L_ConvertBufferExt

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_ConvertBufferExt(pBuffer, nWidth, nBitsPerPixelSrc, nBitsPerPixelDst, nOrderSrc, nOrderDst, pPaletteSrc, pPaletteDst, uFlags, uLowBit, uHighBit)

Converts data in the specified buffer to the specified bits per pixel and color order. You can convert from any bits per pixel to any bits per pixel.

Returns

Comments

Note: This function will also work for 12 and 16-bit grayscale images, but only in the Document/Medical Imaging editions . If you attempt to use this function with a 12 or 16-bit grayscale image, but you do not have a Medical Imaging edition , you will receive an error.

The conversion uses only one buffer, which must be large enough to hold the data before and after conversion.

Image data that is 8 bits per pixel or less must use a palette, and this function can use such data as input, output, or both. Therefore, you may need to specify the palette for the input, or for the output, or both.

If either nBitsPerPixelSrc or nBitsPerPixelDst is 16, uFlags is used to determine whether the data should be treated as color or grayscale.

If nBitsPerPixelSrc is 12, it is assumed to be grayscale. However, the uFlags parameter should also reflect that it is grayscale for future compatibility.

If the source is grayscale, pPaletteSrc can be set to a palette. The palette should contain N entries. If the source uses uLowBit and uHighBit, then N equals 2 raised to the power of (uHighBit - uLowBit + 1). Otherwise, N equals 2 raised to the power of nBitsPerPixelSrc.

uFlags supersedes nOrderSrc and nOrderDst. If you specify ORDER_BGR for nOrderSrc, but use CVT_SRCGRAY in uFlags, it will be assumed that the source buffer contains grayscale data.

Required DLLs and Libraries

Platforms

Windows 95 / 98 / Me, Windows 2000 / XP, Windows CE.

See Also

Example

This example loads a temporary bitmap at 24 bits per pixel, creates a new 16-bit grayscale image, and uses L_ConvertBuffer to convert data from the temporary bitmap to the new one.

BITMAPHANDLE LeadBitmap;   /* Bitmap handle for the final image */

void TestFunction(HWND hWnd, pBITMAPHANDLE pBitmap)
{
   BITMAPHANDLE TmpBitmap;   /* Bitmap handle to hold the input image */
   L_UCHAR L_FAR *pBuf; /* Buffer to hold the row */
   HGLOBAL hBuf; /* Handle to the buffer */
   int i; /* Loop counter */

   /* Load the bitmap, at 24 bits per pixel */
   L_LoadBitmap (TEXT("IMAGE3.CMP"), &TmpBitmap, sizeof(BITMAPHANDLE), 24, 0, NULL, NULL);

   
   /* Create a new 16-bit grayscale bitmap */
   L_CreateBitmap(&LeadBitmap, sizeof(BITMAPHANDLE), TYPE_CONV, TmpBitmap.Width, TmpBitmap.Height,
                  16, ORDER_GRAY, NULL, TmpBitmap.ViewPerspective, NULL, 0);

   /* Allocate and lock the buffer */
   hBuf = GlobalAlloc(GMEM_MOVEABLE,max(LeadBitmap.BytesPerLine, TmpBitmap.BytesPerLine));
   pBuf = (L_UCHAR L_FAR *)GlobalLock( hBuf );

   /* Process each row from TmpBitmap to LeadBitmap */
   L_AccessBitmap(&LeadBitmap);
   L_AccessBitmap(&TmpBitmap);
   for(i=0; i < TmpBitmap.Height; i++)
   {
      L_GetBitmapRow(&TmpBitmap, pBuf, i, TmpBitmap.BytesPerLine);
      L_ConvertBufferExt(pBuf, TmpBitmap.Width, 
         TmpBitmap.BitsPerPixel, LeadBitmap.BitsPerPixel,
         TmpBitmap.Order, LeadBitmap.Order, NULL, NULL,
         CVT_DSTGRAY, 0, 15);
      L_PutBitmapRow(&LeadBitmap, pBuf, i, LeadBitmap.BytesPerLine);
   }
   L_ReleaseBitmap(&LeadBitmap);
   L_ReleaseBitmap(&TmpBitmap);

   /* Free memory that we no longer need */
   GlobalUnlock(hBuf);
   GlobalFree(hBuf);
   /* Free the temporary bitmap */
   L_FreeBitmap(&TmpBitmap);

   /* Force paint palette creation */
   SendMessage (hWnd, WM_QUERYNEWPALETTE, 0, 0L);
   return;
}