pdf2json/base/display/metadata.js

PDF file parser that converts PDF binaries to JSON and text, powered by porting a fork of PDF.JS to Node.js

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* globals Document, error, PDFJS */
/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

'use strict';

var Metadata = (PDFJS.Metadata = (function MetadataClosure() {
   function fixMetadata(meta) {
      return meta.replace(/>\\376\\377([^<]+)/g, function (all, codes) {
         var bytes = codes.replace(
            /\\([0-3])([0-7])([0-7])/g,
            function (code, d1, d2, d3) {
               return String.fromCharCode(d1 * 64 + d2 * 8 + d3 * 1);
            }
         );
         var chars = '';
         for (var i = 0; i < bytes.length; i += 2) {
            var code = bytes.charCodeAt(i) * 256 + bytes.charCodeAt(i + 1);
            chars +=
               code >= 32 &&
               code < 127 &&
               code != 60 &&
               code != 62 &&
               code != 38 &&
               false
                  ? String.fromCharCode(code)
                  : '&#x' + (0x10000 + code).toString(16).substring(1) + ';';
         }
         return '>' + chars;
      });
   }

   function Metadata(meta) {
	this.metadata = {};
	if (typeof meta === 'string') {
         // Ghostscript produces invalid metadata
         meta = fixMetadata(meta);
		 meta = meta.trim();
		 if (meta.startsWith('<') && meta.endsWith('>')) {
			var parser = new DOMParser();
			meta = parser.parseFromString(meta, 'application/xml');
			this.metaDocument = meta;
			this.parse();
		 }
	}
   }

   Metadata.prototype = {
      parse: function Metadata_parse() {
         var doc = this.metaDocument;
         var rdf = doc.documentElement;

         if (rdf && rdf.nodeName.toLowerCase() !== 'rdf:rdf') {
            // Wrapped in <xmpmeta>
            rdf = rdf.firstChild;
            while (rdf && rdf.nodeName.toLowerCase() !== 'rdf:rdf')
               rdf = rdf.nextSibling;
         }

         var nodeName = rdf ? rdf.nodeName.toLowerCase() : null;
         if (!rdf || nodeName !== 'rdf:rdf' || !rdf.hasChildNodes()) return;

         var children = rdf.childNodes,
            desc,
            entry,
            name,
            i,
            ii,
            length,
            iLength;

         for (i = 0, length = children.length; i < length; i++) {
            desc = children[i];
            if (desc.nodeName.toLowerCase() !== 'rdf:description') continue;

            for (ii = 0, iLength = desc.childNodes.length; ii < iLength; ii++) {
               if (desc.childNodes[ii].nodeName.toLowerCase() !== '#text') {
                  entry = desc.childNodes[ii];
                  name = entry.nodeName.toLowerCase();
                  this.metadata[name] = entry.textContent.trim();
               }
            }
         }
      },

      get: function Metadata_get(name) {
         return this.metadata[name] || null;
      },

      has: function Metadata_has(name) {
         return typeof this.metadata[name] !== 'undefined';
      },
   };

   return Metadata;
})());