ckeditor/ckeditor5-basic-styles

/**
 * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
 */

/**
 * @module basic-styles/subscript/subscriptui
 */

import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
import ButtonView from '@ckeditor/ckeditor5-ui/src/button/buttonview';

import subscriptIcon from '../../theme/icons/subscript.svg';

const SUBSCRIPT = 'subscript';

/**
 * The subscript UI feature. It introduces the Subscript button.
 *
 * @extends module:core/plugin~Plugin
 */
export default class SubscriptUI extends Plugin {
    /**
     * @inheritDoc
     */
    init() {
        const editor = this.editor;
        const t = editor.t;

        // Add subscript button to feature components.
        editor.ui.componentFactory.add( SUBSCRIPT, locale => {
            const command = editor.commands.get( SUBSCRIPT );
            const view = new ButtonView( locale );

            view.set( {
                label: t( 'Subscript' ),
                icon: subscriptIcon,
                tooltip: true,
                isToggleable: true
            } );

            view.bind( 'isOn', 'isEnabled' ).to( command, 'value', 'isEnabled' );

            // Execute command.
            this.listenTo( view, 'execute', () => {
                editor.execute( SUBSCRIPT );
                editor.editing.view.focus();
            } );

            return view;
        } );
    }
}