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Getting started with Silverlight

In my work with the Cornball as my first Silverlight project I have had to solve a huge amount of problems which turned out to be quite a high threshold before I could get started with the development for real. Not the least in the difference between a WinForms application and a Silverlight application. In this post I will mention a couple of the things i encountered.

Splash Screen/Preloader
The builtin preloader in Silverlight does not look too bad, but it is definately more fun to create a custom preloader to fit with the rest of the application. I choose to create a very simple but functional preloader. First I had to include all the images as resources in the application for the preloader to actually have a purpose. By adding the images to the project and select Resource as Build Action the images will be included in the XAP-file. To show the images in the application, something of the following will do.

XAML
<Image Name="Card" Source="/SilverlightApplication1;component/Images/Image.png">

Code
Card.Source = new BitmapImage(new Uri("/SilverlightApplication1;component/Images/Image.png", UriKind.Relative));

When the Silverlight application takes more than 500 milliseconds to load the preloader is shown. To create your own preloader three things are required. A XAML-file, some JavaScript and a couple of parameters in the object tag on the html page that displays the Silverlight application. Since the preloader should load fast and run before the application these files should not be place inside the Silverlight application. It is also not possible to execute C# code since the preloader is executed in the client browser.

SplashScreen.xaml
<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Grid.Background>
        <RadialGradientBrush GradientOrigin="0.5,0.5" Center="0.5,0.5" RadiusX="0.5" RadiusY="0.5">
            <GradientStop Color="#FF00AA00" Offset="0.0" />
            <GradientStop Color="#FF006000" Offset="1.0" />
        </RadialGradientBrush>
    </Grid.Background>
    <Border BorderBrush="#AA003000" BorderThickness="1" Height="10" Width="200">
        <Rectangle Fill="#AA003000">
            <Rectangle.RenderTransform>
                <TransformGroup>
                    <ScaleTransform x:Name="ProgressBar" ScaleX="0" ScaleY="1"/>
                </TransformGroup>
            </Rectangle.RenderTransform>
        </Rectangle>
    </Border>
</Grid>

SplashScreen.js
function onSourceDownloadProgressChanged(sender, args)
{
    sender.findName("ProgressBar").ScaleX = args.progress + 0.01;
}

index.html
<object type="application/x-silverlight-2" data="data:application/x-silverlight-2,">
    <param name="source" value="Cornball.xap" />
    <param name="onError" value="onSilverlightError" />
    <param name="minRuntimeVersion" value="3.0.40624.0" />
    <param name="splashScreenSource" value="SplashScreen.xaml"/>
    <param name="onSourceDownloadProgressChanged" value="onSourceDownloadProgressChanged" />
    <param name="autoUpgrade" value="true" />
    <a href="http://go.microsoft.com/fwlink/?LinkID=149156">
        <img src="http://go.microsoft.com/fwlink/?LinkId=108181" alt="Get Microsoft Silverlight" />
    </a>
</object>

BeginAnimation
The animation possibilities is something of the most appealing with Silverlight compared to the previous platforms the Cornball have been created for. It can get a bit tricky before you get a hang of it, but it gets a lot easier with an extension method for the FrameworkElement to start an animation. Thanks to Nick Kramer for this solution.

static class SilverlightHelpers
{
    public static void BeginAnimation(this FrameworkElement obj, DependencyProperty property, DoubleAnimation animation)
    {
        var storyboard = new Storyboard();
        storyboard.Children.Add(animation);
        Storyboard.SetTarget(storyboard, obj);
        Storyboard.SetTargetProperty(storyboard, new PropertyPath(property));
        storyboard.Begin();
    }
}

Usage is incredibly easy since every FrameworkElement now have a BeginAnimation method.

var a = new DoubleAnimation();
a.To = 200;
button.BeginAnimation(Canvas.LeftProperty, a);

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