From 6814b79b65afeeab09d3f03151ec0458be10686f Mon Sep 17 00:00:00 2001
From: Jukka Kurkela <jukka.kurkela@gmail.com>
Date: Wed, 2 Dec 2020 06:51:33 +0200
Subject: [PATCH] Fix CategoryScale.getValueForPixel with autoSkip (#8101)

---
 src/scales/scale.category.js       |  3 +--
 test/specs/scale.category.tests.js | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/scales/scale.category.js b/src/scales/scale.category.js
index 4824dbe9c..6c06719e8 100644
--- a/src/scales/scale.category.js
+++ b/src/scales/scale.category.js
@@ -111,8 +111,7 @@ export default class CategoryScale extends Scale {
 
 	getValueForPixel(pixel) {
 		const me = this;
-		const value = Math.round(me._startValue + me.getDecimalForPixel(pixel) * me._valueRange);
-		return Math.min(Math.max(value, 0), me.ticks.length - 1);
+		return Math.round(me._startValue + me.getDecimalForPixel(pixel) * me._valueRange);
 	}
 
 	getBasePixel() {
diff --git a/test/specs/scale.category.tests.js b/test/specs/scale.category.tests.js
index fec12cac6..884627af6 100644
--- a/test/specs/scale.category.tests.js
+++ b/test/specs/scale.category.tests.js
@@ -476,6 +476,35 @@ describe('Category scale tests', function() {
 		expect(yScale.getPixelForValue(4)).toBeCloseToPixel(538);
 	});
 
+	it('Should be consistent on pixels and values with autoSkipped ticks', function() {
+		var labels = [];
+		for (let i = 0; i < 50; i++) {
+			labels.push('very long label ' + i);
+		}
+		var chart = window.acquireChart({
+			type: 'bar',
+			data: {
+				labels,
+				datasets: [{
+					data: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+				}]
+			}
+		});
+
+		var scale = chart.scales.x;
+		expect(scale.ticks.length).toBeLessThan(50);
+
+		let x = 0;
+		for (let i = 0; i < 50; i++) {
+			var x2 = scale.getPixelForValue(labels[i]);
+			var x3 = scale.getPixelForValue(i);
+			expect(x2).toEqual(x3);
+			expect(x2).toBeGreaterThan(x);
+			expect(scale.getValueForPixel(x2)).toBe(i);
+			x = x2;
+		}
+	});
+
 	it('Should bound to ticks/data', function() {
 		var chart = window.acquireChart({
 			type: 'line',
-- 
2.47.2