在數字貨幣或者股票看盤交易軟體中，為了方便準確定位K線圖中的時間和買賣點，都用到了用十字交叉線來定位買賣時間和買賣點。這裡利用.Net下開源的NPlot圖表外掛，實現了跟著滑鼠移動的十字定位交叉線，並能做到根據螢幕座標轉化為時間和買賣點座標。這裡通過在K線圖上雙擊建立交叉十字線，十字線跟著滑鼠移動而移動，並且實時獲取移動的位置。效果如下：
主要程式碼實現包括PlotSurface2D（PlotSurface2D為NPlot控制元件中的容器類）建立及初始化、PlotSurface2D滑鼠雙擊及移動的事件繫結及程式碼實現，HorizontalLine橫線、VerticalLine豎線的宣告和建立。詳細程式碼如下：PlotSurface2D的宣告及初始化：

private NPlot.Windows.PlotSurface2D KLinePS;

 private void InitKLinePS()
        {
            KLinePS = new NPlot.Windows.PlotSurface2D();
            this.KLinePS.AutoScaleAutoGeneratedAxes = true;
            this.KLinePS.AutoScaleTitle = false;
            this.KLinePS.DateTimeToolTip = true;
            this.KLinePS.DateTimeToolTip = true;
            this.KLinePS.Legend = null;
            this.KLinePS.LegendZOrder = -1;
            this.KLinePS.Location = new System.Drawing.Point(0, 0);
            this.KLinePS.Name = "costPS";
            this.KLinePS.RightMenu = null;
            this.KLinePS.Padding = 1;
           
            //滑鼠tooltips 時間+價格
            this.KLinePS.ShowCoordinates = true;
            this.KLinePS.Size = new System.Drawing.Size(969, 595);
            this.KLinePS.Width = 1300;
            this.KLinePS.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
            this.KLinePS.TabIndex = 2;
            this.KLinePS.Title = "123";
            this.KLinePS.TitleFont = new System.Drawing.Font("Arial", 14F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Pixel);

        }
 

HorizontalLine橫線、VerticalLine豎線的宣告，這裡只是宣告，具體的建立包括在滑鼠雙擊事件中： 

VerticalLine lineCrossX;// = new VerticalLine(10);
        HorizontalLine lineCrossY;// = new HorizontalLine(10);

滑鼠事件的繫結： 

 KLinePS.MouseMove += new System.Windows.Forms.MouseEventHandler(KLinePS_MouseMove);
            KLinePS.MouseDoubleClick += new System.Windows.Forms.MouseEventHandler(KLinePS_MouseDoubleClick);
 

滑鼠雙擊事件的實現：

private void KLinePS_MouseDoubleClick(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            System.Drawing.Point here = new System.Drawing.Point(e.X, e.Y);
            //螢幕座標轉化為業務座標
            double x = this.KLinePS.PhysicalXAxis1Cache.PhysicalToWorld(here, true);
            double y = this.KLinePS.PhysicalYAxis1Cache.PhysicalToWorld(here, true);
            DateTime dateTime = new DateTime((long)x);
            //水平線建立
            lineCrossY = new HorizontalLine(y);
            lineCrossY.LengthScale = 0.89f;
            lineCrossY.OrdinateValue = y;
            lineCrossY.Pen = Pens.Green;
            //line.OrdinateValue = 2;
            this.KLinePS.Add(lineCrossY);
            ////  ///////垂直線///////////
            lineCrossX = new VerticalLine(x);
            lineCrossX.LengthScale = 0.89f;
            lineCrossX.Pen = Pens.Red;
            lineCrossX.AbscissaValue = x;
            this.KLinePS.Add(lineCrossX);            
            this.KLinePS.Refresh();
        }
 

滑鼠移動事件的實現：

private void KLinePS_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            if (this.KLinePS.PhysicalXAxis1Cache == null || this.KLinePS.PhysicalYAxis1Cache == null)
                return;
            System.Drawing.Point here = new System.Drawing.Point(e.X, e.Y);
            double x = this.KLinePS.PhysicalXAxis1Cache.PhysicalToWorld(here, true);
            double y = this.KLinePS.PhysicalYAxis1Cache.PhysicalToWorld(here, true);
            if (lineCrossY != null && lineCrossX != null)
            {
                lineCrossY.OrdinateValue = y;
                lineCrossX.AbscissaValue = x;
            }
            this.KLinePS.Refresh();
        }