WPF: Applying a custom theme (skin) to a custom control

Question

I have an application set up so that I can adjust its skin at run time. I am doing it as follows each time I change the skin:

Uri uri = new Uri("SomeThemeAssembly;component/Themes/StandardTheme.xaml", UriKind.Relative)
Application.Current.Resources.MergedDictionaries.Clear();
ResourceDictionary resource = (ResourceDictionary)Application.LoadComponent(uri);
Application.Current.Resources.MergedDictionaries.Add(resource);

This works fine.

I have also created a custom control with its controltemplate defined in Themes/Generic.xaml using ComponentResourceKeys for the relevant resources, etc

x:Key="{ComponentResourceKey 
TypeInTargetAssembly={x:Type local:MyCustomControl}, 
ResourceId=MyBrush}"

The style of the custom control itself doesnt use a componentresourcekey as I want it to style all instances.

<Style TargetType="{x:Type local:MyCustomControl}">

Again this all works fine and standard controls I have used to compose elements of my custom control are appropriately styled when I change the skin.

However there are a number of custom properties( brushes, widths, etc) on my control that need to be styled to fit in with the skins I am applying.

In examples I have seen using the standard windows themes adding an additional file

Luna.StandardColor.Xaml

for example, to the themes directory of the custom control allows a modified control template to be set and picked up when that particular theme is applied. This won't work for me, as far as I can tell anyway, as my skins are not themes.

Can something similar be achieved when using 'skins' in the manner I have?

Obviously I can add Styles and ControlTemplates to my skin assemblies but this feels wrong especially as there is a standard naming convention across the skin assemblies for resources. So only a single more maintainable style would be required if it could be stored in Themes/StandardTheme.xaml in my custom control's assembly.

Having tried to read around on this subject I have the impression want I want to do is either impossible or will require loads of extra leg work.

Any thoughts appreciated.

It is hard for me to understand what exactly you are asking. Can you please explain in one or two sentences exactly what you are trying to achieve. — Matt West
When I reskin my app at runtime I want the Style for my CustomControl to be different to that in generic.xaml. Similar to if I had changed the theme. The new style should also be in the CustomControls Themes directory. — DocGigawatts

Matt West Matt West · Accepted Answer · 2011-05-06T21:06:42

In the CustomControls Themes Directory add a MyNewTheme.xaml file that's a resource dictionary that has an implicit style set for your control. Then merge that resource dictionary in with your other one as needed. For example:

Uri uri = new Uri("SomeThemeAssembly;component/Themes/MyNewTheme.xaml", UriKind.Relative)
Uri controlsUri = new Uri("ControlAssembly;component/Themes/MyNewTheme.xaml", UriKind.Relative)
Application.Current.Resources.MergedDictionaries.Clear();
ResourceDictionary resource = (ResourceDictionary)Application.LoadComponent(uri);
Application.Current.Resources.MergedDictionaries.Add(resource);
ResourceDictionary resource = (ResourceDictionary)Application.LoadComponent(controlsUri);
Application.Current.Resources.MergedDictionaries.Add(resource);

WPF: Applying a custom theme (skin) to a custom control

1 Answers