Flex(flash)检测摄像头的3种状态

在视频程序的编写过程中，我们经常要使用摄像头，在使用摄像头前有必要对摄像头的现有状态做个检测:
1.被占用

2.没安装摄像头

3.正常

看下面代码：
http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="init()">

import mx.controls.Alert;
private var camera:Camera;
private var isExistsCamera:Boolean=false;
private var isBusyCamera:Boolean=false;
private var intervalId:uint;
private var times:int;

private function init():void
{
camera=Camera.getCamera();
if (camera == null)
{
if (Camera.names.length <= 0)
{
this.isExistsCamera=false;
Alert.show("没安装摄像头");
}
}
else
{
this.vdpaly.attachCamera(this.camera);
this.isCameraBusy();
}
}

private function isCameraBusy():void
{
this.intervalId=setInterval(callback,50);
}

private function callback():void
{
trace("currentFPS=" + camera.currentFPS.toString());

if (camera.currentFPS > 0)
{
//视频设备可用
clearInterval(this.intervalId);
this.isBusyCamera=false;
Alert.show("摄像头正常");
}
else
{
times++;
trace("times=" + times.toString());

if (times > 30)
{
//视频设备忙
clearInterval(intervalId);
this.isBusyCamera=true;
Alert.show("摄像头被占用");
}
}
}

private function cl():void
{
Alert.show(this.camera.currentFPS.toString());
}

]]>

代码说明：

camera == null，那么就是没安装摄像头

如果摄像头被占用，那么camera.currentFPS 肯定不会大 于0,而是等于0