如何仅获取可见曲线数据的PointPairList,而不是Curveitem列表中的所有点?该列表应在缩放或平移时动态更改。
谢谢。
看起来没有一个ZedGraph API方法可以为您完成这项工作。但是,下面的代码演示了一个VisiblePoints方法,它返回一个PointPairList,并在一个非常特定的ZedGraph使用情况下工作。
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using ZedGraph;
namespace ZedGraphMain
{
public class ZedGraphDemo : Form
{
public ZedGraphDemo()
{
var graphControl = new ZedGraphControl();
graphControl.Dock = DockStyle.Fill;
graphControl.IsShowPointValues = true;
Controls.Add(graphControl);
var points = new PointPairList();
for (double i = 0; i <= 5.0; i += 1)
points.Add(i, i);
var curve = graphControl.GraphPane.AddCurve("A Label", points, Color.ForestGreen);
graphControl.RestoreScale(graphControl.GraphPane);
graphControl.ZoomEvent += (_, __, ___) => LogVisibility(graphControl, curve, points);
}
private static PointPairList VisiblePoints(ZedGraphControl control, LineItem lineItem, PointPairList points)
{
var pointPairList = new PointPairList();
pointPairList.AddRange(points.Where(pp => IsVisible(control, lineItem, pp)).ToList());
return pointPairList;
}
private static bool IsVisible(ZedGraphControl control, LineItem lineItem, PointPair point)
{
GraphPane pane = control.GraphPane;
Scale xScale = lineItem.GetXAxis(pane).Scale;
Scale yScale = lineItem.GetYAxis(pane).Scale;
return point.X > xScale.Min && point.X < xScale.Max && point.Y > yScale.Min && point.Y < yScale.Max;
}
private static void LogVisibility(ZedGraphControl control, LineItem lineItem, PointPairList points)
{
List<PointPair> visiblePoints = VisiblePoints(control, lineItem, points);
Console.Out.WriteLine(DateTime.Now + ": " + string.Join(",", visiblePoints.Select(pp => string.Format("({0:N1}, {1:N1})", pp.X, pp.Y))));
}
}
}
我相信PointPairList始终包含所有点。
绘制的点总是存在的,只是它们如何随着缩放和平移而转换为像素。
我知道我需要为大数据集创建自己的AverageFilteredList。我有成千上万的点,由于内存使用而导致应用程序停滞不前(实现已删除以简洁为要):
public class AverageFilteredPointList : IPointList
{
<snip>
public int Count { get; set; }
public int MaxPts { get; set; }
public PointPair this[int index] { get; set; }
public void SetBounds(double min, double max, int maxPts) { }
}
如果您想收集可见的“点”信息,我认为您将不得不实现自己的IPointList类,以处理其自身内部点的缩放/平移。
此外,我不确定这是否会对您有所帮助,但您可以使用以下GraphPane函数来确定像素位置所在的实际DataPoint:
ReverseTransform(pt, out xSampleData, out ySampleData);