学会用C#文件读取的shp（shapefile格式）文件并在窗口绘制

【实例截图】

【核心代码】

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;
namespace frmform
{
    public partial class frmform : Form
    {
        public frmform()
        {
            InitializeComponent();
        }
        string path;
        Graphics gc = null;
        polygonfile pg = new polygonfile();
        private void btnopen_Click(object sender, EventArgs e)
        {
            OpenFileDialog openflg = new OpenFileDialog();
            openflg.Filter = "*.shp|*.SHP";
            openflg.Multiselect = false;
            if (openflg.ShowDialog() == DialogResult.OK)
            {
                path = openflg.FileName;
                txtaddress.Text = path;
            }
            string s = pg.readfile(path);
            txtshow.Text = "共有多边形"   pg.PolygonNumber  "\n\t"  s;
            draw();
            
        }

        private void frmform_Load(object sender, EventArgs e)
        {
            gc = this.panel.CreateGraphics();

        }
        public void draw()
        {
            for (int i = 0; i < pg.PolygonNumber; i  )
            {
                PointF[] ps = pg.mpys[i].polygon.ToArray();
                pt(ps);
                gc.DrawPolygon(Pens.Red, ps);
            }
        }
        public void pt(params PointF[] pt)
        {
            for (int i = 0; i < pt.Length; i  )
            {
                pt[i].X = (float)((pt[i].X - pg.HBoundingBox[0]) / (pg.HBoundingBox[2] - pg.HBoundingBox[0]) * this.panel.Width);
                pt[i].Y = (float)((pg.HBoundingBox[3] - pt[i].Y) / (pg.HBoundingBox[3] - pg.HBoundingBox[1]) * this.panel.Height);
            }
        }
    }
}