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/underline/underlineediting
 */

import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
import AttributeCommand from '../attributecommand';

const UNDERLINE = 'underline';

/**
 * The underline editing feature.
 *
 * It registers the `'underline'` command, the <kbd>Ctrl+U</kbd> keystroke
 * and introduces the `underline` attribute in the model which renders to the view as an `<u>` element.
 *
 * @extends module:core/plugin~Plugin
 */
export default class UnderlineEditing extends Plugin {
    /**
     * @inheritDoc
     */
    static get pluginName() {
        return 'UnderlineEditing';
    }

    /**
     * @inheritDoc
     */
    init() {
        const editor = this.editor;

        // Allow strikethrough attribute on text nodes.
        editor.model.schema.extend( '$text', { allowAttributes: UNDERLINE } );
        editor.model.schema.setAttributeProperties( UNDERLINE, {
            isFormatting: true,
            copyOnEnter: true
        } );

        editor.conversion.attributeToElement( {
            model: UNDERLINE,
            view: 'u',
            upcastAlso: {
                styles: {
                    'text-decoration': 'underline'
                }
            }
        } );

        // Create underline command.
        editor.commands.add( UNDERLINE, new AttributeCommand( editor, UNDERLINE ) );

        // Set the Ctrl+U keystroke.
        editor.keystrokes.set( 'CTRL+U', 'underline' );
    }
}