mediawiki-extensions-RevisionSlider/modules/ext.RevisionSlider.PointerView.js

( function () {
	/**
	 * Module containing presentation logic for the revision pointers
	 *
	 * @param {Pointer} pointer
	 * @param {string} name
	 * @constructor
	 */
	var PointerView = function ( pointer, name ) {
		this.pointer = pointer;
		this.name = name;
	};

	/**
	 * @class mw.libs.revisionSlider.PointerView
	 */
	$.extend( PointerView.prototype, {
		/**
		 * @type {string}
		 */
		name: '',

		/**
		 * @type {Pointer}
		 */
		pointer: null,

		/**
		 * @type {jQuery}
		 */
		$html: null,

		/**
		 * Initializes the DOM element
		 */
		initialize: function () {
			this.$html = $( '<div>' )
				.addClass( 'mw-revslider-pointer mw-revslider-pointer-cursor ' + this.name );
		},

		/**
		 * @return {jQuery}
		 */
		render: function () {
			this.initialize();
			return this.getElement();
		},

		/**
		 * @return {jQuery}
		 */
		getElement: function () {
			return this.$html;
		},

		/**
		 * Returns whether a pointer is the newer revision pointer based on its CSS class
		 *
		 * @return {boolean}
		 */
		isNewerPointer: function () {
			return this.getElement().hasClass( 'mw-revslider-pointer-newer' );
		},

		/**
		 * Returns the offset (margin-left) depending on whether its the newer or older pointer
		 *
		 * @return {number}
		 */
		getOffset: function () {
			return this.isNewerPointer() ? 16 : 0;
		},

		// For correct positioning of the pointer in the RTL mode the left position is flipped in the container.
		// 30 pixel have to be added to cover the arrow and its margin.
		getAdjustedLeftPositionWhenRtl: function ( pos ) {
			return this.getElement().offsetParent().width() - pos - 30;
		},

		/**
		 * Sets the HTML attribute for the position
		 *
		 * @param {number} pos
		 */
		setDataPositionAttribute: function ( pos ) {
			if ( this.getElement() === null ) {
				this.initialize();
			}
			this.getElement().attr( 'data-pos', pos );
		},

		/**
		 * Moves the pointer to a position
		 *
		 * @param {number} posInPx
		 * @param {number} revisionWidth
		 * @param {number} [baseDuration] Duration per revisionWidth, is adjusted by log() distance
		 * @return {jQuery}
		 */
		animateTo: function ( posInPx, revisionWidth, baseDuration ) {
			var animatePos = { left: posInPx },
				currentPos = this.getElement().position(),
				distance, duration;
			baseDuration = typeof baseDuration !== 'undefined' ? baseDuration : 100;
			if ( this.getElement().css( 'direction' ) === 'rtl' ) {
				animatePos.left = this.getAdjustedLeftPositionWhenRtl( animatePos.left );
			}
			distance = Math.abs( animatePos.left - currentPos.left ) / revisionWidth;
			duration = baseDuration * Math.log( 5 + distance );
			return this.getElement().animate( animatePos, duration, 'linear' );
		},

		/**
		 * Slides the pointer to the revision it's pointing at
		 *
		 * @param {Slider} slider
		 * @param {number} [duration]
		 * @return {jQuery}
		 */
		slideToPosition: function ( slider, duration ) {
			var relativePos = this.pointer.getPosition() - slider.getOldestVisibleRevisionIndex();
			return this.animateTo( ( relativePos - 1 ) * slider.getView().revisionWidth, slider.getView().revisionWidth, duration );
		},

		/**
		 * Slides the pointer to the side of the slider when it's not in the current range of revisions
		 *
		 * @param {Slider} slider
		 * @param {boolean} posBeforeSlider
		 * @param {number} [duration]
		 * @return {jQuery}
		 */
		slideToSide: function ( slider, posBeforeSlider, duration ) {
			if ( posBeforeSlider ) {
				return this.animateTo( this.getOffset() - 2 * slider.getView().revisionWidth, slider.getView().revisionWidth, duration );
			} else {
				return this.animateTo( slider.getRevisionsPerWindow() * slider.getView().revisionWidth + this.getOffset(), slider.getView().revisionWidth, duration );
			}
		},

		/**
		 * Decides based on its position whether the pointer should be sliding to the side or to its position
		 *
		 * @param {Slider} slider
		 * @param {number} [duration]
		 * @return {jQuery}
		 */
		slideToSideOrPosition: function ( slider, duration ) {
			var firstVisibleRev = slider.getOldestVisibleRevisionIndex(),
				posBeforeSlider = this.pointer.getPosition() < firstVisibleRev,
				isVisible = !posBeforeSlider && this.pointer.getPosition() <= firstVisibleRev + slider.getRevisionsPerWindow();
			if ( isVisible ) {
				return this.slideToPosition( slider, duration );
			} else {
				return this.slideToSide( slider, posBeforeSlider, duration );
			}
		}
	} );

	mw.libs.revisionSlider = mw.libs.revisionSlider || {};
	mw.libs.revisionSlider.PointerView = PointerView;
}() );