MediaWiki:Imagemap-Highlight.js

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$(document).ready(function() {

    var
//add this class to all elements created by the script. the reason is that we call the script again on
//window resize, and use the class to remove all the "artefacts" we created in the previous run.
		myClassName = 'imageMapHighlighterArtefacts'
		, liHighlightClass = 'liHighlighting'
		, specialAreaMark = 'area_mark'
		, specialLiClassesMark = 'list_classes'
// "2d context" attributes used for highlighting.
		, areaHighLighting = {fillStyle: 'rgba(0,0,0,0.35)', strokeStyle: 'yellow', lineJoin: 'round', lineWidth: 2}
//every imagemap that wants highlighting, should reside in a div of this 'class':
		, hilightDivMarker = '.imageMapHighlighter'
// specifically for wikis - redlinks tooltip adds this message
		, he = mw && mw.config && mw.config.get('wgUserLanguage') == 'he'
		, expandLegend = he ? 'הצגת מקרא' : 'ּShow Legend'
		, collapseLegend = he ? 'הסתרת המקרא' : 'Hide Legend'
		;


	function drawMarker(context, areas) { // mthis is where the magic is done.

		function drawPoly(coords) {
			context.moveTo(coords.shift(), coords.shift());
			while (coords.length)
				context.lineTo(coords.shift(), coords.shift());
		}

		for (var i in areas) {
			var coords = areas[i].coords.split(',');
			context.beginPath();
			switch (areas[i].shape) {
				case 'rect': drawPoly([coords[0], coords[1], coords[0], coords[3], coords[2], coords[3], coords[2], coords[1]]); break;
				case 'circle': context.arc(coords[0],coords[1],coords[2],0,Math.PI*2);  break;//x,y,r,startAngle,endAngle
				case 'poly': drawPoly(coords); break;
			}
			context.closePath();
			context.stroke();
			context.fill();
		}
	}

	function mouseAction(e, fromMap) {
		var $this = $(this),
			activate = e.type == 'mouseover',
			caption = $this.text(),
			ol = $this.parent(),
			context = ol.data('context'),
			special = ol.data(specialAreaMark);
		
		$this.toggleClass(liHighlightClass, activate); // mark/unmark the list item. 
		
		context.clearRect(0, 0, context.canvas.width, context.canvas.height); // prepare for a new day.
		
		ol.find('li').each(function() {
			var $li = $(this);
			var licap = $li.text();
			var param;
			if (activate && licap === caption) { // highlight!!!
				param = special && special.hover  || areaHighLighting;
			} else {
				param = special && special.nover && (special.nover[licap] || special.nover.default);
			}
			if (param) {
				$.extend(context, param);
				drawMarker(context, $li.data('areas'));
			}
		});
	}

	function handleOneMap() {
		var img = $(this), 
			w = img.width(), 
			h = img.height(),
			map = img.parent().siblings('map:first'),
			dims = {position: 'absolute', width: w + 'px', height: h + 'px', border: 0, top:0, left:0},
			specialHighlight = img.closest(hilightDivMarker).data(specialAreaMark),
			specialLiClasses = img.closest(hilightDivMarker).data(specialLiClassesMark);
		
		
		if (!($('area', map).length))
			return;	//not an imagemap, or map with 0 areas.

		var jcanvas = $('<canvas>', {'class': myClassName})
			.css(dims)
			.attr({width: w, height: h});
		var bgimg = $('<img>', {'class': myClassName, src: img.attr('src')})
			.css(dims);//completely inert image. this is what we see.
		var context = $.extend(jcanvas[0].getContext("2d"), areaHighLighting);
		
	// this is where the magic is done: prepare a sandwich of the inert bgimg at the bottom,
	// the canvas above it, and the original image on top,
	// so canvas won't steal the mouse events.
	// pack them all TIGHTLY in a newly minted "relative" div, so when page chnage
	// (other scripts adding elements, window resize etc.), canvas and imagese remain aligned.
		var div = $('<div>').css({position: 'relative', width: w + 'px', height: h + 'px'});
		img.before(div);	// put the div just above the image, and ...
		div.append(bgimg)	// place the background image in the div
			.append(jcanvas)// and the canvas. both are "absolute", so they don't occupy space in the div
			.append(img);	// now yank the original image from the window and place it on the div.
		img.fadeTo(1, 0);	// make the image transparent - we see canvas and bgimg through it. 
							// the original, now transparent image is creating our mouse events
		
		var ol = $('<ol>', {'class': myClassName})
			.css({clear: 'both', margin: 0, listStyle: 'none', maxWidth: w + 'px', float: 'left', position: 'relative'})
			.attr({'data-expandtext' : expandLegend, 'data-collapsetext': collapseLegend})
			.data(specialAreaMark, specialHighlight)
			.data('context', context);

		// ol below image, hr below ol. original caption pushed below hr.
		div.after($('<hr>', {'class': myClassName}).css('clear', 'both'))
			.after(ol);
		var lis = {};	//collapse areas with same caption to one list item
		var someli; // select arbitrary one
		$('area', map).each(function() {
			var html = mw.html.escape(this.title);
			var li = lis[html];	// title already met? use the same li
			if (!li) {			//no? create a new one.
				var href = this.href;
				lis[html] = li = $('<li>', {'class': myClassName})
					.append($('<a>', {href: href}).html(html))  
					.on('mouseover mouseout', mouseAction)
					.data('areas', [])
					.addClass(specialLiClasses && (specialLiClasses[html] || specialLiClasses['default']))
					.appendTo(ol);
			}
			li.data('areas').push(this);	//add the area to the li
			someli = li; // whichever - we just want one...
			$(this).on('mouseover mouseout', 
				function(e) {
					li.trigger(e.type, true);
				});
		});
		if (someli) someli.trigger('mouseout');
		mw.loader.using('jquery.makeCollapsible').then( function () {
			ol.addClass('mw-collapsed')
				.makeCollapsible();
		});
	}

	function init() {
		mw.util.addCSS('li.' + myClassName + '{white-space:nowrap;border:solid 1px transparent;border-radius:6px;}\n' + //css for li element
					'li.' +  myClassName + '.' + liHighlightClass + '{background-color:yellow;border-color:green;}\n' + //css for highlighted li element.
					'.rtl li.' + myClassName + '{float: right; margin-left: 3em;}\n' +
					'.ltr li.' + myClassName + '{float: left; margin-right: 3em;}');
		$(hilightDivMarker+ ' img').each(handleOneMap);
	}

	//has at least one "imagehighlight" div, and canvas-capable browser:
	if ( $(hilightDivMarker).length && $('<canvas>')[0].getContext )
		mw.loader.using( ['jquery.makeCollapsible', 'mediawiki.util'] ).done( init );
});