C＃ - 如何在图表或其他控件上绘制线条

Question

我想在图表上的2个点之间绘制一条线，但我不能使用ChartStyle.Line，所以我尝试使用Graphics.DrawLine。

我的问题是我无法在图表上绘图。 我怎么解决这个问题？

        PointF pontoantigo = new PointF();

            if (chart1.Series[0].Points.Count > 0)
            {
                 pontoantigo = new PointF((int)chart1.Series[0].Points[0].XValue, (int)chart1.Series[0].Points[0].YValues[0]);
            }


            chart1.Series[0].Points.Clear();

            chart1.Series[0].Points.AddXY(posicao_atual_master.X, posicao_atual_master.Y);
            PointF pontoatual = new PointF((int)chart1.Series[0].Points[0].XValue, (int)chart1.Series[0].Points[0].YValues[0]);

            Pen p = new Pen(Color.Red);
            Graphics g = chart1.CreateGraphics();
            g.DrawLine(p, pontoantigo, pontoatual);

编辑：

功能更新旧点和新点的值：

  pontoantigo = new PointF();
            if (chart1.Series[0].Points.Count > 0)
            {
                pontoantigo = new PointF((int)chart1.Series[0].Points[0].XValue, (int)chart1.Series[0].Points[0].YValues[0]);
            }


            chart1.Series[0].Points.Clear();

            chart1.Series[0].Points.AddXY(posicao_atual_master.X, posicao_atual_master.Y);
            pontoatual = new PointF((int)chart1.Series[0].Points[0].XValue, (int)chart1.Series[0].Points[0].YValues[0]);

POSTPAINT：

   private void chart1_PostPaint(object sender, ChartPaintEventArgs e)
    {

        Pen p = new Pen(Color.Red);
        Graphics g = e.ChartGraphics.Graphics;
        g.DrawLine(p, pontoantigo, pontoatual);

    }

还是行不通

Answer 1

您可以使用此函数将DataPoints转换为绘图Points ：

Point PointFromDataPoint(Chart chart, ChartArea ca, DataPoint pt)
{
    Axis ax = chart2.ChartAreas[0].AxisX;
    Axis ay = chart2.ChartAreas[0].AxisY;
    int x = (int)ax.ValueToPixelPosition(pt.XValue);                    
    int y = (int)ay.ValueToPixelPosition(pt.YValues[0]);
    return new Point(x, y);
}

如果您设置了两个DataPoints （!!） pontoantigo和pontoatual您可以编写PrePaint事件：

private void chart1_PrePaint(object sender, ChartPaintEventArgs e)
{
    using (Pen pen = new Pen(Color.Green, 2f))
        e.ChartGraphics.Graphics.DrawLine(pen,
            PointFromDataPoint(chart1, chart1.ChartAreas[0], pontoantigo),
            PointFromDataPoint(chart1, chart1.ChartAreas[0], pontoatual));
}

这是结合这个小帖子和设置两个DataPoints的结果，如下所示：

 DataPoint pontoantigo = chart1.Series[0].Points.First();
 DataPoint pontoatual  = chart1.Series[0].Points.Last();