有没有办法在极坐标图上画点 [英] Is there a way to draw a Point on a Polar Chart

问题描述

我想在圆环和分段线之间的每个交叉处添加一个彩色点（红色或绿色）。有没有比制作只有两个数据点的240系列更简单的方法？

解决方案

1-无需创建其他 Series 。只需在所需位置添加所需的 DataPoints ！这是最简单的方法，因为您已经知道值了。

2-另一种方法是，可以使用 xxxPaint 事件并绘制实心圆（或您喜欢的任何一个..）。为此，您需要将值转换为像素。通常可以使用 AxisX / AxisY.ValueToPixelPosition 方法来实现。 但是对于极谱图，这将不起作用。取而代之的是，您需要自己计算像素坐标。

第二种方法比较难，但是当然可以让您更好地控制绘制点的样式..

这里是添加 DataPoints 的结果：

第一个版本的示例代码；首先，我们建立一个具有其轴属性的极坐标图：

 图表图= chart2; 
 chart.Series.Clear（）; 
 
 ChartArea ca = chart.ChartAreas [0]; 
 Axis ax = ca.AxisX; 
 Axis ay = ca.AxisY; 
 
轴，最小值= 0; 
轴，最大值= 360; 
 ax.Interval = 15; // 15°间隔
 ax.Crossing = 0; //从顶部开始细分！ 
 
 ay.Minimum = 0; 
 ay.Maximum = 10; 
 ay.Interval = 1; 
 
 
 Series s0 = chart.Series.Add（ points）; 
 s0.MarkerStyle = MarkerStyle.Circle; 
 s0.SetCustomProperty（ PolarDrawingStyle， Marker）; 
 s0.MarkerSize = 6; 
 s0.MarkerColor = Color.Teal; 
 s0.ChartType = SeriesChartType.Polar; 
  

然后我们在交叉口处添加点，最后对其中一个点进行样式设置以显示它们都可以会有所不同..：

 为（double vx = ax.Minimum; vx< ax.Maximum; vx + = ax。间隔）
 for（双vy = ay.Minimum; vy< = ay.Maximum; vy + = ay.Interval）
 s0.Points.AddXY（vx，vy）; 
 
 s0.Points [333] .MarkerColor = Color.Red; 
 s0.Points [333] .MarkerSize = 12; 
  

---

用于计算像素坐标的代码

或者，如果您不想首先添加 DataPoints ，您可以像在添加它们的循环中那样计算值来替换它们。

I want to add a colored point (red or green) on every "crossing" between the rings and segment lines. Is there a simpler way than making 240 Series which just have two datapoints?

解决方案

1 - There is no need to create different Series. Just add the DataPoints you want at the spots you want! This is the easiest way, since you already know the values.

2 - As an alternative you can use a xxxPaint event and draw filled circles (or whatever you fancy..). For this you need to convert the values to pixels. This can usually be achieved with the AxisX/AxisY.ValueToPixelPosition methods. However for Polar Charts this will not work. Instead you need to calculate the pixel coordinates yourself..

The 2nd way is a bit harder, but of course will give you more control over the style of the points you draw..

Here is the result of adding DataPoints:

Example code for the 1st version; first we set up a polar chart with its axis properties:

Chart chart = chart2;
chart.Series.Clear();

ChartArea ca = chart.ChartAreas[0];
Axis ax = ca.AxisX;
Axis ay = ca.AxisY;

ax.Minimum  = 0;
ax.Maximum  = 360;
ax.Interval = 15;   // 15° interval
ax.Crossing = 0;    // start the segments at the top!

ay.Minimum  = 0;
ay.Maximum  = 10;
ay.Interval = 1;


Series s0 = chart.Series.Add("points");
s0.MarkerStyle = MarkerStyle.Circle;   
s0.SetCustomProperty("PolarDrawingStyle", "Marker");
s0.MarkerSize = 6; 
s0.MarkerColor = Color.Teal;
s0.ChartType = SeriesChartType.Polar;

And then we add the points at the crossings and finally style one of them to show that they all can be different..:

for (double vx = ax.Minimum; vx < ax.Maximum; vx += ax.Interval)
    for (double vy = ay.Minimum; vy <= ay.Maximum; vy += ay.Interval)
        s0.Points.AddXY(vx, vy);

s0.Points[333].MarkerColor = Color.Red;
s0.Points[333].MarkerSize = 12;

---

For the code to calculate the pixel coordinates see this post!

Using the function in the link and this PrePaint event:

private void chart2_PrePaint(object sender, ChartPaintEventArgs e)
{
    Chart chart = chart2;
    ChartArea ca = chart.ChartAreas[0];
    Series s0 = chart.Series["points"];

    foreach (DataPoint dp in s0.Points)
    {
        PointF pt = PolarValueToPixelPosition(dp, chart, ca);
        e.ChartGraphics.Graphics.DrawEllipse(Pens.OrangeRed, pt.X - 5, pt.Y - 5, 9, 9);
    }
}

we can adorn each point with a circle:

Or course, if you don't want to add the DataPoints in the first place, you can replace them by calculating the values like I did in the loops that added them..

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