Added 'angle' option to Polar Charts (#5279)

* added 'angle' option to polar charts. image comparison test is work in progress; not currently passing

* removed unnecessary variable assignment

* code cleanup based on PR; for 'angle' option on polarCharts

* Made polar chart image comparison test pass by removing debug flag. Also explicitly marked _computeAngle as private.

* Removed visibleCount computation in polar chart

* split out code related to updating the radius in polar chart's update function, into it's own 'updateRadius' function

* made updateRadius method private

* fix linting error

* updated polar charts to read custom angles from "chart.options.elements.arc.angle" instead of "chart.options.angle"

Author: slinhart

src/controllers/controller.polarArea.js

@@ -117,25 +117,47 @@ module.exports = function(Chart) {
 		linkScales: helpers.noop,
 
 		update: function(reset) {
+			var me = this;
+			var dataset = me.getDataset();
+			var meta = me.getMeta();
+			var start = me.chart.options.startAngle || 0;
+			var starts = me._starts = [];
+			var angles = me._angles = [];
+			var i, ilen, angle;
+
+			me._updateRadius();
+
+			meta.count = me.countVisibleElements();
+
+			for (i = 0, ilen = dataset.data.length; i < ilen; i++) {
+				starts[i] = start;
+				angle = me._computeAngle(i);
+				angles[i] = angle;
+				start += angle;
+			}
+
+			helpers.each(meta.data, function(arc, index) {
+				me.updateElement(arc, index, reset);
+			});
+		},
+
+		/**
+		 * @private
+		 */
+		_updateRadius: function() {
 			var me = this;
 			var chart = me.chart;
 			var chartArea = chart.chartArea;
-			var meta = me.getMeta();
 			var opts = chart.options;
 			var arcOpts = opts.elements.arc;
 			var minSize = Math.min(chartArea.right - chartArea.left, chartArea.bottom - chartArea.top);
+
 			chart.outerRadius = Math.max((minSize - arcOpts.borderWidth / 2) / 2, 0);
 			chart.innerRadius = Math.max(opts.cutoutPercentage ? (chart.outerRadius / 100) * (opts.cutoutPercentage) : 1, 0);
 			chart.radiusLength = (chart.outerRadius - chart.innerRadius) / chart.getVisibleDatasetCount();
 
 			me.outerRadius = chart.outerRadius - (chart.radiusLength * me.index);
 			me.innerRadius = me.outerRadius - chart.radiusLength;
-
-			meta.count = me.countVisibleElements();
-
-			helpers.each(meta.data, function(arc, index) {
-				me.updateElement(arc, index, reset);
-			});
 		},
 
 		updateElement: function(arc, index, reset) {
@@ -147,25 +169,14 @@ module.exports = function(Chart) {
 			var scale = chart.scale;
 			var labels = chart.data.labels;
 
-			var circumference = me.calculateCircumference(dataset.data[index]);
 			var centerX = scale.xCenter;
 			var centerY = scale.yCenter;
 
-			// If there is NaN data before us, we need to calculate the starting angle correctly.
-			// We could be way more efficient here, but its unlikely that the polar area chart will have a lot of data
-			var visibleCount = 0;
-			var meta = me.getMeta();
-			for (var i = 0; i < index; ++i) {
-				if (!isNaN(dataset.data[i]) && !meta.data[i].hidden) {
-					++visibleCount;
-				}
-			}
-
 			// var negHalfPI = -0.5 * Math.PI;
 			var datasetStartAngle = opts.startAngle;
 			var distance = arc.hidden ? 0 : scale.getDistanceFromCenterForValue(dataset.data[index]);
-			var startAngle = datasetStartAngle + (circumference * visibleCount);
-			var endAngle = startAngle + (arc.hidden ? 0 : circumference);
+			var startAngle = me._starts[index];
+			var endAngle = startAngle + (arc.hidden ? 0 : me._angles[index]);
 
 			var resetRadius = animationOpts.animateScale ? 0 : scale.getDistanceFromCenterForValue(dataset.data[index]);
 
@@ -211,12 +222,31 @@ module.exports = function(Chart) {
 			return count;
 		},
 
-		calculateCircumference: function(value) {
+		/**
+		 * @private
+		 */
+		_computeAngle: function(index) {
+			var me = this;
 			var count = this.getMeta().count;
-			if (count > 0 && !isNaN(value)) {
-				return (2 * Math.PI) / count;
+			var dataset = me.getDataset();
+			var meta = me.getMeta();
+
+			if (isNaN(dataset.data[index]) || meta.data[index].hidden) {
+				return 0;
 			}
-			return 0;
+
+			// Scriptable options
+			var context = {
+				chart: me.chart,
+				dataIndex: index,
+				dataset: dataset,
+				datasetIndex: me.index
+			};
+
+			return helpers.options.resolve([
+				me.chart.options.elements.arc.angle,
+				(2 * Math.PI) / count
+			], context, index);
 		}
 	});
 };

test/fixtures/controller.polarArea/angle-array.json

@@ -0,0 +1,34 @@
+{
+    "config": {
+        "type": "polarArea",
+        "data": {
+            "labels": ["A", "B", "C", "D", "E"],
+            "datasets": [{
+                "data": [11, 16, 21, 7, 10],
+                "backgroundColor": [
+                    "rgba(255, 99, 132, 0.8)",
+                    "rgba(54, 162, 235, 0.8)",
+                    "rgba(255, 206, 86, 0.8)",
+                    "rgba(75, 192, 192, 0.8)",
+                    "rgba(153, 102, 255, 0.8)",
+                    "rgba(255, 159, 64, 0.8)"
+                ]
+            }]
+        },
+        "options": {
+            "elements": {
+                "arc": {
+                    "angle": [
+                        1.0566, 1.7566, 1.0566, 2.1566, 0.2566
+                    ]
+                }
+            },
+            "responsive": false,
+            "legend": false,
+            "title": false,
+            "scale": {
+                "display": false
+            }
+        }
+    }
+}

test/fixtures/controller.polarArea/angle-array.png

@@ -0,0 +1,27 @@
+{
+    "config": {
+        "type": "polarArea",
+        "data": {
+            "labels": ["A", "B", "C", "D", "E"],
+            "datasets": [{
+                "data": [11, 16, 21, 7, 10],
+                "backgroundColor": [
+                    "rgba(255, 99, 132, 0.8)",
+                    "rgba(54, 162, 235, 0.8)",
+                    "rgba(255, 206, 86, 0.8)",
+                    "rgba(75, 192, 192, 0.8)",
+                    "rgba(153, 102, 255, 0.8)",
+                    "rgba(255, 159, 64, 0.8)"
+                ]
+            }]
+        },
+        "options": {
+            "responsive": false,
+            "legend": false,
+            "title": false,
+            "scale": {
+                "display": false
+            }
+        }
+    }
+}

test/fixtures/controller.polarArea/angle-undefined.json

@@ -1,3 +1,5 @@
+describe('auto', jasmine.specsFromFixtures('controller.polarArea'));
+
 describe('Chart.controllers.polarArea', function() {
 	it('should be constructed', function() {
 		var chart = window.acquireChart({