Textbox border issue c#

Question

Below is the code by which I am trying to create a custom textbox who should have double underline in its bottom border , single border on up side and no borders on left and right side but it is not working as i am not getting top border . also there are something in its left and right border . . Also i am getting flickering problem on the top side of the control . Please suggest what modification should i have to make in my code Or please suggest new code block

 public partial class doubleunderlinetextbox : TextBox
    {
        public doubleunderlinetextbox()
        {
            // InitializeComponent();
            //BorderStyle = BorderStyle.None;
            BorderStyle = System.Windows.Forms.BorderStyle.None;
            AutoSize = false; //Allows you to change height to have bottom padding
            Controls.Add(new Label()
            { Height = 1, Dock = DockStyle.Bottom, BackColor = Color.Black });
        }

   [DllImport("user32")]
        private static extern IntPtr GetWindowDC(IntPtr hwnd);
        struct RECT
        {
            public int left, top, right, bottom;
        }
        struct NCCALSIZE_PARAMS
        {
            public RECT newWindow;
            public RECT oldWindow;
            public RECT clientWindow;
            IntPtr windowPos;
        }

        float clientPadding = 0;
        int actualBorderWidth = 2;
        Color borderColor = Color.Black;
        protected override void WndProc(ref Message m)
        {
            //We have to change the clientsize to make room for borders
            //if not, the border is limited in how thick it is.
            if (m.Msg == 0x83)
            { //WM_NCCALCSIZE 
                if (m.WParam == IntPtr.Zero)
                {
                    RECT rect = (RECT)Marshal.PtrToStructure(m.LParam, typeof(RECT));
                    rect.left += 2;
                    rect.right -= 2;
                    rect.top -= 0;
                    rect.bottom -= 0;// (int)clientPadding;
                    Marshal.StructureToPtr(rect, m.LParam, false);
                }
                else
                {
                    NCCALSIZE_PARAMS rects = (NCCALSIZE_PARAMS)Marshal.PtrToStructure(m.LParam, typeof(NCCALSIZE_PARAMS));
                    rects.newWindow.left += (int)clientPadding;
                    rects.newWindow.right -= (int)clientPadding;
                    rects.newWindow.top -=2 ;
                    rects.newWindow.bottom -= 2;
                    Marshal.StructureToPtr(rects, m.LParam, false);
                }
            }
            if (m.Msg == 0x85)
            {//WM_NCPAINT    
                IntPtr wDC = GetWindowDC(Handle);
                using (Graphics g = Graphics.FromHdc(wDC))
                {
                    ControlPaint.DrawBorder(g, new Rectangle(0, 0, Size.Width, Size.Height),
                        Color.Transparent, 1, ButtonBorderStyle.Solid,
                        borderColor, actualBorderWidth, ButtonBorderStyle.Solid,
                        Color.Transparent, 1, ButtonBorderStyle.Solid,
                        borderColor, actualBorderWidth, ButtonBorderStyle.Solid);
                }
                return;
            }
            base.WndProc(ref m);
        }

this is what i am getting

This is what I am trying to get

Answer 1

Hi,@OmkarHcl. You could use the following code to accomplish it.

Codebedhind:

  doubleunderlinetextbox tb = new doubleunderlinetextbox();
            tb.Location = new Point(51, 257);
            tb.Size = new Size(212, 100);
           
            tb.Text = "hello";
            this.Controls.Add(tb);

doubleunderlinetextbox:

  public class doubleunderlinetextbox : TextBox
    {

        public doubleunderlinetextbox()
        {
            AutoSize = false;
            BorderStyle = BorderStyle.None;
            
            SetStyle(ControlStyles.UserPaint, true);
            SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        }


        protected override void OnPaint(PaintEventArgs e)
        {

            base.OnPaint(e);

            Rectangle borderRect = new Rectangle(0, 0, Width, Height);


            using (Pen topBorderPen = new Pen(BorderColor, 2))
            {
                e.Graphics.DrawLine(topBorderPen, borderRect.Left, borderRect.Top + 1, borderRect.Right, borderRect.Top + 1);
            }
            using (Pen underlineBorderPen = new Pen(BorderColor, 2))
            {
                e.Graphics.DrawLine(underlineBorderPen, borderRect.Left, borderRect.Bottom - 6, borderRect.Right, borderRect.Bottom - 6);

            }
            using (Pen underlineBorderPen = new Pen(BorderColor, 6))
            {
                e.Graphics.DrawLine(underlineBorderPen, borderRect.Left, borderRect.Bottom, borderRect.Right, borderRect.Bottom);
            }
            if (!string.IsNullOrEmpty(Text))
            {
                TextRenderer.DrawText(e.Graphics, Text, Font, borderRect, ForeColor, TextFormatFlags.VerticalCenter | TextFormatFlags.HorizontalCenter);
            }
        }

        private Color borderColor = Color.Black;

        public Color BorderColor
        {
            get { return borderColor; }
            set
            {
                borderColor = value;
                Invalidate();
            }
        }
        

    }

The result:

Update: I updated the code as follows, it will block part of the top line when entering text.

 public class doubleunderlinetextbox : TextBox
    {


        private Rectangle outerRect;
        private Rectangle innerRect;

        public doubleunderlinetextbox()
        {
            SetStyle(ControlStyles.UserPaint, true);
            SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            AutoSize = false;

            Multiline = true;
            int padding = 8;
            outerRect = new Rectangle(0, 0, Width, Height);

            innerRect = new Rectangle(outerRect.Left + padding, outerRect.Top + padding, outerRect.Width - padding * 2, outerRect.Height - padding * 3);

