NULLHANDLE);

   /* Create the bitmap   */
   pBitmapFileHeader.pbfh = (PBITMAPFILEHEADER)
                             _wpQueryBitmapData(somSelf,NULL);
   pBitmapInfoHeader.pbinfoh = &(pBitmapFileHeader.pbfh->bmp);
   *phBitmap = GpiCreateBitmap (hps,
                                pBitmapInfoHeader.pbinfoh2,
                                CBM_INIT,
                                (PBYTE)pBitmapFileHeader.pbfh +
                                   pBitmapFileHeader.pbfh->offBits,
                                pBitmapInfoHeader.pbinfo2);
   if(!*phBitmap)
   {
      RemoveBitmapFromMem(&hdc,&hps,NULL,NULL);
      return FALSE;
   }

   /*
    *  Select the bitmap into the presentation space  */
   GpiSetBitmap (hps, *phBitmap);

   /* Clean up the resources we allocated   */
   RemoveBitmapFromMem(&hdc,&hps,NULL,NULL);
   return !!*phBitmap;
}