Pie and donuts really handle data_order as advertised by documentation. (#1814)

spec/arc-spec.js

@@ -97,6 +97,82 @@ describe('c3 chart arc', function () {
         });
     });
 
+    describe('sort pie chart', function() {
+
+        var createPie = function(order) {
+            return {
+                data: {
+                    order: order,
+                    columns: [
+                        ['data1', 30],
+                        ['data2', 150],
+                        ['data3', 120]
+                    ],
+                    type: 'pie'
+                }
+            };
+        };
+
+        var collectArcs = function() {
+            return d3.selectAll('.c3-arc')
+                .data()
+                .sort(function(a, b) {
+                    return a.startAngle - b.startAngle;
+                })
+                .map(function(item) {
+                    return item.data.id;
+                });
+        };
+
+        it('should update data_order to desc', function () {
+            args = createPie('desc');
+            expect(true).toBeTruthy();
+        });
+
+        it('it should have descending ordering', function () {
+            expect(collectArcs()).toEqual([ 'data2', 'data3', 'data1' ]);
+        });
+
+        it('should update data_order to asc', function () {
+            args = createPie('asc');
+            expect(true).toBeTruthy();
+        });
+
+        it('it should have ascending ordering', function () {
+            expect(collectArcs()).toEqual([ 'data1', 'data3', 'data2' ]);
+        });
+
+        it('should update data_order to NULL', function () {
+            args = createPie(null);
+            expect(true).toBeTruthy();
+        });
+
+        it('it should have no ordering', function () {
+            expect(collectArcs()).toEqual([ 'data1', 'data2', 'data3' ]);
+        });
+
+        it('should update data_order to Array', function () {
+            args = createPie([ 'data3', 'data2', 'data1' ]);
+            expect(true).toBeTruthy();
+        });
+
+        it('it should have array specified ordering', function () {
+            expect(collectArcs()).toEqual([ 'data3', 'data2', 'data1' ]);
+        });
+
+        it('should update data_order to Function', function () {
+            var names = [ 'data2', 'data1', 'data3' ];
+            args = createPie(function(a, b) {
+                return names.indexOf(a.id) - names.indexOf(b.id);
+            });
+            expect(true).toBeTruthy();
+        });
+
+        it('it should have array specified ordering', function () {
+            expect(collectArcs()).toEqual([ 'data2', 'data1', 'data3' ]);
+        });
+    });
+
     describe('show gauge', function () {
 
         describe('with a 180 degree gauge', function(){

src/arc.js

@@ -3,13 +3,11 @@ import { c3_chart_internal_fn } from './core';
 import { isFunction } from './util';
 
 c3_chart_internal_fn.initPie = function () {
-    var $$ = this, d3 = $$.d3, config = $$.config;
+    var $$ = this, d3 = $$.d3;
     $$.pie = d3.layout.pie().value(function (d) {
         return d.values.reduce(function (a, b) { return a + b.value; }, 0);
     });
-    if (!config.data_order) {
-        $$.pie.sort(null);
-    }
+    $$.pie.sort($$.getOrderFunction() || null);
 };
 
 c3_chart_internal_fn.updateRadius = function () {

src/data.js

@@ -236,21 +236,31 @@ c3_chart_internal_fn.isOrderAsc = function () {
     var config = this.config;
     return typeof(config.data_order) === 'string' && config.data_order.toLowerCase() === 'asc';
 };
-c3_chart_internal_fn.orderTargets = function (targets) {
+c3_chart_internal_fn.getOrderFunction = function() {
     var $$ = this, config = $$.config, orderAsc = $$.isOrderAsc(), orderDesc = $$.isOrderDesc();
     if (orderAsc || orderDesc) {
-        targets.sort(function (t1, t2) {
+        return function (t1, t2) {
             var reducer = function (p, c) { return p + Math.abs(c.value); };
             var t1Sum = t1.values.reduce(reducer, 0),
                 t2Sum = t2.values.reduce(reducer, 0);
-            return orderAsc ? t2Sum - t1Sum : t1Sum - t2Sum;
-        });
+            return orderDesc ? t2Sum - t1Sum : t1Sum - t2Sum;
+        };
     } else if (isFunction(config.data_order)) {
-        targets.sort(config.data_order);
+        return config.data_order;
     } else if (isArray(config.data_order)) {
-        targets.sort(function (t1, t2) {
-            return config.data_order.indexOf(t1.id) - config.data_order.indexOf(t2.id);
-        });
+        var order = config.data_order;
+        return function (t1, t2) {
+            return order.indexOf(t1.id) - order.indexOf(t2.id);
+        };
+    }
+};
+c3_chart_internal_fn.orderTargets = function (targets) {
+    var fct = this.getOrderFunction();
+    if (fct) {
+        targets.sort(fct);
+        if (this.isOrderAsc() || this.isOrderDesc()) {
+            targets.reverse();
+        }
     }
     return targets;
 };