如何在C＃中的图表上放置以对数表示的行的对数刻度 [英] How to put a logarithmic scale with rows represented in logarithm on chart in C #

问题描述

我正在用C＃开发图表，我需要图形线以对数表示，刻度已经可以放了，只是根据下图缺少对数刻度的垂直线：

我的图表当前如下所示：

解决方案

更新：

要获得两个周期之间的额外线条，您需要为图表区域的x轴打开MinorGrid：

  chart.ChartAreas [0] .AxisX.MinorGrid.Enabled = true; 
 chart.ChartAreas [0] .AxisX.MinorGrid.Interval = 1; 
  

这显然比我自己画画容易得多，因为我认为这很必要。 >

不过，我将所有者自定义的解决方案留在下面，因为它在做额外的特殊操作（例如使用不常用的笔或自定义间隔）时可能很有用。

（我很高兴看到结果相同：-）

  private void chart_PrePaint（对象发送方， e）
 {
 ChartArea ca = chart.ChartAreas [0]; 
 Graphics g = e.ChartGraphics.Graphics; 
 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias; 
 
 //首先获取y的最高值和最低值：
 int y0 =（int）ca.AxisY.ValueToPixelPosition（ca.AxisY.Minimum）; 
 int y1 =（int）ca.AxisY.ValueToPixelPosition（ca.AxisY.Maximum）; 
 
 int iCount = 10; //每个周期的网格线数
 var xes = new List< double>（）; //网格位置值
 double xx = ca.AxisX.Minimum; 
 do {
 xx * = ca.AxisX.LogarithmBase; //下一个周期
 double delta = 1d * xx / iCount; //此时间段内的距离
 for（int i = 1; i< icount; i ++）xes.Add（i * delta）; //收集值
} while（xx< ca.AxisX.Maximum）; 
 
 //现在我们可以绘制.. 
使用（钢笔=​​新的Pen（Color.FromArgb（64，Color.Blue））
 {DashStyle = System.Drawing。 Drawing2D.DashStyle.Dot}）
 foreach（xes中的var xv）
 {
 float x =（float）ca.AxisX.ValueToPixelPosition（xv）; 
 g.DrawLine（pen，x，y0，x，y1）; 
} 
} 
  

您可以缓存x值列表，但可以

请注意，当收集网格停止值时，我们从1开始计数，因为我们不想加倍一个时期的起点： 1..9 + 10..90 等。因此，我们实际上只添加了 count-1 网格停止。.

I'm developing a chart in C # and I need the graph lines to be represented in logarithm, the scale can already put, just missing the vertical lines in logarithmic scale according to the image below:

My chart currently looks like this:

解决方案

Update:

To get those additional lines between the periods you need to turn on the MinorGrid for the x-axis of your chartArea:

chart.ChartAreas[0].AxisX.MinorGrid.Enabled = true;
chart.ChartAreas[0].AxisX.MinorGrid.Interval = 1;

This is obviosly a lot easier than drawing them yourself, as I thought was necessary..

I leave the owner-drawn solution below, though, as it may be useful when doing extra special stuff, like using unsusual pens or customizing the intervals..

(And I was glad to see that the results are identical :-)

Old solution with owner-drawn GridLines:

Here is how you can owner-draw the gridlines for a logarithmic axis.

To define the interval rules I first collect a List of double values for the stop values. along the x-axis.

Here is an example using 10 gridlines in each period..

The chart's x-axis was set up with Minimum = 0.1d and Maximum = 1000.

private void chart_PrePaint(object sender, ChartPaintEventArgs e)
{
    ChartArea ca = chart.ChartAreas[0];
    Graphics g = e.ChartGraphics.Graphics;
    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

    // first get y top and bottom values:
    int y0 = (int)ca.AxisY.ValueToPixelPosition(ca.AxisY.Minimum);
    int y1 = (int)ca.AxisY.ValueToPixelPosition(ca.AxisY.Maximum);

    int iCount = 10;                         // number of gridlines per period
    var xes = new List<double>();            // the grid position values
    double xx = ca.AxisX.Minimum;
    do {
       xx *= ca.AxisX.LogarithmBase;         // next period
       double delta = 1d * xx / iCount ;     // distance in this period
       for (int i = 1; i < icount; i++) xes.Add(i * delta);  // collect the values
    }  while (xx < ca.AxisX.Maximum);

    // now we can draw..
    using (Pen pen = new Pen(Color.FromArgb(64, Color.Blue))
          {DashStyle = System.Drawing.Drawing2D.DashStyle.Dot} )
       foreach (var xv in xes)
       {
           float x = (float)ca.AxisX.ValueToPixelPosition(xv);
           g.DrawLine(pen, x, y0, x, y1);
       }
}

You could cache the x-values list but would have to re-calculate whenever the data or the axis view changes..

Note that, when collection the grid stop values, we count from 1 because we don't want to double the starting points of a period: 1..9 + 10..90 etc. So we actually add only count-1 grid stops..

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