From: Ben McCann <322311+benmccann@users.noreply.github.com>
Date: Tue, 7 Jan 2020 12:26:29 +0000 (-0800)
Subject: Improve calculation for number of ticks that can fit (#6927)
X-Git-Tag: v3.0.0-alpha~149
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3b55de73facd9a46cfb70bf4968c732c90cc1bb1;p=thirdparty%2FChart.js.git

Improve calculation for number of ticks that can fit (#6927)
---

diff --git a/src/core/core.scale.js b/src/core/core.scale.js
index 0350d3fe9..022e3dd8e 100644
--- a/src/core/core.scale.js
+++ b/src/core/core.scale.js
@@ -884,7 +884,7 @@ class Scale extends Element {
 		const me = this;
 		const tickOpts = me.options.ticks;
 		const axisLength = me._length;
-		const ticksLimit = tickOpts.maxTicksLimit || axisLength / me._tickSize() + 1;
+		const ticksLimit = tickOpts.maxTicksLimit || axisLength / me._tickSize();
 		const majorIndices = tickOpts.major.enabled ? getMajorIndices(ticks) : [];
 		const numMajorIndices = majorIndices.length;
 		const first = majorIndices[0];
diff --git a/src/scales/scale.time.js b/src/scales/scale.time.js
index ba6ad2049..6d28e496e 100644
--- a/src/scales/scale.time.js
+++ b/src/scales/scale.time.js
@@ -755,12 +755,9 @@ class TimeScale extends Scale {
 		const format = displayFormats[timeOpts.unit] || displayFormats.millisecond;
 		const exampleLabel = me._tickFormatFunction(exampleTime, 0, ticksFromTimestamps(me, [exampleTime], me._majorUnit), format);
 		const size = me._getLabelSize(exampleLabel);
-		let capacity = Math.floor(me.isHorizontal() ? me.width / size.w : me.height / size.h);
-
-		if (me.options.offset) {
-			capacity--;
-		}
-
+		// subtract 1 - if offset then there's one less label than tick
+		// if not offset then one half label padding is added to each end leaving room for one less label
+		const capacity = Math.floor(me.isHorizontal() ? me.width / size.w : me.height / size.h) - 1;
 		return capacity > 0 ? capacity : 1;
 	}
 }
diff --git a/test/specs/scale.time.tests.js b/test/specs/scale.time.tests.js
index 465a7e0f4..53428d9b8 100644
--- a/test/specs/scale.time.tests.js
+++ b/test/specs/scale.time.tests.js
@@ -1397,8 +1397,8 @@ describe('Time scale tests', function() {
 					this.chart = window.acquireChart({
 						type: 'line',
 						data: {
-							labels: ['2017', '2019', '2020', '2025', '2042'],
-							datasets: [{data: [0, 1, 2, 3, 4, 5]}]
+							labels: ['2017', '2019', '2020', '2025'],
+							datasets: [{data: [0, 1, 2, 3, 4]}]
 						},
 						options: {
 							scales: {
@@ -1421,7 +1421,7 @@ describe('Time scale tests', function() {
 					var scale = this.chart.scales.x;
 
 					expect(scale.getPixelForValue(moment('2017').valueOf())).toBeCloseToPixel(scale.left);
-					expect(scale.getPixelForValue(moment('2042').valueOf())).toBeCloseToPixel(scale.left + scale.width);
+					expect(scale.getPixelForValue(moment('2025').valueOf())).toBeCloseToPixel(scale.left + scale.width);
 				});
 
 				it ('should add offset from the edges if offset is true', function() {
@@ -1437,7 +1437,7 @@ describe('Time scale tests', function() {
 					var lastTickInterval = scale.getPixelForTick(numTicks - 1) - scale.getPixelForTick(numTicks - 2);
 
 					expect(scale.getPixelForValue(moment('2017').valueOf())).toBeCloseToPixel(scale.left + firstTickInterval / 2);
-					expect(scale.getPixelForValue(moment('2042').valueOf())).toBeCloseToPixel(scale.left + scale.width - lastTickInterval / 2);
+					expect(scale.getPixelForValue(moment('2025').valueOf())).toBeCloseToPixel(scale.left + scale.width - lastTickInterval / 2);
 				});
 
 				it ('should not add offset if min and max extend the labels range', function() {