CODEWITHSUNDEEP
c#winformsundo
Adam Haile
Adam Haile

Reputation: 31359

.NET RichTextBox undo

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?

Upvotes: 6

Views: 2340

Answers (2)

Morty
Morty

Reputation: 3229

Instead of replacing the text, you need to replace the selected text:

richTextBox.SelectAll();
richTextBox.SelectedText = NewText;

This was however tested with a current version of winforms, which has the same issue.

Upvotes: 1

BFree
BFree

Reputation: 103770

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.

Upvotes: 2

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