//创建一个新的类,用来连接别的窗体,并且别的窗体为唯一窗体

List<Form> F = new List<Form>();
        private void opendao(Form f)
        {
            Form F1 = null;
            bool isopen = false;
            foreach(Form gf in F)
            {
                gf.Hide();
                if(gf.Name == f.Name)
                {
                    isopen = true;
                    F1 = gf;
                }
            }


            if (isopen)
            {
                f.Close();
                F1.Show();
            }
            else
            {
                f.MdiParent = this;
                f.WindowState = FormWindowState.Maximized;
                f.Parent = panel1;
                f.FormBorderStyle = FormBorderStyle.None;
                f.Show();
                F.Add(f);
            }
           
        }

       
//连接到第二个窗口

 private void button1_Click(object sender, EventArgs e)
        {
            Form2 f2 = new Form2();
            f2.Name = "1";
            opendao(f2);
           
        }

//连接到第二个窗口   

 private void button2_Click(object sender, EventArgs e)
        {
            Form3 f3 = new Form3();
            f3.Name = "2";
            opendao(f3);
        }

 private void toolStripMenuItem1_Click(object sender, EventArgs e)
        {
            pageSetupDialog1.Document = printDocument1;
            DialogResult dr = pageSetupDialog1.ShowDialog();

            if (dr == DialogResult.OK)
            {


            }
        }

//注:第一个代码为绘画,将字符串绘画,重要!

private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            string s = textBox1.Text;
            Font f = new System.Drawing.Font("微软雅黑", 25.5f);
            Brush b = new SolidBrush(Color.Red);
            e.Graphics.DrawString(s, f, b, 20, 20);
        }

//打印

        private void 打印PToolStripMenuItem_Click(object sender, EventArgs e)
        {
            printDialog1.Document = printDocument1;
            DialogResult dr = printDialog1.ShowDialog();
            if (dr == DialogResult.OK)
            {
                printDocument1.Print();
            }
        }

        private void 打印预览VToolStripMenuItem_Click(object sender, EventArgs e)
        {
            printPreviewDialog1.Document = printDocument1;
            printPreviewDialog1.ShowDialog();

        }

  private void 自动换行ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (textBox1.WordWrap)
            {
                //不自动换行
                textBox1.WordWrap = false;
                textBox1.ScrollBars = ScrollBars.Both;
                自动换行ToolStripMenuItem.Checked = false;
            }
            else
            {
                //自动换行
                textBox1.WordWrap = true;
                textBox1.ScrollBars = ScrollBars.Vertical;
                自动换行ToolStripMenuItem.Checked = true;
            }
        }

   
//此为第二个窗口的设置
         Form1 F1;
        public Form2(Form1 f1)
        {
            InitializeComponent();

            F1 = f1;
        }
        int a = 0;
        private void button1_Click(object sender, EventArgs e)
        {
            string s = textBox1.Text;

            a = F1.textBox1.Text.IndexOf(s, a + 1);
            if (a != -1)
            {
                F1.textBox1.Select(a, s.Length);
                F1.textBox1.Focus();
            }
            else
            {
                MessageBox.Show("无匹配项！");
            }
        }

//此为第一个窗口使用
        private void 查找ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form2 f2 = new Form2(this);
            f2.Owner = this;
            f2.Show();

        }