113 lines
3.9 KiB
JavaScript
113 lines
3.9 KiB
JavaScript
// Copyright 2007 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 Detection for whether the user has Picasa installed.
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* Only Picasa versions 2 and later can be detected, and only from Firefox or
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* Internet Explorer. Picasa for Linux cannot be detected.
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*
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* In the future, Picasa may provide access to the installed version number,
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* but until then we can only detect that Picasa 2 or later is present.
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*
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* To check for Picasa on Internet Explorer requires using document.write, so
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* this file must be included at page rendering time and cannot be imported
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* later as part of a dynamically loaded module.
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*
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* @author brenneman@google.com (Shawn Brenneman)
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* @see ../demos/useragent.html
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*/
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goog.provide('goog.userAgent.picasa');
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goog.require('goog.string');
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goog.require('goog.userAgent');
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/**
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* Variable name used to temporarily save the Picasa state in the global object
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* in Internet Explorer.
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* @type {string}
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* @private
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*/
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goog.userAgent.picasa.IE_HAS_PICASA_ = 'hasPicasa';
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(function() {
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var hasPicasa = false;
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if (goog.userAgent.IE) {
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// In Internet Explorer, Picasa 2 can be detected using conditional comments
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// due to some nice registry magic. The precise version number is not
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// available, only the major version. This may be updated for Picasa 3. This
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// check must pollute the global namespace.
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goog.global[goog.userAgent.picasa.IE_HAS_PICASA_] = hasPicasa;
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// NOTE(user): Some browsers do not like seeing
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// slash-script anywhere in the text even if it's inside a string
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// and escaped with a backslash, make a string in a way that
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// avoids problems.
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document.write(goog.string.subs(
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'<!--[if gte Picasa 2]>' +
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'<%s>' +
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'this.%s=true;' +
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'</%s>' +
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'<![endif]-->',
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'script', goog.userAgent.picasa.IE_HAS_PICASA_, 'script'));
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hasPicasa = goog.global[goog.userAgent.picasa.IE_HAS_PICASA_];
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// Unset the variable in a crude attempt to leave no trace.
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goog.global[goog.userAgent.picasa.IE_HAS_PICASA_] = undefined;
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} else if (navigator.mimeTypes &&
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navigator.mimeTypes['application/x-picasa-detect']) {
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// Picasa 2.x registers a file handler for the MIME-type
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// 'application/x-picasa-detect' for detection in Firefox. Future versions
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// may make precise version detection possible.
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hasPicasa = true;
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}
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/**
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* Whether we detect the user has Picasa installed.
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* @type {boolean}
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*/
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goog.userAgent.picasa.HAS_PICASA = hasPicasa;
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/**
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* The installed version of Picasa. If Picasa is detected, this means it is
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* version 2 or later. The precise version number is not yet available to the
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* browser, this is a placeholder for later versions of Picasa.
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* @type {string}
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*/
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goog.userAgent.picasa.VERSION = hasPicasa ? '2' : '';
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})();
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/**
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* Whether the installed Picasa version is as new or newer than a given version.
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* This is not yet relevant, we can't detect the true Picasa version number yet,
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* but this may be possible in future Picasa releases.
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* @param {string} version The version to check.
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* @return {boolean} Whether the installed Picasa version is as new or newer
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* than a given version.
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*/
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goog.userAgent.picasa.isVersion = function(version) {
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return goog.string.compareVersions(
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goog.userAgent.picasa.VERSION, version) >= 0;
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};
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