@theia/core/src/browser/preload/theme-preload-contribution.ts

Theia is a cloud & desktop IDE framework implemented in TypeScript.

// *****************************************************************************
// Copyright (C) 2023 TypeFox and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// http://www.eclipse.org/legal/epl-2.0.
//
// This Source Code may also be made available under the following Secondary
// Licenses when the conditions for such availability set forth in the Eclipse
// Public License v. 2.0 are satisfied: GNU General Public License, version 2
// with the GNU Classpath Exception which is available at
// https://www.gnu.org/software/classpath/license.html.
//
// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
// *****************************************************************************

import { PreloadContribution } from './preloader';
import { DEFAULT_BACKGROUND_COLOR_STORAGE_KEY } from '../frontend-application-config-provider';
import { injectable } from 'inversify';
import { DefaultTheme } from '@theia/application-package/lib/application-props';

@injectable()
export class ThemePreloadContribution implements PreloadContribution {

    initialize(): void {
        const dark = window.matchMedia?.('(prefers-color-scheme: dark)').matches;
        const value = window.localStorage.getItem(DEFAULT_BACKGROUND_COLOR_STORAGE_KEY) || DefaultTheme.defaultBackgroundColor(dark);
        document.documentElement.style.setProperty('--theia-editor-background', value);
    }

}