Question

My question is: Am I reading MSDN wrong OR is MSDN wrong? I am trying to reference an image Resource via relative URI.

The MSDN page titled Pack URIs in WPF clearly states that:

“Resource file in subfolder of local assembly” = “/Subfolder/ResourceFile.xaml“

in Table 2: Relative URIs in Markup (here
http://msdn.microsoft.com/en-gb/library/aa970069.aspx ).

So, I created new WPF/.NET 4.0 projects in Vs2010 (v10.0.40219.1 SP1Rel) to test.

Startup Project: TryUri
    App.xaml
    MainWindow.xaml
Custom Ctrl Project: TryUri.CCL
    Icons/folder.png <-- Marked As Resource!
    Views/TestUC.xaml

In TestUC.xaml:

<Canvas>
    <Border>
        <Image Source="/Icons/folder.png" Height="Auto" Width="Auto" />
    </Border>
</Canvas>

In MainWindow.xaml:

// xmlns:uc="clr-namespace:TryUri.CCL.Views;assembly=TryUri.CCL"

<uc:TestUC />

Result: The image does not show up!!

When I change the path to “../Icons/folder.png” It does work.

If I copy the Icons/folder.png into the TryUri.CCL/Views/ folder, then “Icons/folder.png” works.

However, I can never get a leading forward slash to work as in “/Icons/folder.png” the way that MSDN states.

Answer 1

The reason, when running as a separate assembly, that your Relative Pack URI must begin with ../ or no leading backslash is because of how relative URIs are used, from MSDN (emphasis mine):

Absolute vs. Relative Pack URIs

…

If a leading backslash is used, however, the relative pack URI reference is then considered relative to the root of the application.

Therefore if you’d like the images to remain relative to your referenced assembly, simply omit the leading slash or use ../ if in a sub-folder.

See the image below for an example of how this looks at runtime: