Implementing IUriToStreamResolver.UriToStreamAsync and using it in WebView

Question

I am using a WebView to load local content and handle those requests myself. I have implemented IUriToStreamResolver:

 public class MyUriToStreamResolver : IUriToStreamResolver    
{        
    public IAsyncOperation<IInputStream> UriToStreamAsync(Uri uri)
    {            
         Debug.WriteLine(uri.ToString());            
         //process uri and return       
    }    
}

And in my MainPage constructor, I create a uri to a TestPage and call NavigateToLocalStreamUri:

MyUriToStreamResolver resolver = new MyUriToStreamResolver();

Uri uri2 = new Uri("ms-appdata:///local/TestPage.html");
AW_WebView.NavigateToLocalStreamUri(uri2, resolver);

However when I do this, I run into this error: 

System.ArgumentException: Value does not fall within the expected range.
   at Windows.UI.Xaml.Controls.WebView.NavigateToLocalStreamUri(Uri source, IUriToStreamResolver streamResolver)
   at WebViewTest.MainPage..ctor() in c:\Users\Test\Documents\Visual Studio 2013\Projects\WebViewTest\WebViewTest\MainPage.xaml.cs:line 35

I'm not exactly sure why this is happening and what I could do to fix it. Any help is appreciated, thank you!

Answer 1

Figured it out, instead of creating a new Uri object your self, you would have to call WebView's BuildLocalStreamUri method. 

AW_WebView.BuildLocalStreamUri("MyTag", "TestPage.html");

Answer 2

For local content you don't need your own resolver as well -- is that what you are doing?

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Tim Heuer | Program Manager, XAML | http://timheuer.com/blog | @timheuer

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Answer 3

I believe, for local content, you would just be able to refer to it in the source property? 

I was just using TestPage.html as a sample to see how it works.

Answer 4

Tim,

I have created my own stream resolver but it doesn't render anything - I need to modify the storage file in memory before returning the stream.  What am I doing wrong here?

        private async Task<IInputStream> GetSampleTextAsync(System.Uri uri)
        {
            StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(uri);

            var text = await FileIO.ReadTextAsync(file);

            // I need to modify the text here

            // do not dispose of the memory stream
            var memoryStream = new MemoryStream();

            var writer = new StreamWriter(memoryStream);

            await writer.WriteAsync(text);
            await writer.FlushAsync();

            memoryStream.Position = 0;

            var inputStream = memoryStream.AsInputStream();

            return inputStream;
        }

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Michael S. Scherotter
Principal Architect Evangelist Microsoft Corporation,
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