[cairo] Color fonts

[Behdad Esfahbod]

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/
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