C / C++ / MFC

Don Guy wrote:

Does Image Encoding can convert raw image date to PNG format?

Don Guy wrote:

I know Image.Save() can save a BMP file in PNG or JPG format, but here the purpose is not convert and save into the hard drive. But i want the PNG formatted data, which can be later used for other purposes.

BYTE * WebKitWnd::GetPNGImageFromBackingStore(UINT& iLength)
{
	BYTE *pRet = nullptr;
	iLength = 0;

	CDC memDC;
	memDC.CreateCompatibleDC(NULL);

	DIBSECTION ds;
	BITMAPINFOHEADER &bmInfo = ds.dsBmih;
	if(NULL != m_hBacking && NULL != ::GetObject(m_hBacking, sizeof(ds), &ds))
	{
		Bitmap bmp(m_hBacking,NULL);
		Graphics g(&bmp);
		CLSID  encoderClsid;
		BYTE *png_buffer = nullptr;
		if(TRUE == GetEncoderClsid(L"image/png", &encoderClsid))
		{
			IStream *buffer;
			VERIFY_SUCCEEDED(::CreateStreamOnHGlobal(NULL, FALSE, &buffer));
			bmp.Save(buffer,&encoderClsid,NULL);
			STATSTG statstg;
			VERIFY_SUCCEEDED(buffer->Stat(&statstg, STATFLAG_DEFAULT));
			ULONG m_bmpBufferSize = (ULONG)statstg.cbSize.LowPart;
			BYTE *png_buffer = new(std::nothrow) BYTE[m_bmpBufferSize];
			if(png_buffer)
			{
				LARGE_INTEGER li = {0};
				buffer->Seek(li, STREAM_SEEK_SET, NULL);
				ULONG m_nRead;
				buffer->Read(png_buffer,m_bmpBufferSize, &m_nRead);
				pRet = png_buffer;
				iLength = m_bmpBufferSize;
				buffer->Release();
			}
		}
	}
	memDC.DeleteDC();
	return pRet;
}