Aliasing Resources (WPF)

Question

I am trying to alias a resource in XAML, as follows:

Answer 1

I tried using the same setup as Kent and received the following error:

Property 'Resources' does not support values of type 'System.Windows.Controls.Image'.

I also tried a few other types and got the same thing (only with a different full-qualified type name).

I was only able to re-key an Image in the <UserControl.Resources> in the following way:

<UserControl.Resources>
    <Image x:Key="myimg"
           Source="{Binding Source={StaticResource appimg}, Path=Source}"
           Stretch="{Binding Source={StaticResource appimg}, Path=Stretch}"/>
</UserControl.Resources>

I have to wonder: Why? Resources weren't designed to be re-keyed. I have a suspicion that what you are ultimately trying to accomplish could be done better and easier in some other way. Possibly with setters in a style.

Answer 2

Try as I might, I cannot reproduce your problem. I think there is more at play than the code you have posted. This works fine for me:

App.xaml:

<Application x:Class="WpfApplication1.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    StartupUri="Window1.xaml">
    <Application.Resources>
        <Image x:Key="bulletArrowUp" Source="Leaves.jpg" Stretch="None"/>
        <Image x:Key="bulletArrowDown" Source="Leaves.jpg" Stretch="None"/>
    </Application.Resources>
</Application>

Window1.xaml:

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"
    Title="Window1" Height="300" Width="300">
    <local:UserControl1/>
</Window>

UserControl1.xaml:

<UserControl x:Class="WpfApplication1.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <UserControl.Resources>
        <StaticResourceExtension x:Key="columnHeaderSortUpImage" ResourceKey="bulletArrowUp"/>
        <StaticResourceExtension x:Key="columnHeaderSortDownImage" ResourceKey="bulletArrowDown"/>
    </UserControl.Resources>
    <ContentControl Content="{StaticResource columnHeaderSortUpImage}"/>
</UserControl>

I added the Leaves.jpg image to my project and it displayed just fine.