自定义TabControl

Vs自带的TabControl太丑，想改造一下。

自定义TabControl，从TabControl派生一个自定义的标签控件GTabControl。

public class GTabControl :TabControl

在构造函数中添加如下代码：

base.SetStyle(
          ControlStyles.UserPaint |                      // 控件将自行绘制，而不是通过操作系统来绘制
          ControlStyles.OptimizedDoubleBuffer |          // 该控件首先在缓冲区中绘制，而不是直接绘制到屏幕上，这样可以减少闪烁
          ControlStyles.AllPaintingInWmPaint |           // 控件将忽略 WM_ERASEBKGND 窗口消息以减少闪烁
          ControlStyles.ResizeRedraw |                   // 在调整控件大小时重绘控件
          ControlStyles.SupportsTransparentBackColor,    // 控件接受 alpha 组件小于 255 的 BackColor 以模拟透明
          true);                                         // 设置以上值为 true
     base.UpdateStyles();

这段代码的意思就像注释里说的，注意ControlStyles这个枚举是可以按位组合的，所以上面要用「或（|）」来进行连接，这样系统就会完全忽视TabControl这个基类的界面显示，而使用我们自己的方式来呈现UI。（一步一步玩控件：TabControl——从制作山寨Safari窗体开始）

以上是学习的过程。

using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System;
using System.Runtime.InteropServices;

namespace CSharpCustomTabControl
{
    /// <summary>
    /// Description of CustomTabControl.
    /// </summary>
    [ToolboxBitmap(typeof(TabControl))]
    public class CustomTabControl : TabControl
    {
        
        public CustomTabControl() : base()
        {
            if (this._DisplayManager.Equals(TabControlDisplayManager.Custom)) {
                this.SetStyle(ControlStyles.UserPaint, true);
                this.ItemSize = new Size(0, 15);
                this.Padding = new Point(9,0);
            }
            
            this.SetStyle(ControlStyles.SupportsTransparentBackColor, true);
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            this.SetStyle(ControlStyles.ResizeRedraw, true);
            this.ResizeRedraw = true;
        }
        
        TabControlDisplayManager _DisplayManager = TabControlDisplayManager.Custom;
    
        [System.ComponentModel.DefaultValue(typeof(TabControlDisplayManager), "Custom")]
        public TabControlDisplayManager DisplayManager {
            get {
                return this._DisplayManager;
            }
            set {
                if (this._DisplayManager != value) {
                    if (this._DisplayManager.Equals(TabControlDisplayManager.Custom)) {
                        this.SetStyle(ControlStyles.UserPaint, true);
                        this.ItemSize = new Size(0, 15);
                        this.Padding = new Point(9,0);
                    } else {
                        this.ItemSize = new Size(0, 0);
                        this.Padding = new Point(6,3);
                        this.SetStyle(ControlStyles.UserPaint, false);
                    }
                }
            }
        }

        protected override void OnPaintBackground(PaintEventArgs pevent)
        {
            if (this.DesignMode == true) {
                LinearGradientBrush backBrush = new LinearGradientBrush(
                            this.Bounds,
                            SystemColors.ControlLightLight,
                            SystemColors.ControlLight,
                            LinearGradientMode.Vertical);
                pevent.Graphics.FillRectangle(backBrush, this.Bounds);
                    backBrush.Dispose();
            } else {
                this.PaintTransparentBackground(pevent.Graphics, this.ClientRectangle);
            }
        }
         
    protected void PaintTransparentBackground(Graphics g, Rectangle clipRect)
    {
        if ((this.Parent != null)) {
            clipRect.Offset(this.Location);
            PaintEventArgs e = new PaintEventArgs(g, clipRect);
            GraphicsState state = g.Save();
            g.SmoothingMode = SmoothingMode.HighSpeed;
            try {
                g.TranslateTransform((float)-this.Location.X, (float)-this.Location.Y);
                this.InvokePaintBackground(this.Parent, e);
                this.InvokePaint(this.Parent, e);
            }

