[cairo] Color fonts

[Behdad Esfahbod]

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/
>



-- 
behdad
http://behdad.org/
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