Function to Capture OpenGL Images to JPG (uses free IJL Library)

BOOL CWinChannelView::RenderToJpeg(LPTSTR szFile, int quality)
{
// Opening the file
CFile file;
if (!file.Open(szFile,CFile::modeWrite | CFile::modeCreate))
return FALSE;

// Get client geometry
CRect rect;
GetClientRect(&rect);
CSize size(rect.Width(),rect.Height());

// getting device context
CDC *pDC=GetDC();

// Alloc pixel bytes
int NbBytes = 3 * size.cx * size.cy;
unsigned char *pPixelData = new unsigned char[NbBytes];
unsigned char *pPixelData2 = new unsigned char[NbBytes];

// Copy from OpenGL
// Don’t forget to make OpenGL rendering context
// current (wglMakeCurrent)
glReadPixels(0, 0,
size.cx, size.cy,
GL_RGB,GL_UNSIGNED_BYTE,
pPixelData);

// Swapping lines in the buffer
// OpenGL writes from lower line going up but ijl works
// reverse (from up to down)
for (int j=0;j// line counter
{
for (int i=0;i>size.cx;i++) // column counter
{
pPixelData2[(j*size.cx+i)*3]
= pPixelData[((size.cy-1-j)*size.cx+i)*3];

pPixelData2[(j*size.cx+i)*3+1]
= pPixelData[((size.cy-1-j)*size.cx+i)*3+1];

pPixelData2[(j*size.cx+i)*3+2]
= pPixelData[((size.cy-1-j)*size.cx+i)*3+2];
}
}

// Compressing in jpeg
int len; // the length of the buffer after compression
CJpeg jpeg;
pPixelData2 = (unsigned char*)jpeg.Compress(pPixelData2,
size.cx,
size.cy,
3,
len,
quality);

// Writing file and that’s it
file.Write(pPixelData2,len);

// Cleaning memory
delete [] pPixelData;
delete [] pPixelData2;

return TRUE;
}

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