Refactor autoskip functionality into a separate method (#4614)

diff --git a/src/core/core.scale.js b/src/core/core.scale.js
index c584514fbf0081443877ed1935ff238d886828aa..6f2634c609aa6575ef52a37ef1652d1104b9f53b 100644 (file)
--- a/src/core/core.scale.js
+++ b/src/core/core.scale.js
@@ -569,6 +569,55 @@ module.exports = function(Chart) {
                                0;
                },
 
+               /**
+                * Returns a subset of ticks to be plotted to avoid overlapping labels.
+                * @private
+                */
+               _autoSkip: function(ticks) {
+                       var skipRatio;
+                       var me = this;
+                       var isHorizontal = me.isHorizontal();
+                       var optionTicks = me.options.ticks.minor;
+                       var tickCount = ticks.length;
+                       var labelRotationRadians = helpers.toRadians(me.labelRotation);
+                       var cosRotation = Math.cos(labelRotationRadians);
+                       var longestRotatedLabel = me.longestLabelWidth * cosRotation;
+                       var result = [];
+                       var i, tick, shouldSkip;
+
+                       // figure out the maximum number of gridlines to show
+                       var maxTicks;
+                       if (optionTicks.maxTicksLimit) {
+                               maxTicks = optionTicks.maxTicksLimit;
+                       }
+
+                       if (isHorizontal) {
+                               skipRatio = false;
+
+                               if ((longestRotatedLabel + optionTicks.autoSkipPadding) * tickCount > (me.width - (me.paddingLeft + me.paddingRight))) {
+                                       skipRatio = 1 + Math.floor(((longestRotatedLabel + optionTicks.autoSkipPadding) * tickCount) / (me.width - (me.paddingLeft + me.paddingRight)));
+                               }
+
+                               // if they defined a max number of optionTicks,
+                               // increase skipRatio until that number is met
+                               if (maxTicks && tickCount > maxTicks) {
+                                       skipRatio = Math.max(skipRatio, Math.floor(tickCount / maxTicks));
+                               }
+                       }
+
+                       for (i = 0; i < tickCount; i++) {
+                               tick = ticks[i];
+
+                               // Since we always show the last tick,we need may need to hide the last shown one before
+                               shouldSkip = (skipRatio > 1 && i % skipRatio > 0) || (i % skipRatio === 0 && i + skipRatio >= tickCount);
+                               if (shouldSkip && i !== tickCount - 1 || helpers.isNullOrUndef(tick.label)) {
+                                       continue;
+                               }
+                               result.push(tick);
+                       }
+                       return result;
+               },
+
                // Actually draw the scale on the canvas
                // @param {rectangle} chartArea : the area of the chart to draw full grid lines on
                draw: function(chartArea) {
@@ -586,16 +635,9 @@ module.exports = function(Chart) {
                        var scaleLabel = options.scaleLabel;
 
                        var isRotated = me.labelRotation !== 0;
-                       var skipRatio;
-                       var useAutoskipper = optionTicks.autoSkip;
                        var isHorizontal = me.isHorizontal();
 
-                       // figure out the maximum number of gridlines to show
-                       var maxTicks;
-                       if (optionTicks.maxTicksLimit) {
-                               maxTicks = optionTicks.maxTicksLimit;
-                       }
-
+                       var ticks = optionTicks.autoSkip ? me._autoSkip(me.getTicks()) : me.getTicks();
                        var tickFontColor = helpers.valueOrDefault(optionTicks.fontColor, globalDefaults.defaultFontColor);
                        var tickFont = parseFontOptions(optionTicks);
                        var majorTickFontColor = helpers.valueOrDefault(optionMajorTicks.fontColor, globalDefaults.defaultFontColor);
@@ -605,58 +647,17 @@ module.exports = function(Chart) {
 
                        var scaleLabelFontColor = helpers.valueOrDefault(scaleLabel.fontColor, globalDefaults.defaultFontColor);
                        var scaleLabelFont = parseFontOptions(scaleLabel);
-
                        var labelRotationRadians = helpers.toRadians(me.labelRotation);
-                       var cosRotation = Math.cos(labelRotationRadians);
-                       var longestRotatedLabel = me.longestLabelWidth * cosRotation;
-                       var tickCount = me._ticks.length;
 
                        var itemsToDraw = [];
 
-                       if (isHorizontal) {
-                               skipRatio = false;
-
-                               if ((longestRotatedLabel + optionTicks.autoSkipPadding) * tickCount > (me.width - (me.paddingLeft + me.paddingRight))) {
-                                       skipRatio = 1 + Math.floor(((longestRotatedLabel + optionTicks.autoSkipPadding) * tickCount) / (me.width - (me.paddingLeft + me.paddingRight)));
-                               }
-
-                               // if they defined a max number of optionTicks,
-                               // increase skipRatio until that number is met
-                               if (maxTicks && tickCount > maxTicks) {
-                                       while (!skipRatio || tickCount / (skipRatio || 1) > maxTicks) {
-                                               if (!skipRatio) {
-                                                       skipRatio = 1;
-                                               }
-                                               skipRatio += 1;
-                                       }
-                               }
-
-                               if (!useAutoskipper) {
-                                       skipRatio = false;
-                               }
-                       }
-
-
                        var xTickStart = options.position === 'right' ? me.left : me.right - tl;
                        var xTickEnd = options.position === 'right' ? me.left + tl : me.right;
                        var yTickStart = options.position === 'bottom' ? me.top : me.bottom - tl;
                        var yTickEnd = options.position === 'bottom' ? me.top + tl : me.bottom;
 
-                       helpers.each(me._ticks, function(tick, index) {
+                       helpers.each(ticks, function(tick, index) {
                                var label = tick.label;
-                               // If the callback returned a null or undefined value, do not draw this line
-                               if (helpers.isNullOrUndef(label)) {
-                                       return;
-                               }
-
-                               var isLastTick = tickCount === index + 1;
-
-                               // Since we always show the last tick,we need may need to hide the last shown one before
-                               var shouldSkip = (skipRatio > 1 && index % skipRatio > 0) || (index % skipRatio === 0 && index + skipRatio >= tickCount);
-                               if (shouldSkip && !isLastTick || helpers.isNullOrUndef(label)) {
-                                       return;
-                               }
-
                                var lineWidth, lineColor, borderDash, borderDashOffset;
                                if (index === (typeof me.zeroLineIndex !== 'undefined' ? me.zeroLineIndex : 0)) {
                                        // Draw the first index specially