Merge pull request #1834 from damiansilbergleithcunniff/issue-1764-default-pie-chart-colors

Issue 1764: Add default colors for Pie Charts

docs/05-Pie-Doughnut-Chart.md

@@ -137,6 +137,8 @@ myDoughnutChart.update();
 
 Calling `addData(segmentData, index)` on your Chart instance passing an object in the same format as in the constructor. There is an optional second argument of 'index', this determines at what index the new segment should be inserted into the chart.
 
+If you don't specify a color and highliht, one will be chosen from the global default array: segmentColorDefault and the corresponding segmentHighlightColorDefault.  The index of the addded data is used to lookup a corresponding color from the defaults.
+
 ```javascript
 // An object in the same format as the original data source
 myDoughnutChart.addData({

src/Chart.Core.js

@@ -173,6 +173,12 @@
 			// String - Colour behind the legend colour block
 			multiTooltipKeyBackground: '#fff',
 
+			// Array - A list of colors to use as the defaults
+			segmentColorDefault: ["#A6CEE3", "#1F78B4", "#B2DF8A", "#33A02C", "#FB9A99", "#E31A1C", "#FDBF6F", "#FF7F00", "#CAB2D6", "#6A3D9A", "#B4B482", "#B15928" ],
+
+			// Array - A list of highlight colors to use as the defaults
+			segmentHighlightColorDefaults: [ "#CEF6FF", "#47A0DC", "#DAFFB2", "#5BC854", "#FFC2C1", "#FF4244", "#FFE797", "#FFA728", "#F2DAFE", "#9265C2", "#DCDCAA", "#D98150" ],
+
 			// Function - Will fire on animation progression.
 			onAnimationProgress: function(){},
 

src/Chart.Doughnut.js

@@ -92,6 +92,10 @@
 		},
 		addData : function(segment, atIndex, silent){
 			var index = atIndex !== undefined ? atIndex : this.segments.length;
+			if ( typeof(segment.color) === "undefined" ) {
+				segment.color = Chart.defaults.global.segmentColorDefault[index % Chart.defaults.global.segmentColorDefault.length];
+				segment.highlight = Chart.defaults.global.segmentHighlightColorDefaults[index % Chart.defaults.global.segmentHighlightColorDefaults.length];				
+			}
 			this.segments.splice(index, 0, new this.SegmentArc({
 				value : segment.value,
 				outerRadius : (this.options.animateScale) ? 0 : this.outerRadius,