Winform多行标题TabControl

今天写示例程序的时候，遇到了需要多行标题TabControl的情况。
整体流程很简单，就是将标题拆分，然后根据行数和最大行宽设置每一Page标题的高度及宽度即可。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Collections;

namespace UITabControlTest
{
    public partial class SubForm : Form
    {
        private Dictionary<TabPage, TabPageInfo> allTabMap = new Dictionary<TabPage, TabPageInfo>();

        public SubForm()
        {
            InitializeComponent();
            tabMain.DrawMode = TabDrawMode.OwnerDrawFixed;
        }

        private void SubForm_Load(object sender, EventArgs e)
        {
            tabPage1.Text = "line1\nline2\nline3\nline4\nlin5";
            tabPage2.Text = "line1\nline2\nline3\nline4";
            tabPage3.Text = "line1\nline2\nline3";
            tabPage4.Text = "line1\nline2";

            int lineNum = 0;
            foreach (TabPage tab in this.tabMain.TabPages)
            {
                TabPageInfo pInfo = new TabPageInfo(tab.Text,"\n");
                allTabMap.Add(tab, pInfo);
                lineNum = lineNum>pInfo.LineNum?lineNum:pInfo.LineNum;
            }

            foreach (TabPage tab in this.tabMain.TabPages)
            {
                TabPageInfo pInfo = allTabMap[tab];
                tab.Text = pInfo.MaxLine;
            }

            //some thing is wrong, the font height is 14, the padding height is around 9, why?
            tabMain.Padding = new Point(0, Convert.ToInt32(tabMain.Font.Height * (lineNum - 1) * 0.65));
        }

        private void tabMain_DrawItem(object sender, DrawItemEventArgs e)
        {
            TabControl tabControl = (TabControl)sender;
            TabPage currentTab = tabControl.TabPages[e.Index];
            TabPageInfo info = allTabMap[currentTab];
            string tabText = info.AllLine;
            
            StringFormat sf = new StringFormat();
            sf.Alignment = StringAlignment.Center;
            sf.LineAlignment = StringAlignment.Center;
            RectangleF tabRect = (RectangleF)e.Bounds;
            RectangleF textRect = tabRect;
            if (e.Index == tabControl.SelectedIndex)
            {
                tabRect.Inflate(1, 1);
            }

            Graphics g = e.Graphics;
            g.Clip = new Region(tabRect);
            g.Clear(Control.DefaultBackColor);
            g.ResetClip();
            g.DrawString(tabText, e.Font, SystemBrushes.ControlText, textRect, sf);
        }
    }

    class TabPageInfo
    {
        public int LineNum
        {
            get
            {
                return nLineNum;
            }
        }

        public String MaxLine
        {
            get
            {
                //prevent auto wrap
                return szMaxLine+"  ";
            }
        }

        public String getLine(int index)
        {
            if (index < nLineNum)
            { 
                return szLines[index];
            }
            else
            {
                return "";
            }
        }

        public String AllLine
        {
            get
            {
                return szAllLine;
            }
        }

        private int nLineNum = 0;
        private String[] szLines;
        private String szAllLine;
        private String szMaxLine;

        public TabPageInfo(String pageTitle, String splitString)
        {
            szAllLine = pageTitle.Replace(splitString, "\n");
            String [] separators = new String[]{splitString};
            szLines = pageTitle.Split(separators,StringSplitOptions.RemoveEmptyEntries);
            nLineNum = szLines.Length;

            int nMaxLineWidth = 0;
            foreach(String line in szLines)
            {
                if (nMaxLineWidth < line.Length)
                {
                    nMaxLineWidth = line.Length;
                    szMaxLine = line;
                }
            }
        }
    }
}