From 7205ff5e2aa4515bae0c62bb9d8355745837270e Mon Sep 17 00:00:00 2001
From: Simon Brunel <simonbrunel@users.noreply.github.com>
Date: Sun, 22 Jan 2017 21:10:17 +0100
Subject: [PATCH] Replace `onEvent` by `before/afterEvent`

---
 docs/09-Advanced.md         |  9 +++------
 src/core/core.controller.js | 10 +++++++---
 src/core/core.legend.js     |  2 +-
 src/core/core.plugin.js     | 16 ++++++++++++++++
 test/platform.dom.tests.js  |  2 +-
 5 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/docs/09-Advanced.md b/docs/09-Advanced.md
index d3d69d9af..05642fcab 100644
--- a/docs/09-Advanced.md
+++ b/docs/09-Advanced.md
@@ -439,12 +439,9 @@ Plugins should implement the `IPlugin` interface:
 
 	destroy: function(chartInstance) { }
 
-	/**
-	 * Called when an event occurs on the chart
-	 * @param e {Core.Event} the Chart.js wrapper around the native event. e.native is the original event
-	 * @return {Boolean} true if the chart is changed and needs to re-render
-	 */
-	onEvent: function(chartInstance, e) {}
+	// Called when an event occurs on the chart
+	beforeEvent: function(chartInstance, event) {}
+	afterEvent: function(chartInstance, event) {}
 }
 ```
 
diff --git a/src/core/core.controller.js b/src/core/core.controller.js
index f67b29ff9..b38df58b2 100644
--- a/src/core/core.controller.js
+++ b/src/core/core.controller.js
@@ -664,7 +664,10 @@ module.exports = function(Chart) {
 		eventHandler: function(e) {
 			var me = this;
 			var tooltip = me.tooltip;
-			var hoverOptions = me.options.hover;
+
+			if (plugins.notify(me, 'beforeEvent', [e]) === false) {
+				return;
+			}
 
 			// Buffer any update calls so that renders do not occur
 			me._bufferedRender = true;
@@ -672,7 +675,8 @@ module.exports = function(Chart) {
 
 			var changed = me.handleEvent(e);
 			changed |= tooltip && tooltip.handleEvent(e);
-			changed |= plugins.notify(me, 'onEvent', [e]);
+
+			plugins.notify(me, 'afterEvent', [e]);
 
 			var bufferedRequest = me._bufferedRequest;
 			if (bufferedRequest) {
@@ -684,7 +688,7 @@ module.exports = function(Chart) {
 
 				// We only need to render at this point. Updating will cause scales to be
 				// recomputed generating flicker & using more memory than necessary.
-				me.render(hoverOptions.animationDuration, true);
+				me.render(me.options.hover.animationDuration, true);
 			}
 
 			me._bufferedRender = false;
diff --git a/src/core/core.legend.js b/src/core/core.legend.js
index b80bdbe25..4816b285f 100644
--- a/src/core/core.legend.js
+++ b/src/core/core.legend.js
@@ -526,7 +526,7 @@ module.exports = function(Chart) {
 				delete chartInstance.legend;
 			}
 		},
-		onEvent: function(chartInstance, e) {
+		afterEvent: function(chartInstance, e) {
 			var legend = chartInstance.legend;
 			if (legend) {
 				legend.handleEvent(e);
diff --git a/src/core/core.plugin.js b/src/core/core.plugin.js
index f89b412d2..bda2ff457 100644
--- a/src/core/core.plugin.js
+++ b/src/core/core.plugin.js
@@ -274,6 +274,22 @@ module.exports = function(Chart) {
 	 * @param {Number} easingValue - The current animation value, between 0.0 and 1.0.
 	 * @param {Object} options - The plugin options.
 	 */
+	/**
+	 * @method IPlugin#beforeEvent
+ 	 * @desc Called before processing the specified `event`. If any plugin returns `false`,
+	 * the event will be discarded.
+	 * @param {Chart.Controller} chart - The chart instance.
+	 * @param {IEvent} event - The event object.
+	 * @param {Object} options - The plugin options.
+	 */
+	/**
+	 * @method IPlugin#afterEvent
+	 * @desc Called after the `event` has been consumed. Note that this hook
+	 * will not be called if the `event` has been previously discarded.
+	 * @param {Chart.Controller} chart - The chart instance.
+	 * @param {IEvent} event - The event object.
+	 * @param {Object} options - The plugin options.
+	 */
 	/**
 	 * @method IPlugin#resize
 	 * @desc Called after the chart as been resized.
diff --git a/test/platform.dom.tests.js b/test/platform.dom.tests.js
index 19c5bbe1a..a022cc75d 100644
--- a/test/platform.dom.tests.js
+++ b/test/platform.dom.tests.js
@@ -320,7 +320,7 @@ describe('Platform.dom', function() {
 		it('should notify plugins about events', function() {
 			var notifiedEvent;
 			var plugin = {
-				onEvent: function(chart, e) {
+				afterEvent: function(chart, e) {
 					notifiedEvent = e;
 				}
 			};
-- 
2.47.3