using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;

namespace ReNamefolder
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private int percentNum = 0;
private void Form1_Paint(object sender, PaintEventArgs e)
{
PaintPercent(e.Graphics, percentNum);
}

public void PaintPercent(Graphics g, double valueY)
{
double temlX = doSomething(50, valueY); //开方获取x方向的距离
double myRadians = Math.Atan2(valueY, temlX);
// 把弧度单位转化为角度单位
double myDegrees = myRadians * 180 / Math.PI;

double starX = temlX;
double starY = -valueY;

double rotationNum = 180;
rotationNum += myDegrees * 2;

double startAngle = -myDegrees;

SolidBrush redBrush123 = new SolidBrush(Color.Beige);
g.FillEllipse(redBrush123, new Rectangle(0, 0, 100, 100));

GraphicsPath path = new GraphicsPath();

path.AddArc(0, 0, 100, 100, (float)startAngle, (float)rotationNum);
SolidBrush redBrush = new SolidBrush(Color.Red);

g.FillPath(redBrush, path);

}

private double doSomething(double rV, double hV)
{
return Math.Sqrt(Math.Pow(rV, 2) - Math.Pow(hV, 2));

}

private void trackBar1_Scroll(object sender, EventArgs e)
{
textBox1.Text = trackBar1.Value.ToString();

percentNum = trackBar1.Value - 50;

this.Refresh();
}
}
}

C#画百分比水平球图形