chartjs · simonbrunel · Feb 24, 2019 · Feb 9, 2019 · Feb 9, 2019 · Feb 10, 2019
diff --git a/samples/legend/callbacks.html b/samples/legend/callbacks.html
@@ -0,0 +1,124 @@
+<!doctype html>
+<html>
+<head>
+	<title>Legend Callbacks</title>
+	<script src="../../dist/Chart.min.js"></script>
+	<script src="../utils.js"></script>
+	<style>
+		body, html {
+			height: 100%;
+			font-family: sans-serif;
+		}
+		canvas{
+			-moz-user-select: none;
+			-webkit-user-select: none;
+			-ms-user-select: none;
+		}
+
+		#log {
+			position: absolute;
+			right: 0;
+			top: 0;
+			bottom: 0;
+			background-color: #EEE;
+			float: right;
+			width: 20%;
+			padding: 8px;
+			overflow-y: auto;
+			white-space: pre;
+			line-height: 1.5em;
+		}
+	</style>
+</head>
+
+<body>
+	<div id="log"></div>
+	<div style="width:75%;">
+		<canvas id="canvas"></canvas>
+	</div>
+	<script>
+		var logEntry = 1;
+		var logElement = document.getElementById('log');
+		var utils = Samples.utils;
+		var inputs = {
+			min: 20,
+			max: 80,
+			count: 8,
+			decimals: 2,
+			continuity: 1
+		};
+		var config;
+
+		function log(text) {
+			logElement.innerText += logEntry + '. ' + text + '\n';
+			logElement.scrollTop = logElement.scrollHeight;
+			logEntry++;
+		}
+
+		function generateData() {
+			return utils.numbers(inputs);
+		}
+		function generateLabels() {
+			return utils.months({count: inputs.count});
+		}
+
+		utils.srand(42);
+
+		config = {
+			type: 'line',
+			data: {
+				labels: generateLabels(),
+				datasets: [{
+					label: 'My First dataset',
+					backgroundColor: utils.color(0),
+					borderColor: utils.color(0),
+					data: generateData(),
+					fill: false,
+				}, {
+					label: 'My Second dataset',
+					fill: false,
+					backgroundColor: utils.color(1),
+					borderColor: utils.color(1),
+					data: generateData(),
+				}]
+			},
+			options: {
+				legend: {
+					onHover: function(event, legendItem) {
+						log('onHover: ' + legendItem.text);
+					},
+					onLeave: function(event, legendItem) {
+						log('onLeave: ' + legendItem.text);
+					},
+					onClick: function(event, legendItem) {
+						log('onClick:' + legendItem.text);
+					}
+				},
+				title: {
+					display: true,
+					text: 'Chart.js Line Chart'
+				},
+				scales: {
+					xAxes: [{
+						display: true,
+						scaleLabel: {
+							display: true,
+							labelString: 'Month'
+						}
+					}],
+					yAxes: [{
+						display: true,
+						scaleLabel: {
+							display: true,
+							labelString: 'Value'
+						}
+					}]
+				}
+			}
+		};
+
+		new Chart(document.getElementById('canvas'), config);
+	</script>
+</body>
+
+</html>
diff --git a/samples/samples.js b/samples/samples.js
@@ -148,6 +148,9 @@
 		}, {
 			title: 'Point style',
 			path: 'legend/point-style.html'
+		}, {
+			title: 'Callbacks',
+			path: 'legend/callbacks.html'
 		}]
 	}, {
 		title: 'Tooltip',

diff --git a/src/plugins/plugin.legend.js b/src/plugins/plugin.legend.js
@@ -30,6 +30,7 @@ defaults._set('global', {
 		},
 
 		onHover: null,
+		onLeave: null,
 
 		labels: {
 			boxWidth: 40,
@@ -106,6 +107,11 @@ var Legend = Element.extend({
 		// Contains hit boxes for each dataset (in dataset order)
 		this.legendHitBoxes = [];
 
+		/**
+ 		 * @private
+ 		 */
+		this._hoveredItem = null;
+
 		// Are we in doughnut mode which has a different data type
 		this.doughnutMode = false;
 	},
@@ -458,20 +464,42 @@ var Legend = Element.extend({
 		}
 	},
 
