Silverlight with F#: Managing embedded resources

One of my blog reader asked why I inline XAML instead of putting it into a separate file and hooking up the variables manually in F#.  My answer was laziness: I did not spend the time to figure out how. (If you subscribe to Larry Wall’s philosophy, laziness is a virtue …)  Well, that question prompted me to look into how to externalize the xaml file and load it in.  This dovetailed nicely with recipe 2.14 of the book Silverlight 2 Recipes, which shows how to load embedded resources.  I put the xaml code in a separate file called page.xaml and added the following compiler flag:

 --resource page.xaml

Here’s the xaml file:

<Canvas 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    
    x:Name="LayoutRoot" Background="White">
    <TextBlock>Hi There Reader</TextBlock>
    <TextBlock Canvas.Left="20" Canvas.Top="20">Hi There</TextBlock>
    <TextBlock Canvas.Left="40"
     Canvas.Top="40">Silverlight</TextBlock>
    <TextBlock Canvas.Left="60" Canvas.Top="60">
     Silverlight</TextBlock>
    <TextBlock Canvas.Left="80" Canvas.Top="80">
     Silverlight</TextBlock>
    <TextBlock Canvas.Left="100" Canvas.Top="100">
     Silverlight</TextBlock>
</Canvas>

Here's the code that loads the xaml file and hook the control with a variable:

#light
namespace SilverLightFSharp

open System
open System.Resources
open System.Reflection
open System.IO
open System.Windows
open System.Windows.Browser
open System.Windows.Controls
open System.Windows.Markup
open List

// Recipe 2-14 and XAML from Recipe 3-3 of the Silverlight 2 Recipes book
type MyPage() = class
    inherit UserControl()
    
    do
       
        let assembly = Assembly.GetExecutingAssembly();
        let sr = new StreamReader(assembly.GetManifestResourceStream("page.xaml"));
        let xamlControls = sr.ReadToEnd()

        // Load xaml dynamically        
        let canvas = XamlReader.Load(xamlControls) :?> Canvas

       
        base.Width <- 400.0
        base.Height <- 300.0
        base.Content <- canvas
end

type ErrorPage = class
    inherit UserControl
    
    new (msg:string ) as this = {} then
    
        let textarea = new TextBlock(Text=msg,
                                     TextWrapping=TextWrapping.Wrap,
                                     Margin=new Thickness(4.0,4.0,4.0,4.0))
    
        let sp = new StackPanel(HorizontalAlignment = HorizontalAlignment.Stretch,
                                Margin=new Thickness(8.0,8.0,10.0,8.0))
        sp.Children.Add(textarea)                                

        base.Width <- 600.0
        base.Height <- 1000.0
        base.Content <- sp
end    


type MyApp = class
    inherit Application
    
    new () as this = {} then
        this.Startup.Add(fun _ -> 
            let rootPanel = new StackPanel()
            try 
                this.RootVisual <- rootPanel
                rootPanel.Children.Add(new MyPage())
            with _ as e ->
               let msg = e.Message + e.StackTrace
               rootPanel.Children.Clear()
               rootPanel.Children.Add(new ErrorPage(msg)))

        this.UnhandledException.Add(fun args ->
           args.Handled <- true
           try
               let msg = args.ExceptionObject.Message + args.ExceptionObject.StackTrace
               let errmsg = msg.Replace('"','\'').Replace("\r\n",@"\n") 
               "throw new Error(\"Unhandled error in Silverlight 2 Application " + msg + "\");"
               |> HtmlPage.Window.Eval |> ignore
           with _  -> HtmlPage.Window.Eval("throw new Error(\"Custom Error!\");") |> ignore)
end