Chart: Vertical line and string on X label

Question

I am using WinForms to create a line chart. I have two related questions:

1. How can I draw a vertical line on the chart?

   I have tried to draw a vertical line between two points at (0,0) and (0,5) using:

   chart1.Series["Pakistan"].Points.AddXY(0, 0);
   chart1.Series["Pakistan"].Points.AddXY(0, 5);
   

   However, I get an askew line from (0,0) to (1,5).

2. How can I label this line with a string on the X axis?

Answer 1

您可以使用 aStripLine在 x 轴上显示一条垂直线：

StripLine stripLine = new StripLine();
stripLine.Interval = 0; // only show 1 line
stripLine.Offset = 0; // start it at x=0
stripLine.StripWidth = 1; // the width is 1
// set colors, etc
chart1.ChartAreas["Default"].AxisX.StripLines.Add(stripLine);

您还可以创建第二系列 type RangeColumn，它在每个 x 值处接收 2 个 y 值，以创建垂直线：

Series lineSeries = chart1.Series.Add("line");
lineSeries.ChartType = RangeColumn;
lineSeries.Points.AddXY(0, new []{0, 1});
// Set line widths, colors, etc

最后，您可以使用`Graphics 对象处理绘制线条的PostPaint事件Chart：

private void chart1_PostPaint(object sender, ChartPaintEventArgs e)
{
  if(sender is ChartArea)
  {

    ChartArea area = (ChartArea)sender;
    if(area.Name == "Default")
    {
        // Get Graphics object from chart
        Graphics graph = e.ChartGraphics.Graphics;

        // Convert X and Y values to screen position
        float pixelYMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,1);
        float pixelXMax = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,0);
        float pixelYMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.Y,0);
        float pixelXMin = (float)e.ChartGraphics.GetPositionFromAxis("Default",AxisName.X,0);

        PointF point1 = PointF.Empty;
        PointF point2 = PointF.Empty;

        // Set Maximum and minimum points
        point1.X = pixelXMax;
        point1.Y = pixelYMax;
        point2.X = pixelXMin;
        point2.Y = pixelYMin;

        // Convert relative coordinates to absolute coordinates.
        point1 = e.ChartGraphics.GetAbsolutePoint(point1);
        point2 = e.ChartGraphics.GetAbsolutePoint(point2);

        // Draw connection line
        graph.DrawLine(new Pen(Color.Yellow,3), point1,point2);
    }
  }
}

处理PostPaint可能是最好的选择，它将让您最好地控制您的线路及其外观。