Per-controller options to fix mixed charts

src/controllers/controller.line.js

@@ -10,9 +10,6 @@ var resolve = helpers.options.resolve;
 var isPointInArea = helpers.canvas._isPointInArea;
 
 defaults._set('line', {
-	showLines: true,
-	spanGaps: false,
-
 	hover: {
 		mode: 'label'
 	},
@@ -29,9 +26,12 @@ defaults._set('line', {
 	}
 });
 
-function lineEnabled(dataset, options) {
-	return valueOrDefault(dataset.showLine, options.showLines);
-}
+defaults._set('datasets', {
+	line: {
+		showLine: true,
+		spanGaps: false
+	}
+});
 
 module.exports = DatasetController.extend({
 
@@ -44,9 +44,11 @@ module.exports = DatasetController.extend({
 		var meta = me.getMeta();
 		var line = meta.dataset;
 		var points = meta.data || [];
+		var options = me.chart.options;
 		var scale = me.getScaleForId(meta.yAxisID);
 		var dataset = me.getDataset();
-		var showLine = lineEnabled(dataset, me.chart.options);
+		var datasetDefaults = me._defaults();
+		var showLine = me._showLine = resolve([dataset.showLine, options.showLines, datasetDefaults.showLine]);
 		var i, ilen;
 
 		// Update Line
@@ -181,6 +183,7 @@ module.exports = DatasetController.extend({
 		var dataset = chart.data.datasets[me.index];
 		var custom = element.custom || {};
 		var options = chart.options;
+		var datasetDefaults = me._defaults();
 		var elementOptions = options.elements.line;
 		var values = {};
 		var i, ilen, key;
@@ -202,16 +205,17 @@ module.exports = DatasetController.extend({
 			values[key] = resolve([
 				custom[key],
 				dataset[key],
-				elementOptions[key]
+				elementOptions[key],
+				datasetDefaults[key]
 			]);
 		}
 
 		// The default behavior of lines is to break at null values, according
 		// to https://github.com/chartjs/Chart.js/issues/2435#issuecomment-216718158
 		// This option gives lines the ability to span gaps
-		values.spanGaps = valueOrDefault(dataset.spanGaps, options.spanGaps);
-		values.tension = resolve([custom.tension, dataset.lineTension, elementOptions.tension]);
-		values.steppedLine = resolve([custom.steppedLine, dataset.steppedLine, elementOptions.stepped]);
+		values.spanGaps = valueOrDefault(dataset.spanGaps, options.spanGaps, datasetDefaults.spanGaps);
+		values.tension = resolve([custom.tension, dataset.lineTension, elementOptions.tension, datasetDefaults.tension]);
+		values.steppedLine = resolve([custom.steppedLine, dataset.steppedLine, elementOptions.stepped, datasetDefaults.steppedLine]);
 
 		return values;
 	},
@@ -311,11 +315,11 @@ module.exports = DatasetController.extend({
 		var meta = me.getMeta();
 		var points = meta.data || [];
 		var area = chart.chartArea;
-		var ilen = points.length;
 		var halfBorderWidth;
 		var i = 0;
+		var ilen = points.length;
 
-		if (lineEnabled(me.getDataset(), chart.options)) {
+		if (me._showLine) {
 			halfBorderWidth = (meta.dataset._model.borderWidth || 0) / 2;
 
 			helpers.canvas.clipArea(chart.ctx, {

src/controllers/controller.scatter.js

@@ -21,8 +21,6 @@ defaults._set('scatter', {
 		}]
 	},
 
-	showLines: false,
-
 	tooltips: {
 		callbacks: {
 			title: function() {
@@ -35,5 +33,11 @@ defaults._set('scatter', {
 	}
 });
 
+defaults._set('datasets', {
+	scatter: {
+		showLine: false
+	}
+});
+
 // Scatter charts use line controllers
 module.exports = LineController;

src/core/core.datasetController.js

@@ -1,5 +1,6 @@
 'use strict';
 
+var defaults = require('../core/core.defaults');
 var helpers = require('../helpers/index');
 
 var resolve = helpers.options.resolve;
@@ -100,6 +101,7 @@ helpers.extend(DatasetController.prototype, {
 		me.index = datasetIndex;
 		me.linkScales();
 		me.addElements();
+		me._type = me.getMeta().type;
 	},
 
 	updateIndex: function(datasetIndex) {
@@ -234,6 +236,15 @@ helpers.extend(DatasetController.prototype, {
 		me.resyncElements();
 	},
 
+	/**
+	 * Returns the default dataset-level options
+	 * @private
+	 */
+	_defaults: function() {
+		var me = this;
+		return defaults.datasets[me._type] || {};
+	},
+
 	update: helpers.noop,
 
 	transition: function(easingValue) {

src/core/core.defaults.js

@@ -17,8 +17,7 @@ defaults._set('global', {
 	defaultFontFamily: "'Helvetica Neue', 'Helvetica', 'Arial', sans-serif",
 	defaultFontSize: 12,
 	defaultFontStyle: 'normal',
-	defaultLineHeight: 1.2,
-	showLines: true
+	defaultLineHeight: 1.2
 });
 
 module.exports = defaults;

test/specs/controller.line.tests.js

@@ -573,6 +573,61 @@ describe('Chart.controllers.line', function() {
 		expect(meta.dataset._model.borderWidth).toBe(0.55);
 	});
 
+	it('should fall back to the dataset default spanGaps option', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				datasets: [{
+					data: [0, 0],
+					label: 'dataset1'
+				}],
+				labels: ['label1', 'label2']
+			}
+		});
+
+		var meta = chart.getDatasetMeta(0);
+
+		expect(meta.dataset._model.spanGaps).toBe(false);
+	});
+
+	it('should obey the global spanGaps option', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				datasets: [{
+					data: [0, 0],
+					label: 'dataset1'
+				}],
+				labels: ['label1', 'label2']
+			},
+			options: {
+				spanGaps: true
+			}
+		});
+
+		var meta = chart.getDatasetMeta(0);
+
+		expect(meta.dataset._model.spanGaps).toBe(true);
+	});
+
+	it('should obey the dataset spanGaps option', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				datasets: [{
+					data: [0, 0],
+					label: 'dataset1',
+					spanGaps: true
+				}],
+				labels: ['label1', 'label2']
+			}
+		});
+
+		var meta = chart.getDatasetMeta(0);
+
+		expect(meta.dataset._model.spanGaps).toBe(true);
+	});
+
 	it('should handle number of data point changes in update', function() {
 		var chart = window.acquireChart({
 			type: 'line',

test/specs/controller.scatter.test.js

@@ -47,5 +47,28 @@ describe('Chart.controllers.scatter', function() {
 			expect(meta.dataset.draw.calls.count()).toBe(0);
 			expect(meta.data[0].draw.calls.count()).toBe(1);
 		});
+
+		it('should draw a line if true', function() {
+			var chart = window.acquireChart({
+				type: 'scatter',
+				data: {
+					datasets: [{
+						data: [{x: 10, y: 15}],
+						showLine: true,
+						label: 'dataset1'
+					}],
+				},
+				options: {}
+			});
+
+			var meta = chart.getDatasetMeta(0);
+			spyOn(meta.dataset, 'draw');
+			spyOn(meta.data[0], 'draw');
+
+			chart.update();
+
+			expect(meta.dataset.draw.calls.count()).toBe(1);
+			expect(meta.data[0].draw.calls.count()).toBe(1);
+		});
 	});
 });