            finally {
                g.Restore(state);
                clipRect.Offset(-this.Location.X, -this.Location.Y);
            }
        }
        else {
            System.Drawing.Drawing2D.LinearGradientBrush backBrush = new System.Drawing.Drawing2D.LinearGradientBrush(this.Bounds, SystemColors.ControlLightLight, SystemColors.ControlLight, System.Drawing.Drawing2D.LinearGradientMode.Vertical);
            g.FillRectangle(backBrush, this.Bounds);
            backBrush.Dispose();
        }
    }
    
        protected override void OnPaint(PaintEventArgs e)
        {
            
            //   Paint the Background
            this.PaintTransparentBackground(e.Graphics, this.ClientRectangle);
            
            this.PaintAllTheTabs(e);
             this.PaintTheTabPageBorder(e);
             this.PaintTheSelectedTab(e);
        }

        private void PaintAllTheTabs(System.Windows.Forms.PaintEventArgs e) {
            if (this.TabCount > 0) {
                for (int index = 0; index < this.TabCount ; index++){
                    this.PaintTab(e, index);
                }
            }
        }
        
        private void PaintTab(System.Windows.Forms.PaintEventArgs e, int index) {
            GraphicsPath path = this.GetPath(index);
            this.PaintTabBackground(e.Graphics, index, path);
            this.PaintTabBorder(e.Graphics, index, path);
            this.PaintTabText(e.Graphics, index);
            this.PaintTabImage(e.Graphics, index);
        }

        private void PaintTabBackground(System.Drawing.Graphics graph, int index, System.Drawing.Drawing2D.GraphicsPath path){
            Rectangle rect = this.GetTabRect(index);
                System.Drawing.Brush buttonBrush =
                    new System.Drawing.Drawing2D.LinearGradientBrush(
                        rect,
                        SystemColors.ControlLightLight,
                        SystemColors.ControlLight,
                        LinearGradientMode.Vertical);
            
            if (index == this.SelectedIndex) {
                buttonBrush = new System.Drawing.SolidBrush(SystemColors.ControlLightLight);
            }

            graph.FillPath(buttonBrush, path);
            buttonBrush.Dispose();
        }

        private void PaintTabBorder(System.Drawing.Graphics graph, int index, System.Drawing.Drawing2D.GraphicsPath path){
            Pen borderPen = new Pen(SystemColors.ControlDark);

            if (index == this.SelectedIndex) {
                 borderPen = new Pen(ThemedColors.ToolBorder);
            }
            graph.DrawPath(borderPen, path);
            borderPen.Dispose();
        }

        private void PaintTabImage(System.Drawing.Graphics graph, int index){
            Image tabImage = null;
            if (this.TabPages[index].ImageIndex > -1 && this.ImageList != null) {
                tabImage = this.ImageList.Images[this.TabPages[index].ImageIndex];
            }else if (this.TabPages[index].ImageKey.Trim().Length > 0 && this.ImageList != null){
                tabImage = this.ImageList.Images[this.TabPages[index].ImageKey];    
            }
            if ( tabImage != null) {
                Rectangle rect = this.GetTabRect(index);
                graph.DrawImage(tabImage, rect.Right - rect.Height - 4, 4, rect.Height - 2, rect.Height - 2);
            }
        }

    private void PaintTabText(System.Drawing.Graphics graph, int index)
    {
        Rectangle rect = this.GetTabRect(index);
        Rectangle rect2 = new Rectangle(rect.Left + 8, rect.Top + 1, rect.Width - 6, rect.Height);
        if (index == 0) rect2 = new Rectangle(rect.Left + rect.Height, rect.Top + 1, rect.Width - rect.Height, rect.Height); 

        string tabtext = this.TabPages[index].Text;

        System.Drawing.StringFormat format = new System.Drawing.StringFormat();
        format.Alignment = StringAlignment.Near;
        format.LineAlignment = StringAlignment.Center;
        format.Trimming = StringTrimming.EllipsisCharacter;

        Brush forebrush = null;

        if (this.TabPages[index].Enabled == false) {
            forebrush = SystemBrushes.ControlDark;
        }
        else {
            forebrush = SystemBrushes.ControlText;
        }

