Winforms Textbox - Using Ctrl-Backspace to Delete Whole Word

Question

I have a Winforms dialog that contains among other controls a TextBox that allows a single line of input. I would like to allow the user to be able to press Ctrl-Backspace to delete an entire word. This is not the default behaviour with the out-of-the-box TextBox; I get a rectangle character, rather than having the word deleted.

I have confirmed the ShortcutsEnabled property is set to True.

I did find that I can use a RichTextBox rather than a TextBox to get the behaviour I want. The problem with this is that the apperance of the RichTextBox (border in particular) is different from that of the TextBox, and I don't need or want the ability to mark up text.

So my question is how to best handle this situation? Is there some property on the TextBox that I am missing? Or is it best to use the RichTextBox, update the appearance so it is consistent, and disable markup of the text?

I am relatively happy to write the code to handle the KeyDown and KeyPress events explicity if there is no better way, but thought it was worth checking first.

Answer 1

This is the way yo go :)

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    //if ctrl+bcksp
    if (e.KeyChar == 127)
    {
        //if not last word
        if (textBox1.Text.Split (' ').Count() > 1)
        {
            //remoce last word form list and put it back together (gotta love lambda)
            textBox1.Text = textBox1.Text.Split (' ').Take (textBox1.Text.Split (' ').Count() - 1).Aggregate ((a,b) => a + " " + b);
            //set selection at the end
            textBox1.SelectionStart = textBox1.Text.Length;
        }
        else if (textBox1.Text.Split (' ').Count() == 1)
        {
            textBox1.Text = "";
        }
    }
}

Answer 2

I'm not sure it is possible without a custom KeyDown or KeyPress event, the following code works though:

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    if ((e.KeyCode == Keys.Back) && e.Control)
    {
        e.SuppressKeyPress = true;
        int selStart = textBox1.SelectionStart;
        while (selStart > 0 && textBox1.Text.Substring(selStart - 1, 1) == " ")
        {
            selStart--;
        }
        int prevSpacePos = -1;
        if (selStart != 0)
        {
            prevSpacePos = textBox1.Text.LastIndexOf(' ', selStart - 1);
        }
        textBox1.Select(prevSpacePos + 1, textBox1.SelectionStart - prevSpacePos - 1);
        textBox1.SelectedText = "";
    }
}

Answer 3

I would simulate Ctrl+Backspace by sending Ctrl+Shift+Left and Backspace to the TextBox. The effect is virtually the same, and there is no need to manually process control’s text. You can achieve it using this code:

class TextBoxEx : TextBox
{
    protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    {
        if (keyData == (Keys.Control | Keys.Back))
        {
            SendKeys.SendWait("^+{LEFT}{BACKSPACE}");
            return true;
        }
        return base.ProcessCmdKey(ref msg, keyData);
    }
}

You can also modify the app.config file to force the SendKey class to use newer method of sending keys:

<configuration>
  <appSettings>
    <add key="SendKeys" value="SendInput" />
  </appSettings>
</configuration>

Answer 4

I have same problem. I think this can be solved with a better solution. (I am still not able to do:( ) For example, if we use the 'property' or 'whatever' that makes enable RichTextBox (CTRL + Backspace)able for TextBox, the problem can be solved. Anyone knows where we should find the property of this?

Answer 5

This is what I landed up using, it also handles multi line textboxes

private void HandleCtrlBackspace_KeyDown(object sender, KeyEventArgs e) {
  switch (e.KeyData) {
    case (Keys.Back | Keys.Control):
      e.SuppressKeyPress = true;
      TextBox textbox = (TextBox)sender;
      int i;
      if (textbox.SelectionStart.Equals(0)) {
        return;
      }
      int space = textbox.Text.LastIndexOf(' ', textbox.SelectionStart - 1);
      int line = textbox.Text.LastIndexOf("\r\n", textbox.SelectionStart - 1);
      if (space > line) {
        i = space;
      } else {
        i = line;
      }
      if (i > -1) {
        while (textbox.Text.Substring(i - 1, 1).Equals(' ')) {
          if (i.Equals(0)) {
            break;
          }
          i--;
        }
        textbox.Text = textbox.Text.Substring(0, i) + textbox.Text.Substring(textbox.SelectionStart);
        textbox.SelectionStart = i;
      } else if (i.Equals(-1)) {
        textbox.Text = textbox.Text.Substring(textbox.SelectionStart);
      }
      break;
  }
}