实在抱歉，是二次贝塞尔曲线，不是一次杯赛儿曲线。o(╯□╰)o
鼠标拖动划线,然后拖动变成曲线

前天在天地会看到一朋友说，想要先画一条线，然后可以随意拖动这条线，然后我就想到了二次贝塞尔曲线，真是个好东东，于是就做了个实例，一来给那位朋友帮个忙，二来我博客也好久没更新AS相关的东东了，呵呵。
这里只贴出来BezierLine的代码，要是想看整个实例的源码，在最下面有链接下载的。
废话少说，上代码。

BezierLine：

package com.litefeel.display 
{
    import flash.display.Sprite;
    import flash.events.MouseEvent;
    /**
     * lite3@qq.com
     * www.litefeel.com
     * @author lite3
     */    public class BezierLine extends Sprite
    {
        // 终点坐标
        private var endX:Number;
        private var endY:Number;

        private var centerX:Number;
        private var centerY:Number;

        // 控制点坐标
        private var _controlX:Number;
        private var _controlY:Number;

        // 线条样式属性
        private var _thickness:Number;
        private var _color:uint;
        private var _pixelHinting:Boolean;
        private var _scaleMode:String;
        private var _caps:String;
        private var _joints:String;
        private var _miterLimit:Number;

        public function BezierLine(beginX:Number, beginY:Number, endX:Number, endY:Number) 
        {
            this.endX = endX - beginX;
            this.endY = endY - beginY;
            setStyle(3);
            graphics.lineTo(this.endX, this.endY);
            x = beginX;
            y = beginY;
            centerX = this.endX / 2;
            centerY = this.endY / 2;

            this.buttonMode = true;
            this.useHandCursor = true;

            addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
        }

        /**
         * 设置线条样式
         * @param   thickness
         * @param   color
         * @param   alpha
         * @param   pixelHinting
         * @param   scaleMode
         * @param   caps
         * @param   joints
         * @param   miterLimit
         */        public function setStyle(thickness:Number, color:uint = 0, alpha:Number = 1, pixelHinting:Boolean = false, scaleMode:String = "normal", caps:String = null, joints:String = null, miterLimit:Number = 3):void
        {
            _thickness = thickness;
            _color = color;
            this.alpha = alpha;
            _pixelHinting = pixelHinting;
            _scaleMode = scaleMode;
            _caps = caps;
            _joints = joints;
            _miterLimit = miterLimit;
            drawLineByControlPoint(controlX, controlY);
        }

        /**
         * 划线 贝塞尔曲线
         * @param   controlX
         * @param   controlY
         */        public function drawLineByControlPoint(controlX:Number, controlY:Number):void
        {
            _controlX = controlX;
            _controlY = controlY;

            graphics.clear();
            graphics.moveTo(0, 0);
            graphics.lineStyle(_thickness, _color, 1, _pixelHinting, _scaleMode, _caps, _joints, _miterLimit);
            graphics.curveTo(controlX, controlY, endX, endY);

        }
        /** 控制点X */        public function get controlX():Number { return _controlX; }

        /** 控制点Y */        public function get controlY():Number { return _controlY; }

        public function get thickness():Number { return _thickness; }
        public function set thickness(value:Number):void 
        {
            if (_thickness != value)
            {
                _thickness = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get color():uint { return _color; }
        public function set color(value:uint):void 
        {
            if (_color != value)
            {
                _color = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get pixelHinting():Boolean { return _pixelHinting; }
        public function set pixelHinting(value:Boolean):void 
        {
            if (_pixelHinting != value)
            {
                _pixelHinting = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get scaleMode():String { return _scaleMode; }
        public function set scaleMode(value:String):void 
        {
            if (_scaleMode != value)
            {
                _scaleMode = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get caps():String { return _caps; }
        public function set caps(value:String):void 
        {
            if (_caps != value)
            {
                _caps = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get joints():String { return _joints; }
        public function set joints(value:String):void 
        {
            if (_joints != value)
            {
                _joints = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        public function get miterLimit():Number { return _miterLimit; }
        public function set miterLimit(value:Number):void 
        {
            if (_miterLimit != value)
            {
                _miterLimit = value;
                drawLineByControlPoint(_controlX, _controlY);
            }
        }

        private function mouseDownHandler(e:MouseEvent):void 
        {
            stage.addEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
            stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
        }

        private function mouseMoveHandler(e:MouseEvent):void 
        {
            drawLineByControlPoint((mouseX - centerX) * 2 + centerX, (mouseY - centerY) * 2 + centerY);
        }

        private function mouseUpHandler(e:MouseEvent):void 
        {
            stage.removeEventListener(MouseEvent.MOUSE_MOVE, mouseMoveHandler);
            stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
        }
    }
}

源码下载☞