Re: font-backend mechanism on Windows and Mac?

["Adrian Robert" <adrian.b.robert@gmail.com>]

On 9/13/07, Kenichi Handa <handa@m17n.org> wrote:
> In article <55f7df060709130853q25979167p465e8e7591000ca2@mail.gmail.com>, "Adrian Robert" <adrian.b.robert@gmail.com> writes:
>
> > I assume it does, however I can't replicate the error as described
> > because dragging windows from other apps over emacs does not cause
> > redraws under my port.  (Did I understand the symptom report
> > correctly?)  I guess something else causing a redraw could work:
> > Moving cursor over?  Dragging mouse selection over?
>
> As far as I know, the bug is in expose_window (xdisp.c) and
> what called from there.  And expose_window is triggered by
> Expose or GraphicExpose events.  So, if Mac Cocoa uses
> "backing store", such events doesn't happend, thus the bug
> won't be revealed.  Isn't it possbile to suppress backing
> streo on Cocoa?

It is, but because this is not used normally (not recommended under
Cocoa) rectangle expose events aren't even generated by the port, so
I'd need to add that to check.  However, looking at the patch, it
seems the change is to use multiple clip rects in some row overlap
cases.  In the Cocoa port there is a bug where the upper parts of
Tibetan text are cut off until cursor is moved over them, and it may
be related to this.  I'll try the patch as soon as I get time, next
week.

FWIW, I can't see any reason this patch would slow things down
noticeably in X, though I have not looked at the W32 code.


-Adrian