dibutil.c

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      /* allocate memory block for logical palette */
      hLogPal = GlobalAlloc(GHND, sizeof(LOGPALETTE) + sizeof(PALETTEENTRY) *
                wNumColors);

      /* if not enough memory, clean up and return NULL */
      if (!hLogPal)
      {
     GlobalUnlock(hDIB);
     return NULL;
      }

      /* lock memory block and get pointer to it */
      lpPal = (LPLOGPALETTE)GlobalLock(hLogPal);

      /* set version and number of palette entries */
      lpPal->palVersion = PALVERSION;
      lpPal->palNumEntries = wNumColors;

      /*  store RGB triples (if Win 3.0 DIB) or RGB quads (if OS/2 DIB)
       *  into palette
       */
      for (i = 0; i < wNumColors; i++)
      {
     if (bWinStyleDIB)
     {
        lpPal->palPalEntry[i].peRed = lpbmi->bmiColors[i].rgbRed;
        lpPal->palPalEntry[i].peGreen = lpbmi->bmiColors[i].rgbGreen;
        lpPal->palPalEntry[i].peBlue = lpbmi->bmiColors[i].rgbBlue;
        lpPal->palPalEntry[i].peFlags = 0;
     }
     else
     {
        lpPal->palPalEntry[i].peRed = lpbmc->bmciColors[i].rgbtRed;
        lpPal->palPalEntry[i].peGreen = lpbmc->bmciColors[i].rgbtGreen;
        lpPal->palPalEntry[i].peBlue = lpbmc->bmciColors[i].rgbtBlue;
        lpPal->palPalEntry[i].peFlags = 0;
     }
      }

      /* create the palette and get handle to it */
      hPal = CreatePalette(lpPal);

      /* if error getting handle to palette, clean up and return NULL */
      if (!hPal)
      {
     GlobalUnlock(hLogPal);
     GlobalFree(hLogPal);
     return NULL;
      }
   }

   /* clean up */
   GlobalUnlock(hLogPal);
   GlobalFree(hLogPal);
   GlobalUnlock(hDIB);

   /* return handle to DIB's palette */
   return hPal;
}


/*************************************************************************
 *
 * DIBToBitmap()
 *
 * Parameters:
 *
 * HDIB hDIB        - specifies the DIB to convert
 *
 * HPALETTE hPal    - specifies the palette to use with the bitmap
 *
 * Return Value:
 *
 * HBITMAP          - identifies the device-dependent bitmap
 *
 * Description:
 *
 * This function creates a bitmap from a DIB using the specified palette.
 * If no palette is specified, default is used.
 *
 * NOTE:
 *
 * The bitmap returned from this funciton is always a bitmap compatible
 * with the screen (e.g. same bits/pixel and color planes) rather than
 * a bitmap with the same attributes as the DIB.  This behavior is by
 * design, and occurs because this function calls CreateDIBitmap to
 * do its work, and CreateDIBitmap always creates a bitmap compatible
 * with the hDC parameter passed in (because it in turn calls
 * CreateCompatibleBitmap).
 *
 * So for instance, if your DIB is a monochrome DIB and you call this
 * function, you will not get back a monochrome HBITMAP -- you will
 * get an HBITMAP compatible with the screen DC, but with only 2
 * colors used in the bitmap.
 *
 * If your application requires a monochrome HBITMAP returned for a
 * monochrome DIB, use the function SetDIBits().
 *
 * Also, the DIBpassed in to the function is not destroyed on exit. This
 * must be done later, once it is no longer needed.
 *
 * History:   Date      Author               Reason
 *            6/01/91   Garrett McAuliffe    Created
 *            9/15/91   Patrick Schreiber    Added header and comments
 *            3/27/92   Mark Bader           Added comments about resulting
 *                                           bitmap format
 *
 ************************************************************************/


HBITMAP FAR DIBToBitmap(HDIB hDIB, HPALETTE hPal)
{
   LPSTR lpDIBHdr, lpDIBBits;  // pointer to DIB header, pointer to DIB bits
   HBITMAP hBitmap;            // handle to device-dependent bitmap
   HDC hDC;                    // handle to DC
   HPALETTE hOldPal = NULL;    // handle to a palette

   /* if invalid handle, return NULL */

   if (!hDIB)
      return NULL;

   /* lock memory block and get a pointer to it */
   lpDIBHdr = GlobalLock(hDIB);

   /* get a pointer to the DIB bits */
   lpDIBBits = FindDIBBits(lpDIBHdr);

   /* get a DC */
   hDC = GetDC(NULL);
   if (!hDC)
   {
      /* clean up and return NULL */
      GlobalUnlock(hDIB);
      return NULL;
   }

