mediocre-blog/assets/viz/2/goog/fs/url.js

107 lines
3.2 KiB
JavaScript

// Copyright 2015 The Closure Library Authors. All Rights Reserved.
//
// 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.
/**
* @fileoverview Wrapper for URL and its createObjectUrl and revokeObjectUrl
* methods that are part of the HTML5 File API.
*/
goog.provide('goog.fs.url');
/**
* Creates a blob URL for a blob object.
* Throws an error if the browser does not support Object Urls.
*
* @param {!Blob} blob The object for which to create the URL.
* @return {string} The URL for the object.
*/
goog.fs.url.createObjectUrl = function(blob) {
return goog.fs.url.getUrlObject_().createObjectURL(blob);
};
/**
* Revokes a URL created by {@link goog.fs.url.createObjectUrl}.
* Throws an error if the browser does not support Object Urls.
*
* @param {string} url The URL to revoke.
*/
goog.fs.url.revokeObjectUrl = function(url) {
goog.fs.url.getUrlObject_().revokeObjectURL(url);
};
/**
* @typedef {{createObjectURL: (function(!Blob): string),
* revokeObjectURL: function(string): void}}
*/
goog.fs.url.UrlObject_;
/**
* Get the object that has the createObjectURL and revokeObjectURL functions for
* this browser.
*
* @return {goog.fs.url.UrlObject_} The object for this browser.
* @private
*/
goog.fs.url.getUrlObject_ = function() {
var urlObject = goog.fs.url.findUrlObject_();
if (urlObject != null) {
return urlObject;
} else {
throw Error('This browser doesn\'t seem to support blob URLs');
}
};
/**
* Finds the object that has the createObjectURL and revokeObjectURL functions
* for this browser.
*
* @return {?goog.fs.url.UrlObject_} The object for this browser or null if the
* browser does not support Object Urls.
* @private
*/
goog.fs.url.findUrlObject_ = function() {
// This is what the spec says to do
// http://dev.w3.org/2006/webapi/FileAPI/#dfn-createObjectURL
if (goog.isDef(goog.global.URL) &&
goog.isDef(goog.global.URL.createObjectURL)) {
return /** @type {goog.fs.url.UrlObject_} */ (goog.global.URL);
// This is what Chrome does (as of 10.0.648.6 dev)
} else if (
goog.isDef(goog.global.webkitURL) &&
goog.isDef(goog.global.webkitURL.createObjectURL)) {
return /** @type {goog.fs.url.UrlObject_} */ (goog.global.webkitURL);
// This is what the spec used to say to do
} else if (goog.isDef(goog.global.createObjectURL)) {
return /** @type {goog.fs.url.UrlObject_} */ (goog.global);
} else {
return null;
}
};
/**
* Checks whether this browser supports Object Urls. If not, calls to
* createObjectUrl and revokeObjectUrl will result in an error.
*
* @return {boolean} True if this browser supports Object Urls.
*/
goog.fs.url.browserSupportsObjectUrls = function() {
return goog.fs.url.findUrlObject_() != null;
};