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| 1 | +// Last time updated at Sep 23, 2014, 08:32:23 |
| 2 | + |
| 3 | +// Latest file can be found here: https://cdn.webrtc-experiment.com/Screen-Capturing.js |
| 4 | + |
| 5 | +// Muaz Khan - www.MuazKhan.com |
| 6 | +// MIT License - www.WebRTC-Experiment.com/licence |
| 7 | +// Documentation - https://github.com/muaz-khan/Chrome-Extensions/tree/master/Screen-Capturing.js |
| 8 | +// Demo - https://www.webrtc-experiment.com/Screen-Capturing/ |
| 9 | + |
| 10 | +// ___________________ |
| 11 | +// Screen-Capturing.js |
| 12 | + |
| 13 | +// Source code: https://github.com/muaz-khan/Chrome-Extensions/tree/master/desktopCapture |
| 14 | +// Google AppStore installation path: https://chrome.google.com/webstore/detail/screen-capturing/ajhifddimkapgcifgcodmmfdlknahffk |
| 15 | + |
| 16 | +// This JavaScript file is aimed to explain steps needed to integrate above chrome extension |
| 17 | +// in your own webpages |
| 18 | + |
| 19 | +// Usage: |
| 20 | +// getScreenConstraints(function(screen_constraints) { |
| 21 | +// navigator.webkitGetUserMedia({ video: screen_constraints }, onSuccess, onFailure ); |
| 22 | +// }); |
| 23 | + |
| 24 | +// First Step: Download the extension, modify "manifest.json" and publish to Google AppStore |
| 25 | +// https://github.com/muaz-khan/Chrome-Extensions/tree/master/desktopCapture#how-to-publish-yourself |
| 26 | + |
| 27 | +// Second Step: Listen for postMessage handler |
| 28 | +// postMessage is used to exchange "sourceId" between chrome extension and you webpage. |
| 29 | +// though, there are tons other options as well, e.g. XHR-signaling, websockets, etc. |
| 30 | +window.addEventListener('message', function(event) { |
| 31 | + if (event.origin != window.location.origin) { |
| 32 | + return; |
| 33 | + } |
| 34 | + |
| 35 | + onMessageCallback(event.data); |
| 36 | +}); |
| 37 | + |
| 38 | +// and the function that handles received messages |
| 39 | + |
| 40 | +function onMessageCallback(data) { |
| 41 | + // "cancel" button is clicked |
| 42 | + if (data == 'PermissionDeniedError') { |
| 43 | + chromeMediaSource = 'PermissionDeniedError'; |
| 44 | + if (screenCallback) return screenCallback('PermissionDeniedError'); |
| 45 | + else throw new Error('PermissionDeniedError'); |
| 46 | + } |
| 47 | + |
| 48 | + // extension notified his presence |
| 49 | + if (data == 'rtcmulticonnection-extension-loaded') { |
| 50 | + chromeMediaSource = 'desktop'; |
| 51 | + } |
| 52 | + |
| 53 | + // extension shared temp sourceId |
| 54 | + if (data.sourceId && screenCallback) { |
| 55 | + screenCallback(sourceId = data.sourceId); |
| 56 | + } |
| 57 | +} |
| 58 | + |
| 59 | +// global variables |
| 60 | +var chromeMediaSource = 'screen'; |
| 61 | +var sourceId; |
| 62 | +var screenCallback; |
| 63 | + |
| 64 | +// this method can be used to check if chrome extension is installed & enabled. |
| 65 | +function isChromeExtensionAvailable(callback) { |
| 66 | + if (!callback) return; |
| 67 | + |
| 68 | + if (chromeMediaSource == 'desktop') return callback(true); |
| 69 | + |
| 70 | + // ask extension if it is available |
| 71 | + window.postMessage('are-you-there', '*'); |
| 72 | + |
| 73 | + setTimeout(function() { |
| 74 | + if (chromeMediaSource == 'screen') { |
| 75 | + callback(false); |
| 76 | + } else callback(true); |