   /* select and realize palette */
   if (hPal)
      hOldPal = SelectPalette(hDC, hPal, FALSE);
   RealizePalette(hDC);

   /* create bitmap from DIB info. and bits */
   hBitmap = CreateDIBitmap(hDC, (LPBITMAPINFOHEADER)lpDIBHdr, CBM_INIT,
                lpDIBBits, (LPBITMAPINFO)lpDIBHdr, DIB_RGB_COLORS);

   /* restore previous palette */
   if (hOldPal)
      SelectPalette(hDC, hOldPal, FALSE);

   /* clean up */
   ReleaseDC(NULL, hDC);
   GlobalUnlock(hDIB);

   /* return handle to the bitmap */
   return hBitmap;
}


/*************************************************************************
 *
 * BitmapToDIB()
 *
 * Parameters:
 *
 * HBITMAP hBitmap  - specifies the bitmap to convert
 *
 * HPALETTE hPal    - specifies the palette to use with the bitmap
 *
 * Return Value:
 *
 * HDIB             - identifies the device-dependent bitmap
 *
 * Description:
 *
 * This function creates a DIB from a bitmap using the specified palette.
 *
 * History:   Date      Author               Reason
 *            6/01/91   Garrett McAuliffe    Created
 *            9/15/91   Patrick Schreiber    Added header and comments
 *            12/10/91  Patrick Schreiber    Added bits per pixel validation
 *                                           and check GetObject return value
 *
 ************************************************************************/


HDIB FAR BitmapToDIB(HBITMAP hBitmap, HPALETTE hPal)
{
   BITMAP bm;                   // bitmap structure
   BITMAPINFOHEADER bi;         // bitmap header
   BITMAPINFOHEADER FAR *lpbi;  // pointer to BITMAPINFOHEADER
   DWORD dwLen;                 // size of memory block
   HANDLE hDIB, h;              // handle to DIB, temp handle
   HDC hDC;                     // handle to DC
   WORD biBits;                 // bits per pixel

   /* check if bitmap handle is valid */

   if (!hBitmap)
      return NULL;

   /* fill in BITMAP structure, return NULL if it didn't work */
   if (!GetObject(hBitmap, sizeof(bm), (LPSTR)&bm))
      return NULL;

   /* if no palette is specified, use default palette */
   if (hPal == NULL)
      hPal = GetStockObject(DEFAULT_PALETTE);

   /* calculate bits per pixel */
   biBits = bm.bmPlanes * bm.bmBitsPixel;

   /* make sure bits per pixel is valid */
   if (biBits <= 1)
      biBits = 1;
   else if (biBits <= 4)
      biBits = 4;
   else if (biBits <= 8)
      biBits = 8;
   else /* if greater than 8-bit, force to 24-bit */
      biBits = 24;

   /* initialize BITMAPINFOHEADER */
   bi.biSize = sizeof(BITMAPINFOHEADER);
   bi.biWidth = bm.bmWidth;
   bi.biHeight = bm.bmHeight;
   bi.biPlanes = 1;
   bi.biBitCount = biBits;
   bi.biCompression = BI_RGB;
   bi.biSizeImage = 0;
   bi.biXPelsPerMeter = 0;
   bi.biYPelsPerMeter = 0;
   bi.biClrUsed = 0;
   bi.biClrImportant = 0;

   /* calculate size of memory block required to store BITMAPINFO */
   dwLen = bi.biSize + PaletteSize((LPSTR)&bi);

   /* get a DC */
   hDC = GetDC(NULL);

   /* select and realize our palette */
   hPal = SelectPalette(hDC, hPal, FALSE);
   RealizePalette(hDC);

   /* alloc memory block to store our bitmap */
   hDIB = GlobalAlloc(GHND, dwLen);

   /* if we couldn't get memory block */
   if (!hDIB)
   {
      /* clean up and return NULL */
      SelectPalette(hDC, hPal, TRUE);
      RealizePalette(hDC);
      ReleaseDC(NULL, hDC);
      return NULL;
   }

   /* lock memory and get pointer to it */
   lpbi = (VOID FAR *)GlobalLock(hDIB);

   /* use our bitmap info. to fill BITMAPINFOHEADER */
   *lpbi = bi;

   /*  call GetDIBits with a NULL lpBits param, so it will calculate the
    *  biSizeImage field for us
    */
   GetDIBits(hDC, hBitmap, 0, (WORD)bi.biHeight, NULL, (LPBITMAPINFO)lpbi,
         DIB_RGB_COLORS);

   /* get the info. returned by GetDIBits and unlock memory block */
   bi = *lpbi;
   GlobalUnlock(hDIB);

   /* if the driver did not fill in the biSizeImage field, make one up */
   if (bi.biSizeImage == 0)
      bi.biSizeImage = WIDTHBYTES((DWORD)bm.bmWidth * biBits) * bm.bmHeight;

