bug#63187: 30.0.50; Tail of longer lines painted after end of nearby lines on macOS

[Aaron Jensen <aaronjensen@gmail.com>]

On Sun, Jul 23, 2023 at 7:20 AM Alan Third <alan@idiocy.org> wrote:
>
> On Thu, Jul 20, 2023 at 10:02:53PM -0400, Aaron Jensen wrote:
> >
> > I've been using this for about a month now and have seen no artifacts:
> >
> > diff --git a/src/nsterm.m b/src/nsterm.m
> > index 78089906752..d23fb650ab8 100644
> > --- a/src/nsterm.m
> > +++ b/src/nsterm.m
> > @@ -2708,9 +2708,6 @@ Hide the window (X11 semantics)
> >      EmacsView *view = FRAME_NS_VIEW (f);
> >
> >      [view copyRect:srcRect to:dest];
> > -#ifdef NS_IMPL_COCOA
> > -    [view setNeedsDisplayInRect:destRect];
> > -#endif
> >    }
> >
> >    unblock_input ();
> > @@ -10435,7 +10432,7 @@ @implementation EmacsLayer
> >     cache.  If no free surfaces are found in the cache then a new one
> >     is created.  */
> >
> > -#define CACHE_MAX_SIZE 2
> > +#define CACHE_MAX_SIZE 1
> >
> >  - (id) initWithColorSpace: (CGColorSpaceRef)cs
> >  {
> > @@ -10621,7 +10618,7 @@ - (void) display
> >  {
> >    NSTRACE_WHEN (NSTRACE_GROUP_FOCUS, "[EmacsLayer display]");
> >
> > -  if (context)
> > +  if (context && context != [NSGraphicsContext currentContext])
> >      {
> >        [self releaseContext];
> >
> >
> > I'm not sure what the ramifications are for CACHE_MAX_SIZE 1 on slower
> > machines, but I don't notice any performance issues on my M1.
> >
> > Alan, what do you think we should do? Is there anything else you think
> > I should test for the next bit of time?
>
> I dug out my mac and built this and it still flickers with animated
> gifs. It's pretty easy to make happen, so it must be some hardware
> performance thing.
>
> Anyway, I've tried simplifying the double buffering code and put in
> all the wee changes I've thought about. Who knows if this will work
> any better...
>
> (It may be worth making the single/double buffering a run-time option
> as theoretically the single buffering will perform better, although
> always at the increased risk of tearing effects etc.)

Thanks, I'll try this one out. FYI there was a typo in a comment: doible

Aaron