/// <summary>
/// Replace selection with insert text.
/// </summary>
/// <param name="insert">The text to be inserted.</param>
/// <returns>The resulting value.</returns>
public TextSlice Insert(string insert)
{
var text = Head + insert + Tail;
var result = new TextSlice(text, Start + insert.Length, 0, true);
return(result);
}
/// <summary>
/// Handle selection changed.
/// </summary>
/// <param name="e"></param>
protected override void OnSelectionChanged(RoutedEventArgs e)
{
base.OnSelectionChanged(e);
if (!_isUpdatingText)
{
TextSlice = new TextSlice(Text, SelectionStart, SelectionLength, CaretIndex != SelectionStart);
}
UpdateSelectionCondition();
}
/// <summary>
/// Handle text changing.
/// </summary>
/// <param name="e"></param>
protected override void OnTextChanged(TextChangedEventArgs e)
{
base.OnTextChanged(e);
// The text as it is now.
var now = Text;
// Find the common prefix for what was and what is now.
var head = 0;
while (head < was.Length && head < now.Length && was[head] == now[head])
{
head++;
}
// Find the common suffix.
var wasTail = was.Length;
var nowTail = now.Length;
while (head < wasTail && head < nowTail && was[wasTail - 1] == now[nowTail - 1])
{
wasTail--;
nowTail--;
}
// Extract the deleted text.
var nowChanged = now.Substring(head, nowTail - head);
var wasChanged = was.Substring(head, wasTail - head);
if (nowChanged == string.Empty && wasChanged.Length != 0 && char.IsUpper(wasChanged[0]))
{
// If we've inserted nothing and deleted something that starts with a capital, we're
// can restore the shift key.
ShiftToggleState.IsChecked = true;
}
else if (wasChanged == string.Empty && nowChanged == " " && head != 0 && now[head - 1].IsSentenceEnding())
{
// If we've inserted a space and deleted nothing, check whetehr a fullstop precedes
// the space and if so press the shift key.
ShiftToggleState.IsChecked = true;
}
// What is becomes what was.
was = now;
if (!_isUpdatingText)
{
TextSlice = new TextSlice(Text, SelectionStart, SelectionLength, SelectionStart != CaretIndex);
}
}