feat: optimize the maximum value logic and update the documentation

Author: lxfu1

__tests__/unit/scales/linear-breaks.spec.ts

@@ -60,10 +60,8 @@ describe('Linear Scale with Breaks', () => {
     });
 
     const { domain, range } = scale.getOptions();
-    expect(domain).toStrictEqual([0, 200, 300, 500, 600, 800, 980]);
-    expect(range).toStrictEqual([
-      0, 0.20408163265306123, 0.35816326530612247, 0.45816326530612245, 0.6892857142857143, 0.7392857142857143, 1,
-    ]);
+    expect(domain).toStrictEqual([0, 200, 300, 500, 600, 800, 1000]);
+    expect(range).toStrictEqual([0, 0.2, 0.35000000000000003, 0.45, 0.6749999999999999, 0.725, 1]);
   });
 
   test('single break: update', () => {
@@ -109,17 +107,18 @@ describe('Linear Scale with Breaks', () => {
     expect(scale2).toBeInstanceOf(Linear);
     expect(scale2.getOptions()).toEqual(scale.getOptions());
   });
-  test('breaks with nice', () => {
+  test.only('breaks with nice', () => {
     const scale = new Linear({
       domain: [0, 3106679],
       breaks: [{ start: 5000, end: 50000, gap: 0.03 }],
     });
 
     const { domain, range } = scale.getOptions();
-    expect(domain).toStrictEqual([0, 5000, 50000, 1000000, 1500000, 2000000, 2500000, 3000000, 3106679]);
+    expect(domain).toStrictEqual([0, 5000, 50000, 1000000, 1500000, 2000000, 2500000, 3000000, 3150000]);
+
     expect(range).toStrictEqual([
-      1, 0.8, 0.7700000000000001, 0.6781128658609403, 0.5171692987914104, 0.35622573172188055, 0.1952821646523506,
-      0.03433859758282076, 0,
+      1, 0.8, 0.7700000000000001, 0.6825396825396826, 0.5238095238095238, 0.3650793650793651, 0.2063492063492064,
+      0.04761904761904767, 0,
     ]);
     scale.update({
       domain: [0, 3106679],
@@ -145,9 +144,8 @@ describe('Linear Scale with Breaks', () => {
       ],
     });
     const scaleOptions2 = scale.getOptions();
-    expect(scaleOptions2.domain).toStrictEqual([0, 5000, 50000, 105000, 3100000, 3106679]);
-    expect(scaleOptions2.range).toStrictEqual([
-      1, 0.8, 0.7700000000000001, 0.49917586754215676, 0.46917586754215673, 0,
-    ]);
+    expect(scaleOptions2.domain).toStrictEqual([0, 5000, 50000, 105000, 3100000, 3108000]);
+
+    expect(scaleOptions2.range).toStrictEqual([1, 0.8, 0.7700000000000001, 0.4993951093951094, 0.46939510939510937, 0]);
   });
 });

docs/api/scales/linear.md

@@ -162,6 +162,45 @@ x2.getTicks(); // [0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5]
 x3.getTicks(); // [2, 4.5, 7, 9.5, 12, 14.5]
 ```
 
+- Breaks
+
+```ts
+import { Linear, LinearOptions } from '@antv/scale';
+
+const options1: LinearOptions = {
+  domain: [0, 3106679],
+  breaks: [{ start: 5000, end: 50000, gap: 0.03 }],
+};
+
+const x1 = new Linear(options1);
+
+x1.getTicks(); // [0, 5000, 50000, 1000000, 1500000, 2000000, 2500000, 3000000, 3150000]
+
+// with nice
+const options2: LinearOptions = {
+  domain: [0, 3106679],
+  nice: true,
+  breaks: [{ start: 5000, end: 50000, gap: 0.03 }],
+};
+
+const x2 = new Linear(options2);
+
+x2.getTicks(); // [0, 5000, 50000, 1000000, 1500000, 2000000, 2500000, 3000000, 3500000]
+
+// multi breaks
+const options3:LinearOptions = {
+  domain: [0, 200],
+  breaks: [
+    { start: 40, end: 100, gap: 0.1 },
+    { start: 120, end: 160, gap: 0.1 },
+  ]
+}
+
+const x3 = new Linear(options3);
+
+x3.getTicks(); // [0, 40, 100, 120, 160, 200]
+```
+
 ## Options
 
 | Key | Description | Type | Default|  
@@ -175,6 +214,15 @@ x3.getTicks(); // [2, 4.5, 7, 9.5, 12, 14.5]
 | clamp | Constrains the return value of map within the scale’s range if it is true. | `boolean` | `false` |
 | nice | Extends the domain so that it starts and ends on nice round values if it is true. | `boolean` | `false` |
 | interpolate | Sets the scale’s range interpolator factory if it is specified. | `(a: number, b: number) => (t: number) => T` | `(a, b) => (t) => a * (1 - t) + b * t` |
+| breaks | Set linear breaks display and style. | [breaks](#breaks) | - |
+
+### breaks
+
+| Key  | Description | Type  | Default Value |
+| ------- | ------- | ------- | ------- |
+| start | start value. | `number`  | -          |
+| end |end value. | `number`  | -          |
+| gap | Proportion of the broken (0 ~ 1). | `number`  | 0.03   |
 
 ## Methods
 

src/scales/linear.ts

@@ -4,6 +4,7 @@ import { LinearOptions, Transform } from '../types';
 import { Base } from './base';
 import { createInterpolateValue } from '../utils';
 import { d3Ticks } from '../tick-methods/d3-ticks';
+import { d3LinearNice } from '../utils/d3-linear-nice';
 
 /**
  * Linear 比例尺
@@ -68,11 +69,13 @@ export class Linear extends Continuous<LinearOptions> {
       niceDomainMax = niceDomain[niceDomain.length - 1];
     }
     const domainMin = Math.min(niceDomainMin, min);
-    const domainMax = Math.max(niceDomainMax, max);
+    let domainMax = Math.max(niceDomainMax, max);
     const sortedBreaks = breaks.filter(({ end }) => end < domainMax).sort((a, b) => a.start - b.start);
     const breaksDomain = d3Ticks(domainMin, domainMax, tickCount, sortedBreaks);
     if (last(breaksDomain) < domainMax) {
-      breaksDomain.push(domainMax);
+      const nicest = d3LinearNice(0, domainMax - last(breaksDomain), 3);
+      breaksDomain.push(last(breaksDomain) + last(nicest));
+      domainMax = last(breaksDomain);
     }
     const [r0, r1] = [range[0], last(range)] as number[];
     const diffDomain = domainMax - domainMin;