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// Copyright 2011 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview A wrapper for the HTML5 FileSaver object.
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 *
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 */
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goog.provide('goog.fs.FileSaver');
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goog.provide('goog.fs.FileSaver.EventType');
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goog.provide('goog.fs.FileSaver.ReadyState');
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goog.require('goog.events.EventTarget');
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goog.require('goog.fs.Error');
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goog.require('goog.fs.ProgressEvent');
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/**
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 * An object for monitoring the saving of files. This emits ProgressEvents of
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 * the types listed in {@link goog.fs.FileSaver.EventType}.
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 *
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 * This should not be instantiated directly. Instead, its subclass
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 * {@link goog.fs.FileWriter} should be accessed via
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 * {@link goog.fs.FileEntry#createWriter}.
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 *
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 * @param {!FileSaver} fileSaver The underlying FileSaver object.
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 * @constructor
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 * @extends {goog.events.EventTarget}
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 */
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goog.fs.FileSaver = function(fileSaver) {
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  goog.fs.FileSaver.base(this, 'constructor');
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  /**
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   * The underlying FileSaver object.
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   *
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   * @type {!FileSaver}
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   * @private
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   */
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  this.saver_ = fileSaver;
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  this.saver_.onwritestart = goog.bind(this.dispatchProgressEvent_, this);
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  this.saver_.onprogress = goog.bind(this.dispatchProgressEvent_, this);
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  this.saver_.onwrite = goog.bind(this.dispatchProgressEvent_, this);
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  this.saver_.onabort = goog.bind(this.dispatchProgressEvent_, this);
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  this.saver_.onerror = goog.bind(this.dispatchProgressEvent_, this);
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  this.saver_.onwriteend = goog.bind(this.dispatchProgressEvent_, this);
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};
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goog.inherits(goog.fs.FileSaver, goog.events.EventTarget);
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/**
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 * Possible states for a FileSaver.
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 *
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 * @enum {number}
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 */
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goog.fs.FileSaver.ReadyState = {
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  /**
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   * The object has been constructed, but there is no pending write.
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   */
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  INIT: 0,
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  /**
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   * Data is being written.
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   */
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  WRITING: 1,
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  /**
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   * The data has been written to the file, the write was aborted, or an error
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   * occurred.
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   */
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  DONE: 2
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};
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/**
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 * Events emitted by a FileSaver.
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 *
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 * @enum {string}
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 */
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goog.fs.FileSaver.EventType = {
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  /**
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   * Emitted when the writing begins. readyState will be WRITING.
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   */
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  WRITE_START: 'writestart',
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  /**
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   * Emitted when progress has been made in saving the file. readyState will be
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   * WRITING.
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   */
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  PROGRESS: 'progress',
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  /**
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   * Emitted when the data has been successfully written. readyState will be
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   * WRITING.
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   */
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  WRITE: 'write',
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  /**
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   * Emitted when the writing has been aborted. readyState will be WRITING.
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   */
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  ABORT: 'abort',
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  /**
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   * Emitted when an error is encountered or the writing has been aborted.
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   * readyState will be WRITING.
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   */
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  ERROR: 'error',
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  /**
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   * Emitted when the writing is finished, whether successfully or not.
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   * readyState will be DONE.
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   */
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  WRITE_END: 'writeend'
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};
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/**
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 * Abort the writing of the file.
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 */
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goog.fs.FileSaver.prototype.abort = function() {
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  try {
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    this.saver_.abort();
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  } catch (e) {
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    throw new goog.fs.Error(e, 'aborting save');
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  }
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};
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/**
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 * @return {goog.fs.FileSaver.ReadyState} The current state of the FileSaver.
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 */
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goog.fs.FileSaver.prototype.getReadyState = function() {
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  return /** @type {goog.fs.FileSaver.ReadyState} */ (this.saver_.readyState);
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};
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/**
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 * @return {goog.fs.Error} The error encountered while writing, if any.
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 */
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goog.fs.FileSaver.prototype.getError = function() {
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  return this.saver_.error &&
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      new goog.fs.Error(this.saver_.error, 'saving file');
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};
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/**
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 * Wrap a progress event emitted by the underlying file saver and re-emit it.
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 *
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 * @param {!ProgressEvent} event The underlying event.
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 * @private
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 */
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goog.fs.FileSaver.prototype.dispatchProgressEvent_ = function(event) {
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  this.dispatchEvent(new goog.fs.ProgressEvent(event, this));
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};
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/** @override */
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goog.fs.FileSaver.prototype.disposeInternal = function() {
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  delete this.saver_;
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  goog.fs.FileSaver.base(this, 'disposeInternal');
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};
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