C#窗体程序画倾斜一定角度的椭圆

　　using System;
　　using System.Collections.Generic;
　　using System.ComponentModel;
　　using System.Data;
　　using System.Drawing;
　　using System.Drawing.Drawing2D;
　　using System.Linq;
　　using System.Text;
　　using System.Threading.Tasks;
　　using System.Windows.Forms;
　　namespace Ellipse
　　{
　　public partial class Form1 : Form
　　{
　　PointF xyPoint = new PointF(); //左上角的X，Y坐标
　　PointF centerPoint = new PointF();//椭圆的中心点
　　PointF movePoint = new PointF();
　　PointF xiePointF=new PointF();
　　PointF xiedPointF = new PointF();//倾斜一定角度后的点
　　private double perAngle = 0;
　　private double nowAngle;
　　PointF[] pointFs=new PointF[201];
　　PointF[] pointFs1=new PointF[201];//与pointFs对称的点数组，椭圆是对称的
　　PointF[] xiePointFs=new PointF[201];//倾斜的椭圆上半部分
　　PointF[] xiePointFs1 = new PointF[201];//倾斜的椭圆下半部分，对称的部分
　　private float a =200;
　　private float b =100;
　　private float stepLength = 2;//通过X坐标逐次加2计算出Y坐标，将所有坐标存在数组中，用DrawCurve连接
　　private float xLength = 0;//点到坐标Y轴的线段距离
　　private float yLength = 0;//颠倒坐标X轴的线段距离
　　private float dbYlength = 0;
　　private float xiedLength = 0;//点到椭圆中心点的线段长度
　　private int angle = 0;//倾斜的角度
　　public Form1()
　　{
　　InitializeComponent();
　　}
　　private void panel1_Paint(object sender， PaintEventArgs e)
　　{
　　}
　　private void panel1_MouseClick(object sender， MouseEventArgs e)////画布鼠标键点击事件，重画图形
　　{
　　if (e.Button != MouseButtons.Left)
　　{
　　return;
　　}
　　if (this.textBox1.Text == "")
　　{
　　this.errorProvider1.SetError(this.textBox1， "请输入倾斜的角度");
　　return;
　　}
　　else
　　{
　　this.errorProvider1.SetError(this.textBox1， "");
　　}
　　xyPoint.X = this.panel1.Width/2-200;
　　xyPoint.Y = this.panel1.Height/2-100;
　　centerPoint.X = xyPoint.X + a;
　　centerPoint.Y = xyPoint.Y + b;
　　Graphics graphics = this.panel1.CreateGraphics();
　　graphics.SmoothingMode = SmoothingMode.HighQuality;
　　graphics.Clear(this.panel1.BackColor);
　　Pen pen = new Pen(Color.Red);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　movePoint.X = index * stepLength + xyPoint.X;
　　xLength = centerPoint.X - movePoint.X;
　　yLength = (float)(Math.Sqrt((1 - (xLength * xLength) / 40000) * 10000));
　　movePoint.Y = b - yLength + xyPoint.Y;
　　pointFs[index] = movePoint;
　　}
　　graphics.DrawCurve(pen， pointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　dbYlength = centerPoint.Y - pointFs[index].Y;
　　pointFs1[index].Y = centerPoint.Y + dbYlength;
　　pointFs1[index].X = pointFs[index].X;
　　}
　　graphics.DrawCurve(pen， pointFs1， 1.5f);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　xiePointF = pointFs[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　xiePointF = pointFs1[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs1[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs1， 1.5f);
　　}
　　private void button1_Click(object sender， EventArgs e)//倾斜角度，每次递增10度
　　{
　　angle += 10;
　　this.textBox1.Text = angle.ToString();
　　if (this.textBox1.Text == "")
　　{
　　this.errorProvider1.SetError(this.textBox1， "请输入倾斜的角度");
　　return;
　　}
　　else
　　{
　　this.errorProvider1.SetError(this.textBox1， "");
　　}
　　xyPoint.X = this.panel1.Width / 2-200;
　　xyPoint.Y = this.panel1.Height / 2-100;
　　centerPoint.X = xyPoint.X + a;
