Re: [cairo] Color fonts

[iofelben gmail com]

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@entry=3646361312)
at cairo-error.c:68
#5  0x00007fd0f1367802 in _cairo_set_error (cr=0x3dd89ecc00,
status=3646361312) at cairo.c:400
#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 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@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 gmail com> wrote:
> > > >
> > > > > On Sat, Jul 15, 2017 at 4:05 AM, Uli Schlachter <psychon znc in
> > > wrote:
> > > > > > On 07.07.2017 15:23, Matthias Clasen wrote:
> > > > > > > On Sat, Jul 1, 2017 at 2:25 AM, Uli Schlachter <psychon@znc.i
> > n> wrote:
> > > > > > > > On 30.06.2017 17:29, Behdad Esfahbod wrote:
> > > > > > > > > On Jun 30, 2017 7:51 PM, "Matthias Clasen" <mclasen@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.
>
>
>
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