pdf-reader-web/helpers/watermark.ts

import { floatToHex } from './utility';
import { xmlParser, getElementsByTagName } from './dom';

type WatermarkAnnotType = {
  obj_type: string;
  obj_attr: WatermarkType;
};

export const parseWatermarkFromXml = (
  xmlString: string
): WatermarkAnnotType => {
  if (!xmlString) return { obj_type: 'watermark', obj_attr: {} };

  const xmlDoc = xmlParser(xmlString);
  const elements = xmlDoc.firstElementChild || xmlDoc.firstChild;
  const data: WatermarkType = {};
  const element = getElementsByTagName(elements as ChildNode, 'watermarks');

  if (element && element[1]) {
    const array: Element[] = Array.prototype.slice.call(element[1].childNodes);
    array.forEach((ele, index) => {
      const attr: any = ele.attributes;
      switch (ele.tagName) {
        case 'Font':
          data.type = 'text';
          data.text = (array[index + 1].textContent as string).trim();
          break;
        case 'Opacity': {
          data.opacity = attr.value.value;
          break;
        }
        case 'Rotation': {
          data.rotation = parseFloat(attr.value.value);
          break;
        }
        case 'Scale': {
          data.scale = parseFloat(attr.value.value);
          break;
        }
        case 'Color': {
          const r = attr.r.value;
          const g = attr.g.value;
          const b = attr.b.value;
          data.textcolor = floatToHex(r, g, b);
          break;
        }
        case 'PageRange': {
          data.pages = (array[index + 1].textContent as string).trim();
          break;
        }
        default:
          break;
      }
    });
  }
  return {
    obj_type: 'watermark',
    obj_attr: {
      vertalign: 'center',
      horizalign: 'center',
      xoffset: 0,
      yoffset: 0,
      isfront: 'yes',
      ...data,
    },
  };
};

export default parseWatermarkFromXml;