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OpenTK Resources (Images, Lottie, Fonts)

On the OpenTK head there is no MAUI asset pipeline. DrawnUI resolves a source string such as "Images/banana.gif" as a path relative to the application's output directory (next to the executable, e.g. bin/Debug/net10.0/). So every raw asset must be copied to the output directory.

The rule

Add the asset to your .csproj as Content with CopyToOutputDirectory:

<ItemGroup>
  <Content Include="Images\**">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </Content>
  <Content Include="Lottie\**">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </Content>
  <Content Include="fonts\**">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </Content>
</ItemGroup>

Then reference it by its relative path, mirroring the folder layout:

new SkiaImage("Images/banana.gif");
new SkiaGif    { Source = "Images/banana.gif" };
new SkiaLottie { Source = "Lottie/iosloader.json" };

Fonts are registered at startup and must likewise sit next to the executable:

Super.UseDrawnUi()
    .ConfigureFonts(fonts => fonts.AddFont("fonts/Orbitron-Regular.ttf", "FontGame"))
    .Build();

Common gotcha — plain <Content> does NOT copy

Warning

In a WinExe/console SDK project, a bare <Content Include="Images\banana.gif" /> is not copied to the output directory by default. The build succeeds, the file shows in the IDE, but at runtime the loader can't find it and the asset silently fails to render. You must add CopyToOutputDirectory (PreserveNewest or Always). This is the #1 reason an OpenTK asset "doesn't load".

Verify the copy landed:

ls bin/Debug/net10.0/Images        # banana.gif must be here

Per-head differences

The same shared DrawnUI code runs on multiple heads, each with its own asset pipeline — keep the asset in all the heads you ship:

Head Where raw assets live
OpenTK Content Include … CopyToOutputDirectory → copied next to the exe
.NET MAUI Resources/Raw/** (MauiAsset; bundled automatically)
Web (Blazor / DrawnUi.Wasm) wwwroot/** (served as a static web asset)

A source path like "Images/banana.gif" should resolve to the same relative location under each head's asset root, so the shared code stays head-agnostic.

See also

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