放大缩小采样图

Question

我使用.NET Winform版本teechart 4.1.2012.1032。

我修改了您提供的示例。 “Extended \ Reducing Number of Points \ DownSampling Additions” 但是，当我放大图表时，fastline的标记计数不是100，downSampling.DisplayedPointCount。 我该如何解决它？

private void InitializeChart() 
    { 
     this.cursorTool1 = new Steema.TeeChart.Tools.CursorTool();// 
     this.tChart1.Tools.Add(this.cursorTool1);// 
     this.cursorTool1.FollowMouse = true;// 
     this.cursorTool1.Style = Steema.TeeChart.Tools.CursorToolStyles.Vertical;// 
     this.cursorTool1.Change += new Steema.TeeChart.Tools.CursorChangeEventHandler(this.cursorTool1_Change);// 

     CreateArrays(); 
     tChart1.Aspect.View3D = false; 
     tChart1.Zoom.Direction = ZoomDirections.Both;//.Horizontal;// 
     tChart1.Series.Add(points = new Steema.TeeChart.Styles.Points()); 
     tChart1.Series.Add(fastLine = new Steema.TeeChart.Styles.FastLine()); 

     downSampling = new Steema.TeeChart.Functions.DownSampling(tChart1.Chart); 
     points.Add(xValues, yValues); 
     points.Active = false; 

     downSampling.DisplayedPointCount = 100; 
     downSampling.Method = Steema.TeeChart.Functions.DownSamplingMethod.MinMaxFirstLast;// Null; 
     fastLine.TreatNulls = Steema.TeeChart.Styles.TreatNullsStyle.DoNotPaint; 
     fastLine.DataSource = points; 
     fastLine.Function = downSampling; 

     this.tChart1.Axes.Custom.Add(new Steema.TeeChart.Axis(this.tChart1.Chart));// 
     this.tChart1[1].CustomVertAxis = this.tChart1.Axes.Custom[0];// 
     this.tChart1[0].CustomVertAxis = this.tChart1.Axes.Custom[0];// 

     this.fastLine.Marks.Visible = true;// 
    } 

    private void CreateArrays() 
    { 
     int length = 2600000; 

     xValues = new Nullable<double>[length]; 
     yValues = new Nullable<double>[length]; 

     Random rnd = new Random(); 
     for (int i = 0; i < length; i++) 
     { 
      xValues[i] = i; 
      yValues[i] = i; 
     } 
    } 

    private void tChart1_Zoomed(object sender, EventArgs e) 
    { 
     tChart1[1].CheckDataSource(); //series 1 is the function series 
    } 

Answer 1

DisplayedPointCount指定了DownSampling函数应该绘制多少个点，并将该数字显示为最大点数。由于I explained here，您可能需要将它与Tolerance属性结合使用以获得您期望的结果。所以，你可以这样做：

public partial class Form1 : Form 
    { 
    public Form1() 
    { 
     InitializeComponent(); 
     InitializeChart(); 
    } 

    private void InitializeChart() 
    { 
     //tChart1.Dock = DockStyle.Fill; 
     tChart1.Aspect.View3D = false; 
     tChart1.Zoomed += tChart1_Zoomed; 

     Steema.TeeChart.Styles.Points points1 = new Steema.TeeChart.Styles.Points(tChart1.Chart); 

     Random y = new Random(); 
     for (int i = 0; i < 10000; i++) 
     { 
     points1.Add(DateTime.Now.AddHours(i), y.Next()); 
     } 

     points1.XValues.DateTime = true; 
     points1.Pointer.HorizSize = 1; 
     points1.Pointer.VertSize = 1; 

     Steema.TeeChart.Functions.DownSampling downSampling1 = new Steema.TeeChart.Functions.DownSampling(tChart1.Chart); 
     downSampling1.Method = Steema.TeeChart.Functions.DownSamplingMethod.Average; 
     downSampling1.Tolerance = 100; 
     downSampling1.DisplayedPointCount = Convert.ToInt32(downSampling1.Tolerance * 4); 

     Steema.TeeChart.Styles.Line line1 = new Steema.TeeChart.Styles.Line(tChart1.Chart); 
     line1.Function = downSampling1; 
     line1.DataSource = points1; 
     line1.Marks.Visible = true; 
     line1.Marks.Style = MarksStyles.PointIndex; 

     UpdateTitle(); 
    } 

    void tChart1_Zoomed(object sender, EventArgs e) 
    { 
     tChart1[1].CheckDataSource(); 
     UpdateTitle(); 
    } 

    private void UpdateTitle() 
    { 
     tChart1.Header.Text = (tChart1[1].Function as Steema.TeeChart.Functions.DownSampling).DisplayedPointCount.ToString(); 
    } 
    }