public override IReadOnlyList <TextChangeRange> GetChangeRanges(SourceText oldText)
{
if (oldText == null)
{
throw new ArgumentNullException(nameof(oldText));
}
// if they are the same text there is no change.
if (oldText == this)
{
return(TextChangeRange.NoChanges);
}
// first, check whether the text buffer is still alive.
if (this.Container is TextBufferContainer container)
{
var lastEventArgs = container.LastEventArgs;
if (lastEventArgs != null && lastEventArgs.OldText == oldText && lastEventArgs.NewText == this)
{
return(lastEventArgs.Changes);
}
}
var oldSnapshot = oldText.TryFindCorrespondingEditorTextImage();
var newSnapshot = this.TryFindCorrespondingEditorTextImage();
return(GetChangeRanges(oldSnapshot, oldText.Length, newSnapshot));
}
