import { type AcEdUiTheme } from '@mlightcad/cad-simple-viewer';
import { AcDbDatabase } from '@mlightcad/data-model';
/**
 * Reads the UI theme from a host element's `data-ml-ui-theme` attribute.
 *
 * @param host - Viewer host element.
 * @returns `'light'`, `'dark'`, or `undefined` when unset or invalid.
 */
export declare function acuiReadUiThemeFromHost(host: HTMLElement): AcEdUiTheme | undefined;
/**
 * Reads the UI theme from the drawing `COLORTHEME` system variable.
 *
 * @param database - Drawing database.
 */
export declare function acuiReadUiThemeFromDatabase(database: AcDbDatabase): AcEdUiTheme;
/**
 * Keeps `data-ml-ui-theme` on the host in sync with `COLORTHEME` and document activation.
 */
export declare class AcUiThemeSync {
    private readonly host;
    private readonly onThemeChanged?;
    /** Applies theme when `COLORTHEME` changes on the active database. */
    private handleSysVarChanged;
    /** Applies theme from a newly activated document's database. */
    private handleDocumentActivated;
    /**
     * @param host - Element receiving `acedApplyUiTheme` and `data-ml-ui-theme`.
     * @param onThemeChanged - Optional callback after each theme application (e.g. toolbar refresh).
     */
    constructor(host: HTMLElement, onThemeChanged?: (() => void) | undefined);
    /** Subscribes to sysvar and document events and performs an initial sync. */
    start(): void;
    /** Unsubscribes from sysvar and document events. */
    stop(): void;
    /**
     * Returns the theme currently applied on the host.
     *
     * Defaults to `'dark'` when the attribute is missing.
     */
    getTheme(): AcEdUiTheme;
    /**
     * Sets the UI theme via `COLORTHEME` when a document is open, otherwise on the host.
     *
     * @param theme - Target light or dark theme.
     */
    setTheme(theme: AcEdUiTheme): void;
    /**
     * Applies theme from the active document or existing host attribute on startup.
     */
    private syncFromCurrentSource;
    /**
     * Calls {@link acedApplyUiTheme} and notifies {@link onThemeChanged}.
     *
     * @param theme - Theme to apply.
     */
    private applyTheme;
}
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