Implement progressive loading of PDFs

src/pdf_manager.js

@@ -0,0 +1,180 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
+/* 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.
+ */
+/* globals NotImplementedException, MissingDataException, PDFJS, Stream,
+           PDFDocument, ChunkedStream, ChunkedStreamManager */
+
+'use strict';
+
+// TODO(mack): Make use of PDFJS.Util.inherit() when it becomes available
+var BasePdfManager = (function BasePdfManagerClosure() {
+  function BasePdfManager() {
+    throw new Error('Cannot initialize BaseManagerManager');
+  }
+
+  BasePdfManager.prototype = {
+    onLoadedStream: function BasePdfManager_onLoadedStream() {
+      throw new NotImplementedException();
+    },
+
+    ensureModel: function BasePdfManager_ensureModel(prop) {
+      var args = [].slice.call(arguments);
+      args.unshift(this.pdfModel);
+      return this.ensure.apply(this, args);
+    },
+
+    ensureXRef: function BasePdfManager_ensureXRef(prop) {
+      var args = [].slice.call(arguments);
+      args.unshift(this.pdfModel.xref);
+      return this.ensure.apply(this, args);
+    },
+
+    ensureCatalog: function BasePdfManager_ensureCatalog(prop) {
+      var args = [].slice.call(arguments);
+      args.unshift(this.pdfModel.catalog);
+      return this.ensure.apply(this, args);
+    },
+
+    getPage: function BasePdfManager_pagePage(pageIndex) {
+      return this.pdfModel.getPage(pageIndex);
+    },
+
+    ensure: function BasePdfManager_ensure(obj, prop) {
+      return new NotImplementedException();
+    },
+
+    requestLoadedStream: function BasePdfManager_requestLoadedStream() {
+      return new NotImplementedException();
+    }
+  };
+
+  return BasePdfManager;
+})();
+
+var LocalPdfManager = (function LocalPdfManagerClosure() {
+  function LocalPdfManager(data, password) {
+    var stream = new Stream(data);
+    this.pdfModel = new PDFDocument(stream, password);
+    this.loadedStream = new PDFJS.Promise();
+    this.loadedStream.resolve(stream);
+  }
+
+  LocalPdfManager.prototype = Object.create(BasePdfManager.prototype);
+  LocalPdfManager.prototype.constructor = LocalPdfManager;
+
+  LocalPdfManager.prototype.ensure =
+      function LocalPdfManager_ensure(obj, prop) {
+    var promise = new PDFJS.Promise();
+    var result;
+    var value = obj[prop];
+    try {
+      if (typeof(value) === 'function') {
+        var args = [].slice.call(arguments, 2);
+        result = value.apply(obj, args);
+      } else {
+        result = value;
+      }
+      promise.resolve(result);
+    } catch (e) {
+      console.log(e.stack);
+      promise.reject(e);
+    }
+    return promise;
+  };
+
+  LocalPdfManager.prototype.requestLoadedStream =
+      function LocalPdfManager_requestLoadedStream() {
+  };
+
+  LocalPdfManager.prototype.onLoadedStream =
+      function LocalPdfManager_getLoadedStream() {
+    return this.loadedStream;
+  };
+
+  return LocalPdfManager;
+})();
+
+var NetworkPdfManager = (function NetworkPdfManagerClosure() {
+
+  var CHUNK_SIZE = 64000;
+
+  function NetworkPdfManager(args, msgHandler) {
+
+    this.msgHandler = msgHandler;
+
+    var params = {
+      msgHandler: msgHandler,
+      httpHeaders: args.httpHeaders,
+      chunkedViewerLoading: args.chunkedViewerLoading
+    };
+    this.streamManager = new ChunkedStreamManager(args.length, CHUNK_SIZE,
+                                                  args.url, params);
+
+    this.pdfModel = new PDFDocument(this.streamManager.getStream(),
+                                    args.password);
+  }
+
+  NetworkPdfManager.prototype = Object.create(BasePdfManager.prototype);
+  NetworkPdfManager.prototype.constructor = NetworkPdfManager;
+
+  NetworkPdfManager.prototype.ensure =
+      function NetworkPdfManager_ensure(obj, prop) {
+    var promise = new PDFJS.Promise();
+    var args = [].slice.call(arguments);
+    args.unshift(promise);
+    this.ensureHelper.apply(this, args);
+    return promise;
+  };
+
+  NetworkPdfManager.prototype.ensureHelper =
+      function NetworkPdfManager_ensureHelper(promise, obj, prop) {
+    try {
+      var result;
+      var value = obj[prop];
+      if (typeof(value) === 'function') {
+        var args = [].slice.call(arguments, 3);
+        result = value.apply(obj, args);
+      } else {
+        result = value;
+      }
+      promise.resolve(result);
+    } catch(e) {
+      if (!(e instanceof MissingDataException)) {
+        console.log(e.stack);
+        promise.reject(e);
+        return;
+      }
+
+      var allArgs = Array.prototype.slice.call(arguments);
+      this.streamManager.requestRange(e.begin, e.end, function() {
+        this.ensureHelper.apply(this, allArgs);
+      }.bind(this));
+    }
+  };
+
+  NetworkPdfManager.prototype.requestLoadedStream =
+      function NetworkPdfManager_requestLoadedStream() {
+    this.streamManager.requestAllChunks();
+  };
+
+  NetworkPdfManager.prototype.onLoadedStream =
+      function NetworkPdfManager_getLoadedStream() {
+    return this.streamManager.onLoadedStream();
+  };
+
+  return NetworkPdfManager;
+})();
+