如何在其中选择时绘制richtextbox可编辑

Question

我必须为富文本框提供选择支持，因此我创建了单独的控件并尝试使用paint()方法绘制它。我已经完成了，但是一旦完成绘图，我就无法编辑rtbox。请找到我使用的以下代码并分享您的想法。

注意：我怀疑由于将selectioncontrol停靠方式设置为Fill而导致问题，但如果我删除或更改了未选择的选择。

partial class Form1
{
    /// <summary>
    /// Required designer variable.
    /// </summary>
    private System.ComponentModel.IContainer components = null;

    /// <summary>
    /// Clean up any resources being used.
    /// </summary>
    /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows Form Designer generated code

    private GraphicCellControl graphiccell;

    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {

        #region picturebox

        this.BackColor = Color.Aquamarine;

        var selectBtn = new Button();
        selectBtn.Size = new Size(100, 30);
        selectBtn.Location = new Point(10, 10);
        selectBtn.Text = "Click";
        selectBtn.Click += selectBtn_Click;

        //var picturebox = new PictureBox();
        //picturebox.Size = new Size(140, 110);
        //picturebox.Location = new Point(4, 4);
        //picturebox.SizeMode = PictureBoxSizeMode.StretchImage;
        //picturebox.Image = new Bitmap(@"..\..\Data\picture.png");

        var richtextbox = new RichTextBox();
        richtextbox.Size = new Size(140, 110);
        richtextbox.Location = new Point(4, 4);
        richtextbox.Text = "Texting information";

        graphiccell = new GraphicCellControl();
        graphiccell.Location = new Point(50, 200);
        graphiccell.Size = new Size(150, 120);
        graphiccell.Controls.Add(richtextbox);
        this.Controls.Add(graphiccell);
        this.Controls.Add(selectBtn);

        #endregion

    }

    void selectBtn_Click(object sender, EventArgs e)
    {
        graphiccell.IsSelected = !graphiccell.IsSelected;
    }

    #endregion
}

public class GraphicCellControl : Control
{
    private SelectionControl selectionControl;
    public GraphicCellControl()
    {
        selectionControl = new SelectionControl();
    }

    private bool isselected;
    public bool IsSelected
    {
        get { return isselected; }
        set
        {
            isselected = value;
            if (isselected && !this.Controls.Contains(selectionControl))
            {
                this.Controls.Add(selectionControl);
                selectionControl.BringToFront();
            }
            else if (!isselected && this.Controls.Contains(selectionControl))
                this.Controls.Remove(selectionControl);
        }
    }
}

public class SelectionControl : Control
{
    public SelectionControl()
    {
        SetStyle(ControlStyles.AllPaintingInWmPaint |
                 ControlStyles.UserPaint | ControlStyles.Opaque |
                 ControlStyles.SupportsTransparentBackColor, true);
        Dock = DockStyle.Fill;
       // Anchor = AnchorStyles.Left | AnchorStyles.Top;
        BackColor = Color.Transparent;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
        e.Graphics.DrawRectangle(new Pen(Color.Gray, 1), 4, 4, this.Size.Width - 10, this.Size.Height - 10);

        e.Graphics.FillEllipse(Brushes.White, 0, 0, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, 0, (this.Size.Height - 10) / 2, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, 0, this.Size.Height - 10, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, (this.Size.Width - 10) / 2, 0, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, (this.Size.Width - 10) / 2, this.Size.Height - 10, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, this.Size.Width - 10, 0, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, this.Size.Width - 10, (this.Size.Height - 10) / 2, 8, 8);
        e.Graphics.FillEllipse(Brushes.White, this.Size.Width - 10, this.Size.Height - 10, 8, 8);

        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), 0, 0, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), 0, (this.Size.Height - 10) / 2, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), 0, this.Size.Height - 10, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), (this.Size.Width - 10) / 2, 0, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), (this.Size.Width - 10) / 2, this.Size.Height - 10, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), this.Size.Width - 10, 0, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), this.Size.Width - 10, (this.Size.Height - 10) / 2, 8, 8);
        e.Graphics.DrawEllipse(new Pen(Color.DarkGray, 2), this.Size.Width - 10, this.Size.Height - 10, 8, 8);
    }
}