---
title: "Game UI skins core: API"
package: "@phaser-ae/ui-skins"
tier: Free
version: 3.0.0-2
released: 2026-10-18
updated: 2026-10-20
description: "The shared engine of the game UI skins, turning one colour into a whole shaded interface theme and letting a game make, recolour and switch skins while it runs."
url: https://phaser.io/packs/ui-skins/api
site: Phaser - https://phaser.io
---

# Game UI skins core: API

`@phaser-ae/ui-skins` — The core of the game UI skins: the colour palette, the theme generator and game.skins. Compose ui-skin-* packs after it for the looks.

## The pack

### `uiSkins`

```ts
function uiSkins(): Pack<{ skins: UiSkinsApi }>
```

Pack `ui-skins`: the core of the game UI skins — `game.skins` to make, restyle and switch skins at run time, and the
shared generator the `ui-skin-*` packs use. It registers no skin itself: compose the ones you want after it
(`ui-skin-candy`, `ui-skin-jelly`…) and choose one with `game.ui.theme`. Requires `ui`.

## Helpers

### `buildUiSkin`

```ts
function buildUiSkin(material: UiSkinMaterialDef, options: UiSkinOptions = {}): UiThemeDef
```

A whole ui theme from a material: every widget role (buttons default, good, warn, bad and flat; the round `icon`
button the pause and sound buttons wear; windows, title bars and panels; sliders, toggles and progress bars;
checkboxes and radios; text fields; lists and scrollbars; labels and headings) plus a style per colour, with the font
it needs. Throws on a colour that is neither a name nor a hex.

### `buildUiSkinStyle`

```ts
function buildUiSkinStyle(material: UiSkinMaterialDef, color: string, overrides: UiStyle = {}, options: UiSkinOptions = {}): UiStyle
```

One button style in a material and a colour, with its hover, pressed (down into its lip) and disabled (the same
button in grey) looks, and a `designHeight` so it fits any button height. `overrides` are merged over the result.

### `UI_SKIN_COLORS`

```ts
const UI_SKIN_COLORS: { readonly green: "#58d11d"; readonly red: "#f23a32"; readonly blue: "#2b8ef2"; readonly yellow: "#ffd21f"; readonly orange: "#ff8a1c"; readonly purple: "#9a4dff"; readonly pink: "#ff4fae"; readonly teal: "#16c4b0"; readonly grey: "#9ba6b9"; readonly brown: "#b5743a"; }
```

The named colours every skin makes a style for. Any CSS hex works where a colour is asked for.

### `uiSkinAlpha`

```ts
const uiSkinAlpha = (css: string, a: number): string=> …
```

A '#rrggbb' colour with an alpha 0..1, as '#rrggbbaa': for a material's translucent parts.

### `uiSkinColor`

```ts
function uiSkinColor(c: string): string
```

A colour name or hex as '#rrggbb'. Throws on anything else.

### `uiSkinFont`

```ts
const uiSkinFont = (o: UiSkinShape, scale = 1): string=> …
```

The caption font at a share of the shape's size, as a style's `font`: `uiSkinFont(o)` for a button, `uiSkinFont(o, 0.62)` for body text.

### `uiSkinLighter`

```ts
const uiSkinLighter = (c: string, t = 0.08): string=> …
```

A colour a little towards white (t, default 0.08): a hover's lift.

### `uiSkinMix`

```ts
function uiSkinMix(a: string, b: string, t: number): string
```

Two '#rrggbb' colours mixed, t of the way from a to b: for a material's blends.

### `uiSkinPalette`

```ts
function uiSkinPalette(color: string): UiSkinPalette
```

Work a colour out into the shades a game button is drawn in. Darks lean warm-to-orange on yellows and oranges, the
way an artist shades them (a yellow button's lip is orange and its outline brown, never olive); a pale colour's
caption is its ink, not white. Throws on a colour that is neither a name nor a hex.

### `uiSkinPress`

```ts
const uiSkinPress = (o: UiSkinShape): UiStyle=> …
```

The usual pressed look for a shape: the face goes down into its lip, or a lipless button nudges down.

### `validateUiSkin`

```ts
function validateUiSkin(material: UiSkinMaterialDef, options: UiSkinOptions = {}): string[]
```

Everything wrong with a material, as sentences (empty when it is sound): a role the widgets draw with that its
theme leaves out, a field the ui pack does not know or will not accept as written, a colour that does not parse.
A new skin pack's test is `assert.deepEqual(validateUiSkin(MY_SKIN), [])`.

## Functions

### `registerUiSkin`

```ts
function registerUiSkin(k: { registry: { add(kind: string, def: unknown): void } }, material: UiSkinMaterialDef, options: UiSkinOptions = {}): void
```

Register a material in a skin pack's attach: its definition (so `game.skins` can make more from it) and its theme,
made with the pack's manifest options, under its name. Requires the `ui-skins` pack composed first.

## Types

### `UiSkinColor`

```ts
type UiSkinColor = keyof typeof UI_SKIN_COLORS
```

A named skin colour.

### `UiSkinMaterialDef`

```ts
interface UiSkinMaterialDef
```

A MATERIAL: everything a skin pack says. `button` draws a button in a palette at a shape; `surfaces`, when given,
returns roles to put over the defaults (a cartoon's cream windows, a wood's planks). Hand one to `registerUiSkin` in
a pack's attach, or to `buildUiSkin` / `validateUiSkin` directly.

