feat(export_to_png): Add button on slice component for export D3 svg …

…to png file

superset/assets/javascripts/components/ExportSlice.js

@@ -0,0 +1,31 @@
+/* eslint camelcase: 0 */
+
+export function hasSvg(slice) {
+  return !['table', 'filter_box'].includes(slice.form_data.viz_type);
+}
+
+export function exportSlice(slice, format) {
+  if (format === 'png') {
+    const tmp = document.getElementById('con_' + slice.slice_id);
+    const svg = tmp.getElementsByTagName('svg')[0];
+    const svg_xml = (new XMLSerializer()).serializeToString(svg);
+    const data_uri = 'data:image/svg+xml;base64,' + window.btoa(svg_xml);
+
+    const image = new Image();
+    image.src = data_uri;
+    image.onload = function () {
+      const canvas = document.createElement('canvas');
+      canvas.width = image.width;
+      canvas.height = image.height;
+
+      const context = canvas.getContext('2d');
+      context.clearRect(0, 0, image.width, image.height);
+      context.drawImage(image, 0, 0);
+
+      const a = document.createElement('a');
+      a.download = slice.slice_name;
+      a.href = canvas.toDataURL('image/png');
+      a.click();
+    };
+  }
+}

superset/assets/javascripts/dashboard/components/SliceCell.jsx

@@ -4,6 +4,8 @@ import PropTypes from 'prop-types';
 
 import { getExploreUrl } from '../../explore/exploreUtils';
 
+import { exportSlice, hasSvg } from '../../components/ExportSlice';
+
 const propTypes = {
   slice: PropTypes.object.isRequired,
   removeSlice: PropTypes.func.isRequired,
@@ -50,6 +52,15 @@ function SliceCell({ expandedSlices, removeSlice, slice }) {
               >
                 <i className="fa fa-table" />
               </a>
+              <a
+                className="exportPNG"
+                onClick={() => { exportSlice(slice, 'png'); }}
+                title="Export PNG"
+                data-toggle="tooltip"
+                style={{ display: hasSvg(slice) ? 'inline' : 'none' }}
+              >
+                <i className="fa fa-download" />
+              </a>
               <a
                 className="exploreChart"
                 href={getExploreUrl(slice.form_data)}
@@ -76,7 +87,7 @@ function SliceCell({ expandedSlices, removeSlice, slice }) {
         className="slice_description bs-callout bs-callout-default"
         style={
           expandedSlices &&
-          expandedSlices[String(slice.slice_id)] ? {} : { display: 'none' }
+            expandedSlices[String(slice.slice_id)] ? {} : { display: 'none' }
         }
         dangerouslySetInnerHTML={{ __html: slice.description_markeddown }}
       />