/// <summary>
/// Return a StyledParagraph reflecting the insertion of a single character
/// into the text. This method will attempt to reuse the given paragraph,
/// but may create a new paragraph. </summary>
/// <param name="aci"> an iterator over the text. The text should be the same as the
/// text used to create (or most recently update) oldParagraph, with
/// the exception of deleting a single character at deletePos. </param>
/// <param name="chars"> the characters in aci </param>
/// <param name="deletePos"> the index where a character was removed </param>
/// <param name="oldParagraph"> a StyledParagraph for the text in aci before the
/// insertion </param>
public static StyledParagraph DeleteChar(AttributedCharacterIterator aci, char[] chars, int deletePos, StyledParagraph oldParagraph)
{
// We will reuse oldParagraph unless there was a length-1 run
// at deletePos. We could do more work and check the individual
// Font and Decoration runs, but we don't right now...
deletePos -= aci.BeginIndex;
if (oldParagraph.Decorations == null && oldParagraph.Fonts == null)
{
oldParagraph.Length -= 1;
return(oldParagraph);
}
if (oldParagraph.GetRunLimit(deletePos) == deletePos + 1)
{
if (deletePos == 0 || oldParagraph.GetRunLimit(deletePos - 1) == deletePos)
{
return(new StyledParagraph(aci, chars));
}
}
oldParagraph.Length -= 1;
if (oldParagraph.Decorations != null)
{
DeleteFrom(deletePos, oldParagraph.DecorationStarts, oldParagraph.Decorations.Count);
}
if (oldParagraph.Fonts != null)
{
DeleteFrom(deletePos, oldParagraph.FontStarts, oldParagraph.Fonts.Count);
}
return(oldParagraph);
}