            TextChanged += CustomTextBox_TextChanged;
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            using (Pen topBorderPen = new Pen(BorderColor, 4))
            {
                e.Graphics.DrawLine(topBorderPen, outerRect.Left, outerRect.Top, outerRect.Right, outerRect.Top);
            }
            using (Pen underlineBorderPen = new Pen(BorderColor, 2))
            {
                e.Graphics.DrawLine(underlineBorderPen, outerRect.Left, outerRect.Bottom-10, outerRect.Right, outerRect.Bottom-10);
            }
            using (Pen underlineBorderPen = new Pen(BorderColor, 4))
            {
                e.Graphics.DrawLine(underlineBorderPen, outerRect.Left, outerRect.Bottom -6 , outerRect.Right, outerRect.Bottom -6);
            }

            using (Pen innerPen = new Pen(InnerBorderColor, 0))
            {
                e.Graphics.DrawRectangle(innerPen, innerRect);
            }

            using (SolidBrush textBrush = new SolidBrush(ForeColor))
            {
                StringFormat format = new StringFormat();
               
                e.Graphics.DrawString(Text, Font, textBrush, innerRect, format);
            }
        }

        protected override void OnSizeChanged(EventArgs e)
        {
            base.OnSizeChanged(e);

            int padding = 8;
            outerRect = new Rectangle(0, 0, Width, Height);
            innerRect = new Rectangle(outerRect.Left + padding, outerRect.Top + padding, outerRect.Width - padding * 2, outerRect.Height - padding * 2);
        }

        private Color borderColor = Color.Black;

        public Color BorderColor
        {
            get { return borderColor; }
            set
            {
                borderColor = value;
                Invalidate();
            }
        }

        private Color innerBorderColor = Color.Transparent;

        public Color InnerBorderColor
        {
            get { return innerBorderColor; }
            set
            {
                innerBorderColor = value;
                Invalidate();
            }
        }

        protected override void WndProc(ref Message m)
        {
            const int WM_CHAR = 0x0102;
            const int WM_PASTE = 0x0302;
            const int WM_CLEAR = 0x0303;
            const int WM_CUT = 0x0300;
            const int WM_KEYDOWN = 0x0100;

            switch (m.Msg)
            {
                case WM_CHAR:
                case WM_PASTE:
                case WM_CLEAR:
                case WM_CUT:
                    if (!innerRect.Contains(PointToClient(Cursor.Position)))
                        return;
                    break;
                case WM_KEYDOWN:
                    if (((Keys)m.WParam) == Keys.Left || ((Keys)m.WParam) == Keys.Right)
                        return;
                    break;
            }

            base.WndProc(ref m);
        }

        private void CustomTextBox_TextChanged(object sender, System.EventArgs e)
        {
            //  Restrict text within the inner rectangle
            if (!innerRect.Contains(PointToClient(Cursor.Position)))
            {
                if (SelectionStart <= innerRect.Left) 
                {
                    SelectionStart = innerRect.Left ;

                }
                   
                else if (SelectionStart >= innerRect.Right)
                    SelectionStart = innerRect.Right - 1;

                Text = Text.Substring(0, innerRect.Left) + Text.Substring(innerRect.Right);
                SelectionStart = innerRect.Left;
            }
        }

        
    }

The result:

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Answer 2

You can use EM_SETRECT to draw outside the text

Something like this :

    public partial class CustomTextBox : RichTextBox
    {
        [DllImport("User32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern int SendMessage(IntPtr hWnd, uint msg, IntPtr wParam, ref RECT lParam);

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
            public RECT(int Left, int Top, int Right, int Bottom)
            {
                left = Left;
                top = Top;
                right = Right;
                bottom = Bottom;
            }
        }

        public const int EM_SETRECT = 0x00B3;

        public const int WM_PAINT = 0x000F;

        public CustomTextBox()
        {
            //InitializeComponent();
            BorderStyle = System.Windows.Forms.BorderStyle.None;
            SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            AutoSize = false;
            this.ScrollBars = System.Windows.Forms.RichTextBoxScrollBars.None;
            RECT rc = new RECT(this.ClientRectangle.Left, this.ClientRectangle.Top + 10, this.ClientRectangle.Right, this.ClientRectangle.Bottom - 10);
            SendMessage(this.Handle, EM_SETRECT, IntPtr.Zero, ref rc);
        }

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            switch (m.Msg)
            {
                case WM_PAINT:
                    PaintEventArgs pe = new PaintEventArgs(this.CreateGraphics(), this.RectangleToScreen(this.ClientRectangle));
                    this.OnPaint(pe);
                    break;
            }
        }

        protected override void OnPaint(PaintEventArgs pe)
        {
            using (Pen penTop = new Pen(BorderColor, 2))
            {
                pe.Graphics.DrawLine(penTop, 0, 2, this.ClientRectangle.Right, 2);
            }
            using (Pen penBottom1 = new Pen(BorderColor, 2))
            {
               pe.Graphics.DrawLine(penBottom1, 0, this.ClientRectangle.Bottom - 5, this.ClientRectangle.Right, this.ClientRectangle.Bottom - 5);
            }
            using (Pen penBottom2 = new Pen(BorderColor, 2))
            {
                pe.Graphics.DrawLine(penBottom2, 0, this.ClientRectangle.Bottom - 2, this.ClientRectangle.Right, this.ClientRectangle.Bottom - 2);
            }
        }

        private Color borderColor = Color.Black;

        public Color BorderColor
        {
            get { return borderColor; }
            set
            {
                borderColor = value;
                Invalidate();
            }
        }
    }