From 41d9be33a257058f398bc05d5b212bcdbae2bb80 Mon Sep 17 00:00:00 2001
From: Jukka Kurkela <jukka.kurkela@gmail.com>
Date: Wed, 19 Jun 2019 20:43:04 +0300
Subject: [PATCH] review comments

---
 src/core/core.scale.js       | 14 ++++++--------
 src/scales/scale.category.js | 12 +++++-------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/core/core.scale.js b/src/core/core.scale.js
index 534d3f2d63c..5e5547d18ce 100644
--- a/src/core/core.scale.js
+++ b/src/core/core.scale.js
@@ -70,9 +70,7 @@ function getPixelForGridLine(scale, index, offsetGridLines) {
 
 	if (offsetGridLines) {
 		if (scale.getTicks().length === 1) {
-			lineValue -= scale.isHorizontal() ?
-				Math.max(lineValue - scale.left, scale.right - lineValue) :
-				Math.max(lineValue - scale.top, scale.bottom - lineValue);
+			lineValue -= Math.max(lineValue - scale._start, scale._end - lineValue);
 		} else if (index === 0) {
 			lineValue -= (scale.getPixelForTick(1) - lineValue) / 2;
 		} else {
@@ -454,7 +452,7 @@ var Scale = Element.extend({
 
 				// Allow 3 pixels x2 padding either side for label readability
 				if (maxLabelWidth + 6 > tickWidth) {
-					tickWidth = maxWidth / (ticks.length - options.offset ? 0.5 : 1);
+					tickWidth = maxWidth / (ticks.length - (options.offset ? 0.5 : 1));
 					maxHeight = me.maxHeight - getTickMarkLength(options.gridLines)
 						- tickOpts.padding - getScaleLabelHeight(options.scaleLabel);
 					maxLabelDiagonal = Math.sqrt(maxLabelWidth * maxLabelWidth + maxLabelHeight * maxLabelHeight);
@@ -700,8 +698,8 @@ var Scale = Element.extend({
 	getPixelForTick: function(index) {
 		var me = this;
 		var offset = me.options.offset;
-		var tickWidth = 1 / Math.max((me._ticks.length - offset ? 0 : 1), 1);
-		var decimal = index * tickWidth + offset ? tickWidth / 2 : 0;
+		var tickWidth = 1 / Math.max(me._ticks.length - (offset ? 0 : 1), 1);
+		var decimal = index * tickWidth + (offset ? tickWidth / 2 : 0);
 		return me.getPixelForDecimal(decimal);
 	},
 
@@ -1134,7 +1132,7 @@ var Scale = Element.extend({
 		var scaleLabelX, scaleLabelY;
 
 		if (me.isHorizontal()) {
-			scaleLabelX = me.left + ((me.right - me.left) / 2); // midpoint of the width
+			scaleLabelX = me.left + me.width / 2; // midpoint of the width
 			scaleLabelY = position === 'bottom'
 				? me.bottom - halfLineHeight - scaleLabelPadding.bottom
 				: me.top + halfLineHeight + scaleLabelPadding.top;
@@ -1143,7 +1141,7 @@ var Scale = Element.extend({
 			scaleLabelX = isLeft
 				? me.left + halfLineHeight + scaleLabelPadding.top
 				: me.right - halfLineHeight - scaleLabelPadding.top;
-			scaleLabelY = me.top + ((me.bottom - me.top) / 2);
+			scaleLabelY = me.top + me.height / 2;
 			rotation = isLeft ? -0.5 * Math.PI : 0.5 * Math.PI;
 		}
 
diff --git a/src/scales/scale.category.js b/src/scales/scale.category.js
index f7bac9f2469..9cef04ff1bb 100644
--- a/src/scales/scale.category.js
+++ b/src/scales/scale.category.js
@@ -67,12 +67,9 @@ module.exports = Scale.extend({
 		var me = this;
 		var offset = me.options.offset;
 
-		// 1 is added because we need the length but we have the indexes
-		var range = Math.max(me.maxIndex + 1 - me.minIndex - (offset ? 0 : 1), 1);
-		var start = me.minIndex - (offset ? 0.5 : 0);
 		return {
-			start: start,
-			range: range
+			start: me.minIndex - (offset ? 0.5 : 0),
+			range: Math.max(me.ticks.length - (offset ? 0 : 1), 1)
 		};
 	},
 
@@ -88,7 +85,7 @@ module.exports = Scale.extend({
 
 		// If value is a data object, then index is the index in the data array,
 		// not the index of the scale. We need to change that.
-		if (!helpers.isNullOrUndef(value)) {
+		if (!isNullOrUndef(value)) {
 			valueCategory = me.isHorizontal() ? value.x : value.y;
 		}
 		if (valueCategory !== undefined || (value !== undefined && isNaN(index))) {
@@ -114,7 +111,8 @@ module.exports = Scale.extend({
 	getValueForPixel: function(pixel) {
 		var me = this;
 		var params = me._getParams();
-		return Math.round(params.start + me.getDecimalForPixel(pixel) * params.range);
+		var value = Math.round(params.start + me.getDecimalForPixel(pixel) * params.range);
+		return Math.min(Math.max(value, 0), me.ticks.length - 1);
 	},
 
 	getBasePixel: function() {