Re: Change to NS drawing routines

[Alan Third]

On Mon, Aug 13, 2018 at 10:10:41PM +0300, Eli Zaretskii wrote:
> > Date: Mon, 13 Aug 2018 19:46:59 +0100
> > From: Alan Third <address@hidden>
> > Cc: address@hidden
> > 
> > Going through the previous email discussions, linked in the thread
> > above, Eli made it clear that he sees using the expose functions to
> > draw, when it’s not an expose event, as being incorrect.
> > 
> > i.e. this:
> > 
> > > > Again, invalidating an area to let the "expose" handler draw
> > > > afterwards is a very standard, primary, canonical, and sometimes
> > > > only way of drawing nowadays. (If you call it is an abuse or
> > > > trick, you'll be laughed.)
> > > 
> > > You can laugh, if you want, but I still think it's abuse, and won't
> > > be convinced by being laughed at.
> > 
> > from http://lists.gnu.org/archive/html/emacs-devel/2013-04/msg00435.html
> > 
> > I can understand the argument to an extent, but I don’t have another
> > solution.
> 
> We could discuss this again, perhaps the details have changed, or we
> might be able o find some compromise everybody can live with.
> 
> For starters, what changes, if any, would you need to make in the
> glyph matrices, and why?

For this none, I can do it all in the NS specific code.

I’ve changed all the NS drawing functions to check whether they are
allowed to draw. If not then I mark the area as dirty.

I’ve added an ns_flush_display function that I believe is called at
the end of redisplay (flush_frame). I wasn’t sure about this but it
looks as though it works, (i.e. everything draws OK) so I assume it’s
safe.

Anyway, ns_flush_display asks Cocoa/GNUstep to redraw the frame, which
results in drawRect being called which calls expose_frame on the
rectangles that have been marked as dirty.
-- 
Alan Third