- `name: string` — The material's name, and its theme's.
- `look: string` — What it looks like, in a line.
- `color: string` — Its main colour by default: a `UI_SKIN_COLORS` name or a hex.
- `surface: string` — Its windows' colour by default.
- `font: UiThemeFont` — The caption font: a baked Typography GLB, usually from the CDN catalogue. Loaded when the skin is chosen.
- `size: number` — Caption px at the design height (64).
- `radius: number | 'pill'` — Button corners.
- `depth: number` — The lip, px at the design height.
- `iconRadius?: number | 'pill'` — The round icon button's corners. Default 'pill' (a circle on a square button).
- `trim?: string` — Its trim's colour by default, for a material that draws a rim, bezel or frame in a colour of its own. Default white.
- `accent?: string` — Its accent by default: title bars, slider fills, knobs, dots and selected rows. Default its main colour.
- `button(p: UiSkinPalette, o: UiSkinShape): UiStyle` — A button in palette `p` at shape `o`: its look, hover and pressed states (disabled is made for it, in grey).
- `surfaces?(ctx: UiSkinSurfaceContext): Record<string, UiStyle>` — Roles to lay over the default windows and parts.

### `UiSkinOptions`

```ts
interface UiSkinOptions
```

How a skin is made from its material: the same in a skin pack's manifest options and in `game.skins.make`. All optional.

- `name?: string` — The theme's name, for `game.ui.theme = name`. Default the material's.
- `color?: string` — The main colour (the `default` button, icon buttons, sliders, title bars): a colour name or a CSS hex. Default the material's.
- `surface?: string` — The hue of the default windows, panels, grooves and boxes; the generator sets their lightness. A material that draws its own keeps them (cartoon's cream parts, wood's oak and metal's steel windows). Default the material's.
- `radius?: number | 'pill'` — Button corners, px at the design height, or 'pill'. Default the material's.
- `depth?: number` — The lip, px at the design height; 0 makes the buttons flat. Default the material's.
- `trim?: string` — The trim: the colour of a rim, bezel or frame the material draws in a colour of its own (candy's white rim, bezel's silver chrome; gold in a yellow). Materials with no trim ignore it. Default the material's.
- `accent?: string` — The accent: title bars, slider fills, knobs, dots and selected rows, a second colour beside the buttons'. Default the material's, else the main colour.
- `roles?: { good?: string; warn?: string; bad?: string; flat?: string }` — The colours of the roles that mean something. Defaults green, orange, red and grey.
- `colors?: Record<string, string>` — Extra named colours, each a style beside the ten built in: `{ mint: '#3df0b0' }` makes `style: 'mint'`.
- `designHeight?: number` — The button height the styles are drawn for, px: buttons and headings of any height scale to match. Default 64.

### `UiSkinPalette`

```ts
interface UiSkinPalette
```

The shades a colour is worked out into. Every one is a '#rrggbb' string.

- `face: string` — The face's top: the colour, a little lighter.
- `faceTo: string` — The face's bottom.
- `lip: string` — The lip under the face: darker, hue-shifted (a yellow's lip is orange).
- `ink: string` — The outline and a stroked caption's ink: the colour's deepest shade.
- `light: string` — A highlight: the light edge under debossed letters.
- `text: string` — A caption colour that reads on the face without a stroke: white, or the ink on a light colour.

### `UiSkinsApi`

```ts
interface UiSkinsApi
```

`game.skins`: the composed skins, and skins made from them at run time.

- `readonly materials: ReadonlyArray<string>` — The materials composed (one per `ui-skin-*` pack), by name.
- `make(spec: UiSkinSpec): UiThemeDef` — A theme from a composed material: define it with `game.ui.defineTheme`. Throws when the material is not composed or a colour does not parse.
- `use(spec: UiSkinSpec): string` — Make a theme, define it (replacing one of the same name, live) and switch to it; returns its name.
- `style(material: string, color: string, overrides?: UiStyle): UiStyle` — One button style in a composed material and a colour, `overrides` on top: `game.ui.defineStyle('mint', game.skins.style('candy', '#3df0b0'))`.
- `palette(color: string): UiSkinPalette` — The shades a colour is worked out into.

### `UiSkinShape`

```ts
interface UiSkinShape
```

The shape a skin settles on, at its design height: the caption's family and size, the corners and the lip.

- `family: string` — The caption font's family.
- `size: number` — The caption's px size at the design height.
- `radius: number | 'pill'` — Button corners: px, or 'pill'.
- `depth: number` — The lip, px; 0 for a flat button.
- `trim: string` — The trim's colour, '#rrggbb': a rim, bezel or frame the material draws in a colour of its own (candy's white rim, bezel's chrome).

### `UiSkinSpec`

```ts
interface UiSkinSpec extends UiSkinOptions
```

What `game.skins.make` takes: a composed material's name and how to make it.

- `material: string` — The material: the name of a composed `ui-skin-*` pack's skin ('candy', 'jelly'…).

### `UiSkinSurfaceContext`

```ts
interface UiSkinSurfaceContext
```

What a material's `surfaces` hook is handed: the main palette, the shape, and the surface colour's shades.

- `main: UiSkinPalette` — The main colour's palette: the buttons'.
- `accent: UiSkinPalette` — The accent colour's palette: the default title bars, slider fills, knobs, dots and selected rows wear it. The main palette unless an accent is chosen.
- `shape: UiSkinShape` — The skin's shape.
- `deep: string` — The surface colour, deep: a window's top.
- `deeper: string` — Deeper: a window's bottom.
- `rim: string` — Lit: a window's rim.
- `groove: string` — Darkest: grooves and boxes.
- `defaults: Readonly<Record<string, UiStyle>>` — The default windows and parts, to build on.
- `font(scale: number): string` — The caption font at a share of the button size: `font(0.62)` is body text.

---

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