[MPEG-OTSPEC] Requesting progress update on COLRv1 in fontTools, FreeType, etc.

[William_J_G Overington]

Regarding the parlance, maybe I am wrong about this but it seems to me 
that there is a gap, in that it seems to me that three terms are needed, 
yet there are only two defined.

I refer to the specification terms base glyph and colour glyph. I was 
familiar with the term base glyph but not colour glyph as used in the 
specification.

In my writing I have used three terms, as follows.

base glyph, as the specification has it.

coloured glyph for each glyph that is one colour

colourful glyph as what the specification has as colour glyph

For example, as in the following from page 2 of Chapter 3 of my novel 
The Mariposa System.

http://www.users.globalnet.co.uk/~ngo/the_mariposa_system_the_novel_chapter_003.pdf

> ‘Now to try to build the colourful glyph!’

> Mariposa goes into colour mode and adds the two coloured glyphs to the 
> monochrome glyph, noting that the monochrome glyph had disappeared 
> when she enters colour mode.

For information here, that is describing the process used in the 
High-Logic FontCreator 8 software that I use. I do not know how 
construction of the colourful glyph is done in other software, but it 
seems to me that three items of parlance are needed generally, because a 
completed OpenType COLR/CPAL font has some of each of what I have named 
base glyph, coloured glyph and colourful glyph.

On a different aspect of the specification, originally if one used FFFF 
as the colour index it allowed the colour actually used to be set by the 
end user as the foreground colour. Does the system now allow/ will you 
please consider allowing, similar 'tunnel through' colours, so that 
there would be a feature whereby an end user could also select in an 
application first decoration colour and second decoration colour so 
that, say, one could have, for example, a font with some glyphs of holly 
with berries and the end user could choose to have green leaves with red 
berries or gold leaves with silver berries or whatever colour 
combination desired, with the way that the specification is done such 
that there is a default colour? So, for example, displaying the glyphs 
in an application that does not have a decoration colour choosing 
facility, or it is switched off, the holly appears as green leaves with 
red berries yet the colours can be chosen by the end user in 
applications where a decoration colour choosing facility is available 
and switched on.

William Overington

Friday 22 January 2021




------ Original Message ------
From: "Peter Constable" <pgcon6 at msn.com>
To: "Chris Lilley" <chris at w3.org>; "mpeg-otspec at lists.aau.at" 
<mpeg-otspec at lists.aau.at>
Sent: Thursday, 2021 Jan 21 At 17:03
Subject: Re: [MPEG-OTSPEC] Requesting progress update on COLRv1 in 
fontTools, FreeType, etc.


FYI:

While the draft provided before the recent SC29 meeting already included 
linear and radial gradients, we have had in mind to also propose adding 
support at some point for some other gradient types: sweep (or “conic” / 
“angular”) gradients,  and mesh gradients.

Mesh gradients are _very_ different from other gradient types both in 
nature and in how they are defined, and there are two types (Coons 
patch, which use bilinear interpolation, and tensor patch, which use 
bicubic interpolation.  Those definitely will need some time for 
investigation and design discussion.

But sweep gradients are, comparatively, similar to linear and radial 
gradients: they are defined by a color line that gets applied to a 
surface in some geometric way. Linear, radial and sweep gradients are 
the three basic gradient types  that are commonly supported in 2D 
graphics apps or libraries.

With that in mind, we’ve decided to extend our proposal for COLR version 
1 to include sweep gradients. See our proposal doc at 
https://github.com/googlefonts/colr-gradients-spec/blob/master/OFF_AMD2_WD.md 
<https://github.com/googlefonts/colr-gradients-spec/blob/master/OFF_AMD2_WD.md> 
; a description of sweep gradients is added in new sub-clause 
5.7.11.1.2.4.


Peter




From: mpeg-otspec <mpeg-otspec-bounces at lists.aau.at>  On Behalf Of Chris 
Lilley
  Sent: Saturday, January 16, 2021 5:05 AM
  To: mpeg-otspec at lists.aau.at
  Subject: Re: [MPEG-OTSPEC] Requesting progress update on COLRv1 in 
fontTools, FreeType, etc.



Combining the graphical expressiveness of SVG with the typographic 
expressiveness of font variations (and of course using vectors not 
rasters) will make COLRv1 the clear leader among the assorted chromatic 
font options.

On 2021-01-14 23:04, Peter Constable wrote:

But it also goes beyond the SVG table in that everything (for which it 
would be meaningful) in the formats is variable. So, for instance, in a 
variable font, things that could be  varied include the placement of 
colour stops in a gradient, alpha values, rotation angles, and more.
    --  Chris Lilley @svgeesus Technical Director @ W3C W3C Strategy 
Team, Core Web Design W3C Architecture & Technology Team, Core Web & 
Media
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