Split Generic.xaml in Silverlight Applications

If you work with Templated controls in a big Silverlight project, your Generic.xaml might grow fast. Here’s a quick tutorial on how to split the Generic.xaml into multiple resource files.

Step1: Find the resource

You will typically have the control code:

public class TemplatedControl1 : Control {
    public TemplatedControl1() {
        this.DefaultStyleKey = typeof(TemplatedControl1);
    }
}

and the XAML in the Generic.xaml:

<Style TargetType="local:TemplatedControl1">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:TemplatedControl1">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Step2: Create a new resource file

Create a copy of Generic.xaml and rename to TemplatedControl1.xaml. Delete the TemplatedControl1 style from Generic.xaml. So Generic.xaml looks like:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:SilverlightApplication1">
</ResourceDictionary>
and TemplatedControl1.xaml looks like:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:SilverlightApplication1">

    <Style TargetType="local:TemplatedControl1">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="local:TemplatedControl1">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

Step3: Create reference in App.xaml

<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="SilverlightApplication1.App"
             >
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source='/SilverlightApplication1;Component/Themes/TemplatedControl1.xaml'/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

If you open the project in Expression Blend you will see that you can edit the template as usual:

blend