[cairo] Color fonts

Sat Jul 29 16:22:57 UTC 2017

On Sat, Jul 29, 2017 at 4:45 PM, <iofelben at gmail.com> wrote:

> Tried to run gnome-characters with Cairo master, switching to noto-
> color-emoji crashes with:
>
> #0  0x00007fd0ecd2868b in raise () at /lib64/libc.so.6
> #1  0x00007fd0ecd2a417 in abort () at /lib64/libc.so.6
> #2  0x00007fd0ecd208fa in __assert_fail_base () at /lib64/libc.so.6
> #3  0x00007fd0ecd20972 in  () at /lib64/libc.so.6
> #4  0x00007fd0f1370b6e in _cairo_error (status=status at entry=3646361312)
> at cairo-error.c:68
> #5  0x00007fd0f1367802 in _cairo_set_error (cr=0x3dd89ecc00,
> status=3646361312) at cairo.c:400
>

Humm. status seems to be garbage.  Let me take a look.

> #6  0x00007fd0f13691b1 in cairo_show_text_glyphs (cr=0x3dd89ecc00,
> utf8=0x3dd8a41b40 "😀", utf8_len=4, glyphs=0x7fffada90d60, num_glyphs=1
> , clusters=0x7fffada91640, num_clusters=1, cluster_flags=(unknown: 0))
> at cairo.c:3742
> #7  0x00007fd0f0283f69 in pango_cairo_renderer_show_text_glyphs.isra ()
> at /lib64/libpangocairo-1.0.so.0
> #8  0x00007fd0f0284161 in pango_cairo_renderer_draw_glyph_item () at
> /lib64/libpangocairo-1.0.so.0
> #9  0x00007fd0f0057e1e in pango_renderer_draw_glyph_item () at
> /lib64/libpango-1.0.so.0
> #10 0x00007fd0f00588b1 in pango_renderer_draw_layout_line () at
> /lib64/libpango-1.0.so.0
> #11 0x00007fd0f0058c65 in pango_renderer_draw_layout () at
> /lib64/libpango-1.0.so.0
> #12 0x00007fd0f028443a in _pango_cairo_do_layout () at
> /lib64/libpangocairo-1.0.so.0
> #13 0x00007fd0ef560bde in ffi_call_unix64 () at /lib64/libffi.so.6
> #14 0x00007fd0ef56054f in ffi_call () at /lib64/libffi.so.6
> #15 0x00007fd0f10ab6f6 in  () at /lib64/libgjs.so.0
> #16 0x00007fd0f10ad066 in  () at /lib64/libgjs.so.0
> #17 0x00007fd0ee3626a8 in js::Invoke(JSContext*, JS::CallArgs,
> js::MaybeConstruct) () at /lib64/libmozjs-38.so
> #18 0x00007fd0ee3584cd in Interpret(JSContext*, js::RunState&) () at
> /lib64/libmozjs-38.so
> #19 0x00007fd0ee362324 in js::RunScript(JSContext*, js::RunState&) ()
> at /lib64/libmozjs-38.so
> #20 0x00007fd0ee362614 in js::Invoke(JSContext*, JS::CallArgs,
> js::MaybeConstruct) () at /lib64/libmozjs-38.so
> #21 0x00007fd0ee664f13 in js_fun_apply(JSContext*, unsigned int,
> JS::Value*) () at /lib64/libmozjs-38.so
> #22 0x00007fd0ee3626a8 in js::Invoke(JSContext*, JS::CallArgs,
> js::MaybeConstruct) () at /lib64/libmozjs-38.so
> #23 0x00007fd0ee363243 in js::Invoke(JSContext*, JS::Value const&,
> JS::Value const&, unsigned int, JS::Value const*,
> JS::MutableHandle<JS::Value>) () at /lib64/libmozjs-38.so
> #24 0x00007fd0ee4b5485 in js::jit::DoCallFallback(JSContext*,
> js::jit::BaselineFrame*, js::jit::ICCall_Fallback*, unsigned int,
> JS::Value*, JS::MutableHandle<JS::Value>) ()
>     at /lib64/libmozjs-38.so
> #25 0x00007fd0f1877510 in  ()
> #26 0x00007fffada948a0 in  ()
> #27 0x00007fffada94368 in  ()
> #28 0x0000000000000000 in  ()
>
> On Sat, 2017-07-29 at 16:30 +0100, Behdad Esfahbod wrote:
> > On Sat, Jul 29, 2017 at 11:58 AM, Uli Schlachter <psychon at znc.in>
> > wrote:
> > > Hi Behdad
> > >
> > > I don't think that is my decision to make. When thinking about
> > > "fonts in
> > > cairo", I'm thinking "Behdad". I'm just asking weird questions from
> > > the
> > > sideline. :-)
> >
> > Thanks. :-)  Pushed!!!!  At least ten people already asked me "what's
> > up with emoji" at GUADEC...
> >
> > > Uli
> > >
> > > P.S.: How relevant and up to date is the CC list here? I always get
> > > a
> > > "your message to gtk-devel-list awaits moderator approval"-mail
> > > when
> > > replying to this thread...
> > >
> >
> > My messages go through, yours probably don't because you are not a
> > member.  It's valuable still.
> >
> > Cheers,
> > b
> >
> > > On 28.07.2017 16:38, Behdad Esfahbod wrote:
> > > > Uli,
> > > >
