private static SafeHBITMAP _CreateHBITMAPFromImageStream(Stream imgStream, out Size bitmapSize)
{
IWICImagingFactory pImagingFactory = null;
IWICBitmapDecoder pDecoder = null;
IWICStream pStream = null;
IWICBitmapFrameDecode pDecodedFrame = null;
IWICFormatConverter pBitmapSourceFormatConverter = null;
IWICBitmapFlipRotator pBitmapFlipRotator = null;
SafeHBITMAP hbmp = null;
try
{
using (var istm = new ManagedIStream(imgStream))
{
pImagingFactory = CLSID.CoCreateInstance<IWICImagingFactory>(CLSID.WICImagingFactory);
pStream = pImagingFactory.CreateStream();
pStream.InitializeFromIStream(istm);
// Create an object that will decode the encoded image
Guid vendor = Guid.Empty;
pDecoder = pImagingFactory.CreateDecoderFromStream(pStream, ref vendor, WICDecodeMetadata.CacheOnDemand);
pDecodedFrame = pDecoder.GetFrame(0);
pBitmapSourceFormatConverter = pImagingFactory.CreateFormatConverter();
// Convert the image from whatever format it is in to 32bpp premultiplied alpha BGRA
Guid pixelFormat = WICPixelFormat.WICPixelFormat32bppPBGRA;
pBitmapSourceFormatConverter.Initialize(pDecodedFrame, ref pixelFormat, WICBitmapDitherType.None, IntPtr.Zero, 0, WICBitmapPaletteType.Custom);
pBitmapFlipRotator = pImagingFactory.CreateBitmapFlipRotator();
pBitmapFlipRotator.Initialize(pBitmapSourceFormatConverter, WICBitmapTransform.FlipVertical);
int width, height;
pBitmapFlipRotator.GetSize(out width, out height);
bitmapSize = new Size { Width = width, Height = height };
var bmi = new BITMAPINFO
{
bmiHeader = new BITMAPINFOHEADER
{
biSize = Marshal.SizeOf(typeof(BITMAPINFOHEADER)),
biWidth = width,
biHeight = height,
biPlanes = 1,
biBitCount = 32,
biCompression = BI.RGB,
biSizeImage = (width * height * 4),
},
};
// Create a 32bpp DIB. This DIB must have an alpha channel for UpdateLayeredWindow to succeed.
IntPtr pBitmapBits;
hbmp = NativeMethods.CreateDIBSection(null, ref bmi, out pBitmapBits, IntPtr.Zero, 0);
// Copy the decoded image to the new buffer which backs the HBITMAP
var rect = new WICRect { X = 0, Y = 0, Width = width, Height = height };
pBitmapFlipRotator.CopyPixels(ref rect, width * 4, bmi.bmiHeader.biSizeImage, pBitmapBits);
var ret = hbmp;
hbmp = null;
return ret;
}
}
finally
{
Utility.SafeRelease(ref pImagingFactory);
Utility.SafeRelease(ref pDecoder);
Utility.SafeRelease(ref pStream);
Utility.SafeRelease(ref pDecodedFrame);
Utility.SafeRelease(ref pBitmapFlipRotator);
Utility.SafeRelease(ref pBitmapSourceFormatConverter);
Utility.SafeDispose(ref hbmp);
}
}