IJL 1.5 - jpg 디코드 함수

ijl를 사용하여 buffer의 jpg를 decode하여 다시 버퍼로 반환하며
ijl 설치시 도움말에 포함되어있는 소스

BOOL DecodeFromJPEGBuffer(
BYTE* lpJpgBuffer,
DWORD dwJpgBufferSize,
BYTE** lppRgbBuffer,
DWORD* lpdwWidth,
DWORD* lpdwHeight,
DWORD* lpdwNumberOfChannels)
{

BOOL bres;
IJLERR jerr;
DWORD dwWholeImageSize;
BYTE* lpTemp = NULL;
// Allocate the IJL JPEG_CORE_PROPERTIES structure.
JPEG_CORE_PROPERTIES jcprops;
bres = TRUE;
__try
{
 // Initialize the Intel(R) JPEG Library.
 jerr = ijlInit(&jcprops);
 if(IJL_OK != jerr)
 {
  bres = FALSE;
  __leave;
 }
 // Get information on the JPEG image
 // (i.e., width, height, and channels).
 jcprops.JPGFile = NULL;
 jcprops.JPGBytes = lpJpgBuffer;
 jcprops.JPGSizeBytes = dwJpgBufferSize;
 jerr = ijlRead(&jcprops, IJL_JBUFF_READPARAMS);
 if(IJL_OK != jerr)
 {
  bres = FALSE;
  __leave;
 }
 // Set the JPG color space ... this will always be
 // somewhat of an educated guess at best because JPEG
 // is "color blind" (i.e., nothing in the bit stream
 // tells you what color space the data was encoded from).
 // However, in this example we assume that we are
 // reading JFIF files which means that 3 channel images
 // are in the YCbCr color space and 1 channel images are
 // in the Y color space.
 switch(jcprops.JPGChannels)
 {
  case 1:
  {
   jcprops.JPGColor = IJL_G;
   jcprops.DIBColor = IJL_RGB;
   jcprops.DIBChannels = 3;
   break;
  }
  case 3:
  {
   jcprops.JPGColor = IJL_YCBCR;
   jcprops.DIBColor = IJL_RGB;
   jcprops.DIBChannels = 3;
   break;
  }
  default:
  {
   // This catches everything else, but no
   // color twist will be performed by the IJL.
   jcprops.JPGColor = IJL_OTHER;
   jcprops.DIBColor = IJL_OTHER;
   jcprops.DIBChannels = jcprops.JPGChannels;
   break;
  }
 }
 // Compute size of desired pixel buffer.
 dwWholeImageSize = jcprops.JPGWidth * jcprops.JPGHeight *
 jcprops.DIBChannels;
 // Allocate memory to hold the decompressed image data.
 lpTemp = new BYTE [dwWholeImageSize];
 if(NULL == lpTemp)
 {
  bres = FALSE;
  __leave;
 }
 // Set up the info on the desired DIB properties.
 jcprops.DIBWidth = jcprops.JPGWidth;
 jcprops.DIBHeight = jcprops.JPGHeight;
 jcprops.DIBPadBytes = 0;
 jcprops.DIBBytes = lpTemp;
 // Now get the actual JPEG image data into the pixel buffer.
 jerr = ijlRead(&jcprops, IJL_JBUFF_READWHOLEIMAGE);
 if(IJL_OK != jerr)
 {
  bres = FALSE;
  __leave;
 }
} // __try
__finally
{
 if(FALSE == bres)
 {
  if(NULL != lpTemp)
  {
   delete [] lpTemp;
   lpTemp = NULL;
  }
 }
 // Clean up the Intel(R) JPEG Library.
 ijlFree(&jcprops);
 *lpdwWidth = jcprops.DIBWidth;
 *lpdwHeight = jcprops.DIBHeight;
 *lpdwNumberOfChannels = jcprops.DIBChannels;
 *lppRgbBuffer = lpTemp;
} // __finally

return bres;
} // DecodeFromJPEGBuffer()