Gum Icons Reference

There are three independent icon pipelines in Gum. Pick the right one before authoring or adding code.

At a glance

Where	Format on disk	Runtime form	Theming	Detail skill
Tool WPF chrome (variable grid, dock/anchor/alignment, toggle-button option displays)	SVG in Gum/Content/Svg/	PathGeometry resources in Gum/Themes/GumIcons.xaml, consumed via <controls:GumIcon Icon="…"/>	Fill follows the control's Foreground (theme brush)	this file
Tool tree view (Screens/Components/Behaviors panel, '!' overlay, sizing/origin badges)	PNG in Gum/Content/Icons/UpdatedTreeViewIcons/	TreeIconCatalog (index to artwork + color key), drawn by TreeIconRegistry (WPF) and AvaloniaTreeIcons (Avalonia)	White-on-transparent source, multiplicatively tinted from Frb.Colors.Icon.* per a key→color map	gum-tool-tree-view
Forms runtime default visuals (in-game UI on the user's MonoGame/Skia/etc. surface — not the tool itself)	Sprite sheet (PNG atlas) shipped with Styling.ActiveStyle	Sprite coords from Icons table, drawn through the runtime sprite system	Style-driven (V2/V3 styling); no DynamicResource concept	gum-forms-default-visuals

Don't mix them. A tree-view PNG is not a GumIcon. A GumIcon PathGeometry cannot be drawn into the MonoGame viewport. The Forms sprite sheet has nothing to do with the tool's WPF chrome.

Pipeline 1 — Tool WPF chrome (GumIcon)

The standard for any icon in the WPF tool outside the tree view. Replaces ad-hoc {wpf:FluentIcon …} usage from the FluentIcons.Wpf NuGet.

These icons live inside WPF displayer controls (e.g. the variable grid's origin/alignment/dock toggles). For how such a displayer gets attached to a variable, see gum-tool-variable-grid.

Components:

• Gum/Content/Svg/*.svg — authored sources.
• Gum/GumFigmaIconRipper/Program.cs — console tool. Uses SharpVectors at build time only (no runtime dependency). Walks the SVG drawing tree; flattens into a primary geometry (≥95% opacity fills/strokes) and an optional .Secondary geometry (lower-opacity detail). Clips to a 2px live area inside a 32×32 viewBox.
• Gum/Themes/GumIcons.xaml — generated ResourceDictionary of PathGeometry keyed by SVG filename. Merged in Frb.Styles.Defaults.xaml, so it's globally available.
• Gum/Themes/GumIconKind.g.cs — generated enum + GumIconKindMap.GetResourceKey, plus a TypeConverter that accepts Icon="folder-star" or Icon="FolderStar" in XAML.
• Gum/Controls/GumIcon.cs + style/template in Frb.Styles.Defaults.xaml — templated Control with PART_Path/PART_PathSecondary/PART_Image/PART_Box. Both paths fill from {TemplateBinding Foreground}, so the icon inherits theme tint from its parent button/style. SecondaryOpacity defaults to 0.32.

Avalonia head. Tool/Gum.Avalonia/Themes/GumIcon.cs reads the same GumIcons.xaml, embedded unchanged, at runtime: new GumIcon { Icon = "AnchorTopLeft" } draws in the inherited TextElement.Foreground with the secondary tone at 0.32. Running the ripper updates both heads; there is no Avalonia-specific generated file.

Adding a new icon:

1. Author SVG following the format spec below. Drop into Gum/Content/Svg/YourIconName.svg.
2. Run GumFigmaIconRipper from its own directory (it computes input/output paths relative to Directory.GetCurrentDirectory(), expecting cwd = Gum/GumFigmaIconRipper):

   cd Gum/GumFigmaIconRipper && dotnet run
   

   Do not use dotnet run --project Gum/GumFigmaIconRipper from the repo root — the ripper will look in the wrong place. The ripper rewrites Gum/Themes/GumIcons.xaml and Gum/Themes/GumIconKind.g.cs in full.
3. Commit the SVG, the regenerated GumIcons.xaml, and the regenerated GumIconKind.g.cs together.
4. In XAML, use <controls:GumIcon Icon="YourIconName"/> (where controls is clr-namespace:Gum.Controls). GumIcon is a Control, not a markup extension — set the button's child element rather than its Content attribute when you have other content:

   <Button Click="LeftButton_Click" ToolTip="Dock Left">
       <controls:GumIcon Icon="DockLeft" />
   </Button>
   

Migrating from FluentIcons.Wpf:

• Replace Content="{wpf:FluentIcon Icon=Foo}" with Content="{controls2:GumIcon Icon=YourEquivalent}" (or a nested <controls:GumIcon Icon="…"/> element).
• The icon library is yours, not Microsoft's — names are whatever the SVG filename was.