+	/**
+	 * @private
+	 */
+	_getLegendItemAt: function(x, y) {
+		var me = this;
+		var i, hitBox, lh;
+
+		if (x >= me.left && x <= me.right && y >= me.top && y <= me.bottom) {
+			// See if we are touching one of the dataset boxes
+			lh = me.legendHitBoxes;
+			for (i = 0; i < lh.length; ++i) {
+				hitBox = lh[i];
+
+				if (x >= hitBox.left && x <= hitBox.left + hitBox.width && y >= hitBox.top && y <= hitBox.top + hitBox.height) {
+					// Touching an element
+					return me.legendItems[i];
+				}
+			}
+		}
+
+		return null;
+	},
+
 	/**
 	 * Handle an event
 	 * @private
 	 * @param {IEvent} event - The event to handle
-	 * @return {boolean} true if a change occured
 	 */
 	handleEvent: function(e) {
 		var me = this;
 		var opts = me.options;
 		var type = e.type === 'mouseup' ? 'click' : e.type;
-		var changed = false;
+		var hoveredItem;
 
 		if (type === 'mousemove') {
-			if (!opts.onHover) {
+			if (!opts.onHover && !opts.onLeave) {
 				return;
 			}
 		} else if (type === 'click') {
@@ -483,33 +511,26 @@ var Legend = Element.extend({
 		}
 
 		// Chart event already has relative position in it
-		var x = e.x;
-		var y = e.y;
+		hoveredItem = me._getLegendItemAt(e.x, e.y);
 
-		if (x >= me.left && x <= me.right && y >= me.top && y <= me.bottom) {
-			// See if we are touching one of the dataset boxes
-			var lh = me.legendHitBoxes;
-			for (var i = 0; i < lh.length; ++i) {
-				var hitBox = lh[i];
-
-				if (x >= hitBox.left && x <= hitBox.left + hitBox.width && y >= hitBox.top && y <= hitBox.top + hitBox.height) {
-					// Touching an element
-					if (type === 'click') {
-						// use e.native for backwards compatibility
-						opts.onClick.call(me, e.native, me.legendItems[i]);
-						changed = true;
-						break;
-					} else if (type === 'mousemove') {
-						// use e.native for backwards compatibility
-						opts.onHover.call(me, e.native, me.legendItems[i]);
-						changed = true;
-						break;
-					}
+		if (type === 'click') {
+			if (hoveredItem && opts.onClick) {
+				// use e.native for backwards compatibility
+				opts.onClick.call(me, e.native, hoveredItem);
+			}
+		} else {
+			if (opts.onLeave && hoveredItem !== me._hoveredItem) {
+				if (me._hoveredItem) {
+					opts.onLeave.call(me, e.native, me._hoveredItem);
 				}
+				me._hoveredItem = hoveredItem;
 			}
-		}
 
-		return changed;
+			if (opts.onHover && hoveredItem) {
+				// use e.native for backwards compatibility
+				opts.onHover.call(me, e.native, hoveredItem);
+			}
+		}
 	}
 });
 

diff --git a/test/specs/plugin.legend.tests.js b/test/specs/plugin.legend.tests.js
@@ -11,6 +11,7 @@ describe('Legend block tests', function() {
 			// a callback that will handle
 			onClick: jasmine.any(Function),
 			onHover: null,
+			onLeave: null,
 
 			labels: {
 				boxWidth: 40,
@@ -653,4 +654,53 @@ describe('Legend block tests', function() {
 			expect(chart.legend.options).toEqual(jasmine.objectContaining(Chart.defaults.global.legend));
 		});
 	});
+
+	describe('callbacks', function() {
+		it('should call onClick, onHover and onLeave at the correct times', function() {
+			var clickItem = null;
+			var hoverItem = null;
+			var leaveItem = null;
+
+			var chart = acquireChart({
+				type: 'line',
+				data: {
+					labels: ['A', 'B', 'C', 'D'],
+					datasets: [{
+						data: [10, 20, 30, 100]
+					}]
+				},
+				options: {
+					legend: {
+						onClick: function(_, item) {
+							clickItem = item;
+						},
+						onHover: function(_, item) {
+							hoverItem = item;
+						},
+						onLeave: function(_, item) {
+							leaveItem = item;
+						}
+					}
+				}
+			});
+
+			var hb = chart.legend.legendHitBoxes[0];
+			var el = {
+				x: hb.left + (hb.width / 2),
+				y: hb.top + (hb.height / 2)
+			};
+
+			jasmine.triggerMouseEvent(chart, 'click', el);
+
+			expect(clickItem).toBe(chart.legend.legendItems[0]);
+
+			jasmine.triggerMouseEvent(chart, 'mousemove', el);
+
+			expect(hoverItem).toBe(chart.legend.legendItems[0]);
+
+			jasmine.triggerMouseEvent(chart, 'mousemove', chart.getDatasetMeta(0).data[0]);
+
+			expect(leaveItem).toBe(chart.legend.legendItems[0]);
+		});
+	});
 });