The Visual Studio Image Library distributes xaml icons with a root element of Viewbox.
It's possible to refer to the PNG files directly with <Image Source="..."> but I'm not sure you can refer to the Viewbox xaml files directly, though maybe there's a pack URI dark magic incantation.

You could build each icon file as a resource in the assembly and load the Viewbox instance directly with using Application.GetResourceStream() and XamlReader.Load() and set MenuItem.Icon with a little bit of reusable code. e.g. https://learn.microsoft.com/en-us/dotnet/desktop/wpf/app-development/wpf-application-resource-content-and-data-files?view=netframeworkdesktop-4.8

Back when I was working with WPF more (and if I recall correctly) the image resources were defined in our code as DrawingImage/GeometryDrawing instead of Viewbox, which you could bind to Image.Source, there may be a tool out there to convert those VS files.

The markup method though is as you suggest, throw all viewbox elements into a ResourceDictionary and give each viewbox a resource key, then merge that resource dictionary into Window.Resources of each window xaml definition, or if you don't want to do that for each window add them to the app resources in the App.xaml file.
The resource dictionary option looks like this:

MyResourceDictionary.xaml -
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
   <Viewbox x:Key="AddDocument" x:Shared="false" ... />
</ResourceDictionary>

MainWindow.xaml -
<Window.Resources>
      <ResourceDictionary>
         <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="MyResourceDictionary.xaml"/>
         </ResourceDictionary.MergedDictionaries>
      </ResourceDictionary>
   </Window.Resources>
   <DockPanel>
      <Menu DockPanel.Dock="Top">
         <MenuItem Header="_File" >
            <MenuItem Header="_New" Icon="{StaticResource AddDocument}" />
         </MenuItem>
      </Menu>
   </DockPanel>

cheers,
Tony

On 28/07/2024 17:56, Greg Keogh via ozdotnet wrote:

Folks, in a video I saw a few weeks ago I learned that the Visual Studio team uses XAML for most of their images, not png or similar. I'm keen to do the same because I imagine that I would no longer need tedious sets of 16x16 32x32 48x48 ... etc images because each XAML file is composed from scalable geometry elements that would look good at any size.

I downloaded the Image Library which contains thousands of XAML, png and svg sets of standard images. But I can't figure out how to simply use the XAML files in a WPF app. All the examples I can find seem to have pasted the contents of the XAML images into resource files and then reference them by x:Key. I don't want to manually paste XAML around like that, I just want to add a file like FolderClosedBlue.xaml (for example) to my project and use it as the icon for a menu or button as simply as possible. How can I replace this sort of thing?...

<MenuItem Header="_Foo Command" Command="...">

<MenuItem.Icon>

< use the XAML image file somehow instead of a resource png? >

</MenuItem.Icon>

</MenuItem>

Is there some coding trick I'm not aware of to simply use an image defined in a XAML file in my app?

Cheers, Greg K