wisemapping-frontend/packages/mindplot/src/components/export/SVGExporter.ts

/*
 *    Copyright [2021] [wisemapping]
 *
 *   Licensed under WiseMapping Public License, Version 1.0 (the "License").
 *   It is basically the Apache License, Version 2.0 (the "License") plus the
 *   "powered by wisemapping" text requirement on every single page;
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the license at
 *
 *       http://www.wisemapping.org/license
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */
import Exporter from './Exporter';

class SVGExporter extends Exporter {
  private svgElement: Element;

  private prolog = '<?xml version="1.0" encoding="utf-8" standalone="yes"?>\n';

  constructor(svgElement: Element) {
    super('svg', 'image/svg+xml');
    this.svgElement = svgElement;
  }

  export(): Promise<string> {
    // Replace all images for in-line images ...
    let svgTxt: string = new XMLSerializer()
      .serializeToString(this.svgElement);
    svgTxt = this.prolog + svgTxt;

    // Are namespace declared ?. Otherwise, force the declaration ...
    if (svgTxt.indexOf('xmlns:xlink=') === -1) {
      svgTxt = svgTxt.replace('<svg ', '<svg xmlns:xlink="http://www.w3.org/1999/xlink" ');
    }

    // Add white background. This is mainly for PNG export ...
    const svgDoc = SVGExporter.parseXMLString(svgTxt, 'application/xml');
    const svgElement = svgDoc.getElementsByTagName('svg')[0];
    svgElement.setAttribute('style', 'background-color:white');

    const result = new XMLSerializer()
      .serializeToString(svgDoc);
    return Promise.resolve(result);
  }

  private static parseXMLString = (xmlStr: string, mimeType: DOMParserSupportedType) => {
    const parser = new DOMParser();
    const xmlDoc = parser.parseFromString(xmlStr, mimeType);

    // Is there any parsing error ?.
    if (xmlDoc.getElementsByTagName('parsererror').length > 0) {
      const xmmStr = new XMLSerializer().serializeToString(xmlDoc);
      console.log(xmmStr);
      throw new Error(`Unexpected error parsing: ${xmlStr}. Error: ${xmmStr}`);
    }

    return xmlDoc;
  };
}
export default SVGExporter;