public TextMarker TryCreate(int startOffset, int length)
{
if (_markers == null)
throw new InvalidOperationException("Cannot create a marker when not attached to a document");
var textLength = _document.TextLength;
if (startOffset < 0 || startOffset > textLength) return null;
//throw new ArgumentOutOfRangeException(nameof(startOffset), startOffset, "Value must be between 0 and " + textLength);
if (length < 0 || startOffset + length > textLength) return null;
//throw new ArgumentOutOfRangeException(nameof(length), length, "length must not be negative and startOffset+length must not be after the end of the document");
var marker = new TextMarker(this, startOffset, length);
_markers.Add(marker);
return marker;
}
public void Remove(TextMarker marker)
{
if (marker == null)
throw new ArgumentNullException(nameof(marker));
var m = marker;
if (_markers != null && _markers.Remove(m))
{
Redraw(m);
m.OnDeleted();
}
}