Question

Hello, how to go from:

<Application
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 x:Class="teste.App">
 <Application.Resources>
  <!-- Resources scoped at the Application level should be defined here. -->
  <ResourceDictionary>
   <ResourceDictionary.MergedDictionaries>
    **<ResourceDictionary Source="Green.xaml"/>**  
   </ResourceDictionary.MergedDictionaries>
  </ResourceDictionary>
 </Application.Resources>
</Application>

To:

<Application
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 x:Class="teste.App">
 <Application.Resources>
  <!-- Resources scoped at the Application level should be defined here. -->
  <ResourceDictionary>
   <ResourceDictionary.MergedDictionaries>
    **<ResourceDictionary Source="Blue.xaml"/>**  
   </ResourceDictionary.MergedDictionaries>
  </ResourceDictionary>
 </Application.Resources>
</Application>

Dynamically, when users choose the theme… Is it possible?
Thank you
Josi

Answer 1

You could change the resource dictionary dynamically in the code behind, on the load of the page.xaml:

Application:

//Load in resources either from application 
        ResourceDictionary dictionary = Application.Current.Resources as ResourceDictionary;

Then once you have the resource dictionary you can apply it using simple logic:

//Load in xaml
        if (user1)
            themefile = @"[Assembly];component/Themes/blue.xaml";
        else
            themefile = @"[Assembly];component/Themes/green.xaml";

NB: [Assembly] is the namespace of the component where the xaml file exists.

Then merge it into the dictioanry for the page with:

 XDocument xaml = XDocument.Load(themefile);
 ResourceDictionary rd = XamlReader.Load(xaml.ToString()) as ResourceDictionary;

        dictionary.MergedDictionaries.Add(rd);