打印控件：

要打印，第一步先要想到制作打印对象

PrintDocument - 默认事件

Font f = new Font("黑体",20);

Brush b = new SolidBrush(Color.Red);

e.Graphics.DrawString(textBox1.Text, f, b, 20, 50);

通过对于事件数据的绘制来制作要打印的内容

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MDI 窗体容器

 IsMdiContainer----------------确定该窗体是否是MDI容器

MenuStrip-------------------往MDI容器中放置的菜单

企业仓库，销售，财务三个模块的制作（用到MDI容器和唯一窗体）：

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace WindowsFormsApplication5{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        List
     
       formlist = new List();        private void 仓库模块ToolStripMenuItem_Click(object sender, EventArgs e)        {            bool has = false;            Form2 f2 = new Form2();            foreach(Form f in formlist)            {                if(f is Form2)                {                    has = true;                    f2 = f as Form2;                }            }            if (has == false)            {                f2.MdiParent = this;                f2.WindowState = FormWindowState.Maximized;                f2.Parent = panel1;                f2.Show();                formlist.Add(f2);            }            else             {                foreach (Form f in formlist) { f.Hide(); }                f2.Show();            }        }        private void 销售模块ToolStripMenuItem_Click(object sender, EventArgs e)        {            bool has = false;            Form3 f3 = new Form3();            foreach (Form f in formlist)            {                if (f is Form3)                {                    has = true;                    f3 = f as Form3;                }            }            if (has == false)            {                f3.MdiParent = this;                f3.WindowState = FormWindowState.Maximized;                f3.Parent = panel1;                f3.Show();                formlist.Add(f3);            }            else            {                foreach (Form f in formlist) { f.Hide(); }                f3.Show();            }        }        private void 财务模块ToolStripMenuItem_Click(object sender, EventArgs e)        {            bool has = false;            Form4 f4 = new Form4();            foreach (Form f in formlist)            {                if (f is Form4)                {                    has = true;                    f4= f as Form4;                }            }            if (has == false)            {                f4.MdiParent = this;                f4.WindowState = FormWindowState.Maximized;                f4.Parent = panel1;                f4.Show();                formlist.Add(f4);            }            else            {                foreach (Form f in formlist) { f.Hide(); }                f4.Show();            }        }    }}