protected override void OnKeyPress(KeyPressEventArgs e)
{
if (!DisallowedCharacters.IsEmpty() && DisallowedCharacters.Contains(e.KeyChar))
{
e.Handled = true;
}
base.OnKeyPress(e);
}
protected override void OnTextChanged(EventArgs e)
{
string oldBackingText = _backingText;
if (!DisallowedCharacters.IsEmpty())
{
string newText = Text;
foreach (char c in DisallowedCharacters)
{
newText = newText.Replace(c.ToString(), "");
}
// Prevents control-key combinations (Ctrl+A for example) from breaking, since they also fire
// this event even though the text doesn't actually end up changing in that case.
if (newText != Text)
{
int oldCaretPosition = SelectionStart;
int oldTextLength = Text.Length;
Text = newText;
int newCaretPosition = oldCaretPosition - (oldTextLength - newText.Length);
Select(newCaretPosition < 0 ? 0 : newCaretPosition, 0);
}
}
_backingText = Text;
// Prevents non-text key combinations from firing the TextChanged event.
// How in the hell does "text changed" mean "key pressed but literally no text changed at all".
// Microsoft...
// 2021-03-09:
// I guess I finally figured out why they did this. It's probably so that you can select a character,
// overwrite it with the same one, and now your text is the same but you can still run things that
// react to "text entry" (like I'm having to do with my search drop-down).
if (!StrictTextChangedEvent || oldBackingText != Text)
{
base.OnTextChanged(e);
}
}
