Beyond_Beyaan.BBSingleLineTextBox.KeyDown C# (CSharp) Метод

        public bool KeyDown(KeyboardInputEventArgs e)
        {
            if (isSelected)
            {
                if (e.Key == KeyboardKeys.Enter || e.Key == KeyboardKeys.Return)
                {
                    isSelected = false;
                }
                else if (e.Key == KeyboardKeys.Back)
                {
                    if (SelectedText.Length > 0)
                    {
                        DeleteSelectedText();
                    }
                    else if (Text.Length > 0)
                    {
                        Text = Text.Substring(0, Text.Length - 1);
                    }
                }
                else if (e.Key == KeyboardKeys.Delete)
                {
                    if (SelectedText.Length > 0)
                    {
                        DeleteSelectedText();
                    }
                }
                else if (e.Key == KeyboardKeys.A && e.ModifierKeys == KeyboardKeys.Control)
                {
                    SelectedText = Text;
                    SelectedTextIndex = 0;
                }
                else if (char.IsLetterOrDigit(e.CharacterMapping.Character) ||
                    char.IsLetterOrDigit(e.CharacterMapping.Shifted) ||
                    char.IsSymbol(e.CharacterMapping.Character) ||
                    char.IsSymbol(e.CharacterMapping.Shifted) ||
                    char.IsPunctuation(e.CharacterMapping.Character) ||
                    char.IsPunctuation(e.CharacterMapping.Shifted) ||
                    char.IsWhiteSpace(e.CharacterMapping.Character))
                {
                    if (SelectedText.Length > 0)
                    {
                        ReplaceSelectedText(e.Shift ? e.CharacterMapping.Shifted.ToString() : e.CharacterMapping.Character.ToString());
                        return true;
                    }

                    string prevText = Text;
                    Text = Text + (e.Shift ? e.CharacterMapping.Shifted : e.CharacterMapping.Character);
                    text.SetText(Text);
                    if (text.GetWidth() > width - 8)
                    {
                        text.SetText(prevText);
                        Text = prevText;
                    }
                }
                else if (e.Key == KeyboardKeys.Decimal)
                {
                    if (SelectedText.Length > 0)
                    {
                        ReplaceSelectedText(".");
                        return true;
                    }
                    string prevText = Text;
                    Text = Text + ".";
                    text.SetText(Text);
                    if (text.GetWidth() > width - 8)
                    {
                        text.SetText(prevText);
                        Text = prevText;
                    }
                }
                return true;
            }
            return false;
        }