[cairo] Color fonts

[Uli Schlachter]

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. :-)

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...

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.org> 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.in> 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.