c++ & gdi+: stretch a screenshot

[deepzero]

hi,

for quiet some time i am occupied by this little assignment:

Take a screenshot, shrink it (while preserving the aspect ration) and save it to disk.

my code:

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
	using namespace Gdiplus;
	UINT  num = 0;          // number of image encoders
	UINT  size = 0;         // size of the image encoder array in bytes	ImageCodecInfo* pImageCodecInfo = NULL;	GetImageEncodersSize(&num, &size);
	if(size == 0)
		return -1;  // Failure	pImageCodecInfo = (ImageCodecInfo*)(GlobalAlloc(0,size));
	if(pImageCodecInfo == NULL)
		return -1;  // Failure	GetImageEncoders(num, size, pImageCodecInfo);	for(UINT j = 0; j < num; ++j)
	{
		if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
		{
			*pClsid = pImageCodecInfo[j].Clsid;
			GlobalFree(pImageCodecInfo);
			return j;  // Success
		}    
	}	GlobalFree(pImageCodecInfo);
	return 0;
}int main()
{
	ULONG_PTR m_gdiplusToken;
	Gdiplus::GdiplusStartupInput gdiplusStartupInput;
	Gdiplus::GdiplusStartup(&m_gdiplusToken, &gdiplusStartupInput, NULL);
	Bitmap* bm = new Bitmap(1450,1050,PixelFormat32bppARGB);//create an empty image	HDC scrn = GetDC(0);//take screenshot
	Graphics gr(scrn);//assign it to a graphics object	gr.DrawImage(bm,100,100,1450,1050);//shrink it to 100x100	CLSID clsid;
	GetEncoderClsid(L"image/jpeg", &clsid);//get jpg encoder	bm->Save(L"D:\\wtf.jpg",&clsid);//save image	return 0;
}

obviously i am not the greatest gdi+ expert around...

but i cant see why this code just fails without any error (image is just not created....)

Edited April 3, 2011 by deepzero

[Killboy]

Looks like you forgot to fill gdiplusStartupInput, at least .GdiplusVersion must be 1