[cairo] Color fonts

[Andrea Canciani]

On Fri, Jul 28, 2017 at 4:38 PM, Behdad Esfahbod <behdad at behdad.org> wrote:

> Uli,
>
> Can we commit this?  I don't think waiting another few years will result
> in a superior patchset. :)
>

Would it be possible to add a test?
I have written one in the branch where color glyphs were added to the
quartz backend (not yet merged):
https://cgit.freedesktop.org/~ranma42/cairo/commit/?h=wip/quartz-font-wanna-ct&id=9696ac368796d4d5129d3f31fdde724a71b35d00

As stated in the code, that test will need some changes to work on other
font backends.

Sorry if this sounds like a pushback. Actually I would love to get the
colored glyphs in and to update the quartz backend to support them :)

Andrea


>
> 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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