C＃ - 如何在圖表或其他控件上繪制線條

Question

我想在圖表上的2個點之間繪制一條線，但我不能使用ChartStyle.Line，所以我嘗試使用Graphics.DrawLine。

我的問題是我無法在圖表上繪圖。 我怎么解決這個問題？

        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);

編輯：

功能更新舊點和新點的值：

  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);

    }

還是行不通

Answer 1

您可以使用此函數將DataPoints轉換為繪圖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);
}

如果您設置了兩個DataPoints （!!） pontoantigo和pontoatual您可以編寫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));
}

這是結合這個小帖子和設置兩個DataPoints的結果，如下所示：

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