How to dynamically load internal xaml in Silverlight 3 at runtime? - xaml

Question

I have a few internal Canvas xaml files which I want to load dynamically at runtime. For example, I want to display the Canvas in a page. However, I cannot seem to get it to work. I've tried using XamlReader, Application.LoadComponent, and using an XDocument; all to no avail. I cannot seem to find the best practice for this on-line either.
The Canvases are stored like this: MyApp/Resources/Logos/Logo1.xaml. I'm not sure if Logo1.xaml should have a build action of "Component" or "Resource". In any case, using the URI of "MyApp;components/Resources/Logos/Logo1.xaml" seems to be correct, but Application.LoadComponent gets an XamlParseException at Line 0 Position 0.
Here's a pseudo-example of Logo1.xaml:
<Canvas
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="286.233" Height="143.425">
<Canvas>
<Path />
<Path />
<Path />
<Path />
</Canvas>
</Canvas>
The data for the path elements has been omitted for brevity's sake.
Any ideas?

Answer 1

I got this to work using build action "Resource" and the XamlLoader with a ContentControl:
var resourceName = string.Format("MyApp;component/Resources/Logos/{0}.xaml", logoName);
var uri = new Uri(resourceName, UriKind.Relative);
var streamResourceInfo = Application.GetResourceStream(uri);
string xaml = null;
using (var resourceStream = streamResourceInfo.Stream)
{
using (var streamReader = new StreamReader(resourceStream))
{
xaml = streamReader.ReadToEnd();
}
}
Canvas canvas = XamlReader.Load(xaml) as Canvas;
this.contentControl.Content = canvas;

Answer 2

The accepted answer is not intuitive to me, but may suit some people.
I generally feel more comfortable with System.IO.File.WriteAllText and System.IO.File.ReadAllText. I borrowed a code piece from MSDN. For a test, just create a new Canvas at runtime:
Canvas newCanvas = new Canvas()
Then, just write it out, with File.WriteAllText, simple too, avoiding all the URI stuff, which as a beginner I find confusing. Lastly, just read it back in as above. Done. This proves you can simply just read in some valid code for a canvas from a text file, and it can be loaded dynamically.
private void Button2_Click(object sender, RoutedEventArgs e)
{
Canvas newCanvas = new Canvas();
newCanvas.Name = "newCanvas";
string savedCanvas = XamlWriter.Save(newCanvas);
File.WriteAllText("savedCanvas.txt", savedCanvas);
savedCanvas = File.ReadAllText("savedCanvas.txt");
// Load the canvas
StringReader stringReader2 = new StringReader(savedCanvas);
XmlReader xmlReader2 = XmlReader.Create(stringReader2);
Canvas newCreatedCanvas = (Canvas)XamlReader.Load(xmlReader2);
this.Content = newCreatedCanvas;
}
The ideas are from MSDN as below:
XamlReader.Load Method (XmlReader)
.NET Framework 4
Reads the XAML input in the specified XmlReader and returns an object that is the root of the corresponding object tree.
Namespace: System.Windows.Markup
Assembly: PresentationFramework (in PresentationFramework.dll)