Getting a ComponentResourceKey to Work?

Question

I am building a WPF app with several assemblies, and I want to share a resource dictionary among them. That requires a ComponentResourceKey. I have built a small demo to test out the CRK, and I can't seem to get it working.

My demo has two projects, a WPF project called Demo, and a DLL called Common. The Common project has a folder called Themes. It contains my resource dictionary, generic.xaml. Here is the text of the Resource dictionary:

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

    <SolidColorBrush 
        x:Key="{ComponentResourceKey TypeInTargetAssembly={x:Type local:SharedResources}, ResourceId=RedSolidBrush}" 
        Color="Red"/>

</ResourceDictionary>

Common also contains a class called SharedResources.cs. It contains a property for referencing the Brush resource in the dictionary:

public static ComponentResourceKey RedSolidBrush
{
    get { return new ComponentResourceKey(typeof (SharedResources), "RedSolidBrush"); }
}

Finally, the main window in my Demo project references the brush resource to fill a rectangle:

<Window x:Class="ComponentResourceKeyDemo.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:res="clr-namespace:Common;assembly=Common"
    Title="Window1" Height="300" Width="300">
    <Grid>
        <Rectangle Height="100" Width="100" Stroke="Black" Fill="{DynamicResource {ComponentResourceKey TypeInTargetAssembly={x:Type res:SharedResources}, ResourceId=RedSolidBrush}}" />
    </Grid>
</Window>

I can't find the reason it's not working. It compiles fine in VS 2008 and Blend, but the resource isn't invoked. The only clue I have is an error message in Blend:

The Resource "{ComponentResourceKey ResourceId=RedSolidBrush, TypeInTargetAssembly={x:Type res:SharedResources}}" could not be resolved.

Any idea why this isn't working? Thanks for your help.

Merritt

I used the following example from "Pro WPF in C# 2008"in building my demo: books.google.com/… – Merritt

Answer 1

I found my problem. I was confusing the Component Resource Key with the Resource ID inside the resource dictionary. In other words, my Component Resource Key was the same as the Resource ID. I changed my static property to this:

public static ComponentResourceKey RedBrushKey
{
    get {return new ComponentResourceKey(typeof(SharedResources), "RedSolidBrush"); }
}

The property name is now RedBrushKey, instead of RedSolidBrush. And the key is now working.

Merritt

I also made one other change to my demo app. Originally, I had created a plain-vanilla Class Library project to hold the shared resource dictionary. I deleted that project and replaced it with a WPF Custom Control Library. I did some later testing, and it appears that the type of the project is important. A simple Class Library set up the same way as my WPF Custom Control Library wouldn't work. – Merritt

The solution also works with plain Class Library projects. The retrofit for a Class Library to support Component Resource Key markup extensions is described in this thread: #2089541 – Merritt

I discovered a simpler approach to cross-assembly resource sharing, using Pack URIs. It is explained here: #2095531 – Merritt

Are you sure the key and the ID being the same was the problem? I do the exact same thing and don't have issues like this. Though I use a readonly static to avoid new'ing it up every time: public static readonly ComponentResourceKey Foo = new ComponentResourceKey(typeof(Blah), "Foo"); – Again