# useTheme API

> Auto-generated API reference for `useTheme` from @vuetify/v0 (Vuetify0).
> Source of truth: https://0.vuetifyjs.com/api/use-theme

## Related

- https://0.vuetifyjs.com/composables/plugins/use-theme
- https://0.vuetifyjs.com/components/providers/theme
- https://0.vuetifyjs.com/composables/system/use-media-query
- https://0.vuetifyjs.com/composables/registration/create-tokens
- https://0.vuetifyjs.com/guide/features/theming

## Functions

### createTheme

Creates a new theme instance.

```ts
(_options?: ThemeOptions<ThemeRecord>) => ThemeContext<ThemeTicketInput, ThemeTicket<ThemeTicketInput>>
```

### createThemeContext

```ts
<_E>(_options?: ThemePluginOptions | undefined) => ContextTrinity<_E>
```

### createThemePlugin

```ts
(_options?: ThemePluginOptions | undefined) => Plugin
```

### useTheme

```ts
<_E>(namespace?: string) => _E
```

## Options

| Name | Type | Default | Required | Description |
|---|---|---|---|---|
| `events` | `boolean \| undefined` | `false` | no | Enable event emission for registry operations |
| `reactive` | `boolean \| undefined` | `false` | no | Enable reactive behavior for registry operations |
| `adapter` | `ThemeAdapter \| undefined` | — | no | The theme adapter to use. |
| `default` | `ID \| undefined` | — | no | The default theme ID to select on initialization. |
| `foreground` | `boolean \| undefined` | — | no | Automatically generate `on-*` foreground colors for each theme color using APCA contrast analysis. |
| `palette` | `TokenCollection \| undefined` | — | no | A collection of tokens to use for resolving theme colors. |
| `rgb` | `boolean \| undefined` | — | no | Output CSS variable values as decomposed RGB channels (`R, G, B`) instead of hex strings. |
| `themes` | `Record<ID, Z> \| undefined` | — | no | A record of themes to register. |
| `target` | `string \| HTMLElement \| null \| undefined` | — | no | The target element or selector to apply theme classes to. |

## Methods

| Name | Type | Description |
|---|---|---|
| `clear` | `() => void` | Clear the entire registry |
| `has` | `(id: ID) => boolean` | Check if a ticket exists by ID |
| `keys` | `() => readonly ID[]` | Get all registered IDs |
| `browse` | `(value: E["value"]) => readonly ID[] \| undefined` | Browse for an ID(s) by value |
| `lookup` | `(index: number) => ID \| undefined` | Lookup a ticket by index number |
| `get` | `(id: ID) => E \| undefined` | Get a ticket by ID |
| `upsert` | `(id: ID, ticket?: Partial<Z>, event?: string) => E` | Update or insert a ticket by ID |
| `values` | `() => readonly E[]` | Get all values of registered tickets |
| `entries` | `() => readonly [ID, E][]` | Get all entries of registered tickets |
| `unregister` | `(id: ID) => void` | Unregister a ticket by ID |
| `reindex` | `() => void` | Reset the index directory and update all tickets |
| `move` | `(id: ID, toIndex: number) => E \| undefined` | Move a ticket to a new index position |
| `reorder` | `(ids: ID[]) => void` | Reorder the registry to match a canonical permutation of ids in one pass. |
| `seek` | `(direction?: "first" \| "last", from?: number, predicate?: (ticket: E) => boolean) => E \| undefined` | Seek for a ticket based on direction and optional predicate |
| `on` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Listen for registry events |
| `off` | `<K extends Extensible<RegistryEventName>>(event: K, cb: RegistryEventCallback<E, K>) => void` | Stop listening for registry events |
| `emit` | `<K extends Extensible<RegistryEventName>>(event: K, data: EventPayload<E, K>) => void` | Emit an event with data |
| `dispose` | `() => void` | Clears the registry and removes all listeners |
| `offboard` | `(ids: ID[]) => Partial<Z>[]` | Offboard multiple tickets at once, returning the input shapes that were removed. |
| `batch` | `<R>(fn: () => R) => R` | Execute operations in a batch, deferring cache invalidation and event emission until complete |
| `reset` | `() => void` | Reset selection state without destroying the registry |
| `select` | `(id: ID) => void` | Select a ticket by ID |
| `unselect` | `(id: ID) => void` | Unselect a ticket by ID |
| `toggle` | `(id: ID) => void` | Toggle a ticket's selection state |
| `selected` | `(id: ID) => boolean` | Check if a ticket is currently selected |
| `apply` | `(values: unknown[], options?: { multiple?: boolean; }) => void` | Apply external values to the model |
| `mandate` | `() => void` | Mandate selected ID based on "mandatory" option |
| `onboard` | `(registrations: Partial<Z>[]) => E[]` | Onboard multiple tickets at once |
| `cycle` | `(themes?: ID[]) => void` | Cycles through the provided themes in order. |
| `register` | `(registration?: Partial<Z>) => E` | Register a theme with optional colors.  When `colors` is provided, onboards them as flat tokens for alias resolution and stores them as the ticket value. |

## Properties

| Name | Type | Description |
|---|---|---|
| `collection` | `ReadonlyMap<ID, E>` | The collection of tickets in the registry |
| `size` | `number` | The number of tickets in the registry |
| `selectedIds` | `Reactive<Set<ID>>` | Set of currently selected ticket IDs |
| `selectedItems` | `ComputedRef<Set<E>>` | Computed Set of selected ticket instances |
| `selectedValues` | `ComputedRef<Set<E["value"] extends Ref<infer U, infer U> ? U : E["value"]>>` | Computed Set of selected ticket values |
| `disabled` | `MaybeRefOrGetter<boolean>` | Disabled state for the entire model instance |
| `multiple` | `MaybeRefOrGetter<boolean>` | Whether the selection allows multiple selections |
| `selectedId` | `Readonly<Ref<ID \| undefined, ID \| undefined>>` | — |
| `selectedIndex` | `Readonly<Ref<number, number>>` | — |
| `selectedItem` | `Readonly<Ref<E \| undefined, E \| undefined>>` | — |
| `selectedValue` | `Readonly<Ref<E["value"] \| undefined, E["value"] \| undefined>>` | — |
| `colors` | `ComputedRef<Record<string, Colors>>` | A computed reference to the resolved colors of all registered themes. |
| `isDark` | `Readonly<Ref<boolean, boolean>>` | A ref indicating whether the current theme is dark. |