RichTextBox

This has many formatting options. It applies colors, background colors, multiple fonts, and margins to the text. It adds more complexity than the regular TextBox.

The RichTextBox provides needed features to programs. Please drag a RichTextBox to your Form from the ToolBox in Visual Studio.

Color example

Here we generate colored text blocks. In the Form1_Load event, the Font is changed, and then the BackColor is set to a light shade of blue.

using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            richTextBox1.Font = new Font("Consolas", 18f, FontStyle.Bold);
            richTextBox1.BackColor = Color.AliceBlue;
            string[] words =
            {
                "Dot",
                "Net",
                "Perls",
                "is",
                "a",
                "nice",
                "website."
            };
            Color[] colors =
            {
                Color.Aqua,
                Color.CadetBlue,
                Color.Cornsilk,
                Color.Gold,
                Color.HotPink,
                Color.Lavender,
                Color.Moccasin
            };
            for (int i = 0; i < words.Length; i++)
            {
                string word = words[i];
                Color color = colors[i];
                {
                    richTextBox1.SelectionBackColor = color;
                    richTextBox1.AppendText(word);
                    richTextBox1.SelectionBackColor = Color.AliceBlue;
                    richTextBox1.AppendText(" ");
                }
            }
        }
    }
}

DetectUrls

Sometimes a link to a web page will be entered. If you set the DetectUrls property to true, the RichTextBox will add hyperlink styles to any possible link.

using System.Diagnostics;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void richTextBox1_LinkClicked(object sender, LinkClickedEventArgs e)
        {
            Process.Start(e.LinkText);
        }
    }
}

TextChanged

RichTextBox has a TextChanged event handler. Whenever the text changes for any reason in the RichTextBox, the code in the TextChanged event handler executes.

using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void richTextBox1_TextChanged(object sender, EventArgs e)
        {
            this.Text = richTextBox1.Text;
        }
    }
}

Select, SelectedText

The RichTextBox also offers the ability to select text based on a starting index and a count of characters, with the Select method.

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            richTextBox1.AppendText("Dot Net Perls");
            richTextBox1.Select(4, 3);
            this.Text = richTextBox1.SelectedText;
        }
    }
}

ZoomFactor

One useful property on the RichTextBox control is the ZoomFactor property. You can set its default value in the Windows Forms designer.

AutoWordSelection

This can be True or False. When True, the selection when the user drags over some text will expand to contain the word being hovered over.

RightMargin

RightMargin is somewhat confusing to use and you will have to experiment. The goal is to have some whitespace on the right side of the enclosed text box space.

TextLength

In my testing, this property returned the same number as using richTextBox1.Text.Length. Often we can take the string length of the Text property.

Copy, Paste

You will find the Copy and Paste methods. There is also a CanPaste boolean method for testing if pasting is possible. Windows Forms programs use the system clipboard.

Rtf

RTF stands for Rich Text Format, and this describes a certain file type where text formatting is encoded with special characters embedded in the text.

We can control the RichTextBox programmatically through C# code. And we can change many properties inside the Visual Studio designer before the program ever executes.