internal override void OnInput(InputEventArgs e)
{
// Text input will start an edit.
// Escape is meant to be for CancelEdit. But DataGrid
// may not handle KeyDown event for Escape if nothing
// is cancelable. Such KeyDown if unhandled by others
// will ultimately get promoted to TextInput and be handled
// here. But BeginEdit on escape could be confusing to the user.
// Hence escape key is special case and BeginEdit is performed if
// there is atleast one non espace key character.
if (DataGridHelper.HasNonEscapeCharacters(e as TextCompositionEventArgs))
{
BeginEdit(e, true);
}
else if (DataGridHelper.IsImeProcessed(e as KeyEventArgs))
{
if (DataGridOwner != null)
{
DataGridCell cell = DataGridOwner.CurrentCellContainer;
if (cell != null && !cell.IsEditing)
{
Debug.Assert(e.RoutedEvent == Keyboard.PreviewKeyDownEvent, "We should only reach here on the PreviewKeyDown event because the TextBox within is expected to handle the preview event and hence trump the successive KeyDown event.");
BeginEdit(e, false);
//
// The TextEditor for the TextBox establishes contact with the IME
// engine lazily at background priority. However in this case we
// want to IME engine to know about the TextBox in earnest before
// PostProcessing this input event. Only then will the IME key be
// recorded in the TextBox. Hence the call to synchronously drain
// the Dispatcher queue.
//
Dispatcher.Invoke((Action) delegate(){}, System.Windows.Threading.DispatcherPriority.Background);
}
}
}
}