On Sun, 7 Oct 2018, 19:36 David Reitter, <david.reitter@gmail.com> wrote:

> On Oct 7, 2018, at 7:14 AM, Alan Third <alan@idiocy.org> wrote:
>
> > The attached patch fixes it, but it marks the whole area dirty instead
> > of copying it, so it will be redrawn at the next expose event. I can’t
> > see any difference in simple testing, but it may slow down scrolling
> > on very complex buffers.
>
> Thank you.
> I can’t see any obvious difference in speed either on a modern laptop.
>
> NSView scrollRect has been deprecated, so replacing it is a good thing all
> other things being equal. Implementing true scrolling rather than redrawing
> would still be worth a try, as display doesn’t seem particularly fast.
>
> I’ll apply it to my own branch and report back if users complain.
>

I did eventually find this was a fair bit slower if I made the frame quite
large and zoomed the text out quite a lot, so I suppose it might affect
people using sublimetext style "maps".

I have come up with a possible work around continuing to use scrollRect,
but I've not had time to try implementing it yet.

As you say it would be better to use proper scrolling without scrollRect,
but I don't see any obvious way to do it. I suspect I just don't have
enough knowledge of the cocoa APIs.