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Inverted time scale functionality added - Issue #3279 #5731

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Inverted time scale functionality added - Issue #3279 #5731

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100 changes: 91 additions & 9 deletions src/scales/scale.time.js
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,46 @@ function buildLookupTable(timestamps, min, max, distribution) {
return table;
}

/**
* Has the same functionatilites as `buildLookupTable` but this functions
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functionatilites -> functionalities

* builds an inverted table for the time scale
*/
function buildLookupTableReverse(timestamps, min, max, distribution) {

if (distribution === 'linear' || !timestamps.length) {
return [
{time: max, pos: 0},
{time: min, pos: 1}
];
}

var table = [];
var items = [max];
var i, ilen, prev, curr, next;

for (i = 0, ilen = timestamps.length; i < ilen; ++i) {
curr = timestamps[i];
if (curr > min && curr < max) {
items.push(curr);
}
}

items.push(min);

for (i = 0, ilen = items.length; i < ilen; ++i) {
next = items[i + 1];
prev = items[i - 1];
curr = items[i];

// only add points that breaks the scale linearity
if (prev === undefined || next === undefined || Math.round((next + prev) / 2) !== curr) {
table.push({time: curr, pos: i / (ilen - 1)});
}
}

return table;
}

// @see adapted from http://www.anujgakhar.com/2014/03/01/binary-search-in-javascript/
function lookup(table, key, value) {
var lo = 0;
Expand Down Expand Up @@ -159,14 +199,48 @@ function lookup(table, key, value) {
return {lo: i1, hi: null};
}

/**
* @see adapted from http://www.anujgakhar.com/2014/03/01/binary-search-in-javascript/
* This binary search is altered to do a reverse lookup
*/
function lookupReverse(table, key, value) {
var lo = table.length - 1;
var hi = 0;
var mid, i0, i1;

while (hi >= 0 && hi <= lo) {
mid = (lo + hi) >> 1;
i0 = table[mid];
i1 = table[mid - 1] || null;
if (!i1) {
// given value is outside table (before first item)
return {lo: null, hi: i0};
} else if (i1[key] < value) {
lo = mid - 1;
} else if (i0[key] > value) {
hi = mid + 1;
} else {
return {lo: i0, hi: i1};
}
}

// given value is outside table (after last item)
return {lo: i0, hi: null};
}

/**
* Linearly interpolates the given source `value` using the table items `skey` values and
* returns the associated `tkey` value. For example, interpolate(table, 'time', 42, 'pos')
* returns the position for a timestamp equal to 42. If value is out of bounds, values at
* index [0, 1] or [n - 1, n] are used for the interpolation.
*/
function interpolate(table, skey, sval, tkey) {
var range = lookup(table, skey, sval);
function interpolate(table, skey, sval, tkey, isReverse) {
var range = '';
if (isReverse) {
range = lookupReverse(table, skey, sval);
} else {
range = lookup(table, skey, sval);
}

// Note: the lookup table ALWAYS contains at least 2 items (min and max)
var prev = !range.lo ? table[0] : !range.hi ? table[table.length - 2] : range.lo;
Expand Down Expand Up @@ -365,22 +439,23 @@ function computeOffsets(table, ticks, min, max, options) {
var left = 0;
var right = 0;
var upper, lower;
var isReverse = options.ticks.reverse;

if (options.offset && ticks.length) {
if (!options.time.min) {
upper = ticks.length > 1 ? ticks[1] : max;
lower = ticks[0];
left = (
interpolate(table, 'time', upper, 'pos') -
interpolate(table, 'time', lower, 'pos')
interpolate(table, 'time', upper, 'pos', isReverse) -
interpolate(table, 'time', lower, 'pos', isReverse)
) / 2;
}
if (!options.time.max) {
upper = ticks[ticks.length - 1];
lower = ticks.length > 1 ? ticks[ticks.length - 2] : min;
right = (
interpolate(table, 'time', upper, 'pos') -
interpolate(table, 'time', lower, 'pos')
interpolate(table, 'time', upper, 'pos', isReverse) -
interpolate(table, 'time', lower, 'pos', isReverse)
) / 2;
}
}
Expand Down Expand Up @@ -602,6 +677,7 @@ module.exports = function() {
var min = me.min;
var max = me.max;
var options = me.options;
var isReverse = me.options.ticks.reverse;
var timeOpts = options.time;
var timestamps = [];
var ticks = [];
Expand Down Expand Up @@ -642,7 +718,11 @@ module.exports = function() {
// PRIVATE
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);
if (isReverse) {
me._table = buildLookupTableReverse(me._timestamps.data.reverse(), min, max, options.distribution);
} else {
me._table = buildLookupTable(me._timestamps.data, min, max, options.distribution);
}
me._offsets = computeOffsets(me._table, ticks, min, max, options);
me._labelFormat = determineLabelFormat(me._timestamps.data, timeOpts);

