屏幕

Screen是个单例对象,使用前需要调用一次 nw.Screen.Init()进行启动,Screen.on(...)可对屏幕事件进行监听

示例

//启动时必须进行一次调用,之后便可调用任何nw.Screen函数了
nw.Screen.Init();

var screenCB = {
  onDisplayBoundsChanged: function(screen) {
    console.log('displayBoundsChanged', screen);
  },
  onDisplayAdded: function(screen) {
    console.log('displayAdded', screen);
  },
  onDisplayRemoved: function(screen) {
    console.log('displayRemoved', screen)
  }
};

//监听屏幕边界与增删
nw.Screen.on('displayBoundsChanged', screenCB.onDisplayBoundsChanged);
nw.Screen.on('displayAdded', screenCB.onDisplayAdded);
nw.Screen.on('displayRemoved', screenCB.onDisplayRemoved);

Screen.Init()

用途:启动时初始屏幕单例对象,只需要调用一次

Screen.screens

用途:获取连接到本机的屏幕数量

屏幕具有以下结构:

screen {
// 屏幕的唯一ID
  id: int,

//物理屏幕分辨率，不一定从0开始也可以是负数，这取决于屏幕排列
  bounds: {
    x: int,
    y: int,
    width: int,
    height: int
  },
 
// 屏幕范围内的可用区域
  work_area: {
    x: int,
    y: int,
    width: int,
    height: int
  },

  scaleFactor: float,
  isBuiltIn: bool,
  rotation: int,
  touchSupport: int
}

Screen.chooseDesktopMedia (sources, callback) WindowsLinux

用途:选择屏幕进行共享

sources String[] - 源类型数组,可选: "screen" 和 "window".
callback Function - 已选streamId的回调函数. streamId为 false即意味着执行失败或现有session存活.

示范:

nw.Screen.Init(); // 启动一次
nw.Screen.chooseDesktopMedia(["window","screen"], 
  function(streamId) {
    var vid_constraint = {
      mandatory: {
        chromeMediaSource: 'desktop', 
        chromeMediaSourceId: streamId, 
        maxWidth: 1920, 
        maxHeight: 1080
      }, 
      optional: []
    };
    navigator.webkitGetUserMedia({audio: false, video: vid_constraint}, success_func, fallback_func);
  }
);

事件: displayBoundsChanged(screen)

触发:更改屏幕分辨率时,可带有screen(Screen.screens)的进行回调

事件: displayAdded (screen)

触发:添加新屏幕时,可带有screen(Screen.screens)的进行回调

事件: displayRemoved (screen)

触发:移除新屏幕时,可带有screen(Screen.screens)的进行回调

Screen.DesktopCaptureMonitor

用途:使用此API监视桌面上的屏幕和窗口的更改，并实现自己的UI

该API与 Screen.chooseDesktopMedia类似的功能,但它没有GUI.

Screen.DesktopCaptureMonitor是个 EventEmitter实例. 可通过 Screen.DesktopCaptureMonitor.on()进行监听.

示例

var dcm = nw.Screen.DesktopCaptureMonitor;
nw.Screen.Init();
dcm.on("added", function (id, name, order, type) {
   //选择第一个stream并关闭
   var constraints = {
      audio: {
         mandatory: {
             chromeMediaSource: "system",
             chromeMediaSourceId: dcm.registerStream(id)
          }
      },
      video: {
         mandatory: {
             chromeMediaSource: 'desktop',
             chromeMediaSourceId: dcm.registerStream(id)
         }
      }
  };

  //用约束调用getUserMedia之类的后续操作

  dcm.stop();
});

dcm.on("removed", function (id) { });
dcm.on("orderchanged", function (id, new_order, old_order) { });
dcm.on("namechanged", function (id, name) { });
dcm.on("thumbnailchanged", function (id, thumbnail) { });
dcm.start(true, true);

Screen.DesktopCaptureMonitor.started

用途:判断 DesktopCaptureMonitor桌面捕获监视器是否已启动( Boolean)

Screen.DesktopCaptureMonitor.start(should_include_screens, should_include_windows)

用途:使DesktopCaptureMonitor桌面捕获监视器开始监视系统并触发事件

should_include_screens Boolean - 是否包括屏幕
should_include_windows Boolean - 是否包括窗口

如果 DesktopCaptureMonitor桌面捕获监视器正在运行，屏幕可能会闪烁

Screen.DesktopCaptureMonitor.stop()

用途:使DesktopCaptureMonitor桌面捕获监视器停止始监视系统

当选择了stream后 DesktopCaptureMonitor桌面捕获监视器应该被停止.

Screen.DesktopCaptureMonitor.registerStream(id)

用途:注册并返回在 getUserMedia约束中传递给 chromeMediaSourceId的有效stream ID

事件: added (id, name, order, type, primary)

触发:添加源的时候

id String - 媒体ID. 使用 registerStream(id)可获取与 getUserMedia()一同使用的有效stream ID. 详细参阅上文registerStream
name String -窗口或屏幕的标题
order Integer - 窗口的z顺序
type String - 流的类型,可选值: screen, window, other 或 unknown
primary Boolean - Windows 如果源是主监视器时,该项为 true

事件: removed (order)

触发:删除源的时候

order Integer - 媒体源的顺序

事件: orderchanged (id, new_order, old_order)

触发:变更源的Z顺序的时候

id String - 更改了z顺序的屏幕或窗口的媒体ID
new_order Integer - 新的z顺序
old_order Integer - 旧的z顺序

事件: namechanged (id, name)

触发:变更源的名称(如窗口更改了标题时)的时候

id String - 更改了名称的屏幕或窗口的媒体ID
name String - 屏幕或窗口的新名称

事件: thumbnailchanged (id, thumbnail)

触发:变更源的缩略图的时候

id String - 更新了缩略图的屏幕或窗口的媒体ID
thumbnail String - 缩略图png的base64编码