Author format (passable to a designer or icon-producing AI):

SVG, 32×32 viewBox="0 0 32 32". Keep all visible content within a 2px margin (live area 2..30; the ripper hard-clips outside this). Single solid color (any — color is replaced by theme Foreground at runtime). Use fill-opacity ≥0.95 for the primary tone and <0.95 for any secondary detail (the ripper auto-routes secondary geometry into a .Secondary resource that draws at 0.32 opacity, giving free two-tone). Pure path geometry only — no gradients, filters, masks, or embedded raster; text must be converted to outlines.

Pipeline 2 — Tool tree view (PNG ImageList)

Used by the element tree, its search results, the Standards palette, and tree context menus, in both heads. White-on-transparent PNGs are tinted at draw time with a theme color (Frb.Colors.Icon.*); the index-to-artwork-and-color table is Tool/TreeViewPlugin.Core/TreeIconCatalog.cs, shared by the WPF TreeIconRegistry and the Avalonia AvaloniaTreeIcons (which links the same PNGs as AvaloniaResources).

To add a tree-view icon, see gum-tool-tree-view. The short version: drop a white-on-transparent PNG into Gum/Content/Icons/UpdatedTreeViewIcons/, add a constant to TreeNodeImageIndices, and add an entry (key, artwork path, theme color key) to TreeIconCatalog. Both heads pick it up; ElementTreeViewTests.EveryCatalogIcon_ResolvesToLinkedArtwork fails if the Avalonia head cannot find the PNG.

Do not migrate tree-view icons to GumIcon: tree nodes carry an ImageIndex that TreeNodeImageLogic computes headlessly, and the catalog maps that index to tinted artwork in both heads.

Pipeline 3 — Forms runtime default visuals

In-game UI icons (Forms controls' check marks, arrows, etc.) come from a sprite sheet bundled with the active styling. This is a runtime concern (MonoGame/Skia/Raylib), not WPF chrome, and is handled by the Forms styling system rather than any of the above.

To add an in-game icon, see gum-forms-default-visuals. Coordinates live in the Icons table and are referenced by sprite name from styling.

Notable existing third-party usage to be aware of

• wpf:FluentIcon (FluentIcons.Wpf NuGet) — still used in StateAnimationPlugin, AnchorControl.xaml, DockControl.xaml, and a few ToggleButtonOptionDisplay templates. Treat as legacy: prefer GumIcon for any new chrome icon, and migrate existing ones opportunistically.
• MaterialDesignThemes PackIcon — used for tree-view collapse buttons (sized via UpdateCollapseButtonSizes). Distinct from the tree's image-list icons; left as-is for now.
• gumcli svg <project> <element> — exports a Gum project element to an SVG file (via SkiaGum's SKSvgCanvas). Unrelated to icon authoring; do not confuse with this pipeline.

Gotchas

• The ripper is not wired into MSBuild. If you edit an SVG and forget to run it (cd Gum/GumFigmaIconRipper && dotnet run), GumIcons.xaml and GumIconKind.g.cs will be stale and the new icon won't appear. The CI build won't catch this — only a visual inspection will.
• The ripper writes GumIconKind.g.cs and GumIcons.xaml externally. Editors and agent file caches that don't re-stat after a sub-process write may show stale content. If a new GumIconKind.YourIcon member appears missing, re-read the file fresh (e.g. via shell grep) before assuming the ripper failed.
• Live-area clip is silent. Anything in the SVG outside 2..30 on either axis is clipped without warning. Designers used to authoring at the full 32×32 will see edges chopped.
• Two-tone is opacity-driven, not class- or layer-driven. SharpVectors flattens the SVG drawing tree; tone routing happens by the resolved fill/stroke alpha at draw time, not by <g class="secondary"> or layer name. Use fill-opacity (or RGBA) to mark secondary detail.
• Theme tint is Foreground, not a custom brush. GumIcon's template binds path Fill to TemplateBinding Foreground. Tinting a single icon differently means setting Foreground on the GumIcon (or its containing button). There's no separate IconBrush resource.
• Tree-view PNG source must be white. A pre-colored tree-view PNG will multiply with the theme color and look wrong. The tree-view pipeline does not support two-tone.