new capture setup/teardown

examples/test-scatterplot.html

@@ -40,8 +40,8 @@
 
   function update() {
     scatterplot.update({
-      values: generateRandomData(1000, -10000, 10000),
-      categories: { name: 'Gender', 0: 'male', 2: 'female', 1: 'N/A'},
+      values: generateRandomData(2000, -10000, 10000),
+      categories: { name: 'Gender', 0: 'male', 1: 'female', 2: 'N/A'},
       title: 'Scatterplot',
       xAxisLabel: 'X Axis Values',
       yAxisLabel: 'Y Axis Values',

src/charts/Chart.js

@@ -22,8 +22,10 @@ export default class {
     this.render(args);
   }
 
-  prepareSVGForCapture() {
-    throw Error('prepareSVGForCapture() not implemented.');
+  captureSetup() {
+  }
+
+  captureTeardown() {
   }
 
   get containerWidth() {
@@ -35,6 +37,7 @@ export default class {
   }
 
   toPNG() {
+    this.captureSetup();
     html2canvas(this.container).then((canvas) => {
       const img = canvas.toDataURL('image/png');
       const a = document.createElement('a');
@@ -43,6 +46,7 @@ export default class {
       document.body.appendChild(a);
       a.click();
       document.body.removeChild(a);
+      this.captureTeardown();
     });
   }
 }

src/charts/impl/Heatmap.js

@@ -48,10 +48,6 @@ export default class extends Chart {
     return 'heatmap';
   }
 
-  prepareSVGForCapture() {
-    return this.svg;
-  }
-
   prepareValues({ values, rows, cols }) {
     this.data = [];
     rows.forEach((row, i) => {