Fix category scale autoSkip (#6847)

diff --git a/src/scales/scale.category.js b/src/scales/scale.category.js
index 15d1afc55d55d34b56a6f16857d894f388f18a83..eb0c7082d5f6f4099b72b5200728005a3dfe5621 100644 (file)
--- a/src/scales/scale.category.js
+++ b/src/scales/scale.category.js
@@ -7,36 +7,42 @@ const defaultConfig = {
 
 class CategoryScale extends Scale {
        _parse(raw, index) {
-               var labels = this._getLabels();
-               var first = labels.indexOf(raw);
-               var last = labels.lastIndexOf(raw);
+               const labels = this._getLabels();
+               const first = labels.indexOf(raw);
+               const last = labels.lastIndexOf(raw);
                return first === -1 || first !== last ? index : first;
        }
 
        determineDataLimits() {
-               var me = this;
-               var max = me._getLabels().length - 1;
+               const me = this;
+               const max = me._getLabels().length - 1;
 
                me.min = Math.max(me._userMin || 0, 0);
                me.max = Math.min(me._userMax || max, max);
        }
 
        buildTicks() {
-               var me = this;
-               var labels = me._getLabels();
-               var min = me.min;
-               var max = me.max;
+               const me = this;
+               const min = me.min;
+               const max = me.max;
+               const offset = me.options.offset;
+               let labels = me._getLabels();
 
                // If we are viewing some subset of labels, slice the original array
                labels = (min === 0 && max === labels.length - 1) ? labels : labels.slice(min, max + 1);
+
+               me._numLabels = labels.length;
+               me._valueRange = Math.max(labels.length - (offset ? 0 : 1), 1);
+               me._startValue = me.min - (offset ? 0.5 : 0);
+
                return labels.map(function(l) {
                        return {value: l};
                });
        }
 
        getLabelForValue(value) {
-               var me = this;
-               var labels = me._getLabels();
+               const me = this;
+               const labels = me._getLabels();
 
                if (value >= 0 && value < labels.length) {
                        return labels[value];
@@ -45,9 +51,7 @@ class CategoryScale extends Scale {
        }
 
        _configure() {
-               var me = this;
-               var offset = me.options.offset;
-               var ticks = me.ticks;
+               const me = this;
 
                Scale.prototype._configure.call(me);
 
@@ -55,16 +59,9 @@ class CategoryScale extends Scale {
                        // For backward compatibility, vertical category scale reverse is inverted.
                        me._reversePixels = !me._reversePixels;
                }
-
-               if (!ticks) {
-                       return;
-               }
-
-               me._startValue = me.min - (offset ? 0.5 : 0);
-               me._valueRange = Math.max(ticks.length - (offset ? 0 : 1), 1);
        }
 
-       // Used to get data value locations.  Value can either be an index or a numerical value
+       // Used to get data value locations. Value can either be an index or a numerical value
        getPixelForValue(value) {
                var me = this;
 
@@ -76,15 +73,17 @@ class CategoryScale extends Scale {
        }
 
        getPixelForTick(index) {
-               var ticks = this.ticks;
-               return index < 0 || index > ticks.length - 1
-                       ? null
-                       : this.getPixelForValue(index + this.min);
+               const me = this;
+               const ticks = me.ticks;
+               if (index < 0 || index > ticks.length - 1) {
+                       return null;
+               }
+               return this.getPixelForValue(index * me._numLabels / ticks.length + this.min);
        }
 
        getValueForPixel(pixel) {
-               var me = this;
-               var value = Math.round(me._startValue + me.getDecimalForPixel(pixel) * me._valueRange);
+               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);
        }