[Flex]as3.0检测当前摄像头状态(占用,没有,正常)三种状态

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：

<?xml version="1.0" encoding="utf-8"?> 
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" 
    layout="absolute" creationComplete="init()"> 
    <mx:Script> 
        <![CDATA[ 
            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("CuPlayer.com提示没安装摄像头"); 
                    } 
                } 
                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) 
                { 
                    //CuPlayer.com提示视频设备可用 
                    clearInterval(this.intervalId); 
                    this.isBusyCamera=false; 
                    Alert.show("CuPlayer.com提示摄像头正常"); 
                } 
                else 
                { 
                    times++; 
                    trace("times=" + times.toString()); 
 
                    if (times > 30) 
                    { 
                        //CuPlayer.com提示视频设备忙 
                        clearInterval(intervalId); 
                        this.isBusyCamera=true; 
                        Alert.show("CuPlayer.com提示摄像头被占用"); 
                    } 
                } 
            } 
             private function cl():void 
            { 
                Alert.show(this.camera.currentFPS.toString()); 
            } 
        ]]> 
    </mx:Script> 
    <mx:VideoDisplay   id="vdpaly"  click="cl()" x="44" y="64" width="232" height="236"/> 
</mx:WindowedApplication> 

 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