Silverlight 3 – Dynamically Loading and Merging Resource Dictionary
This article explains how to dynamically load and merge resource dictionaries declared inside the Silverlight 3 applications and inside the external Silverlight library.
I am assuming that most of you might have already started using Silverlight 3 and have read our previous Silverlight 3 articles. This new version of Silverlight has lots of various new professional features. One of the new features is ‘Merge Resource Dictionaries’. Resource Dictionary is a facility using which styles and templates can be defined for various UIElements provided in Silverlight. Let us explore this feature in this article.
Step 1: Open VS 2008 and Create a new Silverlight 3 application. Name this as ‘SILV3_DynamicLoadingResourceDictionary’, you will get the ASP.NET web application along with the Silverlight application.
Write the following code in the .xaml – in my case MainPage.Xaml in the Silverlight 3 Project:
<Grid x:Name="LayoutRoot" Background="White" Height="700" Width="400">
<Grid.RowDefinitions>
<RowDefinition Height="100"></RowDefinition>
<RowDefinition Height="300"></RowDefinition>
<RowDefinition Height="300"></RowDefinition>
</Grid.RowDefinitions>
<ComboBox Grid.Row="0" x:Name="lstResourceDict" Height="50" SelectionChanged="lstResourceDict_SelectionChanged">
</ComboBox>
<Button x:Name="btnOne" Grid.Row="1" Content="Button ------> 1"></Button>
<Button x:Name="btnTwo" Grid.Row="2" Content="Button ------> 2"></Button>
</Grid>
The above code adds a combobox and two buttons on the page. (Note: The ‘SelectionChanged’ event is specified here which will be used later).
Step 2: In the Silverlight project, right-click and add a resource dictionary and name this as ‘ButtonStyle.xaml’.
Following is the Resource Dictionary file in the Silverlight project: ‘ButtonStyles.xaml’. For this .xaml file, the following properties are set:
Build Action: Content.
Copy to Output Directory: Copy if Newer.
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="RedKey" TargetType="Button">
<Setter Property="Background" Value="Red"></Setter>
<Setter Property="Height" Value="150"></Setter>
<Setter Property="Width" Value="150"></Setter>
</Style>
</ResourceDictionary>
The above .xaml file defines the style for the Button. The ‘x:Key’, here is used to read the style.
Step 3: In the solution, right click and add the Silverlight class library and name it as ‘SILV3_ExternalResourceDictionary’ as shown below.
Remove the Class1.cs from the project and add the following the code to the .xaml file:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="RedKey" TargetType="Button">
<Setter Property="Background" Value="Red"></Setter>
<Setter Property="Height" Value="150"></Setter>
<Setter Property="Width" Value="150"></Setter>
</Style>
</ResourceDictionary>
Step 4: Now to load the XAML resource dictionary dynamically, in the Silverlight project add the following XML file and name it as ‘ResourceDictionaryStorage.xml’:
<?xml version="1.0" encoding="utf-8" ?>
<ResourceDictionaryData>
<FileName Name="ButtonStyles.xaml" Value="RedKey"></FileName>
<FileName Name="/SILV3_ExternalResourceDictionary;component/ExternalButtonStyle.xaml" Value="GoldKey"></FileName>
</ResourceDictionaryData>
Following are the properties set for the above xml file:
Build Action: Content.
Copy to Output Directory: Copy if Newer.
Step 5: Open the MainPage.Xaml file and at the class level, declare the following objects:
C#
ResourceDictionary rd1, rd2;
string rdName;
XDocument xDoc;
string resourceKeyName;
VB.NET
Dim rd1, rd2 As ResourceDictionary
Dim rdName As String
Dim xDoc As XDocument
Dim resourceKeyName As String
In the MainPage.xaml, the following code shown below is written in loaded event: (Note: Add the reference to System.Xml.Linq in the Silverlight project).
C#
//This will Read Keys Collection for the xml file
xDoc = XDocument.Load("ResourceDictionaryStorage.xml");
var KeyCollection = from file in xDoc.Descendants("ResourceDictionaryData").Elements("FileName")
select file;
foreach (var item in KeyCollection)
{
lstResourceDict.Items.Add(item.Attribute("Value").Value);
}
VB.NET
'This will Read Keys Collection for the xml file
xDoc = XDocument.Load("ResourceDictionaryStorage.xml")
Dim KeyCollection = _
From file In xDoc.Descendants("ResourceDictionaryData").Elements("FileName") _
Select file
For Each item In KeyCollection
lstResourceDict.Items.Add(item.Attribute("Value").Value)
Next item
The above code loads the xml file and reads the attribute ‘Value’. This ‘Value’ reads the key of every xml element from the xml file and loads it in a ComboBox.
Step 6: Now in the ‘SelectionChanged’ event of the ComboBox, the values are read. This value represents the key of the resource dictionary style. This key is used to read style information set for a specific UIElement of the Silverlight.
C#
private void lstResourceDict_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
rdName = lstResourceDict.SelectedItem as string;
xDoc = XDocument.Load("ResourceDictionaryStorage.xml");
//This will Read ResourceDictionary file
var FileName = from file in xDoc.Descendants("ResourceDictionaryData").Elements("FileName")
where file.Attribute("Value").Value == rdName
select file;
foreach (var item in FileName)
{
resourceKeyName = item.Attribute("Name").Value;
}
rd1 = new ResourceDictionary();
rd1.Source = new Uri(resourceKeyName, UriKind.Relative);
this.Resources.MergedDictionaries.Add(rd1);
System.Windows.Style btnStyle = rd1[rdName] as Style;
btnOne.Style = btnStyle;
rd2 = new ResourceDictionary();
rd2.Source = new Uri(resourceKeyName, UriKind.Relative);
this.Resources.MergedDictionaries.Add(rd2);
System.Windows.Style btnStyle1 = rd2[rdName] as Style;
btnTwo.Style = btnStyle1;
}
VB.NET
Private Sub lstResourceDict_SelectionChanged(ByVal sender As Object, ByVal e As SelectionChangedEventArgs)
rdName = TryCast(lstResourceDict.SelectedItem, String)
xDoc = XDocument.Load("ResourceDictionaryStorage.xml")
'This will Read ResourceDictionary file
Dim FileName = _
From file In xDoc.Descendants("ResourceDictionaryData").Elements("FileName") _
Where file.Attribute("Value").Value = rdName _
Select file
For Each item In FileName
resourceKeyName = item.Attribute("Name").Value
Next item
rd1 = New ResourceDictionary()
rd1.Source = New Uri(resourceKeyName, UriKind.Relative)
Me.Resources.MergedDictionaries.Add(rd1)
Dim btnStyle As System.Windows.Style = TryCast(rd1(rdName), Style)
btnOne.Style = btnStyle
rd2 = New ResourceDictionary()
rd2.Source = New Uri(resourceKeyName, UriKind.Relative)
Me.Resources.MergedDictionaries.Add(rd2)
Dim btnStyle1 As System.Windows.Style = TryCast(rd2(rdName), Style)
btnTwo.Style = btnStyle1
End Sub
Step 7: Run the application, change the selection for the combobox and the following output will be displayed:
The entire source code of this article can be downloaded over here.
This article has been editorially reviewed by Suprotim Agarwal.
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Mahesh Sabnis is a DotNetCurry author and Microsoft MVP having over 17 years of experience in IT education and development. He is a Microsoft Certified Trainer (MCT) since 2005 and has conducted various Corporate Training programs for .NET Technologies (all versions). Follow him on twitter @
maheshdotnet