| 77 | + }, 2000); |
| 78 | +} |
| 79 | + |
| 80 | +// this function can be used to get "source-id" from the extension |
| 81 | +function getSourceId(callback) { |
| 82 | + if (!callback) throw '"callback" parameter is mandatory.'; |
| 83 | + if(sourceId) return callback(sourceId); |
| 84 | + |
| 85 | + screenCallback = callback; |
| 86 | + window.postMessage('get-sourceId', '*'); |
| 87 | +} |
| 88 | + |
| 89 | +var isFirefox = typeof window.InstallTrigger !== 'undefined'; |
| 90 | +var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0; |
| 91 | +var isChrome = !!window.chrome && !isOpera; |
| 92 | + |
| 93 | +function getChromeExtensionStatus(extensionid, callback) { |
| 94 | + if (isFirefox) return callback('not-chrome'); |
| 95 | + |
| 96 | + if (arguments.length != 2) { |
| 97 | + callback = extensionid; |
| 98 | + extensionid = 'ajhifddimkapgcifgcodmmfdlknahffk'; // default extension-id |
| 99 | + } |
| 100 | + |
| 101 | + var image = document.createElement('img'); |
| 102 | + image.src = 'chrome-extension://' + extensionid + '/icon.png'; |
| 103 | + image.onload = function() { |
| 104 | + chromeMediaSource = 'screen'; |
| 105 | + window.postMessage('are-you-there', '*'); |
| 106 | + setTimeout(function() { |
| 107 | + if (chromeMediaSource == 'screen') { |
| 108 | + callback(extensionid == extensionid ? 'installed-enabled' : 'installed-disabled'); |
| 109 | + } else callback('installed-enabled'); |
| 110 | + }, 2000); |
| 111 | + }; |
| 112 | + image.onerror = function() { |
| 113 | + callback('not-installed'); |
| 114 | + }; |
| 115 | +} |
| 116 | + |
| 117 | +// this function explains how to use above methods/objects |
| 118 | +function getScreenConstraints(callback) { |
| 119 | + var firefoxScreenConstraints = { |
| 120 | + mozMediaSource: 'window', |
| 121 | + mediaSource: 'window' |
| 122 | + }; |
| 123 | + |
| 124 | + if(isFirefox) return callback(null, firefoxScreenConstraints); |
| 125 | + |
| 126 | + // this statement defines getUserMedia constraints |
| 127 | + // that will be used to capture content of screen |
| 128 | + var screen_constraints = { |
| 129 | + mandatory: { |
| 130 | + chromeMediaSource: chromeMediaSource, |
| 131 | + maxWidth: screen.width > 1920 ? screen.width : 1920, |
| 132 | + maxHeight: screen.height > 1080 ? screen.height : 1080 |
| 133 | + }, |
| 134 | + optional: [] |
| 135 | + }; |
| 136 | + |
| 137 | + // this statement verifies chrome extension availability |
| 138 | + // if installed and available then it will invoke extension API |
| 139 | + // otherwise it will fallback to command-line based screen capturing API |
| 140 | + if (chromeMediaSource == 'desktop' && !sourceId) { |
| 141 | + getSourceId(function() { |
| 142 | + screen_constraints.mandatory.chromeMediaSourceId = sourceId; |
| 143 | + callback(sourceId == 'PermissionDeniedError' ? sourceId : null, screen_constraints); |
| 144 | + }); |
| 145 | + return; |
| 146 | + } |
| 147 | + |
| 148 | + // this statement sets gets 'sourceId" and sets "chromeMediaSourceId" |
| 149 | + if (chromeMediaSource == 'desktop') { |
| 150 | + screen_constraints.mandatory.chromeMediaSourceId = sourceId; |
| 151 | + } |
| 152 | + |
| 153 | + // now invoking native getUserMedia API |
| 154 | + callback(null, screen_constraints); |
| 155 | +} |
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