　　centerPoint.Y = xyPoint.Y + b;
　　Graphics graphics = this.panel1.CreateGraphics();
　　graphics.SmoothingMode = SmoothingMode.HighQuality;
　　graphics.Clear(this.panel1.BackColor);
　　Pen pen = new Pen(Color.Red);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　movePoint.X = index * stepLength + xyPoint.X;
　　xLength = centerPoint.X - movePoint.X;
　　yLength = (float)(Math.Sqrt((1 - (xLength * xLength) / 40000) * 10000));
　　movePoint.Y = b - yLength + xyPoint.Y;
　　pointFs[index] = movePoint;
　　}
　　graphics.DrawCurve(pen， pointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　dbYlength = centerPoint.Y - pointFs[index].Y;
　　pointFs1[index].Y = centerPoint.Y + dbYlength;
　　pointFs1[index].X = pointFs[index].X;
　　}
　　graphics.DrawCurve(pen， pointFs1， 1.5f);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　xiePointF = pointFs[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　xiePointF = pointFs1[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs1[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs1， 1.5f);
　　}
　　private void button2_Click(object sender， EventArgs e)//倾斜角度，每次递减10度
　　{
　　angle -= 10;
　　this.textBox1.Text = angle.ToString();
　　if (this.textBox1.Text == "")
　　{
　　this.errorProvider1.SetError(this.textBox1， "请输入倾斜的角度");
　　return;
　　}
　　else
　　{
　　this.errorProvider1.SetError(this.textBox1， "");
　　}
　　xyPoint.X = this.panel1.Width / 2-200;
　　xyPoint.Y = this.panel1.Height / 2-100;
　　centerPoint.X = xyPoint.X + a;
　　centerPoint.Y = xyPoint.Y + b;
　　Graphics graphics = this.panel1.CreateGraphics();
　　graphics.SmoothingMode = SmoothingMode.HighQuality;
　　graphics.Clear(this.panel1.BackColor);
　　Pen pen = new Pen(Color.Red);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　movePoint.X = index * stepLength + xyPoint.X;
　　xLength = centerPoint.X - movePoint.X;
　　yLength = (float)(Math.Sqrt((1 - (xLength * xLength) / 40000) * 10000));
　　movePoint.Y = b - yLength + xyPoint.Y;
　　pointFs[index] = movePoint;
　　}
　　graphics.DrawCurve(pen， pointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　dbYlength = centerPoint.Y - pointFs[index].Y;
　　pointFs1[index].Y = centerPoint.Y + dbYlength;
　　pointFs1[index].X = pointFs[index].X;
　　}
　　graphics.DrawCurve(pen， pointFs1， 1.5f);
　　for (int index = 0; index < pointFs.Length; index++)
　　{
　　xiePointF = pointFs[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs， 1.5f);
　　for (int index = 0; index < pointFs1.Length; index++)
　　{
　　xiePointF = pointFs1[index];
　　double startAngle = Math.Atan2(xiePointF.Y - centerPoint.Y， xiePointF.X - centerPoint.X);
　　string jiaodu = this.textBox1.Text;
　　perAngle = int.Parse(jiaodu) * Math.PI / 180;
　　nowAngle = startAngle + perAngle;
　　xiedLength = (float)Math.Sqrt(Math.Pow(xiePointF.X - centerPoint.X， 2) + Math.Pow(xiePointF.Y - centerPoint.Y， 2));
　　xiedPointF.X = centerPoint.X - (float)(xiedLength * Math.Cos(nowAngle));
　　xiedPointF.Y = centerPoint.Y + (float)(xiedLength * Math.Sin(nowAngle));
　　xiePointFs1[index] = xiedPointF;
　　}
　　graphics.DrawCurve(pen， xiePointFs1， 1.5f);
　　}
　　private void textBox1_TextChanged(object sender， EventArgs e)//输入倾斜的角度
　　{
　　angle = int.Parse(this.textBox1.Text);
　　}
　　}
　　}