【C#】[窗体]圆形窗体(获取路径)

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 圆形窗体
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr BeginPath(IntPtr hdc);

        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern int SetBkMode(IntPtr hdc, int nBkMode);
        const int TRANSPARENT = 1;

        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr EndPath(IntPtr hdc);
        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern IntPtr PathToRegion(IntPtr hdc);

        [System.Runtime.InteropServices.DllImport("gdi32")]
        private static extern int Ellipse(IntPtr hdc, int X1, int Y1, int X2, int Y2);

        [System.Runtime.InteropServices.DllImport("user32")]
        private static extern IntPtr SetWindowRgn(IntPtr hwnd, IntPtr hRgn, bool bRedraw);

        [System.Runtime.InteropServices.DllImport("user32")]
        private static extern IntPtr GetDC(IntPtr hwnd);

        private void Form1_Load(object sender, System.EventArgs e)
        {
            IntPtr dc;
            IntPtr region;
            dc = GetDC(this.Handle);
            BeginPath(dc);
            //根据路径创建不规则窗体
            SetBkMode(dc, TRANSPARENT);
            //设置为透明模式
            Ellipse(dc, 20, 20, 220, 220);
            EndPath(dc);
            region = PathToRegion(dc);
            SetWindowRgn(this.Handle, region, true);
        }

        const int WM_NCHITTEST = 0x0084;
        const int HTCLIENT = 0x0001;
        const int HTCAPTION = 0x0002;
        protected override void WndProc(ref System.Windows.Forms.Message m)
        {
            switch (m.Msg)
            {
                case WM_NCHITTEST:
                    base.WndProc(ref m);
                    if (m.Result == (IntPtr)HTCLIENT)
                        m.Result = (IntPtr)HTCAPTION;
                    break;
                default:
                    base.WndProc(ref m);
                    break;
            }

        }

    }
}

源码下载：http://download.csdn.net/source/3001729