OK, after a lot of effort here’s the answer:
int SaveJpeg(HBITMAP hBmp, LPCWSTR lpszFilename, ULONG uQuality)
{
ULONG *pBitmap = NULL;
CLSID imageCLSID;
EncoderParameters encoderParams;
int iRes = 0;
typedef Status (WINAPI *pGdipCreateBitmapFromHBITMAP)(HBITMAP, HPALETTE, ULONG**);
pGdipCreateBitmapFromHBITMAP lGdipCreateBitmapFromHBITMAP;
typedef Status (WINAPI *pGdipSaveImageToFile)(ULONG *, const WCHAR*, const CLSID*, const EncoderParameters*);
pGdipSaveImageToFile lGdipSaveImageToFile;
// load GdipCreateBitmapFromHBITMAP
lGdipCreateBitmapFromHBITMAP = (pGdipCreateBitmapFromHBITMAP)GetProcAddress(hModuleThread, "GdipCreateBitmapFromHBITMAP");
if(lGdipCreateBitmapFromHBITMAP == NULL)
{
// error
return 0;
}
// load GdipSaveImageToFile
lGdipSaveImageToFile = (pGdipSaveImageToFile)GetProcAddress(hModuleThread, "GdipSaveImageToFile");
if(lGdipSaveImageToFile == NULL)
{
// error
return 0;
}
lGdipCreateBitmapFromHBITMAP(hBmp, NULL, &pBitmap);
iRes = GetEncoderClsid(L"image/jpeg", &imageCLSID);
if(iRes == -1)
{
// error
return 0;
}
encoderParams.Count = 1;
encoderParams.Parameter[0].NumberOfValues = 1;
encoderParams.Parameter[0].Guid = EncoderQuality;
encoderParams.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParams.Parameter[0].Value = &uQuality;
lGdipSaveImageToFile(pBitmap, lpszFilename, &imageCLSID, &encoderParams);
return 1;
}
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what is hModuleThread? Look in here. You can replace with
GetModuleHandle()
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what is GetEncoderClsid? Look here.
Now the question is, how do I save the encoded pBitmap (as a jpeg) into a BYTE buffer?