mediawiki-extensions-MultimediaViewer/resources/mmv/ui/mmv.ui.truncatableTextField.js

/*
 * This file is part of the MediaWiki extension MultimediaViewer.
 *
 * MultimediaViewer is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * MultimediaViewer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with MultimediaViewer.  If not, see <http://www.gnu.org/licenses/>.
 */

const { HtmlUtils } = require( 'mmv.bootstrap' );
const UiElement = require( './mmv.ui.js' );

/**
 * Represents any text field that might need to be truncated to be readable. Text will be adjusted to
 * fit into its container.
 *
 * More specifically, TruncatableTextField should be invoked with a fixed-height container as the first
 * parameter and a flexible-width content (which gets its size from the text inside it) as the second
 * one. The container gets overflow: hidden, and the content is placed inside it; if the content
 * overflows the container, TruncatableTextField will cycle through a set of styles and apply to the
 * container the first one that makes the content not overflow anymore. If none of the styles do that,
 * the last one is applied anyway.
 *
 * The list of styles can be customized; by default, they set progressively smaller font size, and the
 * last one adds an ellipsis to the end. (An ellipsis element is automatically appended to the end of
 * the container to help with this, but it is hidden unless made visible by one of the styles.)
 *
 * grow() and shrink() can be used to show full text (by making the container flexible-height) and hiding
 * them again; TruncatableTextField will not call them automatically (the caller class should e.g. set up
 * a click handler on the ellipsis).
 *
 * repaint() should be called after layout changes to keep the truncation accurate.
 */
class TruncatableTextField extends UiElement {
	/**
	 * @param {jQuery} $container The container for the element.
	 * @param {jQuery} $element The element where we should put the text.
	 * @param {Object} [options]
	 * @param {string[]} [options.styles] a list of styles to try if the text does not fit into the container.
	 *  Will stop at the first which makes the text fit; the last one will be used even if it does not make
	 *  the text fit.
	 */
	constructor( $container, $element, options ) {
		super( $container );

		/** @property {jQuery} $element The DOM element that holds text for this element. */
		this.$element = $element;

		/** @property {Object} options - */
		this.options = Object.assign( {
			styles: [ 'mw-mmv-ttf-small', 'mw-mmv-ttf-smaller', 'mw-mmv-ttf-smallest' ]
		}, options );

		/** @property {boolean} expanded true if the text is long enough to be truncated but the full text is shown */
		this.expanded = false;

		/** @property {jQuery} ellipsis the element which marks that the text was truncated */
		this.$ellipsis = null;

		/** @property {string} normalTitle title attribute to show when the text is not truncated */
		this.normalTitle = null;

		/** @property {string} truncatedTitle title attribute to show when the text is not truncated */
		this.truncatedTitle = null;

		this.init();
	}

	/**
	 * Initializes the DOM.
	 *
	 * @private
	 */
	init() {
		this.$ellipsis = $( '<span>' )
			.text( '…' )
			.hide()
			.addClass( 'mw-mmv-ttf-ellipsis' );

		this.$container
			.addClass( 'mw-mmv-ttf-container empty' )
			.append( this.$element, this.$ellipsis );
	}

	attach() {
		$( window ).on( 'resize.mmv-ttf', mw.util.debounce( this.repaint.bind( this ), 100 ) );
	}

	unattach() {
		$( window ).off( 'resize.mmv-ttf' );
	}

	/**
	 * Sets the string for the element.
	 *
	 * @param {string} value Warning - unsafe HTML is allowed here.
	 */
	set( value ) {
		this.$element.empty().append( HtmlUtils.htmlToTextWithTags( value ) );
		this.changeStyle();
		this.$container.toggleClass( 'empty', !value );
		this.$ellipsis.hide();
		this.shrink();
	}

	empty() {
		this.$element.empty();
		// eslint-disable-next-line mediawiki/class-doc
		this.$container
			.removeClass( this.options.styles.concat( [ 'mw-mmv-ttf-untruncated', 'mw-mmv-ttf-truncated' ] ) )
			.addClass( 'empty' );
		this.$ellipsis.hide();
		this.setTitle( '', '' );
		this.expanded = false;
	}

	/**
	 * Recalculate truncation after layout changes (such as resize)
	 */
	repaint() {
		this.changeStyle();
		this.$ellipsis.hide();
		this.shrink();
	}

	/**
	 * Allows setting different titles for fully visible and for truncated text.
	 *
	 * @param {string} normal
	 * @param {string} truncated
	 */
	setTitle( normal, truncated ) {
		this.normalTitle = normal;
		this.truncatedTitle = truncated;
		this.updateTitle();
	}

	/**
	 * Selects the right title to use (for full or for truncated version). The title can be set with setTitle().
	 */
	updateTitle() {
		const $elementsWithTitle = this.$element.add( this.$ellipsis );
		$elementsWithTitle.attr( 'original-title', this.isTruncated() ? this.truncatedTitle : this.normalTitle );
	}

	/**
	 * Returns true if the text is long enough that it needs to be truncated.
	 *
	 * @return {boolean}
	 */
	isTruncatable() {
		// height calculation logic does not work for expanded state since the container expands
		// to envelop the element, but we never go into expanded state for non-truncatable elements anyway
		return this.$container.height() < this.$element.height() || this.expanded;
	}

	/**
	 * Returns true if the text is truncated at the moment.
	 *
	 * @return {boolean}
	 */
	isTruncated() {
		return this.isTruncatable() && !this.expanded;
	}

	/**
	 * Makes the container fixed-width, clipping the text.
	 * This will only add a .mw-mmv-ttf-truncated class; it's the caller's responsibility to define the fixed
	 * height for that class.
	 */
	shrink() {
		if ( this.isTruncatable() ) {
			this.expanded = false;
			this.$container.addClass( 'mw-mmv-ttf-truncated' ).removeClass( 'mw-mmv-ttf-untruncated' );
			this.$ellipsis.show();
			this.updateTitle();
		}
	}

	/**
	 * Makes the container flexible-width, thereby restoring the full text.
	 */
	grow() {
		if ( this.isTruncatable() ) {
			this.expanded = true;
			this.$container.removeClass( 'mw-mmv-ttf-truncated' ).addClass( 'mw-mmv-ttf-untruncated' );
			this.$ellipsis.hide();
			this.updateTitle();
		}
	}

	/**
	 * Changes the element style if a certain length is reached.
	 */
	changeStyle() {
		let newClass = 'mw-mmv-ttf-normal';

		// eslint-disable-next-line mediawiki/class-doc
		this.$container
			.removeClass( this.options.styles.concat( [ 'mw-mmv-ttf-untruncated', 'mw-mmv-ttf-truncated' ] ) )
			.addClass( newClass );
		this.expanded = false;

		for ( const v of this.options.styles ) {
			if ( !this.isTruncatable() ) {
				break;
			}

			const oldClass = newClass;
			newClass = v;
			// eslint-disable-next-line mediawiki/class-doc
			this.$container.removeClass( oldClass ).addClass( newClass );
		}
	}
}

module.exports = TruncatableTextField;