如何在Chrome DesktopCapture API中点击“停止共享”

Question

我目前正在撰写使用Chrome's DesktopCapture API的Chrome扩展程序。当有人点击“停止共享”时，我很难设置回调。

我尝试使用MediaStream的onended EventHandler，但点击按钮后，MediaStream的ended属性仍然设置为true。

我可以在流（点击按钮之前和之后）之间找到的唯一区别是videoTracks.readyState设置为ended。

编辑： 我还想注意用户是否关闭了之前流式传输的窗口。

Answer 1

我通过在 videoTrack的 onended属性上分配一个EventHandler解决了这个问题：

  // somebody clicked on "Stop sharing"
  stream.getVideoTracks()[0].onended = function () {
    // doWhatYouNeedToDo();
  };

就我的编辑而言（注意到关闭窗口）：它也会触发事件。

Answer 2

stream.onended = () => { // Click on browser UI stop sharing button
  console.info("Recording has ended");
};

从哪里获得流？使用adapter.js（跨浏览器制作基于Promise的通用API）：

navigator.mediaDevices.getUserMedia(..).then((stream) => {..});

Answer 3

现在我们处于非活动状态，您可以像这样使用

uses
  System.Win.ScktComp, Vcl.Imaging.jpeg;

type
  TForm1 = class(TForm)
    Button1: TButton;
    ServerSocket1: TServerSocket;
    procedure ServerSocket1ClientRead(Sender: TObject;
      Socket: TCustomWinSocket);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
ServerSocket1.Port := 1234;
ServerSocket1.Active := True;
end;

procedure TForm1.ServerSocket1ClientRead(Sender: TObject;
  Socket: TCustomWinSocket);
var
  s: string;
  Stream: TMemoryStream;
  Receiving: Boolean;
  stSize: Integer;
  jpg: TJpegImage;
begin
    if Socket.ReceiveLength > 0 then
    begin
      s := Socket.ReceiveText;

      if not Receiving then
      begin
        if Pos(#0, s) > 0 then
        begin
          stSize := strToInt(Copy(s, 1, Pos(#0, s) - 1));
          ShowMessage(IntToStr(Round(stSize / 1024)));
        end
        else
          ;
        Stream := TMemoryStream.Create;
        Receiving := true;
        Delete(s, 1, Pos(#0, s));
      end;
      try
        Stream.Write(AnsiString(s)[1], length(s));
        if Stream.Size = stSize then
        begin
          Stream.Position := 0;
          Receiving := false;
          jpg := TJpegImage.Create;
          jpg.LoadFromStream(Stream);
          jpg.SaveToFile('received.jpg');
          Stream.Free;
        end;
      except
        Stream.Free;
      end;
    end;
  end;

end.