From: Jukka Kurkela <jukka.kurkela@gmail.com>
Date: Thu, 17 Dec 2020 20:18:02 +0000 (+0200)
Subject: Hover: only update styles of changed elements (#8185)
X-Git-Tag: v3.0.0-beta.8~59
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b10d99401746129c90b7d9289aa28de3f1844ab7;p=thirdparty%2FChart.js.git

Hover: only update styles of changed elements (#8185)
---

diff --git a/src/core/core.controller.js b/src/core/core.controller.js
index 80632579d..8fa07ec85 100644
--- a/src/core/core.controller.js
+++ b/src/core/core.controller.js
@@ -994,15 +994,16 @@ class Chart {
 		const me = this;
 		const options = me.options || {};
 		const hoverOptions = options.hover;
+		const diff = (a, b) => a.filter(x => !b.some(y => x.datasetIndex === y.datasetIndex && x.index === y.index));
+		const deactivated = diff(lastActive, active);
+		const activated = diff(active, lastActive);
 
-		// Remove styling for last active (even if it may still be active)
-		if (lastActive.length) {
-			me.updateHoverStyle(lastActive, hoverOptions.mode, false);
+		if (deactivated.length) {
+			me.updateHoverStyle(deactivated, hoverOptions.mode, false);
 		}
 
-		// Built-in hover styling
-		if (active.length && hoverOptions.mode) {
-			me.updateHoverStyle(active, hoverOptions.mode, true);
+		if (activated.length && hoverOptions.mode) {
+			me.updateHoverStyle(activated, hoverOptions.mode, true);
 		}
 	}