Tooltip support for CanvasPattern and CanvasGradient

src/core/core.tooltip.js

@@ -168,14 +168,6 @@ var positioners = {
 	}
 };
 
-/**
- * Helper method to merge the opacity into a color
- */
-function mergeOpacity(colorString, opacity) {
-	var color = helpers.color(colorString);
-	return color.alpha(opacity * color.alpha()).rgbaString();
-}
-
 // Helper to push or concat based on if the 2nd parameter is an array or not
 function pushOrConcat(base, toPush) {
 	if (toPush) {
@@ -734,7 +726,7 @@ var exports = module.exports = Element.extend({
 		return {x1: x1, x2: x2, x3: x3, y1: y1, y2: y2, y3: y3};
 	},
 
-	drawTitle: function(pt, vm, ctx, opacity) {
+	drawTitle: function(pt, vm, ctx) {
 		var title = vm.title;
 
 		if (title.length) {
@@ -744,7 +736,7 @@ var exports = module.exports = Element.extend({
 			var titleFontSize = vm.titleFontSize;
 			var titleSpacing = vm.titleSpacing;
 
-			ctx.fillStyle = mergeOpacity(vm.titleFontColor, opacity);
+			ctx.fillStyle = vm.titleFontColor;
 			ctx.font = helpers.fontString(titleFontSize, vm._titleFontStyle, vm._titleFontFamily);
 
 			var i, len;
@@ -759,7 +751,7 @@ var exports = module.exports = Element.extend({
 		}
 	},
 
-	drawBody: function(pt, vm, ctx, opacity) {
+	drawBody: function(pt, vm, ctx) {
 		var bodyFontSize = vm.bodyFontSize;
 		var bodySpacing = vm.bodySpacing;
 		var body = vm.body;
@@ -776,32 +768,32 @@ var exports = module.exports = Element.extend({
 		};
 
 		// Before body lines
-		ctx.fillStyle = mergeOpacity(vm.bodyFontColor, opacity);
+		ctx.fillStyle = vm.bodyFontColor;
 		helpers.each(vm.beforeBody, fillLineOfText);
 
 		var drawColorBoxes = vm.displayColors;
 		xLinePadding = drawColorBoxes ? (bodyFontSize + 2) : 0;
 
 		// Draw body lines now
 		helpers.each(body, function(bodyItem, i) {
-			var textColor = mergeOpacity(vm.labelTextColors[i], opacity);
+			var textColor = vm.labelTextColors[i];
 			ctx.fillStyle = textColor;
 			helpers.each(bodyItem.before, fillLineOfText);
 
 			helpers.each(bodyItem.lines, function(line) {
 				// Draw Legend-like boxes if needed
 				if (drawColorBoxes) {
 					// Fill a white rect so that colours merge nicely if the opacity is < 1
-					ctx.fillStyle = mergeOpacity(vm.legendColorBackground, opacity);
+					ctx.fillStyle = vm.legendColorBackground;
 					ctx.fillRect(pt.x, pt.y, bodyFontSize, bodyFontSize);
 
 					// Border
 					ctx.lineWidth = 1;
-					ctx.strokeStyle = mergeOpacity(vm.labelColors[i].borderColor, opacity);
+					ctx.strokeStyle = vm.labelColors[i].borderColor;
 					ctx.strokeRect(pt.x, pt.y, bodyFontSize, bodyFontSize);
 
 					// Inner square
-					ctx.fillStyle = mergeOpacity(vm.labelColors[i].backgroundColor, opacity);
+					ctx.fillStyle = vm.labelColors[i].backgroundColor;
 					ctx.fillRect(pt.x + 1, pt.y + 1, bodyFontSize - 2, bodyFontSize - 2);
 					ctx.fillStyle = textColor;
 				}
@@ -820,7 +812,7 @@ var exports = module.exports = Element.extend({
 		pt.y -= bodySpacing; // Remove last body spacing
 	},
 
-	drawFooter: function(pt, vm, ctx, opacity) {
+	drawFooter: function(pt, vm, ctx) {
 		var footer = vm.footer;
 
 		if (footer.length) {
@@ -829,7 +821,7 @@ var exports = module.exports = Element.extend({
 			ctx.textAlign = vm._footerAlign;
 			ctx.textBaseline = 'top';
 
-			ctx.fillStyle = mergeOpacity(vm.footerFontColor, opacity);
+			ctx.fillStyle = vm.footerFontColor;
 			ctx.font = helpers.fontString(vm.footerFontSize, vm._footerFontStyle, vm._footerFontFamily);
 
 			helpers.each(footer, function(line) {
@@ -839,9 +831,9 @@ var exports = module.exports = Element.extend({
 		}
 	},
 
