Re: redisplay - very long lines

[grischka]

> > Would it be possible to add a termination condition in move_it_to to
> > stop after leaving the window vertically or horizontally (with
> > truncate-lines)?
>
> If we can tolerate an incorrect display, maybe.  The invisible part of
> the line could in principle include characters and faces whose
> presence may have global effects on the rest of the displayed portion,
> such as faces that use larger fonts, to say nothing of inline images.

That is not a necessary consequence at all.

After all faces and images don't come fallen from outer space into
the text but if they exist then it was the emacs program itself that
has put them there.  So instead of scanning lines each time it could
as well just remember where and how big they are.