手工画扇型(4)

现在扇型已经画好，数据也得到，关键是要保存其轨迹。思想是把确定的扇型的成员内容保存在类或结构中，当mo移动时候，从新画扇型。在AfterLayerDraw事件下
    /// <summary>
    /// for re-draw sector. store sector
    /// </summary>
    public struct SectorElement
    {
        public ESRI.MapObjects2.Core.Point CenterPoint;
//        public ESRI.MapObjects2.Core.Point RadiusPoint;
        public float SweepAngle;
        public float StartAngle;
        public float Radius;
//        public int Index; // Draw mark need sign.
    }

画扇型，有专门对象来保存SectorElement

        /// <summary>
        /// draw sector for all opened windows.
        /// </summary>
        private void DrawSectorMark()
        {
            if (this.gdiLists == null && this.gdiLists.Count == 0) return;
 
            foreach (object obj in gdiLists.Keys)
            {
                SectorElement gpiElem = (SectorElement)gdiLists[obj];
                
                float clientCenterX =0.0f ,clientCenterY =0.0f,clientRadius = 0.0f;
                map.FromMapPoint(gpiElem.CenterPoint,ref clientCenterX,ref clientCenterY);
                clientRadius = map.FromMapDistance(gpiElem.Radius);

             //注意，创建Graphic必须使用System.Drawing.Graphics.FromHdc

                Graphics gpArc = System.Drawing.Graphics.FromHdc(hDC);
                Pen pen = new Pen(Color.Black,1);
                pen.EndCap    = System.Drawing.Drawing2D.LineCap.ArrowAnchor;
                pen.StartCap    = System.Drawing.Drawing2D.LineCap.RoundAnchor;
                gpArc.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                //draw pie
                System.Drawing.Rectangle rectangle = new System.Drawing.Rectangle((int)(clientCenterX-clientRadius),
                 (int)(clientCenterY -clientRadius),(int)clientRadius*2,(int)clientRadius*2); 

                gpArc.DrawPie(pen,rectangle,gpiElem.StartAngle,gpiElem.SweepAngle);

                //draw index
               //              Font ft    = new Font("Tahoma",10);//(this.Font.Name,this.Font.Size);//,FontStyle.Bold);
                //                 gpArc.DrawString(gpiElem.Index.ToString(),ft,new SolidBrush(Color.Black),(int)(clientCenterX - 5),(int)clientCenterY);

            }
        }