> For the complete documentation index, see [llms.txt](https://docs.flatredball.com/gum/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flatredball.com/gum/code/standard-visuals/textruntime/fonts.md). # Fonts ## Introduction This page is the API reference for the font-related properties on `TextRuntime`. For guidance on which font loading strategy fits your game — KernSmith, FontCache, custom `.fnt`, or direct `BitmapFont` — start at the [Fonts hub](/gum/code/files-and-fonts/fonts.md). By default all `TextRuntime` instances use an Arial 18-point font embedded in the Gum libraries. ## Font-Related Properties | Property | Type | Purpose | | ----------------------------------------------------------------------- | ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------- | | `Font` (a.k.a. `FontFamily`) | `string` | Font family name (e.g. `"Arial"`, `"Noto Sans CJK"`). | | `FontSize` | `int` | Point size. | | `IsBold` | `bool` | Bold style. | | `IsItalic` | `bool` | Italic style. | | `OutlineThickness` | `int` | Outline thickness in pixels (0 = no outline). | | `HasDropshadow` | `bool` | When `true`, KernSmith bakes a drop shadow into the font atlas (see [Baked drop shadow](#baked-drop-shadow)). | | `DropshadowColor` | `Color` | Shadow color. Shortcut for the four channel properties below. | | `DropshadowRed`, `DropshadowGreen`, `DropshadowBlue`, `DropshadowAlpha` | `int` | Shadow color channels (0–255). `DropshadowAlpha` decomposes to KernSmith `ShadowOpacity` at generation time. | | `DropshadowOffsetX`, `DropshadowOffsetY` | `float` | Horizontal / vertical shadow offset in pixels. | | `DropshadowBlur` | `float` | Blur radius in pixels. `0` is a sharp shadow; larger values soften the edges. Single scalar (like shape `DropshadowBlur`), not a per-axis pair. | | `UseFontSmoothing` | `bool` | Whether to use anti-aliased glyph rasterization. | | `UseCustomFont` | `bool` | When `true`, ignore the property combo and load `CustomFontFile` directly. | | `CustomFontFile` | `string` | Path to a specific `.fnt` file (only used when `UseCustomFont` is `true`). | | `BitmapFont` | `BitmapFont` | A directly-assigned font instance — bypasses the property-driven font system entirely. | ### Baked drop shadow When `HasDropshadow` is `true`, KernSmith composites the shadow into each glyph's atlas cell at font-generation time — the same baked model as `OutlineThickness`. The shadow is **not** a per-draw runtime overlay; every character in that font variant always carries the shadow. State-dependent shadows (on/off per frame, animated blur) still need a runtime overlay such as a shape behind the text — see [Shapes — Drop shadow](/gum/code/standard-visuals/shapes-apos.shapes.md#drop-shadow). Requirements and cache behavior: * **KernSmith / `InMemoryFontCreator` required** — shadow fields participate in the property-driven path only when an in-memory font creator is registered (MonoGame, KNI, or Raylib via `KernSmithRaylibFontCreator`). Without it, Gum falls back to FontCache `.fnt` files, which do not encode shadow today. * **Separate font variant per shadow tuple** — like outline thickness, shadow offset/blur/color are keyed into the font cache file name when `HasDropshadow` is true, so each distinct combination generates its own atlas. * **Channel layout** — when shadow is enabled, Gum omits a custom `ChannelConfig` so KernSmith's default RGBA atlas path is preserved. Baked shadow color survives the runtime's text-color modulate instead of being forced to white. **First-enable defaults:** toggling `HasDropshadow` from `false` to `true` seeds a visible shadow when offset and blur are still zero — black (`DropshadowAlpha` 180), `DropshadowOffsetY` 3, `DropshadowBlur` 2. `DropshadowOffsetX` stays 0. Set channels explicitly before enabling if you need a different color. ```csharp // Initialize var title = new TextRuntime(); title.Text = "Quest Log"; title.Font = "Arial"; title.FontSize = 28; title.HasDropshadow = true; title.DropshadowColor = new Color(0, 0, 0, 180); title.DropshadowOffsetY = 3; title.DropshadowBlur = 2; title.AddToRoot(); ``` For KernSmith-only extras on the direct-assignment path (`HardShadow`, custom `Padding`, and so on), see [Advanced Font Effects — Drop Shadow](/gum/code/files-and-fonts/fonts/advanced-font-effects.md#drop-shadow). ## How These Properties Resolve to a Font A `TextRuntime`'s font is chosen by one of these paths, in priority order: 1. **`BitmapFont` is set directly** → that font is used; the component properties are ignored. 2. **`UseCustomFont` is `true`** → `CustomFontFile` is loaded from disk. 3. **`UseCustomFont` is `false` and an `InMemoryFontCreator` is registered** (e.g. KernSmith) → the font is generated in memory from the component properties, including `HasDropshadow` and the dropshadow fields when enabled. 4. **`UseCustomFont` is `false` and no `InMemoryFontCreator` is registered** → Gum looks for a matching `.fnt` file in the project's `FontCache` folder, named according to the component properties. For the full details on each path — when to use it, code samples, and the costs involved — see: * [Font Strategies](/gum/code/files-and-fonts/fonts/font-strategies.md) — full walkthroughs. * [Font Performance](/gum/code/files-and-fonts/fonts/font-performance.md) — generation, memory, and draw-call costs. {% hint style="info" %} **Choosing a font strategy?** Start at the [Fonts hub](/gum/code/files-and-fonts/fonts.md). It has a four-path decision tree that points you at the right approach in about a minute. {% endhint %} ## Missing Font Exceptions By default `TextRuntime` instances do not throw exceptions for missing font files even if `GraphicalUiElement.ThrowExceptionsForMissingFiles` is set. The reason is that the font is decided by a combination of multiple properties that can be assigned in any order, so the runtime doesn't know when assignment is "finished." You have two options for surfacing missing-font errors: 1. **Assign the `BitmapFont` directly** — calling the `BitmapFont` constructor with a missing file throws immediately. 2. **Call `GraphicalUiElement.ThrowExceptionsForMissingFiles` after configuring the `TextRuntime`** — see the example in [Font Strategies — Missing Font Exceptions](/gum/code/files-and-fonts/fonts/font-strategies.md#missing-font-exceptions). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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