这里做的比较简陋，可以美化下
把form设置为非顶级控件，直接放在tabcontrol里边，然后实现tabcontrol的拖拽移除tabpage显示form以及添加tabpage
mousemove的触发时机需要优化一下
这里是比较简单的实现方式，也比较丑，可以实现像QQ那样的效果，可以重绘tabcontrol控件，然后以同样的方式实现拖拽移除显示和添加tabpage
也可以实现类似timQQ那样的形式，可以用自定义控件左边用listview右边放容器，重绘listview控件然后实现拖拽显示和添加，这样做复杂一点，但是会好看很多····
public Form1(){InitializeComponent();}private TabControl tabControl1 = new TabControl();private bool StartMove = false;private bool flag = true;private TabPage MovePage = null;protected override void OnLoad(EventArgs e){base.OnLoad(e);tabControl1.Dock = DockStyle.Fill;this.Controls.Add(tabControl1);this.Controls.SetChildIndex(tabControl1, 0);frm1ToolStripMenuItem.Click += delegate {var frm1 = new Form();frm1.Text = "frm1";var btn=new Button();btn.Text = "btn";btn.Click += delegate { MessageBox.Show("this is frm1"); btn.Text = "frm1"; };frm1.Controls.Add(btn);addfrm(frm1);};frm2ToolStripMenuItem.Click += delegate{var frm1 = new Form();frm1.Text = "frm2";var btn = new Button();btn.Text = "btn";btn.Click += delegate { MessageBox.Show("this is frm2"); };frm1.Controls.Add(btn);addfrm(frm1);};frm3ToolStripMenuItem.Click += delegate{var frm1 = new Form();frm1.Text = "frm3";var btn = new Button();btn.Text = "btn";btn.Click += delegate { MessageBox.Show("this is frm3"); };frm1.Controls.Add(btn);addfrm(frm1);};tabControl1.AllowDrop = true;Func<Point, TabPage> GetTabPageByTab = (point) =>{for (int i = 0; i < this.tabControl1.TabPages.Count; i++){if (tabControl1.GetTabRect(i).Contains(point)){return this.tabControl1.TabPages[i];}}return null;};tabControl1.MouseDown += (o, eg) => {if (flag){StartMove = true;MovePage=GetTabPageByTab(new Point(eg.X, eg.Y));}flag = true;};tabControl1.MouseUp += (o, eg) => {StartMove = false;};tabControl1.SelectedIndexChanged += (o, eg) => {flag = false;//切换的时候因为失去焦点的原因，会触发down事件不触发up事件这里做屏蔽 };tabControl1.MouseMove += (o, eg) => {if (StartMove && flag){if (MovePage != null){this.DoDragDrop(MovePage, DragDropEffects.None);}}};tabControl1.ControlAdded += delegate {StartMove = false;flag = false;};tabControl1.DragOver += (o, eg) => {eg.Effect = DragDropEffects.None;if (tabControl1.TabPages.Count < 2) return;TabPage page = (TabPage)eg.Data.GetData(typeof(TabPage));var frm1 = page.Controls[0] as Form;frm1.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Sizable;frm1.Parent = null;frm1.TopLevel = true;frm1.Owner = this;frm1.Location = new Point(eg.X, eg.Y);frm1.Show();tabControl1.TabPages.Remove(page);MovePage = null;frm1.Move += (oo, ee) =>{for (int i = 0; i < tabControl1.TabPages.Count; i++){if (tabControl1.GetTabRect(i).Contains(this.PointToClient(frm1.Location))){addfrm(frm1);}}};};}private void addfrm(Form frm){if (tabControl1.Visible == false) tabControl1.Visible = true;bool flag = true;frm.TopLevel = false;frm.Dock = DockStyle.Fill;frm.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;frm.Owner = null;foreach (TabPage page in tabControl1.TabPages){if (page.Controls.Count < 1){page.Controls.Add(frm);page.Text=frm.Text;flag = false;frm.Show();return;}}if (flag){var page=new TabPage(frm.Text);page.Controls.Add(frm);tabControl1.TabPages.Add(page);frm.Show();}}
之前闲的没事写的tabcontrol加载窗体，刚好最近要用到这个· 这里简单重绘一个·因为要该背景色 去边框之类的，网上查了很多·不太好使· 这里用简单粗暴的方式直接吧背景色刷成想要的 然后在填充其他要改变背景色的地方
using System.Windows.Forms;using System;using System.Collections.Generic;using ponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace ExerciseUIPrj.controls{public partial class XTabControl : TabControl{Size defaultSize = new Size();const int dheight = 10;public XTabControl(){InitializeComponent();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();this.SizeMode = TabSizeMode.Fixed; // 大小模式为固定 FontChanged += XTabControl_FontChanged;defaultSize = TextRenderer.MeasureText("tabpage1", Font);Margin = new System.Windows.Forms.Padding(0);Padding = new Point(0, 0);Appearance = TabAppearance.Normal;SetItemSize();}//public override Rectangle DisplayRectangle//{// get// {// Rectangle rect = base.DisplayRectangle;// return new Rectangle(rect.Left - 2, rect.Top-2, rect.Width + 4, rect.Height + 4);// }//}public void SetItemSize(){if (Width >= 0 && TabCount > 0){if (Alignment ==TabAlignment.Top || Alignment == TabAlignment.Bottom){int width = (int)((Size.Width - 5) / (double)this.TabCount);this.ItemSize = new Size(width, defaultSize.Height + dheight); // 设定每个标签的尺寸 }else{int width = defaultSize.Width;foreach (TabPage t in TabPages){var w = TextRenderer.MeasureText(t.Name, Font).Width;width = w > width ? w : width;}width = width + dheight;this.ItemSize = new Size(defaultSize.Height + dheight, width); // 设定每个标签的尺寸 //这里w和h是反的}}}private void XTabControl_FontChanged(object sender, EventArgs e){defaultSize = TextRenderer.MeasureText("tabpage1", Font);SetItemSize();}Color dbackColor = Color.FromArgb(220, 220, 220);protected override void OnPaint(PaintEventArgs pe){var g = pe.Graphics;g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;g.FillRectangle(new SolidBrush(Color.White), pe.ClipRectangle);//所有背景全刷，直接刷成白色······Rectangle rect = new Rectangle();if (Alignment == TabAlignment.Left || Alignment == TabAlignment.Right){rect = new Rectangle(0,0, ItemSize.Height+2, Height);g.FillRectangle(new SolidBrush(dbackColor), rect);//吧标签背景色统一填充了}else{rect = new Rectangle(0, 0, Width, ItemSize.Height+2);// g.FillRectangle(new SolidBrush(dbackColor), rect); }for (int i = 0; i < this.TabCount; i++)//这里画标签，可以在里边画图片···这里只画文字···{Rectangle bounds = this.GetTabRect(i);if (SelectedIndex == i){g.FillRectangle(new SolidBrush(Color.White), bounds);}else{g.FillRectangle(new SolidBrush(dbackColor), bounds);}PointF textPoint = new PointF();SizeF textSize = TextRenderer.MeasureText(this.TabPages[i].Text, this.Font);textPoint.X= bounds.X + (bounds.Width - textSize.Width) / 2;textPoint.Y = bounds.Y + (bounds.Height - textSize.Height) / 2;g.DrawString( this.TabPages[i].Text, this.Font, SystemBrushes.ControlText, textPoint.X, textPoint.Y);}}}}