> > > > Can we commit this?  I don't think waiting another few years will
> > > result in
> > > > a superior patchset. :)
> > > >
> > > > Cheers,
> > > >
> > > > behdad
> > > >
> > > > On Wed, Jul 19, 2017 at 1:53 AM, Behdad Esfahbod <behdad at behdad.o
> > > rg> wrote:
> > > >
> > > >> Right.  In the future we would want to make it show glyphs in
> > > the input
> > > >> order, ie. not separate color vs non-color.  That's the order
> > > required by
> > > >> CSS for example.  In a show-text-glyphs call with
> > > CAIRO_TEXT_CLUSTER_FLAG_BACKWARD,
> > > >> it might be desirable to show back-to-front.
> > > >>
> > > >> On Tue, Jul 18, 2017 at 1:59 PM, Matthias Clasen <
> > > >> matthias.clasen at gmail.com> wrote:
> > > >>
> > > >>> On Sat, Jul 15, 2017 at 4:05 AM, Uli Schlachter <psychon at znc.in
> > > > wrote:
> > > >>>
> > > >>>> On 07.07.2017 15:23, Matthias Clasen wrote:
> > > >>>>> On Sat, Jul 1, 2017 at 2:25 AM, Uli Schlachter <psychon at znc.i
> > > n> wrote:
> > > >>>>>> On 30.06.2017 17:29, Behdad Esfahbod wrote:
> > > >>>>>>> On Jun 30, 2017 7:51 PM, "Matthias Clasen" <mclasen at redhat.
> > > com>
> > > >>>> wrote:
> > > >>>>>>> On Fri, 2017-06-30 at 17:02 +0200, Uli Schlachter wrote:
> > > >>>>>>>> On 28.06.2017 14:23, Behdad Esfahbod wrote:
> > > >>>>>>>>> All of you have asked me about the status of color fonts
> > > in
> > > >>>>>>>>> cairo.  There's
> > > >>>>>>>>> some discussion here:
> > > >>>>>>>>
> > > >>>>>>>> what was the solution to make this fit into cairo's
> > > drawing model?
> > > >>>>>>>> Text
> > > >>>>>>>> / glyphs are used as a mask and a mask does not have
> > > colors.
> > > >>>>>>>>
> > > >>>>>>>
> > > >>>>>>> There is no solution to that. The assumption in cairo's
> > > drawing model
> > > >>>>>>> about glyphs/fonts has simply been invalidated by reality.
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> Correct.
> > > >>>>>>
> > > >>>>>> Okay... so what is the new model? What happens when I draw a
> > > color
> > > >>>> glyph
> > > >>>>>> with operator XOR and a red source?
> > > >>>>>
> > > >>>>>
> > > >>>>> The red source is ignored for color glyphs because they are
> > > used as the
> > > >>>>> source.
> > > >>>>
> > > >>>> Hi again,
> > > >>>>
> > > >>>> I just came up with another question: How are overlapping
> > > glyphs handled?
> > > >>>>
> > > >>>> Let's say I have a red glyph and a blue glyph and I draw them
> > > in such a
> > > >>>> way that they overlap. Let's say this additionally overlaps
> > > with a
> > > >>>> non-colored glyph in the same position and I use a green
> > > source with 50%
> > > >>>> alpha (cairo_set_source_rgba(cr, 0, 1, 0, 0.5)).
> > > >>>>
> > > >>>> What's the visible result?
> > > >>>>
> > > >>>>
> > > >>> Here is what my implementation does: It renders the color
> > > glyphs, in
> > > >>> order, followed by the non-color glyphs.
> > > >>>
> > > >>> In practice, I don't think the case of mixed color and non-
> > > color glyphs
> > > >>> in the same call will be all that common.
> > > >>> Most apps will explicitly set a color font just for the emoji
> > > and they
> > > >>> won't render regular text with an emoji font,
> > > >>> with the result that runs of color glyphs and non-color glyphs
> > > will
> > > >>> typically be in separate calls.
> > > >>>
> > > >>
> > > >>
> > > >>
> > > >> --
> > > >> behdad
> > > >> http://behdad.org/
> > > >>
> > > >
> > > >
> > > >
> > >
> > >
> > > --
> > > "Why make things difficult, when it is possible to make them
> > > cryptic
> > > and totally illogical, with just a little bit more effort?" -- A.
> > > P. J.
> >
> >
> >
> > _______________________________________________
> > gtk-devel-list mailing list
> > gtk-devel-list at gnome.org
> > https://mail.gnome.org/mailman/listinfo/gtk-devel-list
>

-- 
behdad
http://behdad.org/
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