[ActionScript 3.0] 动态绘制扇形实例（拖拽绘制）

 package
 {
     import flash.display.Shape;
     import flash.display.Sprite;
     import flash.events.MouseEvent;

     /**
      * @author Frost.Yen
      * @E-mail 871979853@qq.com
      * @create 2015-7-13 上午11:14:16
      *
      */
     [SWF(width="800",height="600")]
     public class DrawSectorTest extends Sprite
     {
         private var _sector:Sprite;
         private var _dragSp:Sprite;
         private var _radian:Number;//弧度
         private const _radius:uint = 100;//半径
         private const _angle:Number = 60;//初始角度
         public function DrawSectorTest()
         {
             _sector = new Sprite();
             _dragSp = new Sprite();
             _sector.x = _dragSp.x = stage.stageWidth*0.5;
             _sector.y = _dragSp.y = stage.stageHeight*0.5;
             this.addChild(_sector);
             this.addChild(_dragSp);

             _dragSp.graphics.beginFill(0,.2);
             _dragSp.graphics.drawRect(0,-5,_radius,10);
             _dragSp.graphics.endFill();

             drawSector(_sector,0,0,_radius,_angle,0);
             _dragSp.rotation = _angle;
             _dragSp.addEventListener(MouseEvent.MOUSE_DOWN,onDragDown);
         }
         private function onDragDown(e:MouseEvent):void
         {
             stage.addEventListener(MouseEvent.MOUSE_MOVE,onDragMove);
             stage.addEventListener(MouseEvent.MOUSE_UP,onDragOut);
         }
         private function onDragMove(e:MouseEvent):void
         {
             _dragSp.rotation = Math.atan2(_dragSp.parent.mouseY - _dragSp.y,_dragSp.parent.mouseX - _dragSp.x) * 180 / Math.PI ;
             _radian = (_dragSp.rotation) * Math.PI / 180;
             /**这是关键，因为rotation的区间是[0,180][0,-180],如果直接用_dragSp.rotation会导致拖拽绘制扇形错误*/
             if (_dragSp.rotation > 180){
                 _radian = _radian + Math.PI;
             }
             if (_radian < 0){
                 _radian = _radian + 2 * Math.PI;
             }
             drawSector(_sector,0,0,_radius,_radian*180/Math.PI,0);
         }
         private function onDragOut(e:MouseEvent):void
         {
             stage.removeEventListener(MouseEvent.MOUSE_MOVE,onDragMove);
             stage.removeEventListener(MouseEvent.MOUSE_UP,onDragOut);

         }
         /**
          * 绘制扇形
          * @param    mc 承载扇形的对象
          * @param    x 圆心角x
          * @param    y 圆心角y
          * @param    r 半径
          * @param    angle 绘制角度
          * @param    startAngle 起始角度
          * @param    color 填充颜色
          * @param    hasFrame 是否填充边框
          */
         private function drawSector(sp:Sprite,x:Number=0,y:Number=0,r:Number=100,angle:Number=60,startAngle:Number=0,color:Number=0xff0000,hasFrame:Boolean=true):void {
             sp.graphics.clear();
             if(hasFrame) {
                 sp.graphics.lineStyle(0,0xffff00);
             }
             sp.graphics.beginFill(color,1);
             sp.graphics.moveTo(x,y);
             angle=(Math.abs(angle)>360)?360:angle;
             var n:Number=Math.ceil(Math.abs(angle)/45);
             var angleA:Number=angle/n;
             angleA=angleA*Math.PI/180;
             startAngle=startAngle*Math.PI/180;
             sp.graphics.lineTo(x+r*Math.cos(startAngle),y+r*Math.sin(startAngle));
             for (var i:int=1; i<=n; i++) {
                 startAngle+=angleA;
                 var angleMid:Number=startAngle-angleA/2;
                 var bx:Number=x+r/Math.cos(angleA/2)*Math.cos(angleMid);
                 var by:Number=y+r/Math.cos(angleA/2)*Math.sin(angleMid);
                 var cx:Number=x+r*Math.cos(startAngle);
                 var cy:Number=y+r*Math.sin(startAngle);
                 sp.graphics.curveTo(bx,by,cx,cy);
             }
             if (angle!=360) {
                 sp.graphics.lineTo(x,y);
             }
             sp.graphics.endFill();
         }
     }
 }