C# TextBox with persistent text

Question

For a game I am trying to make a textbox that will have a text similar to "0 / 100". I would like that text to:

1. Always persist, ie clicking the textbox to NOT make the text disappear. I know I can create event handlers for OnFocus/LoseFocus, but that still makes the text disappear.

2. The user be able to only enter values in the left portion of the text. Ie I would like the user to only modify the "XXX" portion in this example: "XXX / 100".

I found this question, but it is for CSS.

Also, I am aware I could make something look like what I want, but I would prefer to do that only if what I want can't be achieved with only a textbox.

Answer 1

You can use a RichTextBox control to accomplish that:

var rtb = new RichTextBox();
rtb.ShortcutsEnabled = false;
rtb.Location = new Point(16, 16);
rtb.Size = new Size(96, 23);
rtb.Multiline = false;
rtb.Text = " / 100";
rtb.SelectAll();
rtb.SelectionProtected = true;
rtb.Select(0, 0);      
rtb.KeyPress += rtb_KeyPress;
this.Controls.Add(rtb);

void rtb_KeyPress(object sender, KeyPressEventArgs e) {
  RichTextBox rtb = sender as RichTextBox;
  if (rtb.SelectionStart == rtb.TextLength) {
    e.Handled = true;
  } else if (!Char.IsDigit(e.KeyChar)) {
    e.Handled = true;
  } else if (rtb.TextLength == 9) {
    if (rtb.SelectionLength > 0) {
      if (rtb.SelectionStart > 3) {
        e.Handled = true;
      }
    } else {
      e.Handled = true;
    }
  } else if (rtb.SelectionStart == 0 && rtb.SelectionLength == 0) {
    rtb.SelectionProtected = false;
  }
}