C#实现网页画图功能

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
 
public partial class _Default : System.Web.UI.Page
{
  int h = 1000;
  int w = 1000;
  protected void Page_Load(object sender, EventArgs e)
  {
    Bitmap img = new Bitmap(h, w);//创建Bitmap对象
    MemoryStream stream = draw();
 
    img.Save(stream, ImageFormat.Jpeg);     //保存绘制的图片
    Response.Clear();
    Response.ContentType = "image/jpeg";
    Response.BinaryWrite(stream.ToArray());
  }
 
  public MemoryStream draw()
  {
    string[] Words = {"壹","贰","叁","肆","伍","陆"};
    Bitmap img = new Bitmap(h, w);//创建Bitmap对象
    Graphics g = Graphics.FromImage(img);//创建Graphics对象
    g.DrawRectangle(new Pen(Color.White, img.Height), 2, 2, img.Width - 2, img.Height - 2); //矩形 底色
 
 
    ArrayList coordinate = getXY(Words.Length,img.Height,img.Width);
    ArrayList Radius = new ArrayList();
 
    var R = new Random();
    Color Mycolor = Color.FromArgb(R.Next(100, 150), R.Next(255), R.Next(255), R.Next(255));
 
    Font font = new Font("Arial", 20);// 字体
    LinearGradientBrush font_brush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Black, Color.Black, 1.2F, true);
 
    int j = 0;
    //画圆 写字
    foreach (Point p in coordinate)
    {
      int r = R.Next(20, 40);
      Radius.Add(r);
      SolidBrush bush = new SolidBrush(Mycolor);
      g.FillEllipse(bush, p.X - r, p.Y - r, 2*r, 2*r);//画填充椭圆的方法，x坐标、y坐标、宽、高：
 
      g.DrawString(Words[j++], font, font_brush, p); // 标记
    }
 
    //连线
    var penColor = Color.FromArgb(140, R.Next(255), R.Next(255), R.Next(255));
    for (int i = 1; i < coordinate.Count; i++) 
    {
      Pen pen = new Pen(penColor, 2);
      g.DrawLine(pen, (Point)coordinate[0], (Point)coordinate[i]);
    }
    
    MemoryStream stream = new MemoryStream();  //保存绘制的图片
    img.Save(stream, ImageFormat.Jpeg);     //保存绘制的图片
    return stream;
  }
 
  private ArrayList getXY(int len, int h, int w) 
  {
    ArrayList al = new ArrayList();
    double d = 50.0;
    var R = new Random();
    int h2 = (int)(0.1 * h);
    int h3 = (int)(0.9 * h);
    int w1 = (int)(0.1 * w);
    int w2 = (int)(0.9 * w);
 
    while (al.Count < len) 
    {
      Point p = new Point(R.Next(h2,h3), R.Next(w1,w2));
      bool Add = true;
      foreach (Point q in al) 
      {
        if (Dist(p, q) < d)
        {
          Add = false;
          break;
        }
      }
      if (Add)
        al.Add(p);
 
    }
 
    return al;
  }
 
  private double Dist(Point p1,Point p2) 
  {
    return Math.Sqrt(Math.Abs(p1.X - p2.X) * Math.Abs(p1.X - p2.X) + Math.Abs(p1.Y - p2.Y) * Math.Abs(p1.Y - p2.Y));
  }
}