L_SaveBitmapBuffer

#include "l_bitmap.h"

L_LTFIL_API L_INT L_SaveBitmapBuffer(pBuffer, uInitialBufferSize, puFinalFileSize, pBitmap, nFormat, nBitsPerPixel, nQFactor, pfnSaveBufferCB, pUserData, pSaveOptions)

Saves a bitmap to a file in a memory buffer that the user must allocate. The output can be in any of the supported compressed or uncompressed file formats.

Returns

Comments

L_SaveFileBuffer saves a bitmap to a file in a memory buffer that the user must allocate. The output can be in any of the supported compressed or uncompressed file formats. This function is similar to L_SaveFileMemory, except the user is responsible for allocating/reallocating buffers. The SAVEBUFFERCALLBACK notifies the user if the buffer is not large enough. The user can then reallocate the buffer. For more information, see SAVEBUFFERCALLBACK.

If the user wants to allocate a buffer that is large enough to hold the file in memory, an upper bound on the file size can be estimated by the following formula:

RequiredBytes = (Image Width) * (Image Height) * (BitsPerPixel) / 8

Note that this is an estimatethis does not include the size of the file header, and it does not take into account any compression. It is best to use a SAVEBUFFERCALLBACK so that the user can be notified if the buffer is not large enough.

Support for 12 and 16-bit grayscale images is only available in the Document and Medical Imaging toolkits.

This function cannot be used in combination with L_RedirectIO.

This function supports signed data images, but only DICOM and TIFF formats support signed data. This function will return an error code if you attempt to save a signed image to a format other than DICOM or TIFF.

If the bitmap has a region, the region stored in the bitmap will be saved, if the image is saved as one of the TIFF file formats.

In LEADTOOLS version 17 and up, when saving a colored image (such as a 24-bits per pixel image) to bitonal (1-bit per pixel), the toolkit will not use any dithering when converting the image data. This is done because dithering is not the recommended when converting colored images containing text for document processing such as OCR and Barcode. The result text will be fuzzy and hard for a recognition engine to process. To save a colored image as bitonal with Floyd-Stein dithering (the behavior of LEADTOOLS 16.5 and earlier) use the ESO_USEDITHERINGMETHOD along with BITMAPHANDLE.DitheringMethod as illustrated below:

// 'pBitmap' is a colored BITMAPHANDLE
// Setup FloydStein dithering:
bitmapHandle.DitheringMethod = FLOYD_STEIN_DITHERING;
SAVEFILEOPTION saveOptions = {0};
L_GetDefaultSaveFileOption(&saveOptions, sizeof(SAVEFILEOPTION));
saveOptions.Flags |= ESO_USEDITHERINGMETHOD;
// Save the bitmap as 1-bpp with auto-dithering:
L_SaveBitmap(fileName, &bitmapHandle, FILE_CCITT_GROUP4, 1, 0, &saveOptions);
// or any other L_SaveBitmapXyz or L_SaveFileXyz functions such as:
// L_SaveFile(fileName, &bitmapHandle, FILE_CCITT_GROUP4, 1, 0, 0, NULL, NULL, &saveOptions)

Required DLLs and Libraries

Platforms

Win32, x64, Mobile.

See Also

Example

This example loads the file 'pszFile', and then saves it to a memory buffer that the caller allocates. Note that when the buffer becomes filled, the ExampleSaveBufferCB callback is called to notify the caller to reallocate the buffer. After the save is completed, the size of the file in memory is displayed. Finally, the memory buffer containing the file is loaded into pBitmap

//********************************************************************************/
typedef struct _tagMYBUFFER
{
   L_UCHAR   *pBuffer;
   L_SIZE_T  dwBufferSize;
} MYBUFFER,  *pMYBUFFER;


L_INT EXT_CALLBACK ExampleSaveBufferCB(L_SIZE_T    uRequiredSize,
                                       L_UCHAR  ** ppBuffer,
                                       L_SIZE_T *  pdwBufferSize,
                                       L_VOID*     pUserData);

 L_INT SampleSaveBitmapBufferExample(L_TCHAR *pszFile, pBITMAPHANDLE pBitmap)
{
   L_INT nRet;
   BITMAPHANDLE Bitmap;
   L_SIZE_T dwFinalFileSize;
   L_TCHAR szMsg[100];
   MYBUFFER MyBuffer;

   MyBuffer.dwBufferSize = 100;
   MyBuffer.dwBufferSize = 0;
   MyBuffer.pBuffer = NULL;

   nRet = L_LoadBitmap(pszFile, &Bitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if (nRet != SUCCESS)
      return nRet;

   MyBuffer.pBuffer = (L_UCHAR  *)malloc(MyBuffer.dwBufferSize);  //large enough to hold rgbw.bmp
   if (MyBuffer.pBuffer == NULL)
      return FAILURE;
   
   nRet = L_SaveBitmapBuffer(MyBuffer.pBuffer,
                             MyBuffer.dwBufferSize,
                             &dwFinalFileSize,
                             &Bitmap,
                             FILE_BMP,
                             0,
                             0,
                             ExampleSaveBufferCB,
                             &MyBuffer,
                             NULL);
   if (nRet != SUCCESS)
      return nRet;

   wsprintf(szMsg, TEXT("Final Buffer Size: %d"), dwFinalFileSize);
   MessageBox(NULL, szMsg, TEXT("Notice!"), MB_OK);
   nRet = L_LoadBitmapMemory (MyBuffer.pBuffer, pBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, dwFinalFileSize, NULL, NULL);

   free(MyBuffer.pBuffer);
   if(Bitmap.Flags.Allocated)
      L_FreeBitmap(&Bitmap); 

   return SUCCESS;
}