Enable suggestedMin and suggestedMax setts for logarithmic axes (#7955)

Author: etimberg

docs/docs/axes/cartesian/logarithmic.md

@@ -4,6 +4,15 @@ title: Logarithmic Axis
 
 The logarithmic scale is used to chart numerical data. It can be placed on either the x or y-axis. As the name suggests, logarithmic interpolation is used to determine where a value lies on the axis.
 
+## Configuration Options
+
+These options extend the [common configuration for all cartesian axes](index.md#configuration-options).
+
+| Name | Type | Description
+| ---- | ---- | -----------
+| `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)
+
 ## Tick Configuration Options
 
 The following options are provided by the logarithmic scale. They are all located in the `ticks` sub-options. These options extend the [common tick configuration](index.md#tick-configuration).

src/scales/scale.logarithmic.js

@@ -1,4 +1,4 @@
-import {isFinite} from '../helpers/helpers.core';
+import {isFinite, isNullOrUndef} from '../helpers/helpers.core';
 import {_setMinAndMaxByKey, log10} from '../helpers/helpers.math';
 import Scale from '../core/core.scale';
 import LinearScaleBase from './scale.linearbase';
@@ -86,11 +86,19 @@ export default class LogarithmicScale extends Scale {
 
 	handleTickRangeOptions() {
 		const me = this;
+		const {suggestedMax, suggestedMin} = me.options;
 		const DEFAULT_MIN = 1;
 		const DEFAULT_MAX = 10;
 		let min = me.min;
 		let max = me.max;
 
+		if (!isNullOrUndef(suggestedMin)) {
+			min = Math.min(min, suggestedMin);
+		}
+		if (!isNullOrUndef(suggestedMax)) {
+			max = Math.max(max, suggestedMax);
+		}
+
 		if (min === max) {
 			if (min <= 0) { // includes null
 				min = DEFAULT_MIN;

test/specs/scale.logarithmic.tests.js

@@ -1118,4 +1118,29 @@ describe('Logarithmic Scale tests', function() {
 		});
 	});
 
+	it('Should correctly determine the max & min when no values provided and suggested minimum and maximum are set', function() {
+		var chart = window.acquireChart({
+			type: 'bar',
+			data: {
+				datasets: [{
+					yAxisID: 'y',
+					data: []
+				}],
+				labels: ['a', 'b', 'c', 'd', 'e', 'f']
+			},
+			options: {
+				scales: {
+					y: {
+						type: 'logarithmic',
+						suggestedMin: 10,
+						suggestedMax: 100
+					}
+				}
+			}
+		});
+
+		expect(chart.scales.y).not.toEqual(undefined); // must construct
+		expect(chart.scales.y.min).toBe(10);
+		expect(chart.scales.y.max).toBe(100);
+	});
 });

types/scales/index.d.ts

@@ -245,6 +245,17 @@ export const LinearScale: IChartComponent & {
 export type ILogarithmicScaleOptions = ICartesianScaleOptions & {
   stacked?: boolean;
 
+  /**
+   * Adjustment used when calculating the maximum data value.
+   * @see https://www.chartjs.org/docs/next/axes/cartesian/linear#axis-range-settings
+   */
+  suggestedMin?: number;
+  /**
+   * Adjustment used when calculating the minimum data value.
+   * @see https://www.chartjs.org/docs/next/axes/cartesian/linear#axis-range-settings
+   */
+  suggestedMax?: number;
+
   ticks: {
     /**
      * The Intl.NumberFormat options used by the default label formatter