Question

I’m using a RichTextBox in WinForms 3.5 and I found that when I programmatically edit the contained text, those changes are no longer available to the built in undo functionality.

Is there a way to make it so these changes are available for undo/redo?

Answer 1

Here’s just some code I decided to mess around with:

        string buffer = String.Empty;         string buffer2 = String.Empty;         public Form3()         {             InitializeComponent();             this.richTextBox1.KeyDown += new KeyEventHandler(richTextBox1_KeyDown);             this.richTextBox1.TextChanged += new EventHandler(richTextBox1_TextChanged);         }          void richTextBox1_TextChanged(object sender, EventArgs e)         {             buffer2 = buffer;             buffer = richTextBox1.Text;         }          void richTextBox1_KeyDown(object sender, KeyEventArgs e)         {             if (e.Control && e.KeyCode == Keys.Z)             {                 this.richTextBox1.Text = buffer2;             }         }          private void button1_Click(object sender, EventArgs e)         {             richTextBox1.Text = 'Changed';         } 

It’s basically me writing my own Undo feature. All I’m doing is storing the old value in one buffer variable, and the new value in a second buffer variable. Every time the text changes, these values get update. Then, if the user hits ‘CTRL-Z’ it replaces the text with the old value. Hack? A little. But, it works for the most part.