How to Create a Decoder Using an Image Filename

This topic describes how to create a bitmap decoder by using an image filename.

To create a bitmap decoder by using an image filename

1. Create an IWICImagingFactory object to create Windows Imaging Component (WIC) objects.

   // Create WIC factory
   hr = CoCreateInstance(
       CLSID_WICImagingFactory,
       NULL,
       CLSCTX_INPROC_SERVER,
       IID_PPV_ARGS(&m_pIWICFactory)
       );
   

2. Use the CreateDecoderFromFilename method to create an IWICBitmapDecoder from an image file.

   HRESULT hr = S_OK;
   
   IWICBitmapDecoder *pIDecoder = NULL;
   IWICBitmapFrameDecode *pIDecoderFrame  = NULL;
   
   hr = m_pIWICFactory->CreateDecoderFromFilename(
      L"turtle.jpg",                  // Image to be decoded
      NULL,                           // Do not prefer a particular vendor
      GENERIC_READ,                   // Desired read access to the file
      WICDecodeMetadataCacheOnDemand, // Cache metadata when needed
      &pIDecoder                      // Pointer to the decoder
      );
   

3. Get the first IWICBitmapFrameDecode of the image.

   // Retrieve the first bitmap frame.
   if (SUCCEEDED(hr))
   {
      hr = pIDecoder->GetFrame(0, &pIDecoderFrame);
   }
   

   The JPEG file format only supports a single frame. Because the file in this example is a JPEG file, the first frame (0) is used. For image formats that have multiple frames, see How to Retrieve the Frames of an Image for accessing each frame of the image.

4. Process the image frame. For additional information about IWICBitmapSource objects, see the Bitmap Sources Overview.

See Also

Programming Guide

Reference

Samples