c# - 如何更改图表系列颜色

Question

我有一个系列，它用数据库中的记录填充我的图表。显示了 7 条记录，但颜色相同。

我试图更改每个条形颜色但没有成功

下面是我试过的行，但我给了我一个大的绿色条(:

        private void button1_Click(object sender, EventArgs e)
    {
        /*First empty the chart2 to fire the current data*/
        if (cbChart.SelectedItem == null)
        {
            chart.Visible = false;
            chart.Controls.Clear();
        }
        else
            //pnchart.Controls.Clear();
        chart.Visible = true;
        chart.Titles.Clear();


        /*Add a new title*/
        Title bezeichung = new Title("Finance" + Environment.NewLine + "(GWU)", Docking.Top, new Font("Yu Gothic", 8, FontStyle.Bold), Color.Black);
        chart.Titles.Add(bezeichung);          
        chart.Titles.Add(bezeichung2);



         if (cbChart.SelectedItem != null)
        {
      string S =    ConfigurationManager.ConnectionStrings[""].ConnectionString;
      SqlConnection con = new SqlConnection(S);
      SqlCommand cmd = new SqlCommand();
      cmd.Connection = con;
      cmd.CommandType = CommandType.StoredProcedure;
      cmd.CommandText = ("[dbo].[storedprocedure]");
      cmd.Parameters.AddWithValue("@Table_Name", cbChart.SelectedValue.ToString());
      SqlDataReader myReader;  // DataReader to just read Data from the Datbase

            try
            {
                //DO SOMETHING
                con.Open();
                myReader = cmd.ExecuteReader();

                while (myReader.Read())
                {

                   //Parameters (Seriesname, x-axis data & y-axis data)
                    this.chart.Series["Series"].Points.AddXY(myReader["Finance"], myReader["GWU"]);

                    // remove grid lines
                    chart.ChartAreas[0].AxisX.MajorGrid.LineWidth = 0;
                    chart.ChartAreas[0].AxisY.MajorGrid.LineWidth = 0;
                    chart.ChartAreas[0].AxisX.LabelStyle.Angle = -45;

      chart.Series["series1"].Points[0].Color = Color.Green;
      chart.Series["series1"].Points[1].Color = Color.Red;
      chart.Series["series1"].Points[2].Color = Color.PowderBlue;
      chart.Series["series1"].Points[3].Color = Color.Peru;
      chart.Series["series1"].Points[4].Color = Color.Pink;
      chart.Series["series1"].Points[5].Color = Color.Purple;
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                con.Close();
            }
        }

         else
         {

MessageBox.Show("Bitte ", "Info", MessageBoxButtons.OK, MessageBoxIcon.Warning);
         }

    }

这是我运行后收到的错误信息:索引超出有效范围，索引不能为负且必须小于列表的大小

点击按钮后的图表:

Answer 1

您正试图在将点添加到系列之前更改点的颜色。将下面的 block 移出 while 循环，并在尝试按索引访问之前检查系列中是否存在足够的点，

  chart.Series["series1"].Points[0].Color = Color.Green;
  chart.Series["series1"].Points[1].Color = Color.Red;
  chart.Series["series1"].Points[2].Color = Color.PowderBlue;
  chart.Series["series1"].Points[3].Color = Color.Peru;
  chart.Series["series1"].Points[4].Color = Color.Pink;
  chart.Series["series1"].Points[5].Color = Color.Purple;

以下是您需要在代码中进行的更改，

while (myReader.Read())
{
//Parameters (Seriesname, x-axis data & y-axis data)
this.chart.Series["Series"].Points.AddXY(myReader["Finance"], myReader["GWU"]);

}

if(chart.ChartAreas.Count > 0)
{
chart.ChartAreas[0].AxisX.MajorGrid.LineWidth = 0;
chart.ChartAreas[0].AxisY.MajorGrid.LineWidth = 0;
chart.ChartAreas[0].AxisX.LabelStyle.Angle = -45;
}


if(chart.Series["series1"].Points.Count > 5)
{
chart.Series["series1"].Points[0].Color = Color.Green;
chart.Series["series1"].Points[1].Color = Color.Red;
chart.Series["series1"].Points[2].Color = Color.PowderBlue;
chart.Series["series1"].Points[3].Color = Color.Peru;
chart.Series["series1"].Points[4].Color = Color.Pink;
chart.Series["series1"].Points[5].Color = Color.Purple;
}