Plugin system + tests

src/chart.js

@@ -18,6 +18,7 @@ require('./core/core.controller')(Chart);
 require('./core/core.datasetController')(Chart);
 require('./core/core.layoutService')(Chart);
 require('./core/core.legend')(Chart);
+require('./core/core.plugin.js')(Chart);
 require('./core/core.scale')(Chart);
 require('./core/core.scaleService')(Chart);
 require('./core/core.title')(Chart);

src/core/core.plugin.js

@@ -0,0 +1,55 @@
+"use strict";
+
+module.exports = function(Chart) {
+	var helpers = Chart.helpers;
+
+	// Plugins are stored here
+	Chart.plugins = [];
+	Chart.pluginService = {
+		// Register a new plugin
+		register: function(plugin) {
+			if (Chart.plugins.indexOf(plugin) === -1) {
+				Chart.plugins.push(plugin);
+			}
+		},
+
+		// Remove a registered plugin
+		remove: function(plugin) {
+			var idx = Chart.plugins.indexOf(plugin);
+			if (idx !== -1) {
+				Chart.plugins.splice(idx, 1);
+			}
+		},
+
+		// Iterate over all plugins
+		notifyPlugins: function(method, chartInstance, scope) {
+			helpers.each(Chart.plugins, function(plugin) {
+				if (plugin[method] && typeof plugin[method] === 'function') {
+					plugin[method].call(scope, chartInstance);
+				}
+			}, scope);
+		}
+	};
+
+	Chart.PluginBase = Chart.Element.extend({
+		// Plugin methods. All functions are passed the chart instance
+
+		// Called at start of chart init
+		beforeInit: helpers.noop,
+
+		// Called at end of chart init
+		afterInit: helpers.noop,
+
+		// Called at start of update
+		beforeUpdate: helpers.noop,
+
+		// Called at end of update
+		afterUpdate: helpers.noop,
+
+		// Called at start of draw
+		beforeDraw: helpers.noop,
+
+		// Called at end of draw
+		afterDraw: helpers.noop,
+	});
+};

test/core.plugin.tests.js

@@ -0,0 +1,43 @@
+// Plugin tests
+describe('Test the plugin system', function() {
+	beforeEach(function() {
+		Chart.plugins = [];
+	});
+
+	it ('Should register plugins', function() {
+		var myplugin = {};
+		Chart.pluginService.register(myplugin);
+		expect(Chart.plugins.length).toBe(1);
+
+		// Should only add plugin once
+		Chart.pluginService.register(myplugin);
+		expect(Chart.plugins.length).toBe(1);		
+	});
+
+	it ('Should allow unregistering plugins', function() {
+		var myplugin = {};
+		Chart.pluginService.register(myplugin);
+		expect(Chart.plugins.length).toBe(1);
+
+		// Should only add plugin once
+		Chart.pluginService.remove(myplugin);
+		expect(Chart.plugins.length).toBe(0);		
+
+		// Removing a plugin that doesn't exist should not error
+		Chart.pluginService.remove(myplugin);
+	});
+
+	it ('Should allow notifying plugins', function() {
+		var myplugin = {
+			count: 0,
+			trigger: function(chart) {
+				myplugin.count = chart.count;
+			}
+		};
+		Chart.pluginService.register(myplugin);
+		
+		Chart.pluginService.notifyPlugins('trigger', { count: 10 });
+
+		expect(myplugin.count).toBe(10);
+	});
+});