public class Captcha extends Canvas
{
    private const CAPTCHA_WIDTH:uint = 120;
    private const CAPTCHA_HEIGHT:uint = 40;
    private var _securitycode:String;
 
    public function Captcha(type:String,counter:Number):void
    {
 
        // Set CAPTCHA Code
 	_securitycode = randString(type, counter);
 	generateDots();
 	generatePolys(3);
 	drawLines(0, 0, (CAPTCHA_WIDTH)-1, (CAPTCHA_HEIGHT)-1, 5, 5);
 	displayCode(_securitycode);
 	this.width = CAPTCHA_WIDTH;
 	this.height = CAPTCHA_HEIGHT;
	this.horizontalScrollPolicy = "off";
 	this.verticalScrollPolicy = "off";
 
        var largeMask:UIComponent = new UIComponent();
        largeMask.graphics.beginFill(0x00FFFF, 0.5);
        largeMask.graphics.drawRect(0, 0, CAPTCHA_WIDTH, CAPTCHA_HEIGHT);
        largeMask.graphics.endFill();
        largeMask.x = 0;
        largeMask.y = 0;
        this.addChild(largeMask);
 	this.mask = largeMask;
    }
 
    // Generate random security code
    private function randString(type:String,counter:int):String
    {
 	var i:int=1;
 	var randStr:String="";
 	var randNum:int=0;
 	var useList:String="";
 	var alphaChars:String="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 	var secure:String="!@$%&*-_=+?~";
 	for (i = 1; i <= counter; i++) {
 		if (type == "alphaChars") {
 			useList=alphaChars;
 		} else if (type == "alphaCharsnum") {
 			useList=alphaChars+"0123456789";
 		} else if (type == "secure") {
 			useList=alphaChars+"0123456789"+secure;
 		} else {
 			useList="0123456789";
 		}
 
 		randNum=Math.floor(Math.random()*useList.length);
 		randStr=randStr+useList.charAt(randNum);
 	}
 	return randStr;
    }
 
    // Generate Random Dots
    public function generateDots():void
    {
 	for (var a:int=0; a < 1000; a++) {
 		var tmpComponent:UIComponent = new UIComponent();
 		var X:int = Math.floor(Math.random()*CAPTCHA_WIDTH);
 		var Y:int = Math.floor(Math.random()*CAPTCHA_HEIGHT);
 		tmpComponent.graphics.lineStyle(Math.floor(Math.random()*5),
                              RGBToHex(Math.floor(Math.random()*255),
                                                Math.floor(Math.random()*255),
                                                Math.floor(Math.random()*255)),
                              100);
 		tmpComponent.graphics.moveTo(X, Y);
 		tmpComponent.graphics.lineTo(X+1, Y);
 		this.addChild(tmpComponent);
 	}
    }
 
    // Converts color values from RGB to Hex
    private function RGBToHex (r:uint, g:uint, b:uint):uint {
 	var hex:uint = r << 16 ^ g << 8 ^ b;
 	return hex;
    }
 
    // Generate One Polygon
    private function generateOnePoly(sides:uint, radius:uint, color:uint):UIComponent {
        var tmpCmp:UIComponent = new UIComponent();
 	var DSides:uint = Math.floor(360/sides);
        //Highest transparency is 100 - default is 50
 	tmpCmp.graphics.beginFill(color, 50);
 	var cnt:int = -1;
 
 	while (++cnt < sides) {
 		var X:int = Math.floor(radius*Math.sin(DSides*cnt/180*Math.PI));
 		var Y:int = Math.floor(radius*Math.cos(DSides*cnt/180*Math.PI));
 		if (!cnt) {
 			tmpCmp.graphics.moveTo(X, Y);
 		} else {
 			tmpCmp.graphics.lineTo(X, Y);
 		}
        }
 	return tmpCmp;
    }
 
    public function generatePolys(no:uint):void
    {
 	for (var i:uint = 0; i < no; i++) {
 		var tmpComponent:UIComponent = new UIComponent();
 		var tmpRadius:int = Math.floor(Math.random()*40)+10;
 		tmpComponent = generateOnePoly(Math.floor(Math.random()*6)+3, tmpRadius,
                               RGBToHex(Math.floor(Math.random()*255),
                                                  Math.floor(Math.random()*255),
                                                  Math.floor(Math.random()*255)));
 		tmpComponent.x = Math.floor(Math.random()*CAPTCHA_WIDTH);
 		tmpComponent.y = Math.floor(Math.random()*CAPTCHA_HEIGHT);
 		tmpComponent.rotation = Math.floor(Math.random()*360);
 		tmpComponent.alpha = 0.3;
 		this.addChild(tmpComponent);
        }
    }
 
    // Generate Background Lines
    private function drawLines(x:int, y:int, wi:int, hi:int, r:int, c:int):void {
 	var tmpComponent:UIComponent = new UIComponent();
        // (width, 0xHEXCOLOR, transparency)
        tmpComponent.graphics.lineStyle(1, 0x333333, 100);
        var i:int = 0;
        var xd:Number = wi/c;
        var yd:Number = hi/r;
        for (i=0; i<= r; i++) {
            var yy:Number = y+i*yd;
            tmpComponent.graphics.moveTo(x+wi, yy);
            tmpComponent.graphics.lineTo(x, yy);
        }
        for (var j:int=0; j < c; j++) {
            var xx:Number = x+j*xd;
            tmpComponent.graphics.lineTo(xx, y);
            tmpComponent.graphics.lineTo(xx+xd, y+hi);
 
        }
        tmpComponent.graphics.lineTo(x+wi, y);
        this.addChild(tmpComponent);
    }
 
    private function displayCode(code:String):void
    {
        var tmpText:Label = new Label();
 	tmpText.text = code;
 	tmpText.width = CAPTCHA_WIDTH;
 	tmpText.height = CAPTCHA_HEIGHT;
 	tmpText.setStyle("fontSize",30);
 	tmpText.setStyle("horizontalCenter",0);
 	tmpText.setStyle("verticalCenter",0);
 	this.addChild(tmpText);
    }
 
    public function get securitycode():String
    {
        return this._securitycode;
    }
}

private var _captcha:Captcha = new Captcha("alphaChars",7);

private var _securityCode:String = _captcha.securitycode;