Alex Golesh's Blog About Silverlight Development

Silverlight Tip: Enumerating embedded resources

Today I’ve got a “Call for Help” from one of Silverlight MVPs – Bill Reiss. The mail said:

“I would like to enumerate all items that were marked as Content or Resource in the main XAP file.

If I can’t do both I’d settle for one. Any sample code for this would be greatly appreciated.

Bill”

I decided to help with embedded resources, because I did something like this in WPF.

I’ve created sample application, which will display a list of resources in list box – from here it is very easy to use them by name. My sample will load the resource as image.

For application I’ve added 3 sample images and marked them “Resource” in properties:

The application UI:

XAML for sample:

    <StackPanel x:Name="LayoutRoot" Background="White" Orientation="Vertical">
        <StackPanel Orientation="Horizontal" Margin="5">
            <Button Content="Embedded Resources" Padding="5" Margin="5" x:Name="btnEmbedded" Click="btnEmbedded_Click"/>
        </StackPanel>
        <StackPanel Orientation="Horizontal" Margin="5">
            <StackPanel Orientation="Vertical" Margin="5">
                <TextBlock Text="Embedded Resources:" Margin="5,0"/>
                <ListBox x:Name="lstEmbedded" SelectionChanged="lstEmbedded_SelectionChanged" Margin="5"/>
                <Image x:Name="imgEmbedded" Stretch="Uniform" Width="150" Height="150" Margin="5,0"/>
            </StackPanel>
        </StackPanel>
    </StackPanel

At code behind I have 2 event handler functions. First – to handle button click and get the resources.

First of all I have to open XAP file as a resource:

WebClient wc = new WebClient();
wc.OpenReadCompleted += (s, args) =>
{
   if (args.Error == null)
   {
      //rest will be here
   }
};
wc.OpenReadAsync(new Uri("SL_Resources_Test.xap", UriKind.RelativeOrAbsolute));

When the OpenRead completes, first I have to get the list of assembly parts in XAP using application manifest.

XmlReader reader = XmlReader.Create(Application.GetResourceStream(new StreamResourceInfo(args.Result, null), 
                                                                  new Uri("AppManifest.xaml", UriKind.Relative)).Stream);
AssemblyPartCollection parts = new AssemblyPartCollection();
if (reader.Read())
{
   reader.ReadStartElement();
   if (reader.ReadToNextSibling("Deployment.Parts"))
   {
      while (reader.ReadToFollowing("AssemblyPart"))
      {
         parts.Add(new AssemblyPart() { Source = reader.GetAttribute("Source") });
      }
   }
}

Now, when I have a list of all parts (DLLs which could have embedded resources) I will get resources from each one of the DLLs:

List<string> embeddedResources = new List<string>(); //Will use this list as source for ListBox later in code

foreach (var part in parts)
{
   Assembly assy = part.Load(Application.GetResourceStream(new StreamResourceInfo(args.Result, null), 
                                                           new Uri(part.Source, UriKind.Relative)).Stream); //Load current assembly 
   string[] resources = assy.GetManifestResourceNames(); //Get embedded resource names

   foreach (var resource in resources)
   {
      ResourceManager rm = new ResourceManager(resource.Replace(".resources",""), assy); //All resources has “.resources” in the name – so I have to get rid of it

      Stream DUMMY = rm.GetStream("app.xaml"); //Seems like some issue here, but without getting any real stream next statement doesn't work....

      ResourceSet rs = rm.GetResourceSet(Thread.CurrentThread.CurrentUICulture, false, true);

      //to get the actual values - create the table
      //Dictionary<string, object> table = new Dictionary<string, object>();

      IDictionaryEnumerator enumerator = rs.GetEnumerator();
      while (enumerator.MoveNext())
      {
         embeddedResources.Add((string)enumerator.Key);

         //It is also possible to get the value and key instead of just key
         //object obj2 = enumerator.Value;
         //table.Add((string)enumerator.Key, obj2);
      }
   }
}
lstEmbedded.ItemsSource = embeddedResources; //Use prepared list as a source for ListBox 

Now my embedded resources enumerated.

Second part – use the resource by name when selection changed in the list box:

private void lstEmbedded_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    Uri uri = new Uri(lstEmbedded.SelectedItem.ToString(), UriKind.RelativeOrAbsolute);

    BitmapImage img = new BitmapImage(uri);
    imgEmbedded.Source = img; 
}

Running application:

Sample source here.

Stay tuned for more posts and news to come from PDC09.

See you at PDC09 and SDP!

Alex