Change border color in TextBox C#

问题:

I have the following code:

public class OurTextBox : TextBox
{
    public OurTextBox()
        : base()
    {
        this.SetStyle(ControlStyles.UserPaint, true);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
         base.OnPaint(e);
         Pen penBorder = new Pen(Color.Gray, 1);
         Rectangle rectBorder = new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y, e.ClipRectangle.Width - 1, e.ClipRectangle.Height - 1);
         e.Graphics.DrawRectangle(penBorder, rectBorder);
   }
}

This is working perfect, but it doesn't show the text until it gets focus.

Can anybody help me? What is wrong?

Thank in advance.

回答1:

You have to draw text manually as well.

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);
    Pen penBorder = new Pen(Color.Gray, 1);
    Rectangle rectBorder = new Rectangle(e.ClipRectangle.X, e.ClipRectangle.Y, e.ClipRectangle.Width - 1, e.ClipRectangle.Height - 1);
    e.Graphics.DrawRectangle(penBorder, rectBorder);

    Rectangle textRec = new Rectangle(e.ClipRectangle.X + 1, e.ClipRectangle.Y + 1, e.ClipRectangle.Width - 1, e.ClipRectangle.Height - 1);
    TextRenderer.DrawText(e.Graphics, Text, this.Font, textRec, this.ForeColor, this.BackColor, TextFormatFlags.Default);
}

Alternatively you can try to use e.Graphics.DrawString() method if TextRenderer is not giving you desired results (I always have better results with this approach thou).

回答2:

To change border color of TextBox you can override WndProc method and handle WM_NCPAINT message. Then get the window device context of the control using GetWindowDC because we want to draw to non-client area of control. Then to draw, it's enough to create a Graphics object from that context, then draw border for control.

To redraw the control when the BorderColor property changes, you can use RedrawWindow method.

Code

Here is a TextBox which has a BorderColor property. The control uses BorderColor if the property values is different than Color.Transparent and BorderStyle is its default value Fixed3d.

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;

public class MyTextBox : TextBox {
    const int WM_NCPAINT = 0x85;
    const uint RDW_INVALIDATE = 0x1;
    const uint RDW_IUPDATENOW = 0x100;
    const uint RDW_FRAME = 0x400;
    [DllImport("user32.dll")]
    static extern IntPtr GetWindowDC(IntPtr hWnd);
    [DllImport("user32.dll")]
    static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);
    [DllImport("user32.dll")]
    static extern bool RedrawWindow(IntPtr hWnd, IntPtr lprc, IntPtr hrgn, uint flags);
    Color borderColor = Color.Blue;
    public Color BorderColor {
        get { return borderColor; }
        set { borderColor = value;
            RedrawWindow(Handle, IntPtr.Zero, IntPtr.Zero,
                RDW_FRAME | RDW_IUPDATENOW | RDW_INVALIDATE);
        }
    }
    protected override void WndProc(ref Message m) {
        base.WndProc(ref m);
        if (m.Msg == WM_NCPAINT && BorderColor != Color.Transparent &&
            BorderStyle == System.Windows.Forms.BorderStyle.Fixed3D) {
            var hdc = GetWindowDC(this.Handle);
            using (var g = Graphics.FromHdcInternal(hdc))
            using (var p = new Pen(BorderColor))
                g.DrawRectangle(p, new Rectangle(0, 0, Width - 1, Height - 1));
            ReleaseDC(this.Handle, hdc);
        }
    }
    protected override void OnSizeChanged(EventArgs e) {
        base.OnSizeChanged(e);
        RedrawWindow(Handle, IntPtr.Zero, IntPtr.Zero,
               RDW_FRAME | RDW_IUPDATENOW | RDW_INVALIDATE);
    }
}

Result

Here is the result using different colors and different states. All states of border-style is supported as you can see in below image and you can use any color for border:

Download

You can clone or download the working example:

• Download Zip
• Github repository

回答3:

There are several ways to do this and none are ideal. This is just the nature of WinForms. However, you have some options. I will summarise:

One way you can achieve what you want is by embedding a TextBox in a Panel as follows.

public class BorderedTextBox : Panel 
{
    private TextBox textBox;
    private bool focusedAlways = false;
    private Color normalBorderColor = Color.Gray;
    private Color focusedBorderColor = Color.Red;

    public BorderTextBox() 
    {
        this.DoubleBuffered = true;
        this.Padding = new Padding(2);

        this.TextBox = new TextBox();
        this.TextBox.AutoSize = false;
        this.TextBox.BorderStyle = BorderStyle.None;
        this.TextBox.Dock = DockStyle.Fill;
        this.TextBox.Enter += new EventHandler(this.TextBox_Refresh);
        this.TextBox.Leave += new EventHandler(this.TextBox_Refresh);
        this.TextBox.Resize += new EventHandler(this.TextBox_Refresh);
        this.Controls.Add(this.TextBox);
    }

    private void TextBox_Refresh(object sender, EventArgs e) 
    {
        this.Invalidate();
    }

    protected override void OnPaint(PaintEventArgs e) 
    {
        e.Graphics.Clear(SystemColors.Window);
        using (Pen borderPen = new Pen(this.TextBox.Focused || FocusedAlways ? 
            focusedBorderColor : normalBorderColor)) 
        {
            e.Graphics.DrawRectangle(borderPen, 
                new Rectangle(0, 0, this.ClientSize.Width - 1, this.ClientSize.Height - 1));
        }
        base.OnPaint(e);
    }

    public TextBox TextBox
    {
        get { return textbox; }
        set { textbox = value; }
    }

    public bool FocusedAlaways
    {
        get { return focusedAlways; }
        set { focusedAlways = value; }
    }
}

You can also do this without overriding any controls, but the above method is better. The above will draw a border when the control gets focus. if you want the border on permanently, set the FocusedAlways property to True.

I hope this helps.

回答4:

set Text box Border style to None then write this code to container form "paint" event

    private void Form1_Paint(object sender, PaintEventArgs e)
        {
System.Drawing.Rectangle rect = new Rectangle(TextBox1.Location.X, TextBox1.Location.Y, TextBox1.ClientSize.Width, TextBox1.ClientSize.Height);

                rect.Inflate(1, 1); // border thickness
                System.Windows.Forms.ControlPaint.DrawBorder(e.Graphics, rect, Color.DeepSkyBlue, ButtonBorderStyle.Solid);

}