refactor: store coordinate state in options

Author: wwwaker

src/chart.ts

@@ -152,8 +152,6 @@ export class Chart extends EventEmitter.EventEmitter {
    */
   private linkedGraphs: Array<Chart>
   private line: Line<[number, number]>
-  // Keep the rendered mode separately because callers can mutate and reuse options.
-  private wasPolarCoordinateSystem = false
 
   /**
    * `svg` element that holds the graph (canvas + title + axes)
@@ -639,7 +637,7 @@ export class Chart extends EventEmitter.EventEmitter {
       })
     }
 
-    if (this.isPolarCoordinateSystem() || this.getEmitInstance().wasPolarCoordinateSystem) {
+    if (this.isPolarCoordinateSystem() || this.getEmitInstance().options.lastCoordinateSystem === 'polar') {
       // Rebase polar rebuilds and transitions out of the zero-margin polar canvas.
       // Undo the current transform so its next application reproduces the rebuilt domains,
       // preserving zoom and pan even when another Chart instance reuses the SVG.
@@ -684,7 +682,7 @@ export class Chart extends EventEmitter.EventEmitter {
       })
       .attr('width', this.meta.width)
       .attr('height', this.meta.height)
-    this.wasPolarCoordinateSystem = this.isPolarCoordinateSystem()
+    this.options.lastCoordinateSystem = this.options.coordinateSystem
   }
 
   setUpPlugins() {

src/types.ts

@@ -343,6 +343,12 @@ export interface FunctionPlotOptions {
    */
   id?: string
 
+  /**
+   * @private
+   * Last rendered coordinate system, preserved when callers mutate options.
+   */
+  lastCoordinateSystem?: 'cartesian' | 'polar'
+
   /**
    * A css selector or DOM node of the parent element that will contain the graph
    */

test/e2e/polar-grid.test.js

@@ -259,7 +259,18 @@ describe('Polar coordinate system', () => {
       const previous = await scaleState()
       await page.evaluate(
         (mode, reuseOptions) => {
-          const options = reuseOptions ? window.polarOptions : Object.assign({}, window.polarOptions, { id: undefined })
+          const previous = window.polarOptions
+          // New options omit internal metadata while reusing the previous SVG.
+          const options = reuseOptions
+            ? previous
+            : {
+                target: previous.target,
+                width: previous.width,
+                height: previous.height,
+                xAxis: previous.xAxis,
+                yAxis: previous.yAxis,
+                data: previous.data
+              }
           options.coordinateSystem = mode
           window.polarOptions = options
           window.polarChart = functionPlot(options)