将消息发送到后台脚本

Question

我正在尝试实施一个屏幕共享Web应用程序,该应用程序将使用desktopCapture Chrome API在网页上显示用户屏幕.我创建了chrome扩展,并在后台运行了一个事件监听器.我的问题是当我尝试从网页发送消息到扩展名(获取userMedia id)时,我没有在扩展端收到任何内容.我也试图将getUserMedia id返回到网页以显示feed.我已经附上了我拥有的东西.谢谢

表现

{
"name": "Class Mate Manifest",
"description": "Extension that allows for user to share their screen",
"version": "1",
"manifest_version": 2,

"background": {
  "scripts": ["background.js"]
},
"permissions": [
"desktopCapture",
"tabs"
],
"browser_action": {
  "default_icon": "icon.png",
"default_popup": "index.html"
    }
 }

background.js

chrome.runtime.onMessage.addListener(
function(request, sender, sendResponse) {
console.log(request.greeting);
if(request.greeting == yes){
 chrome.desktopCapture.chooseDesktopMedia(["screen", "window"], sendResponse);
 return true;
 }
 });

webpage.js

function gotStream(stream) {
console.log("Received local stream");
var video = document.querySelector("video");
video.src = URL.createObjectURL(stream);
localstream = stream;
// stream.onended = function() { console.log("Ended"); };
}

function getUserMediaError() {
console.log("getUserMedia() failed.");
}

function onAccessApproved(id) {
console.log(id);
if (!id) {
console.log("Access rejected.");
return;
}


navigator.webkitGetUserMedia({
  audio:false,
  video: { mandatory: { chromeMediaSource: "desktop", chromeMediaSourceId: id } }
}, gotStream, getUserMediaError);

}


chrome.runtime.sendMessage({greeting: "yes"}, onAccessApproved);

Answer 1

您不能简单地使用消息传递,就像在任意网页代码的内容脚本中使用它一样.

文档中有两个与网页通信的指南,分别对应两种方法:(external_connectable) (带内容脚本的自定义事件)

假设您要允许http://example.com向您的分机发送消息.

1. 您需要明确列入白名单,在该网站的清单:

     "externally_connectable" : {
       matches: [ "http://example.com" ]
     },
   

2. 您需要获取永久扩展ID.假设结果ID是abcdefghijklmnoabcdefhijklmnoabc

3. 您的网页需要检查是否允许发送消息,然后使用预定义的ID发送:

   // Website code
   // This will only be true if some extension allowed the page to connect
   if(chrome && chrome.runtime && chrome.runtime.sendMessage) {
     chrome.runtime.sendMessage(
       "abcdefghijklmnoabcdefhijklmnoabc",
       {greeting: "yes"},
       onAccessApproved
     );
   }
   

4. 您的扩展程序需要侦听外部邮件,并可能还要查看其来源:

   // Extension's background code
   chrome.runtime.onMessageExternal.addListener(
     function(request, sender, sendResponse) {
       if(!validate(request.sender)) // Check the URL with a custom function
         return;
       /* do work */
     }
   );