Expand Down Expand Up @@ -707,9 +787,10 @@ module.exports = function() {
*/
getPixelForOffset: function(time) {
var me = this;
var isReverse = me.options.ticks.reverse;
var size = me._horizontal ? me.width : me.height;
var start = me._horizontal ? me.left : me.top;
var pos = interpolate(me._table, 'time', time, 'pos');
var pos = interpolate(me._table, 'time', time, 'pos', isReverse);

return start + size * (me._offsets.left + pos) / (me._offsets.left + 1 + me._offsets.right);
},
Expand Down Expand Up @@ -740,10 +821,11 @@ module.exports = function() {

getValueForPixel: function(pixel) {
var me = this;
var isReverse = me.options.ticks.reverse;
var size = me._horizontal ? me.width : me.height;
var start = me._horizontal ? me.left : me.top;
var pos = (size ? (pixel - start) / size : 0) * (me._offsets.left + 1 + me._offsets.left) - me._offsets.right;
var time = interpolate(me._table, 'pos', pos, 'time');
var time = interpolate(me._table, 'pos', pos, 'time', isReverse);

return moment(time);
},
Expand Down
187 changes: 187 additions & 0 deletions test/specs/scale.time.tests.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1317,4 +1317,191 @@ describe('Time scale tests', function() {
});
});
});

describe('when ticks.reverse', function() {
describe('is "true"', function() {
it ('should reverse the labels', function() {
this.chart = window.acquireChart({
type: 'line',
data: {
labels: ['2017', '2019', '2020', '2025', '2042'],
datasets: [{data: [0, 1, 2, 3, 4, 5]}]
},
options: {
scales: {
xAxes: [{
id: 'x',
type: 'time',
time: {
parser: 'YYYY',
},
ticks: {
source: 'labels',
reverse: true
}
}],
yAxes: [{
display: false
}]
}
}
});
var scale = this.chart.scales.x;
expect(scale.getPixelForValue('2017')).toBeCloseToPixel(scale.left + scale.width);
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(scale.left);
});
});
});

describe('when ticks.reverse is "true" and distribution', function() {
describe('is "series"', function() {
beforeEach(function() {
this.chart = window.acquireChart({
type: 'line',
data: {
labels: ['2017', '2019', '2020', '2025', '2042'],
datasets: [{data: [0, 1, 2, 3, 4, 5]}]
},
options: {
scales: {
xAxes: [{
id: 'x',
type: 'time',
time: {
parser: 'YYYY'
},
distribution: 'series',
ticks: {
source: 'labels',
reverse: true
}
}],
yAxes: [{
display: false
}]
}
}
});
});

it ('should reverse the labels and space data out with the same gap, whatever their time values', function() {
var scale = this.chart.scales.x;
var start = scale.left;
var slice = scale.width / 4;

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * 4);
expect(scale.getPixelForValue('2019')).toBeCloseToPixel(start + slice * 3);
expect(scale.getPixelForValue('2020')).toBeCloseToPixel(start + slice * 2);
expect(scale.getPixelForValue('2025')).toBeCloseToPixel(start + slice);
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start);
});

it ('should reverse the labels and should add a step before if scale.min is before the first data', function() {
var chart = this.chart;
var scale = chart.scales.x;
var options = chart.options.scales.xAxes[0];

options.time.min = '2012';
chart.update();

var start = scale.left;
var slice = scale.width / 5;

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * 4);
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start);
});

it ('should reverse the labels and should add a step after if scale.max is after the last data', function() {
var chart = this.chart;
var scale = chart.scales.x;
var options = chart.options.scales.xAxes[0];

options.time.max = '2050';
chart.update();

var start = scale.left;
var slice = scale.width / 5;

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * 5);
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start + slice);
});

it ('should reverse the labels and should add steps before and after if scale.min/max are outside the data range', function() {
var chart = this.chart;
var scale = chart.scales.x;
var options = chart.options.scales.xAxes[0];

options.time.min = '2012';
options.time.max = '2050';
chart.update();

var start = scale.left;
var slice = scale.width / 6;

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * 5);
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start + slice);
});
});
describe('is "linear"', function() {
beforeEach(function() {
this.chart = window.acquireChart({
type: 'line',
data: {
labels: ['2017', '2019', '2020', '2025', '2042'],
datasets: [{data: [0, 1, 2, 3, 4, 5]}]
},
options: {
scales: {
xAxes: [{
id: 'x',
type: 'time',
time: {
parser: 'YYYY'
},
distribution: 'linear',
ticks: {
source: 'labels',
reverse: true
}
}],
yAxes: [{
display: false
}]
}
}
});
});

it ('should reverse the labels and should space data out with a gap relative to their time values', function() {
var scale = this.chart.scales.x;
var start = scale.left;
var slice = scale.width / (2042 - 2017);

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * (2042 - 2017));
expect(scale.getPixelForValue('2019')).toBeCloseToPixel(start + slice * (2042 - 2019));
expect(scale.getPixelForValue('2020')).toBeCloseToPixel(start + slice * (2042 - 2020));
expect(scale.getPixelForValue('2025')).toBeCloseToPixel(start + slice * (2042 - 2025));
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start);
});

it ('should reverse the labels and should take in account scale min and max if outside the ticks range', function() {
var chart = this.chart;
var scale = chart.scales.x;
var options = chart.options.scales.xAxes[0];

options.time.min = '2012';
options.time.max = '2050';
chart.update();

var start = scale.left;
var slice = scale.width / (2050 - 2012);

expect(scale.getPixelForValue('2017')).toBeCloseToPixel(start + slice * (2050 - 2017));
expect(scale.getPixelForValue('2019')).toBeCloseToPixel(start + slice * (2050 - 2019));
expect(scale.getPixelForValue('2020')).toBeCloseToPixel(start + slice * (2050 - 2020));
expect(scale.getPixelForValue('2025')).toBeCloseToPixel(start + slice * (2050 - 2025));
expect(scale.getPixelForValue('2042')).toBeCloseToPixel(start + slice * (2050 - 2042));
});
});
});
});