Generating bitmap files under open GL

OpenGL
1

I would like to save the current screen to some kind of bitmapped file. I.e. I would like to save the contents of the file under .png or .gif or .jpg. I would like this process to be automated and quick. Are there any built in routines? Or do I have to use a third party component? I am running in Visual Studio .NET in c++ if that helps.

Thanks

2

libTIFF makes it pretty easy to write out TIFF files:

http://www.remotesensing.org:16080/libtiff/

3

If all you want is a screen capture:

#pragma once
#include <atlstr.h>
#include <atlimage.h>

bool ScreenCapture(string filename,HWND hWnd){

HDC hDC;
CImage img;  //bitmap holder created
hDC = GetWindowDC(hWnd); //Now get it's DC handle 

HDC hMemDC = CreateCompatibleDC(hDC);
RECT r;
GetWindowRect(hWnd,&r); 
SIZE size;
size.cx = r.right-r.left;
size.cy = r.bottom-r.top;

//capture screen
HBITMAP hBitmap = CreateCompatibleBitmap(hDC, size.cx, size.cy);
if (hBitmap)
{
SelectObject(hMemDC, hBitmap);
    BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC, 0, 0, SRCCOPY);
   
    DeleteDC(hMemDC);
    ReleaseDC(NULL, hDC);
img.Attach(hBitmap); 
img.Save(filename);  
    DeleteObject(hBitmap);
return true;
}

return false;

}

Filename is the name and location of the file. It can be .bmp or .jpg.

If you want more detail than a screen capture, you have to mess with the PIXELFORMATDESCRIPTOR and DIB sections.

4

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