How to Load a Bitmap from a File

Direct2D uses the Windows Imaging Component (WIC) to load bitmaps. To load a bitmap from a file, first use WIC objects to load the image and to convert it to a Direct2D-compatible format, then use the CreateBitmapFromWicBitmap method to create an ID2D1Bitmap.

1. Create an IWICBitmapDecoder by using the IWICImagingFactory::CreateDecoderFromFileName method.

   HRESULT DemoApp::LoadBitmapFromFile(
    ID2D1RenderTarget *pRenderTarget,
    IWICImagingFactory *pIWICFactory,
    PCWSTR uri,
    UINT destinationWidth,
    UINT destinationHeight,
    ID2D1Bitmap **ppBitmap
    )
   {
    IWICBitmapDecoder *pDecoder = NULL;
    IWICBitmapFrameDecode *pSource = NULL;
    IWICStream *pStream = NULL;
    IWICFormatConverter *pConverter = NULL;
    IWICBitmapScaler *pScaler = NULL;
   
    HRESULT hr = pIWICFactory->CreateDecoderFromFilename(
    uri,
    NULL,
    GENERIC_READ,
    WICDecodeMetadataCacheOnLoad,
    &pDecoder
    );
   
   

2. Retrieve a frame from the image and store the frame in an IWICBitmapFrameDecode object.

    if (SUCCEEDED(hr))
    {
    // Create the initial frame.
    hr = pDecoder->GetFrame(0, &pSource);
    }
   

3. The bitmap must be converted to a format that Direct2D can use, so convert the image's pixel format to 32bppPBGRA. (For a list of supported formats, see Pixel Formats and Alpha Modes.). Call the IWICImagingFactory::CreateFormatConverter method to create an IWICFormatConverter object, then call the IWICFormatConverter object's Initialize method to perform the conversion.

    if (SUCCEEDED(hr))
    {
   
    // Convert the image format to 32bppPBGRA
    // (DXGI_FORMAT_B8G8R8A8_UNORM + D2D1_ALPHA_MODE_PREMULTIPLIED).
    hr = pIWICFactory->CreateFormatConverter(&pConverter);
   
    }
   
   
    if (SUCCEEDED(hr))
    {
    hr = pConverter->Initialize(
    pSource,
    GUID_WICPixelFormat32bppPBGRA,
    WICBitmapDitherTypeNone,
    NULL,
    0.f,
    WICBitmapPaletteTypeMedianCut
    );
   

4. Call the CreateBitmapFromWicBitmap method to create an ID2D1Bitmap object that can be drawn by a render target and used with other Direct2D objects.

    if (SUCCEEDED(hr))
    {
   
    // Create a Direct2D bitmap from the WIC bitmap.
    hr = pRenderTarget->CreateBitmapFromWicBitmap(
    pConverter,
    NULL,
    ppBitmap
    );
    }
   
    SafeRelease(&pDecoder);
    SafeRelease(&pSource);
    SafeRelease(&pStream);
    SafeRelease(&pConverter);
    SafeRelease(&pScaler);
   
    return hr;
   }
   

Some code has been omitted from this example.

Related topics

ID2D1Bitmap

CreateBitmapFromWicBitmap

How to Load a Bitmap from a Resource