private static TextPointer Highlight(FlowDocument document, Interval interval)
{
if (document == null)
throw new ArgumentNullException("document");
TextPointer contentStart = document.ContentStart;
// clear any existing highlight
TextRange documentRange = new TextRange(document.ContentStart, document.ContentEnd);
documentRange.ApplyPropertyValue(FlowDocument.BackgroundProperty, FlowDocument.BackgroundProperty.DefaultMetadata.DefaultValue);
if (interval == null)
return null;
// highlight the new text
int startOffset = interval.Start;
int endOffset = interval.End;
TextPointer highlightStart = document.GetPointerFromCharOffset(ref startOffset);
TextPointer highlightStop = document.GetPointerFromCharOffset(ref endOffset);
if (startOffset != 0 || endOffset != 0)
return null;
var textRange = new TextRange(highlightStart, highlightStop);
textRange.ApplyPropertyValue(FlowDocument.BackgroundProperty, Brushes.Yellow);
return textRange.Start;
}
