Add `ticks.precision` option to linear scale. (#4841)

If defined and `stepSize` is not specified, the step size will be rounded to this many decimal places.

diff --git a/docs/axes/cartesian/linear.md b/docs/axes/cartesian/linear.md
index 1d0292074a808926ebdd44dfd938dbef4dfb5154..3f68b79ff1daa0b21edbe15f469721c5e16e02ed 100644 (file)
--- a/docs/axes/cartesian/linear.md
+++ b/docs/axes/cartesian/linear.md
@@ -12,6 +12,7 @@ The following options are provided by the linear scale. They are all located in
 | `min` | `Number` | | User defined minimum number for the scale, overrides minimum value from data. [more...](#axis-range-settings)
 | `max` | `Number` | | User defined maximum number for the scale, overrides maximum value from data. [more...](#axis-range-settings)
 | `maxTicksLimit` | `Number` | `11` | Maximum number of ticks and gridlines to show.
+| `precision` | `Number` | | if defined and `stepSize` is not specified, the step size will be rounded to this many decimal places.
 | `stepSize` | `Number` | | User defined fixed step size for the scale. [more...](#step-size)
 | `suggestedMax` | `Number` | | Adjustment used when calculating the maximum data value. [more...](#axis-range-settings)
 | `suggestedMin` | `Number` | | Adjustment used when calculating the minimum data value. [more...](#axis-range-settings)

diff --git a/docs/axes/radial/linear.md b/docs/axes/radial/linear.md
index 14009be6a5c44ea6d354f38b95ffa47afd0d2580..594901db3350cdb1b4977157db279670dba70c4f 100644 (file)
--- a/docs/axes/radial/linear.md
+++ b/docs/axes/radial/linear.md
@@ -27,6 +27,7 @@ The following options are provided by the linear scale. They are all located in
 | `min` | `Number` | | User defined minimum number for the scale, overrides minimum value from data. [more...](#axis-range-settings)
 | `max` | `Number` | | User defined maximum number for the scale, overrides maximum value from data. [more...](#axis-range-settings)
 | `maxTicksLimit` | `Number` | `11` | Maximum number of ticks and gridlines to show.
+| `precision` | `Number` | | if defined and `stepSize` is not specified, the step size will be rounded to this many decimal places.
 | `stepSize` | `Number` | | User defined fixed step size for the scale. [more...](#step-size)
 | `suggestedMax` | `Number` | | Adjustment used when calculating the maximum data value. [more...](#axis-range-settings)
 | `suggestedMin` | `Number` | | Adjustment used when calculating the minimum data value. [more...](#axis-range-settings)

diff --git a/src/scales/scale.linearbase.js b/src/scales/scale.linearbase.js
index 3e4b5c083f3e187a35e7250f87f871624e4f75b5..5ac01b92a4f19ccdba1702fa1d0931d845e3db08 100644 (file)
--- a/src/scales/scale.linearbase.js
+++ b/src/scales/scale.linearbase.js
@@ -14,12 +14,22 @@ function generateTicks(generationOptions, dataRange) {
        // "nice number" algorithm. See http://stackoverflow.com/questions/8506881/nice-label-algorithm-for-charts-with-minimum-ticks
        // for details.
 
+       var factor;
+       var precision;
        var spacing;
+
        if (generationOptions.stepSize && generationOptions.stepSize > 0) {
                spacing = generationOptions.stepSize;
        } else {
                var niceRange = helpers.niceNum(dataRange.max - dataRange.min, false);
                spacing = helpers.niceNum(niceRange / (generationOptions.maxTicks - 1), true);
+
+               precision = generationOptions.precision;
+               if (precision !== undefined) {
+                       // If the user specified a precision, round to that number of decimal places
+                       factor = Math.pow(10, precision);
+                       spacing = Math.ceil(spacing * factor) / factor;
+               }
        }
        var niceMin = Math.floor(dataRange.min / spacing) * spacing;
        var niceMax = Math.ceil(dataRange.max / spacing) * spacing;
@@ -41,7 +51,7 @@ function generateTicks(generationOptions, dataRange) {
                numSpaces = Math.ceil(numSpaces);
        }
 
-       var precision = 1;
+       precision = 1;
        if (spacing < 1) {
                precision = Math.pow(10, spacing.toString().length - 2);
                niceMin = Math.round(niceMin * precision) / precision;
@@ -154,6 +164,7 @@ module.exports = function(Chart) {
                                maxTicks: maxTicks,
                                min: tickOpts.min,
                                max: tickOpts.max,
+                               precision: tickOpts.precision,
                                stepSize: helpers.valueOrDefault(tickOpts.fixedStepSize, tickOpts.stepSize)
                        };
                        var ticks = me.ticks = generateTicks(numericGeneratorOptions, me);

diff --git a/test/specs/scale.linear.tests.js b/test/specs/scale.linear.tests.js
index 60dd07698c0d0ec68f4bed5b6f765f43ddaf2f97..b42675d8a8d612e85a8b363991f5ddd1e855cafa 100644 (file)
--- a/test/specs/scale.linear.tests.js
+++ b/test/specs/scale.linear.tests.js
@@ -548,6 +548,66 @@ describe('Linear Scale', function() {
                expect(chart.scales.yScale0.ticks).toEqual(['11', '9', '7', '5', '3', '1']);
        });
 
+       describe('precision', function() {
+               it('Should create integer steps if precision is 0', function() {
+                       var chart = window.acquireChart({
+                               type: 'bar',
+                               data: {
+                                       datasets: [{
+                                               yAxisID: 'yScale0',
+                                               data: [0, 1, 2, 1, 0, 1]
+                                       }],
+                                       labels: ['a', 'b', 'c', 'd', 'e', 'f']
+                               },
+                               options: {
+                                       scales: {
+                                               yAxes: [{
+                                                       id: 'yScale0',
+                                                       type: 'linear',
+                                                       ticks: {
+                                                               precision: 0
+                                                       }
+                                               }]
+                                       }
+                               }
+                       });
+
+                       expect(chart.scales.yScale0).not.toEqual(undefined); // must construct
+                       expect(chart.scales.yScale0.min).toBe(0);
+                       expect(chart.scales.yScale0.max).toBe(2);
+                       expect(chart.scales.yScale0.ticks).toEqual(['2', '1', '0']);
+               });
+
+               it('Should round the step size to the given number of decimal places', function() {
+                       var chart = window.acquireChart({
+                               type: 'bar',
+                               data: {
+                                       datasets: [{
+                                               yAxisID: 'yScale0',
+                                               data: [0, 0.001, 0.002, 0.003, 0, 0.001]
+                                       }],
+                                       labels: ['a', 'b', 'c', 'd', 'e', 'f']
+                               },
+                               options: {
+                                       scales: {
+                                               yAxes: [{
+                                                       id: 'yScale0',
+                                                       type: 'linear',
+                                                       ticks: {
+                                                               precision: 2
+                                                       }
+                                               }]
+                                       }
+                               }
+                       });
+
+                       expect(chart.scales.yScale0).not.toEqual(undefined); // must construct
+                       expect(chart.scales.yScale0.min).toBe(0);
+                       expect(chart.scales.yScale0.max).toBe(0.01);
+                       expect(chart.scales.yScale0.ticks).toEqual(['0.01', '0']);
+               });
+       });
+
 
        it('should forcibly include 0 in the range if the beginAtZero option is used', function() {
                var chart = window.acquireChart({