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;
using System.Drawing.Imaging;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.ClientSize = new Size(
                Convert.ToInt32(textBox1.Text),
                Convert.ToInt32(textBox2.Text));
            string path = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory);
            Bitmap bmp = new Bitmap(
                this.ClientSize.Width,
                this.ClientSize.Height,
                PixelFormat.Format32bppArgb);
            FormBorderStyle f = this.FormBorderStyle;
            this.FormBorderStyle = FormBorderStyle.None;
            this.DrawToBitmap(bmp, new Rectangle(0, 0, this.ClientSize.Width, this.ClientSize.Height));
            bmp.Save(path + "\\test.png", ImageFormat.Png);
            
            this.FormBorderStyle = f;
        }
    }
}