Theming in Silverlight

A good design is appreciated if the look and feel is consistent across the application or site you develop. The first and the most best,popular option that comes to our minds is "Themes".

Silverlight allows developers to create rich styles for controls.
Every style has a unique key to identify and it is targeted for a particular element.
To apply style to an element,you have to bind it’s Style property with the unique key of the style defined in the resources at application or local level or defined in resource dictionary.

But is it possible to avoid inline (StaticResource) binding of styles and implicitly apply them to all elements going by the concept of "Themes".
The answer is "YES" and here is the solution. 

How to go about.  ?
In addition to Silverlight library, you will have to install the Silverlight toolkit.
The latest release is here.
There are inbuild themes already available in Silverlight toolkit,but I will create a simple theme from scratch.

Here are the steps:
1) Open Visual Studio and select a Silverlight application.

Silverlight application
2) Add a new folder "Themes" to the project.
Add three Silverlight resource dictionaries each for red,blue and green theme. Set the "Build Action" to Content for each xaml resource file in properties panel ,so that they are added to .xap file and they can be relatively located.

Silverlight resource dictionary       Project structure

Setting the build action to content


3) Add reference to "System.Windows.Controls.Theming".
Adding System.Windows.Controls.Theming to the project

4) In MainPage.xaml, I have added a ListBox with names of colors as ListBoxItems.
In a Stackpanel elements like Button,TextBlock and RadioButton have been added.
What I wish to do is on selecting a particular color from ListBox, I want the themes to be applied to all the elements in the StackPanel without StaticResource binding. But first let us create styles for a every element for red,green and blue themes respectively.

Elements in MainPage.xaml file

Code in MainPage.xaml file.

<UserControl x:Class="Themes_Application.MainPage"
    mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">
  <Grid x:Name="LayoutRoot"  HorizontalAlignment="Center">
            <RowDefinition Height="100"/>
        <ListBox x:Name="lstThemeColor" SelectionChanged="lstThemeColor_SelectionChanged" Width="Auto" BorderBrush="Black" BorderThickness="1" Height="Auto" Grid.Row="0">
            <ListBoxItem Content="Red"/>
            <ListBoxItem Content="Blue"/>
            <ListBoxItem Content="Green"/>

        <StackPanel Grid.Row="1" Orientation="Horizontal" x:Name="pnlElements" >
            <Button Height="50" Width="100" Content="Button1" Margin="5"/>
            <Button Height="50" Width="100" Content="Button2" Margin="5"/>
            <Button Height="50" Width="100" Content="Button3" Margin="5"/>
            <TextBlock Text="TextBlock1" Width="Auto" Height="30" Margin="5"/>
            <TextBlock Text="TextBlock2" Width="Auto" Height="30" Margin="5" />
            <RadioButton Content="RadioButton1" Width="Auto" Height="30" Margin="5"/>
            <RadioButton Content="RadioButton2" Width="Auto" Height="30" Margin="5"/>


5) The best way to create styles is to copy the xaml code created in Expression Blend after right clicking the element and selecting the "Edit Template" option. Expression Blend provides excellent options to create styles. Change the color properties and edit the states for a particular control. Click here “” to learn how to create styles,templates.
After copy-pasting styles for different colors in resource dictionary, remove the "x:Key" property from every style created  for a particular control as it is not required. Your “RedTheme.xaml ” will look like this. Similary there will be styles created for every type of element in BlueTheme.xaml and GreenTheme.xaml files.

Code in RedTheme.xaml file

6) Once the styles are in place ,we now write the logic to apply it to the elements in the StackPanel. The code is written in MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;

//this reference is required…
using System.Windows.Controls.Theming;

namespace Themes_Application
    public partial class MainPage : UserControl
        Uri uri_resource;
        public MainPage()

        //on selecting a color value the theme should be applied.
        private void lstThemeColor_SelectionChanged(object sender, SelectionChangedEventArgs e)
            string color_name = ((ListBoxItem)(lstThemeColor.SelectedItem)).Content.ToString();
            if (color_name == "Red")
                uri_resource = new Uri("Themes/RedTheme.xaml", UriKind.Relative);
            else if (color_name == "Blue")
                uri_resource = new Uri("Themes/BlueTheme.xaml", UriKind.Relative);
            else if (color_name == "Green")
                uri_resource = new Uri("Themes/GreenTheme.xaml", UriKind.Relative);

            //get the theme file and apply it to elements in panel.
            ImplicitStyleManager.SetResourceDictionaryUri(pnlElements, uri_resource);
            ImplicitStyleManager.SetApplyMode(pnlElements, ImplicitStylesApplyMode.Auto);

Here the ImplicitStyleManager is a class that provides methods to do the following tasks.

a) To first locate the resource dictionary which will apply styles to elements. Here it is the xaml files stored in “Themes” folder
b) To get the name of the parent element in which the child controls or descendants have to be applied styles.
c) To implicitly apply styles to the parent element and its descendants.

Thus without doing any StaticResource binding to any of the elements you can create Themes and apply them implicitly.
Here is the final output in browser.

      Green theme applied

       BlueTheme applied

Red Theme applied