ComponentResourceKey as DynamicResource problem

Question

I'm seeing some unexpected behavior using ComponentResourceKey. The problem came up because I was using names used in the SystemColors class.

Consider the following code:

First I expose a ComponentResourceKey in a as a static property:

public enum ColorKeys
{
    ControlColor
}

public class MyColors
{
    public static ComponentResourceKey ControlColorKey
    {
        get 
        { 
            return new ComponentResourceKey(typeof(MyColors), ColorKeys.ControlColor); 
        }
    }
}

Using the key in markup to assign a resource to that key works. Invoking that resource as a DynamicResource with the ComponentResourceKey markup works. But Invoking that same resource using the static property resolves to the SystemColors.ControlColorKey resource.

Here is the xaml:

<Window.Resources>
    <Color x:Key="{x:Static l:MyColors.ControlColorKey}">#FF0000FF</Color>
    <SolidColorBrush x:Key="UsingVerbose" 
                     Color="{DynamicResource {ComponentResourceKey TypeInTargetAssembly={x:Type l:MyColors}, 
                                ResourceId={x:Static l:ColorKeys.ControlColor}}}"/>
    <SolidColorBrush x:Key="UsingStatic" 
                     Color="{DynamicResource {x:Static l:MyColors.ControlColorKey}}"/>                
</Window.Resources>
<Grid>
    <StackPanel>
        <Button Height="20" Width="80" Background="{DynamicResource UsingVerbose}" Content="Verbose"/>
        <Button Height="20" Width="80" Background="{DynamicResource UsingStatic}" Content="Static"/>
    </StackPanel>
</Grid>

When the window is shown, the "Verbose" button corretly displays a blue background. But the lower "Static" button shows the SystemColors.ControlColorKey color.

Changing the name of the static property to another name makes both brushes to resolve to the right color.

But I'm left feeling unsure of why is the DynamicResource resolving differently for the static instance of the key, and the one instantiated by markup?

Thanks,

K

PS: Here is the relevant trace output of the ResourceDictionarySource

System.Windows.ResourceDictionary Start: 10 : New resource dictionary set; Owner='TestMergedDictionaries.Window1'; Owner.HashCode='64923656'; Owner.Type='TestMergedDictionaries.Window1'; OldDictionary='0'; NewDictionary='System.Windows.ResourceDictionary'; NewDictionary.HashCode='44624228'; NewDictionary.Type='System.Windows.ResourceDictionary'
System.Windows.ResourceDictionary Stop: 10 : 
System.Windows.ResourceDictionary Start: 12 : Deferred resource has been added to ResourceDictionary; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'
System.Windows.ResourceDictionary Stop: 12 : 
System.Windows.ResourceDictionary Start: 12 : Deferred resource has been added to ResourceDictionary; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='UsingVerbose'
System.Windows.ResourceDictionary Stop: 12 : 
System.Windows.ResourceDictionary Start: 12 : Deferred resource has been added to ResourceDictionary; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='UsingStatic'
System.Windows.ResourceDictionary Stop: 12 : 
System.Windows.ResourceDictionary Start: 11 : Searching for resource; Element='System.Windows.Controls.Button'; Element.HashCode='52727599'; Element.Type='System.Windows.Controls.Button'; ResourceKey='UsingVerbose'
System.Windows.ResourceDictionary Start: 3 : Found resource item on an element; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='UsingVerbose'; Value='System.Windows.DeferredResourceReference'; Value.HashCode='14347911'; Value.Type='System.Windows.DeferredResourceReference'
System.Windows.ResourceDictionary Stop: 3 : 
System.Windows.ResourceDictionary Stop: 11 : Searching for resource; Element='System.Windows.Controls.Button'; Element.HashCode='52727599'; Element.Type='System.Windows.Controls.Button'; ResourceKey='UsingVerbose'

... removed uninteresting traces ...

System.Windows.ResourceDictionary Start: 11 : Searching for resource; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'
System.Windows.ResourceDictionary Start: 3 : Found resource item on an element; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'; Value='System.Windows.DeferredResourceReference'; Value.HashCode='23488915'; Value.Type='System.Windows.DeferredResourceReference'
System.Windows.ResourceDictionary Stop: 3 : 
System.Windows.ResourceDictionary Stop: 11 : Searching for resource; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'

System.Windows.ResourceDictionary Start: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='23264094'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='System.Windows.Controls.TextBlock'; Value='DefAttributeKeyType typeId=TextBlock'; Value.HashCode='23521433'; Value.Type='System.Windows.Markup.BamlDefAttributeKeyTypeRecord'
System.Windows.ResourceDictionary Stop: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='23264094'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='System.Windows.Controls.TextBlock'; Value='System.Windows.Style'; Value.HashCode='5'; Value.Type='System.Windows.Style'

System.Windows.ResourceDictionary Start: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='UsingStatic'; Value='DefAttributeKeyString'; Value.HashCode='24854661'; Value.Type='System.Windows.Markup.BamlDefAttributeKeyStringRecord'
System.Windows.ResourceDictionary Start: 11 : Searching for resource; Element=''; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'
System.Windows.ResourceDictionary Start: 8 : Found resource item in theme; Dictionary='System.Windows.SystemResourceHost'; Dictionary.HashCode='65273341'; Dictionary.Type='System.Windows.SystemResourceHost'; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'; Value='#FFF0F0F0'
System.Windows.ResourceDictionary Stop: 8 : 
System.Windows.ResourceDictionary Stop: 11 : Searching for resource; Element=''; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'
System.Windows.ResourceDictionary Stop: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='UsingStatic'; Value='#FFF0F0F0'; Value.HashCode='12408161'; Value.Type='System.Windows.Media.SolidColorBrush'

System.Windows.ResourceDictionary Start: 11 : Searching for resource; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'
System.Windows.ResourceDictionary Start: 8 : Found resource item in theme; Dictionary='System.Windows.SystemResourceHost'; Dictionary.HashCode='65273341'; Dictionary.Type='System.Windows.SystemResourceHost'; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'; Value='#FFF0F0F0'
System.Windows.ResourceDictionary Stop: 8 : 
System.Windows.ResourceDictionary Stop: 11 : Searching for resource; Element='TestMergedDictionaries.Window1'; Element.HashCode='64923656'; Element.Type='TestMergedDictionaries.Window1'; ResourceKey='ControlColor'; ResourceKey.HashCode='35'; ResourceKey.Type='System.Windows.SystemResourceKey'

System.Windows.ResourceDictionary Start: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'; Value='KeyElementStart typeId=StaticExtension'; Value.HashCode='54371668'; Value.Type='System.Windows.Markup.BamlKeyElementStartRecord'
System.Windows.ResourceDictionary Stop: 2 : Delayed creation of resource; Dictionary='System.Windows.ResourceDictionary'; Dictionary.HashCode='44624228'; Dictionary.Type='System.Windows.ResourceDictionary'; ResourceKey='TargetType=TestMergedDictionaries.MyColors ID=ControlColor'; ResourceKey.HashCode='1936592'; ResourceKey.Type='System.Windows.ComponentResourceKey'; Value='#FF0000FF'

Answer 1

In your static ControlColorKey, you are creating a new instance of the ComponentResourceKey every time the getter is accessed. Therefore the second usage references a different object and does not get the updated color. If you change your code to a simple static field, it works as expected:

public static ComponentResourceKey ControlColorKey = new ComponentResourceKey(typeof(MyColors), ColorKeys.ControlColor);