   /* realloc the buffer big enough to hold all the bits */
   dwLen = bi.biSize + PaletteSize((LPSTR)&bi) + bi.biSizeImage;
   if (h = GlobalReAlloc(hDIB, dwLen, 0))
      hDIB = h;
   else
   {
      /* clean up and return NULL */
      GlobalFree(hDIB);
      hDIB = NULL;
      SelectPalette(hDC, hPal, TRUE);
      RealizePalette(hDC);
      ReleaseDC(NULL, hDC);
      return NULL;
   }

   /* lock memory block and get pointer to it */
   lpbi = (VOID FAR *)GlobalLock(hDIB);

   /*  call GetDIBits with a NON-NULL lpBits param, and actualy get the
    *  bits this time
    */
   if (GetDIBits(hDC, hBitmap, 0, (WORD)bi.biHeight, (LPSTR)lpbi + (WORD)lpbi
         ->biSize + PaletteSize((LPSTR)lpbi), (LPBITMAPINFO)lpbi,
         DIB_RGB_COLORS) == 0)
   {
      /* clean up and return NULL */
      GlobalUnlock(hDIB);
      hDIB = NULL;
      SelectPalette(hDC, hPal, TRUE);
      RealizePalette(hDC);
      ReleaseDC(NULL, hDC);
      return NULL;
   }
   bi = *lpbi;

   /* clean up */
   GlobalUnlock(hDIB);
   SelectPalette(hDC, hPal, TRUE);
   RealizePalette(hDC);
   ReleaseDC(NULL, hDC);

   /* return handle to the DIB */
   return hDIB;
}


/*************************************************************************
 *
 * PalEntriesOnDevice()
 *
 * Parameter:
 *
 * HDC hDC          - device context
 *
 * Return Value:
 *
 * int              - number of palette entries on device
 *
 * Description:
 *
 * This function gets the number of palette entries on the specified device
 *
 * History:   Date      Author               Reason
 *            6/01/91   Garrett McAuliffe    Created
 *            9/15/91   Patrick Schreiber    Added header and comments
 *
 ************************************************************************/


int FAR PalEntriesOnDevice(HDC hDC)
{
   int nColors;  // number of colors

   /*  Find out the number of palette entries on this
    *  device.
    */

   nColors = GetDeviceCaps(hDC, SIZEPALETTE);

   /*  For non-palette devices, we'll use the # of system
    *  colors for our palette size.
    */
   if (!nColors)
      nColors = GetDeviceCaps(hDC, NUMCOLORS);
   assert(nColors);
   return nColors;
}


/*************************************************************************
 *
 * GetSystemPalette()
 *
 * Parameters:
 *
 * None
 *
 * Return Value:
 *
 * HPALETTE         - handle to a copy of the current system palette
 *
 * Description:
 *
 * This function returns a handle to a palette which represents the system
 * palette.  The system RGB values are copied into our logical palette using
 * the GetSystemPaletteEntries function.  
 *
 * History:   
 *            
 *    Date      Author               Reason        
 *    6/01/91   Garrett McAuliffe    Created        
 *    9/15/91   Patrick Schreiber    Added header and comments
 *    12/20/91  Mark Bader           Added GetSystemPaletteEntries call
 *
 ************************************************************************/


HPALETTE FAR GetSystemPalette(void)
{
   HDC hDC;                // handle to a DC
   static HPALETTE hPal = NULL;   // handle to a palette
   HANDLE hLogPal;         // handle to a logical palette
   LPLOGPALETTE lpLogPal;  // pointer to a logical palette
   int nColors;            // number of colors

   /* Find out how many palette entries we want. */

   hDC = GetDC(NULL);
   if (!hDC)
      return NULL;
   nColors = PalEntriesOnDevice(hDC);   // Number of palette entries

   /* Allocate room for the palette and lock it. */
   hLogPal = GlobalAlloc(GHND, sizeof(LOGPALETTE) + nColors * sizeof(
             PALETTEENTRY));

   /* if we didn't get a logical palette, return NULL */
   if (!hLogPal)
      return NULL;

   /* get a pointer to the logical palette */
   lpLogPal = (LPLOGPALETTE)GlobalLock(hLogPal);

   /* set some important fields */
   lpLogPal->palVersion = PALVERSION;
   lpLogPal->palNumEntries = nColors;

   /* Copy the current system palette into our logical palette */

   GetSystemPaletteEntries(hDC, 0, nColors, 
                           (LPPALETTEENTRY)(lpLogPal->palPalEntry));

   /*  Go ahead and create the palette.  Once it's created,
    *  we no longer need the LOGPALETTE, so free it.
    */