Knowledge Base Nr: 00066 Jpeg-lib.cpp - http://www.swe-kaiser.de

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MFC: Imagefunktionen (jpeg, tiff, png, ...)

  
// ACHTUNG: MFC statisch linken!!!!

class CImageSupport
{
public:
  CImageSupport();
  virtual ~CImageSupport();

  int LoadJPG(const char* lpszFilename);
  int Draw(HDC hdc, int nPosX = 0, int nPosY = 0, int nSizeX = 0, int nSizeY = 0
           , int nTargetPosX = 0, int nTargetPosY = 0
           , int nTargetSizeX = 0, int nTargetSizeY = 0, boolean bNoResize = true);

  int SaveJPG(const char* lpszFilename);
  int GetSizeX() { return m_nWidth; }
  int GetSizeY() { return m_nHeight; }

protected:
  BYTE* m_buffer;
  unsigned int m_nWidth;
  unsigned int m_nHeight;
  unsigned int m_nWidthDW;
};

////////////////////////////////////////////////////////////
//
//  JpegFile - A C++ class to allow reading and writing of
//  RGB and Grayscale JPEG images. (actually, it reads all forms
//  that the JPEG lib will decode into RGB or grayscale) and
//  writes only RGB and Grayscale.
//
//  It is based on a Win32 compilation of the IJG V.6a code.
//
//  This will only work on 32-bit Windows systems. I have only
//  tried this with Win 95, VC++ 4.1.
//
//  This class Copyright 1997, Chris Losinger
//  This is free to use and modify provided my name is included.
//
//  Comments:
//  Thanks to Robert Johnson for discovering a DWORD-alignment bug
//  Thanks to Lee Bode for catching a bug in CMfcappView::OnFileGetdimensionsjpg()
//
////////////////////////////////////////////////////////////
//
//  General Usage:
//
//  #include this file.
//  link with jpeglib2.lib
//
//  All functions here are static. There is no need to have a JpegFile object.
//  There is actually nothing in a JpegFile object anyway.
//
//  So, you can do this :
//
//    BOOL ok = JpegFile::vertFlipBuf(buf, widthbytes, height);
//
//  instead of this :
//
//    JpegFile jpgOb;
//    BOOL ok = jpgOb.vertFlipBuf(buf, widthbytes, height);
//
/////
//
//  Linking usage :
//  It is sometimes necessary to set /NODEFAULTLIB:LIBC (or LIBCD) to use this
//  class.
//
/////
//
//  Error reporting:
//  The class generates message boxes in response to JPEG errors.
//
//  The JpegFile.cpp fn my_error_exit defines the behavior for
//  fatal errors : show msg box, return to caller.
//
//  Warnings are handled by jpeglib.lib - which generates msg boxes too.
//
////////////////////////////////////////////////////////////////

/*
////////////////////////////////////////////////////////////////
//  Reading Usage :

  UINT height;
  UINT width;
  BYTE *dataBuf;
   //read the file
   dataBuf=JpegFile::JpegFileToRGB(fileName,
                &width,
                &height);
  if (dataBuf==NULL) {
    return;
  }

  // RGB -> BGR
  JpegFile::BGRFromRGB(dataBuf, m_width, m_height);


  BYTE *buf;
  // create a DWORD aligned buffer from the JpegFile object
  buf = JpegFile::MakeDwordAlignedBuf(dataBuf,
                  width,
                  height,
                  &m_widthDW);

  // flip that buffer
  JpegFile::VertFlipBuf(m_buf, m_widthDW, m_height);

  // you now have a buffer ready to be used as a DIB

  // be sure to delete [] dataBuf;  // !!!!!!!!!!
  //      delete [] buf;


  // Writing Usage


  // this assumes your data is stored as a 24-bit RGB DIB.
  // if you have a 1,4,8,15/16 or 32 bit DIB, you'll have to
  // do some work to get it into a 24-bit RGB state.

  BYTE *tmp=NULL;

  // assume buf is a DWORD-aligned BGR buffer, vertically flipped
  // as if read from a BMP file.

  // un-DWORD-align
  tmp=JpegFile::RGBFromDWORDAligned(buf,
                  widthPix,
                  widthBytes,
                  height);

  // vertical flip
  JpegFile::VertFlipBuf(tmp, widthPix * 3, height);

  // reverse BGR
  JpegFile::BGRFromRGB(tmp, widthPix, height);

  if (tmp==NULL) {
    AfxMessageBox("~DWORD Memory Error");
    return;
  }

  // write it
  BOOL ok=JpegFile::RGBToJpegFile(fileName,
            tmp,
            width,
            height,
            TRUE,
            75);
  if (!ok) {
    AfxMessageBox("Write Error");
  }

  delete [] tmp;

////////////////////////////////////////////////////////////////