【Winform-自定义控件】自定义Tab Control 带关闭符号(X)的标签页

a form & a tabControl

思路：

DrawMode设一定要设为OwnerDrawFixed

事件：Form_Load、tabControl1_DrawItem、tabControl1_DrawItem

注意：

如果 设置tabControl的SizeMode为fixed，则标签页的长度以最大的为标准
如果 设置tabControl的SizeMode为normal，则标签页的长度随标题变化，
此句代码：tabControl1.Padding = new System.Drawing.Point(21, 3); 表示‘X’与标题间有空隙。

namespace Demo
{
    public partial class Form7 : Form
    {
        const int LEADING_SPACE = 12;
        const int CLOSE_SPACE = 15;
        const int CLOSE_AREA = 15;

        public Form7()
        {
            InitializeComponent();
            this.tabControl1.DrawMode = TabDrawMode.OwnerDrawFixed;
        }

        private void Form7_Load(object sender, EventArgs e)
        {
            // get the inital length
            int tabLength = tabControl1.ItemSize.Width;

            // measure the text in each tab and make adjustment to the size
            for (int i = 0; i < this.tabControl1.TabPages.Count; i++)
            {
                TabPage currentPage = tabControl1.TabPages[i];

                int currentTabLength = TextRenderer.MeasureText(currentPage.Text, tabControl1.Font).Width;
                // adjust the length for what text is written
                currentTabLength += LEADING_SPACE + CLOSE_SPACE + CLOSE_AREA;

                if (currentTabLength > tabLength)
                {
                    tabLength = currentTabLength;
                }
            }

            // create the new size
            Size newTabSize = new Size(tabLength, tabControl1.ItemSize.Height);
            tabControl1.ItemSize = newTabSize;
        }

        private void tabControl1_DrawItem(object sender, DrawItemEventArgs e)
        {
            //add some extra space to the end of every tabPage
            tabControl1.Padding = new System.Drawing.Point(21, 3);

            //render a "x" mark at the end of the Tab caption 
            e.Graphics.DrawString("x", e.Font, Brushes.Black, e.Bounds.Right - CLOSE_AREA, e.Bounds.Top + 4);
            e.Graphics.DrawString(this.tabControl1.TabPages[e.Index].Text, e.Font, Brushes.Black, e.Bounds.Left + LEADING_SPACE, e.Bounds.Top + 4);
            e.DrawFocusRectangle();
        }

        private void tabControl1_MouseDown(object sender, MouseEventArgs e)
        {
            //Looping through the controls.
            for (int i = 0; i < this.tabControl1.TabPages.Count; i++)
            {
                Rectangle r = tabControl1.GetTabRect(i);
                //Getting the position of the "x" mark.
                Rectangle closeButton = new Rectangle(r.Right - 15, r.Top + 4, 9, 7);
                if (closeButton.Contains(e.Location))
                {
                    if (MessageBox.Show("Would you like to Close this Tab?", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                    {
                        this.tabControl1.TabPages.RemoveAt(i);
                        break;
                    }
                }
            }
        }
    }
}