Fix choosing of formatting unit (#4779)

* Don't change minorFormat when determining label capacity

* Fix choosing of formatting unit

diff --git a/src/scales/scale.time.js b/src/scales/scale.time.js
index a87920c6781da99afa5a8a425b1185b0e96b6544..27a340a3b1f02b5b2d9176af8022d0c103acdb54 100644 (file)
--- a/src/scales/scale.time.js
+++ b/src/scales/scale.time.js
@@ -253,7 +253,10 @@ function determineStepSize(min, max, unit, capacity) {
        return factor;
 }
 
-function determineUnit(minUnit, min, max, capacity) {
+/**
+ * Figures out what unit results in an appropriate number of auto-generated ticks
+ */
+function determineUnitForAutoTicks(minUnit, min, max, capacity) {
        var ilen = UNITS.length;
        var i, interval, factor;
 
@@ -269,6 +272,24 @@ function determineUnit(minUnit, min, max, capacity) {
        return UNITS[ilen - 1];
 }
 
+/**
+ * Figures out what unit to format a set of ticks with
+ */
+function determineUnitForFormatting(ticks, minUnit, min, max) {
+       var duration = moment.duration(moment(max).diff(moment(min)));
+       var ilen = UNITS.length;
+       var i, unit;
+
+       for (i = ilen - 1; i >= UNITS.indexOf(minUnit); i--) {
+               unit = UNITS[i];
+               if (INTERVALS[unit].common && duration.as(unit) >= ticks.length) {
+                       return unit;
+               }
+       }
+
+       return UNITS[minUnit ? UNITS.indexOf(minUnit) : 0];
+}
+
 function determineMajorUnit(unit) {
        for (var i = UNITS.indexOf(unit) + 1, ilen = UNITS.length; i < ilen; ++i) {
                if (INTERVALS[UNITS[i]].common) {
@@ -283,8 +304,10 @@ function determineMajorUnit(unit) {
  * Important: this method can return ticks outside the min and max range, it's the
  * responsibility of the calling code to clamp values if needed.
  */
-function generate(min, max, minor, major, capacity, options) {
+function generate(min, max, capacity, options) {
        var timeOpts = options.time;
+       var minor = timeOpts.unit || determineUnitForAutoTicks(timeOpts.minUnit, min, max, capacity);
+       var major = determineMajorUnit(minor);
        var stepSize = helpers.valueOrDefault(timeOpts.stepSize, timeOpts.unitStepSize);
        var weekday = minor === 'week' ? timeOpts.isoWeekday : false;
        var majorTicksEnabled = options.ticks.major.enabled;
@@ -553,10 +576,6 @@ module.exports = function(Chart) {
                        var max = me.max;
                        var options = me.options;
                        var timeOpts = options.time;
-                       var formats = timeOpts.displayFormats;
-                       var capacity = me.getLabelCapacity(min);
-                       var unit = timeOpts.unit || determineUnit(timeOpts.minUnit, min, max, capacity);
-                       var majorUnit = determineMajorUnit(unit);
                        var timestamps = [];
                        var ticks = [];
                        var i, ilen, timestamp;
@@ -570,7 +589,7 @@ module.exports = function(Chart) {
                                break;
                        case 'auto':
                        default:
-                               timestamps = generate(min, max, unit, majorUnit, capacity, options);
+                               timestamps = generate(min, max, me.getLabelCapacity(min), options);
                        }
 
                        if (options.bounds === 'ticks' && timestamps.length) {
@@ -594,14 +613,12 @@ module.exports = function(Chart) {
                        me.max = max;
 
                        // PRIVATE
-                       me._unit = unit;
-                       me._majorUnit = majorUnit;
-                       me._minorFormat = formats[unit];
-                       me._majorFormat = formats[majorUnit];
+                       me._unit = timeOpts.unit || determineUnitForFormatting(ticks, timeOpts.minUnit, me.min, me.max);
+                       me._majorUnit = determineMajorUnit(me._unit);
                        me._table = buildLookupTable(me._timestamps.data, min, max, options.distribution);
                        me._offsets = computeOffsets(me._table, ticks, min, max, options);
 
-                       return ticksFromTimestamps(ticks, majorUnit);
+                       return ticksFromTimestamps(ticks, me._majorUnit);
                },
 
                getLabelForIndex: function(index, datasetIndex) {
@@ -625,16 +642,18 @@ module.exports = function(Chart) {
                 * Function to format an individual tick mark
                 * @private
                 */
-               tickFormatFunction: function(tick, index, ticks) {
+               tickFormatFunction: function(tick, index, ticks, formatOverride) {
                        var me = this;
                        var options = me.options;
                        var time = tick.valueOf();
+                       var formats = options.time.displayFormats;
+                       var minorFormat = formats[me._unit];
                        var majorUnit = me._majorUnit;
-                       var majorFormat = me._majorFormat;
-                       var majorTime = tick.clone().startOf(me._majorUnit).valueOf();
+                       var majorFormat = formats[majorUnit];
+                       var majorTime = tick.clone().startOf(majorUnit).valueOf();
                        var majorTickOpts = options.ticks.major;
                        var major = majorTickOpts.enabled && majorUnit && majorFormat && time === majorTime;
-                       var label = tick.format(major ? majorFormat : me._minorFormat);
+                       var label = tick.format(formatOverride ? formatOverride : major ? majorFormat : minorFormat);
                        var tickOpts = major ? majorTickOpts : options.ticks.minor;
                        var formatter = helpers.valueOrDefault(tickOpts.callback, tickOpts.userCallback);
 
@@ -720,9 +739,9 @@ module.exports = function(Chart) {
                getLabelCapacity: function(exampleTime) {
                        var me = this;
 
-                       me._minorFormat = me.options.time.displayFormats.millisecond;   // Pick the longest format for guestimation
+                       var formatOverride = me.options.time.displayFormats.millisecond;        // Pick the longest format for guestimation
 
-                       var exampleLabel = me.tickFormatFunction(moment(exampleTime), 0, []);
+                       var exampleLabel = me.tickFormatFunction(moment(exampleTime), 0, [], formatOverride);
                        var tickLabelWidth = me.getLabelWidth(exampleLabel);
                        var innerWidth = me.isHorizontal() ? me.width : me.height;