-	drawBackground: function(pt, vm, ctx, tooltipSize, opacity) {
-		ctx.fillStyle = mergeOpacity(vm.backgroundColor, opacity);
-		ctx.strokeStyle = mergeOpacity(vm.borderColor, opacity);
+	drawBackground: function(pt, vm, ctx, tooltipSize) {
+		ctx.fillStyle = vm.backgroundColor;
+		ctx.strokeStyle = vm.borderColor;
 		ctx.lineWidth = vm.borderWidth;
 		var xAlign = vm.xAlign;
 		var yAlign = vm.yAlign;
@@ -906,21 +898,26 @@ var exports = module.exports = Element.extend({
 		var hasTooltipContent = vm.title.length || vm.beforeBody.length || vm.body.length || vm.afterBody.length || vm.footer.length;
 
 		if (this._options.enabled && hasTooltipContent) {
+			ctx.save();
+			ctx.globalAlpha = opacity;
+
 			// Draw Background
-			this.drawBackground(pt, vm, ctx, tooltipSize, opacity);
+			this.drawBackground(pt, vm, ctx, tooltipSize);
 
 			// Draw Title, Body, and Footer
 			pt.x += vm.xPadding;
 			pt.y += vm.yPadding;
 
 			// Titles
-			this.drawTitle(pt, vm, ctx, opacity);
+			this.drawTitle(pt, vm, ctx);
 
 			// Body
-			this.drawBody(pt, vm, ctx, opacity);
+			this.drawBody(pt, vm, ctx);
 
 			// Footer
-			this.drawFooter(pt, vm, ctx, opacity);
+			this.drawFooter(pt, vm, ctx);
+
+			ctx.restore();
 		}
 	},
 

test/fixtures/core.tooltip/opacity.js

@@ -0,0 +1,104 @@
+var patternCanvas = document.createElement('canvas');
+var patternContext = patternCanvas.getContext('2d');
+
+patternCanvas.width = 6;
+patternCanvas.height = 6;
+patternContext.fillStyle = '#ff0000';
+patternContext.fillRect(0, 0, 6, 6);
+patternContext.fillStyle = '#ffff00';
+patternContext.fillRect(0, 0, 4, 4);
+
+var pattern = patternContext.createPattern(patternCanvas, 'repeat');
+
+var gradient;
+
+module.exports = {
+	config: {
+		type: 'line',
+		data: {
+			datasets: [{
+				data: [8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8],
+				pointBorderColor: '#ff0000',
+				pointBackgroundColor: '#00ff00',
+				showLine: false
+			}, {
+				label: '',
+				data: [4, 4, 4, 4, 4, 5, 3, 4, 4, 4, 4],
+				pointBorderColor: pattern,
+				pointBackgroundColor: pattern,
+				showLine: false
+			}, {
+				label: '',
+				data: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+				showLine: false
+			}],
+			labels: ['', '', '', '', '', '', '', '', '', '', '']
+		},
+		options: {
+			legend: false,
+			title: false,
+			scales: {
+				xAxes: [{display: false}],
+				yAxes: [{display: false}]
+			},
+			elements: {
+				line: {
+					fill: false
+				}
+			},
+			tooltips: {
+				mode: 'nearest',
+				intersect: false,
+				callbacks: {
+					label: function() {
+						return '\u200b';
+					}
+				}
+			},
+			layout: {
+				padding: 15
+			}
+		},
+		plugins: [{
+			beforeDatasetsUpdate: function(chart) {
+				if (!gradient) {
+					gradient = chart.ctx.createLinearGradient(0, 0, 512, 256);
+					gradient.addColorStop(0, '#ff0000');
+					gradient.addColorStop(1, '#0000ff');
+				}
+				chart.config.data.datasets[2].pointBorderColor = gradient;
+				chart.config.data.datasets[2].pointBackgroundColor = gradient;
+
+				return true;
+			},
+			afterDraw: function(chart) {
+				var canvas = chart.canvas;
+				var rect = canvas.getBoundingClientRect();
+				var point, event;
+
+				for (var i = 0; i < 3; ++i) {
+					for (var j = 0; j < 11; ++j) {
+						point = chart.getDatasetMeta(i).data[j];
+						event = {
+							type: 'mousemove',
+							target: canvas,
+							clientX: rect.left + point._model.x,
+							clientY: rect.top + point._model.y
+						};
+						chart.handleEvent(event);
+						chart.tooltip.handleEvent(event);
+						chart.tooltip.transition(1);
+						chart.tooltip._view.opacity = j / 10;
+						chart.tooltip.draw();
+					}
+				}
+			}
+		}]
+	},
+	options: {
+		canvas: {
+			height: 256,
+			width: 512
+		}
+	}
+};

test/specs/core.tooltip.tests.js

@@ -1,5 +1,7 @@
 // Test the rectangle element
 describe('Core.Tooltip', function() {
+	describe('auto', jasmine.fixture.specs('core.tooltip'));
+
 	describe('config', function() {
 		it('should not include the dataset label in the body string if not defined', function() {
 			var data = {