        Font tabFont = this.Font;
        if (index == this.SelectedIndex) {
            tabFont = new Font(this.Font, FontStyle.Bold);
            if (index == 0) {
                rect2 = new Rectangle(rect.Left + rect.Height, rect.Top + 1, rect.Width - rect.Height + 5, rect.Height);
            }
        }

        graph.DrawString(tabtext, tabFont, forebrush, rect2, format);

    }

        private void PaintTheTabPageBorder(System.Windows.Forms.PaintEventArgs e) {
            if (this.TabCount > 0) {
                Rectangle borderRect= this.TabPages[0].Bounds;
                borderRect.Inflate(1, 1);
                ControlPaint.DrawBorder(e.Graphics, borderRect, ThemedColors.ToolBorder, ButtonBorderStyle.Solid);
            }
        }

        private void PaintTheSelectedTab(System.Windows.Forms.PaintEventArgs e) {
            Rectangle selrect;
            int selrectRight = 0;
            
            switch(this.SelectedIndex) {
                case -1:
                    break;
                case 0:
                    selrect = this.GetTabRect(this.SelectedIndex);
                    selrectRight = selrect.Right;
                    e.Graphics.DrawLine(SystemPens.ControlLightLight, selrect.Left + 2, selrect.Bottom + 1, selrectRight - 2, selrect.Bottom + 1);
                    break;
                default:
                    selrect = this.GetTabRect(this.SelectedIndex);
                    selrectRight = selrect.Right;
                    e.Graphics.DrawLine(SystemPens.ControlLightLight, selrect.Left + 6 - selrect.Height, selrect.Bottom + 1, selrectRight - 2, selrect.Bottom + 1);
                    break;
            }
        }

        private System.Drawing.Drawing2D.GraphicsPath GetPath(int index) {
            System.Drawing.Drawing2D.GraphicsPath path = new System.Drawing.Drawing2D.GraphicsPath();
            path.Reset();
            
            Rectangle rect = this.GetTabRect(index);

            if (index == 0){
                path.AddLine(rect.Left + 1, rect.Bottom + 1, rect.Left + rect.Height, rect.Top + 2);
                path.AddLine(rect.Left + rect.Height + 4, rect.Top, rect.Right - 3, rect.Top);
                path.AddLine(rect.Right - 1, rect.Top + 2, rect.Right - 1, rect.Bottom + 1);
            } else {
                if (index == this.SelectedIndex) {
                    path.AddLine(rect.Left + 1, rect.Top + 5, rect.Left + 4, rect.Top + 2);
                    path.AddLine(rect.Left + 8, rect.Top, rect.Right - 3, rect.Top);
                    path.AddLine(rect.Right - 1, rect.Top + 2, rect.Right - 1, rect.Bottom + 1);
                    path.AddLine(rect.Right - 1, rect.Bottom + 1, rect.Left + 1, rect.Bottom + 1);
                } else {
                    path.AddLine(rect.Left, rect.Top + 6, rect.Left + 4, rect.Top + 2);
                    path.AddLine(rect.Left + 8, rect.Top, rect.Right - 3, rect.Top);
                    path.AddLine(rect.Right - 1, rect.Top + 2, rect.Right - 1, rect.Bottom + 1);
                    path.AddLine(rect.Right - 1, rect.Bottom + 1, rect.Left, rect.Bottom + 1);
                }
                
            }
            return path;
        }

           public enum TabControlDisplayManager {
            Default,
            Custom
        }

        [DllImport("user32.dll")]
        private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam); 
        
        private const int WM_SETFONT = 0x30;
        private const int WM_FONTCHANGE = 0x1d;
        
        protected override void OnCreateControl()
        {
            base.OnCreateControl();
            this.OnFontChanged(EventArgs.Empty);
        } 
        
        protected override void OnFontChanged(EventArgs e)
        {
            base.OnFontChanged(e);
            IntPtr hFont = this.Font.ToHfont();
            SendMessage(this.Handle, WM_SETFONT, hFont, (IntPtr)(-1));
            SendMessage(this.Handle, WM_FONTCHANGE, IntPtr.Zero, IntPtr.Zero);
            this.UpdateStyles();
            this.ItemSize = new Size(0, this.Font.Height + 2);
        }

    }
}

从网上找到的代码，可以满足要求！