public override bool CanExecute(object parameter)
{
var e = parameter as KeyEventArgs;
if (e == null)
{
return(false);
}
if (!removalKeys.Contains(e.Key))
{
return(false);
}
var area = selectionViewReader.GetCurrentSelectionArea();
var lastLineLength = textViewReader.GetLineLength(caretViewReader.CaretPosition.Line);
// if user pressed delete key and the caret is at the last position in the document and nothing is selected, then no text should be removed
if (e.Key == Key.Delete && caretViewReader.CaretPosition.Line == textViewReader.LinesCount - 1 && caretViewReader.CaretPosition.Column == lastLineLength && area == null)
{
return(false);
}
// if user pressed backspace key and caret is at the first position in the document and nothing is selected, then no text should be removed
if (e.Key == Key.Back && caretViewReader.CaretPosition.Line == 0 && caretViewReader.CaretPosition.Column == 0 && area == null)
{
return(false);
}
if (area?.StartPosition != null && area.EndPosition != null)
{
return(area.StartPosition != area.EndPosition);
}
return(true);
}
public override void Execute(object parameter)
{
var e = parameter as TextCompositionEventArgs;
var selectionArea = selectionViewReader.GetCurrentSelectionArea();
var prevCaretPosition = caretViewReader.CaretPosition;
UpdateCommandState(BeforeCommandExecutedState);
if (selectionArea == null)
{
textView.EnterText(e.Text);
}
else
{
textView.ReplaceText(e.Text, selectionArea);
}
UpdateCommandState(AfterCommandExecutedState);
caretView.HandleTextChange(e.Text);
textView.Postbox.Put(new TextAddedMessage {
Text = e.Text,
PrevCaretPosition = prevCaretPosition,
NewCaretPosition = caretViewReader.CaretPosition
});
}
