| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| 'use strict'; |
| |
| // All of these scripts could be imported with a single call to importScripts, |
| // but then load and compile time errors would all be reported from the same |
| // line. |
| importScripts('metadata_parser.js'); |
| importScripts('byte_reader.js'); |
| importScripts('../util.js'); |
| |
| /** |
| * Dispatches metadata requests to the correct parser. |
| * |
| * @param {Object} port Worker port. |
| * @constructor |
| */ |
| function MetadataDispatcher(port) { |
| this.port_ = port; |
| this.port_.onmessage = this.onMessage.bind(this); |
| |
| // Make sure to update component_extension_resources.grd |
| // when adding new parsers. |
| importScripts('exif_parser.js'); |
| importScripts('image_parsers.js'); |
| importScripts('mpeg_parser.js'); |
| importScripts('id3_parser.js'); |
| |
| var patterns = []; |
| |
| this.parserInstances_ = []; |
| for (var i = 0; i < MetadataDispatcher.parserClasses_.length; i++) { |
| var parserClass = MetadataDispatcher.parserClasses_[i]; |
| var parser = new parserClass(this); |
| this.parserInstances_.push(parser); |
| patterns.push(parser.urlFilter.source); |
| } |
| |
| this.parserRegexp_ = new RegExp('(' + patterns.join('|') + ')', 'i'); |
| |
| this.messageHandlers_ = { |
| init: this.init_.bind(this), |
| request: this.request_.bind(this) |
| }; |
| } |
| |
| /** |
| * List of registered parser classes. |
| * @private |
| */ |
| MetadataDispatcher.parserClasses_ = []; |
| |
| /** |
| * @param {function} parserClass Parser constructor function. |
| */ |
| MetadataDispatcher.registerParserClass = function(parserClass) { |
| MetadataDispatcher.parserClasses_.push(parserClass); |
| }; |
| |
| /** |
| * Verbose logging for the dispatcher. |
| * |
| * Individual parsers also take this as their default verbosity setting. |
| */ |
| MetadataDispatcher.prototype.verbose = false; |
| |
| /** |
| * |init| message handler. |
| * @private |
| */ |
| MetadataDispatcher.prototype.init_ = function() { |
| // Inform our owner that we're done initializing. |
| // If we need to pass more data back, we can add it to the param array. |
| this.postMessage('initialized', [this.parserRegexp_]); |
| this.log('initialized with URL filter ' + this.parserRegexp_); |
| }; |
| |
| /** |
| * |request| message handler. |
| * @param {string} fileURL File URL. |
| * @private |
| */ |
| MetadataDispatcher.prototype.request_ = function(fileURL) { |
| try { |
| this.processOneFile(fileURL, function callback(metadata) { |
| this.postMessage('result', [fileURL, metadata]); |
| }.bind(this)); |
| } catch (ex) { |
| this.error(fileURL, ex); |
| } |
| }; |
| |
| /** |
| * Indicate to the caller that an operation has failed. |
| * |
| * No other messages relating to the failed operation should be sent. |
| * @param {...Object} var_args Arguments. |
| */ |
| MetadataDispatcher.prototype.error = function(var_args) { |
| var ary = Array.apply(null, arguments); |
| this.postMessage('error', ary); |
| }; |
| |
| /** |
| * Send a log message to the caller. |
| * |
| * Callers must not parse log messages for control flow. |
| * @param {...Object} var_args Arguments. |
| */ |
| MetadataDispatcher.prototype.log = function(var_args) { |
| var ary = Array.apply(null, arguments); |
| this.postMessage('log', ary); |
| }; |
| |
| /** |
| * Send a log message to the caller only if this.verbose is true. |
| * @param {...Object} var_args Arguments. |
| */ |
| MetadataDispatcher.prototype.vlog = function(var_args) { |
| if (this.verbose) |
| this.log.apply(this, arguments); |
| }; |
| |
| /** |
| * Post a properly formatted message to the caller. |
| * @param {string} verb Message type descriptor. |
| * @param {Array.<Object>} args Arguments array. |
| */ |
| MetadataDispatcher.prototype.postMessage = function(verb, args) { |
| this.port_.postMessage({verb: verb, arguments: args}); |
| }; |
| |
| /** |
| * Message handler. |
| * @param {Event} event Event object. |
| */ |
| MetadataDispatcher.prototype.onMessage = function(event) { |
| var data = event.data; |
| |
| if (this.messageHandlers_.hasOwnProperty(data.verb)) { |
| this.messageHandlers_[data.verb].apply(this, data.arguments); |
| } else { |
| this.log('Unknown message from client: ' + data.verb, data); |
| } |
| }; |
| |
| /** |
| * @param {string} fileURL File URL. |
| * @param {function(Object)} callback Completion callback. |
| */ |
| MetadataDispatcher.prototype.processOneFile = function(fileURL, callback) { |
| var self = this; |
| var currentStep = -1; |
| |
| function nextStep(var_args) { |
| self.vlog('nextStep: ' + steps[currentStep + 1].name); |
| steps[++currentStep].apply(self, arguments); |
| } |
| |
| var metadata; |
| |
| function onError(err, stepName) { |
| self.error(fileURL, stepName || steps[currentStep].name, err.toString(), |
| metadata); |
| } |
| |
| var steps = |
| [ // Step one, find the parser matching the url. |
| function detectFormat() { |
| for (var i = 0; i != self.parserInstances_.length; i++) { |
| var parser = self.parserInstances_[i]; |
| if (fileURL.match(parser.urlFilter)) { |
| // Create the metadata object as early as possible so that we can |
| // pass it with the error message. |
| metadata = parser.createDefaultMetadata(); |
| nextStep(parser); |
| return; |
| } |
| } |
| onError('unsupported format'); |
| }, |
| |
| // Step two, turn the url into an entry. |
| function getEntry(parser) { |
| webkitResolveLocalFileSystemURL( |
| fileURL, |
| function(entry) { nextStep(entry, parser) }, |
| onError); |
| }, |
| |
| // Step three, turn the entry into a file. |
| function getFile(entry, parser) { |
| entry.file(function(file) { nextStep(file, parser) }, onError); |
| }, |
| |
| // Step four, parse the file content. |
| function parseContent(file, parser) { |
| metadata.fileSize = file.size; |
| try { |
| parser.parse(file, metadata, callback, onError); |
| } catch (e) { |
| onError(e.stack); |
| } |
| } |
| ]; |
| |
| nextStep(); |
| }; |
| |
| // Webworker spec says that the worker global object is called self. That's |
| // a terrible name since we use it all over the chrome codebase to capture |
| // the 'this' keyword in lambdas. |
| var global = self; |
| |
| if (global.constructor.name == 'SharedWorkerGlobalScope') { |
| global.addEventListener('connect', function(e) { |
| var port = e.ports[0]; |
| new MetadataDispatcher(port); |
| port.start(); |
| }); |
| } else { |
| // Non-shared worker. |
| new MetadataDispatcher(global); |
| } |