C# UserControl inherited from GroupBox

[창공]

https://youtu.be/LuyRdCO7wuU

    // groupBoxCc.cs

    public class GroupBoxCc : GroupBox

    {

        private Color borderColor = Color.Blue;

        public Color BorderColor

        {

            get { return borderColor; }

            set { borderColor = value; this.Invalidate(); }

        }

        private Color titleColor = Color.Black;

        public Color TitleColor

        {

            get { return titleColor; }

            set { titleColor = value; this.Invalidate(); }

        }

        protected override void OnPaint(PaintEventArgs e)

        {

            Graphics g = e.Graphics;

            // text Display

            Brush textBrush = new SolidBrush(this.titleColor);

            g.DrawString(" " + this.Text, this.Font, textBrush, new Point(0, 0));

            // Draw border

            Pen pen = new Pen(this.borderColor);

            int startY = this.Font.Height / 2;

            //Rectangle bounds = new Rectangle(0, startY, base.Width - 1, base.Height - 1 - startY);

            //g.DrawRectangle(pen, bounds);

            Rectangle bounds = new Rectangle(0, startY, base.Width - 1, base.Height - 1);

            Size textSize = TextRenderer.MeasureText(" " + this.Text, this.Font);

            g.DrawLine(pen, bounds.X + textSize.Width, bounds.Y, bounds.Width, bounds.Y); // - : top

            g.DrawLine(pen, bounds.X, bounds.Y, bounds.X, bounds.Height);                  // | : left

            g.DrawLine(pen, bounds.X, bounds.Height, bounds.Width, bounds.Height);      // - : bottom

            g.DrawLine(pen, bounds.Width, bounds.Y, bounds.Width, bounds.Height);       // | : right

        }

    }

    // UserControlForm.cs

    public partial class UserControlFomr : Form

    {

        public UserControlFomr()

        {

            InitializeComponent();

        }

        private void UserControlFomr_Load(object sender, EventArgs e)

        {

            groupBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.groupBox_MouseDown);

            groupBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.groupBox_MouseMove);

            groupBoxCc1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.groupBox_MouseDown);

            groupBoxCc1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.groupBox_MouseMove);

        }

        Point mousePoint;

        Size controlSize;

        private void groupBox_MouseDown(object sender, MouseEventArgs e)

        {

            Control con = sender as Control;

            mousePoint = new Point(e.X, e.Y);

            controlSize = con.Size;

        }

        private void groupBox_MouseMove(object sender, MouseEventArgs e)

        {

            Control con = sender as Control;

            int xDiff = con.Size.Width - e.X;

            int yDiff = con.Size.Height - e.Y;

            if(xDiff < 20 && yDiff < 20)

            {

                Cursor.Current = Cursors.SizeNWSE;

            }

            if((e.Button & MouseButtons.Left) != MouseButtons.Left) return;

            if(xDiff < 20 && yDiff < 20)

            {

                con.Size = new Size(controlSize.Width - (mousePoint.X - e.X),

                    controlSize.Height - (mousePoint.Y - e.Y));

                return;

            }

            con.Location = new Point(con.Left - (mousePoint.X - e.X),

                con.Top - (mousePoint.Y - e.Y));

        }

    }