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