public ITextRangeProvider[] GetVisibleRanges()
{
int start_line = -1, end_line = -1;
Document.GetVisibleLineIndexes(TextBoxBase.Bounds, out start_line, out end_line);
ITextRangeProvider range = DocumentRange.Clone();
range.MoveEndpointByUnit(TextPatternRangeEndpoint.Start, TextUnit.Line, start_line);
range.MoveEndpointByUnit(TextPatternRangeEndpoint.End, TextUnit.Line, end_line - start_line);
return(new ITextRangeProvider[] { range });
}