feat(axis): support dataMin and dataMax option for calculating a nice axis extent

src/coord/axisCommonTypes.ts

@@ -163,6 +163,20 @@ export interface NumericAxisBaseOptionCommon extends AxisBaseOptionCommon {
      * Will be ignored if interval is set.
      */
     alignTicks?: boolean
+
+    /**
+     * Data min value to be included in axis extent calculation.
+     * The final min value will be the minimum of this value and the data min.
+     * Only works for value axis.
+     */
+    dataMin?: ScaleDataValue;
+
+    /**
+     * Data max value to be included in axis extent calculation.
+     * The final max value will be the maximum of this value and the data max.
+     * Only works for value axis.
+     */
+    dataMax?: ScaleDataValue;
 }
 
 export interface CategoryAxisBaseOption extends AxisBaseOptionCommon {

src/coord/scaleRawExtentInfo.ts

@@ -21,7 +21,7 @@ import { assert, isArray, eqNaN, isFunction } from 'zrender/src/core/util';
 import Scale from '../scale/Scale';
 import { AxisBaseModel } from './AxisBaseModel';
 import { parsePercent } from 'zrender/src/contain/text';
-import { AxisBaseOption, CategoryAxisBaseOption } from './axisCommonTypes';
+import { AxisBaseOption, CategoryAxisBaseOption, NumericAxisBaseOptionCommon } from './axisCommonTypes';
 import { ScaleDataValue } from '../util/types';
 
 
@@ -69,6 +69,9 @@ export class ScaleRawExtentInfo {
     // Make that the `rawExtentInfo` can not be modified any more.
     readonly frozen: boolean;
 
+    // custom dataMin/dataMax
+    private _dataMinNum: number;
+    private _dataMaxNum: number;
 
     constructor(
         scale: Scale,
@@ -98,6 +101,19 @@ export class ScaleRawExtentInfo {
         const isOrdinal = this._isOrdinal = scale.type === 'ordinal';
         this._needCrossZero = scale.type === 'interval' && model.getNeedCrossZero && model.getNeedCrossZero();
 
+        if (scale.type === 'interval' || scale.type === 'log' || scale.type === 'time') {
+            // Process custom dataMin/dataMax
+            const dataMinRaw = (model as AxisBaseModel<NumericAxisBaseOptionCommon>).get('dataMin', true);
+            if (dataMinRaw != null) {
+                this._dataMinNum = parseAxisModelMinMax(scale, dataMinRaw);
+            }
+
+            const dataMaxRaw = (model as AxisBaseModel<NumericAxisBaseOptionCommon>).get('dataMax', true);
+            if (dataMaxRaw != null) {
+                this._dataMaxNum = parseAxisModelMinMax(scale, dataMaxRaw);
+            }
+        }
+
         let axisMinValue = model.get('min', true);
         if (axisMinValue == null) {
             axisMinValue = model.get('startValue', true);
@@ -173,8 +189,20 @@ export class ScaleRawExtentInfo {
         // (3) If no data, it should be ensured that `scale.setBlank` is set.
 
         const isOrdinal = this._isOrdinal;
-        const dataMin = this._dataMin;
-        const dataMax = this._dataMax;
+        let dataMin = this._dataMin;
+        let dataMax = this._dataMax;
+
+        // Include custom dataMin/dataMax in calculation
+        // If dataMin is set and less than current data minimum, update the minimum value
+        if (this._dataMinNum != null && isFinite(dataMin) && this._dataMinNum < dataMin) {
+            dataMin = this._dataMinNum;
+        }
+
+        // If dataMax is set and greater than current data maximum, update the maximum value
+        if (this._dataMaxNum != null && isFinite(dataMax) && this._dataMaxNum > dataMax) {
+            dataMax = this._dataMaxNum;
+        }
+
         const axisDataLen = this._axisDataLen;
         const boundaryGapInner = this._boundaryGapInner;