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Improve label capacity calculation in time scale #6297

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Improve label capacity calculation in time scale #6297

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e9df23b
Improve label capacity calculation
nagix May 10, 2019
ea7b21b
Revert some changes for size reduction
nagix Jun 20, 2019
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83 changes: 53 additions & 30 deletions src/scales/scale.time.js
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Original file line number Diff line number Diff line change
Expand Up @@ -272,23 +272,50 @@ function determineStepSize(min, max, unit, capacity) {
return factor;
}

function determineMajorUnit(unit) {
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for (var i = UNITS.indexOf(unit) + 1, ilen = UNITS.length; i < ilen; ++i) {
if (INTERVALS[UNITS[i]].common) {
return UNITS[i];
}
}
}

/**
* Figures out what unit results in an appropriate number of auto-generated ticks
*/
function determineUnitForAutoTicks(minUnit, min, max, capacity) {
function determineUnitsForAutoTicks(scale, min, max) {
var timeOpts = scale.options.time;
var minor = timeOpts.unit;
var range = max - min;
var ilen = UNITS.length;
var i, interval, factor;

for (i = UNITS.indexOf(minUnit); i < ilen - 1; ++i) {
interval = INTERVALS[UNITS[i]];
factor = interval.steps ? interval.steps[interval.steps.length - 1] : MAX_INTEGER;

if (interval.common && Math.ceil((max - min) / (factor * interval.size)) <= capacity) {
return UNITS[i];
var i, major, interval, steps, factor, capacity;

if (minor) {
major = determineMajorUnit(minor);
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capacity = scale.getLabelCapacity(max, minor, major);
} else {
for (i = UNITS.indexOf(timeOpts.minUnit); i < ilen; ++i) {
minor = UNITS[i];
major = determineMajorUnit(minor);
interval = INTERVALS[minor];

if (interval.common) {
steps = interval.steps;
factor = steps ? steps[steps.length - 1] : MAX_INTEGER;
capacity = scale.getLabelCapacity(max, minor, major);

if (Math.ceil(range / (factor * interval.size)) <= capacity) {
break;
}
}
}
}

return UNITS[ilen - 1];
return {
minor: minor,
major: major,
capacity: capacity
};
}

/**
Expand All @@ -308,26 +335,19 @@ function determineUnitForFormatting(scale, ticks, minUnit, min, max) {
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) {
return UNITS[i];
}
}
}

/**
* Generates a maximum of `capacity` timestamps between min and max, rounded to the
* `minor` unit, aligned on the `major` unit and using the given scale time `options`.
* 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(scale, min, max, capacity) {
function generate(scale, min, max) {
var adapter = scale._adapter;
var options = scale.options;
var timeOpts = options.time;
var minor = timeOpts.unit || determineUnitForAutoTicks(timeOpts.minUnit, min, max, capacity);
var major = determineMajorUnit(minor);
var units = determineUnitsForAutoTicks(scale, min, max);
var minor = units.minor;
var major = units.major;
var stepSize = valueOrDefault(timeOpts.stepSize, timeOpts.unitStepSize);
var weekday = minor === 'week' ? timeOpts.isoWeekday : false;
var majorTicksEnabled = options.ticks.major.enabled;
Expand All @@ -338,7 +358,7 @@ function generate(scale, min, max, capacity) {
var time;

if (!stepSize) {
stepSize = determineStepSize(min, max, minor, capacity);
stepSize = determineStepSize(min, max, minor, units.capacity);
}

// For 'week' unit, handle the first day of week option
Expand Down Expand Up @@ -623,7 +643,7 @@ module.exports = Scale.extend({
break;
case 'auto':
default:
timestamps = generate(me, min, max, me.getLabelCapacity(min), options);
timestamps = generate(me, min, max);
}

if (options.bounds === 'ticks' && timestamps.length) {
Expand Down Expand Up @@ -800,21 +820,24 @@ module.exports = Scale.extend({
/**
* @private
*/
getLabelCapacity: function(exampleTime) {
getLabelCapacity: function(exampleTime, minor, major) {
var me = this;
var timeOpts = me.options.time;
var options = me.options;
var timeOpts = options.time;
var displayFormats = timeOpts.displayFormats;

// pick the longest format (milliseconds) for guestimation
var format = displayFormats[timeOpts.unit] || displayFormats.millisecond;
var exampleLabel = me.tickFormatFunction(exampleTime, 0, ticksFromTimestamps(me, [exampleTime], me._majorUnit), format);
var format = displayFormats[minor || timeOpts.unit] || displayFormats.millisecond;
var exampleLabel = me.tickFormatFunction(exampleTime, 0, [], format);
var size = me._getLabelSize(exampleLabel);
var capacity = Math.floor(me.isHorizontal() ? me.width / size.w : me.height / size.h);

if (me.options.offset) {
if (options.offset) {
capacity--;
}

if (major && options.ticks.major.enabled) {
capacity = Math.min(capacity, me.getLabelCapacity(exampleTime, major));
}

return capacity > 0 ? capacity : 1;
}
});
Expand Down
10 changes: 5 additions & 5 deletions test/specs/scale.time.tests.js
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Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ describe('Time scale tests', function() {
};

var scaleOptions = Chart.scaleService.getScaleDefaults('time');
var scale = createScale(mockData, scaleOptions, {width: 1000, height: 200});
var scale = createScale(mockData, scaleOptions, {width: 500, height: 200});
var ticks = getTicksLabels(scale);

// `bounds === 'data'`: first and last ticks removed since outside the data range
Expand All @@ -135,7 +135,7 @@ describe('Time scale tests', function() {
var mockData = {
labels: [newDateFromRef(0), newDateFromRef(1), newDateFromRef(2), newDateFromRef(4), newDateFromRef(6), newDateFromRef(7), newDateFromRef(9)], // days
};
var scale = createScale(mockData, Chart.scaleService.getScaleDefaults('time'), {width: 1000, height: 200});
var scale = createScale(mockData, Chart.scaleService.getScaleDefaults('time'), {width: 500, height: 200});
var ticks = getTicksLabels(scale);

// `bounds === 'data'`: first and last ticks removed since outside the data range
Expand Down Expand Up @@ -181,7 +181,7 @@ describe('Time scale tests', function() {
}],
}
}
}, {canvas: {width: 800, height: 200}});
}, {canvas: {width: 400, height: 200}});

var xScale = chart.scales.xScale0;
var ticks = getTicksLabels(xScale);
Expand Down Expand Up @@ -229,7 +229,7 @@ describe('Time scale tests', function() {
}],
}
}
}, {canvas: {width: 800, height: 200}});
}, {canvas: {width: 400, height: 200}});

var tScale = chart.scales.tScale0;
var ticks = getTicksLabels(tScale);
Expand Down Expand Up @@ -595,7 +595,7 @@ describe('Time scale tests', function() {
}],
}
}
}, {canvas: {width: 800, height: 200}});
}, {canvas: {width: 300, height: 200}});

this.scale = this.chart.scales.xScale0;
});
Expand Down