Re: Grayscale, lacuna value, and optional argument

On Mon, 2016-03-14 at 17:52 -0700, Tab Atkins Jr. wrote:
> On Mon, Feb 1, 2016 at 2:25 PM, Amelia Bellamy-Royds
> <amelia.bellamy.royds@gmail.com> wrote:
> > 
> > On 1 February 2016 at 15:02, Chris Lilley <chris@w3.org> wrote:
> > > 
> > > The ED of filters says that the lacuna value for the grayscale
> > > filter is
> > > zero.
> > >   https://drafts.fxtf.org/filters/#FilterProperty
> > > 
> > > However:
> > > 
> > >  - the syntax does not seem to allow the argument to be omitted
> > > so how
> > >    can the lacuna value be used
> > >  - if it did, then 0 is an odd value
> > > 
> > > 0 means no change. Thus seems unintuitive. I would expect
> > > grayscale()
> > > to be equivalent to grayscale(100%) which is likely what authors
> > > would
> > > expect and would be convenient for the most common use case "make
> > > this
> > > grayscale".
> > > 
> > > Suggested fix:
> > > 
> > >  - change the grayscale filter syntax to make the argument
> > > optional
> > >  - change the lacuna value to 1
> > > 
> > > Btw I added some tests for grayscale since there was only one
> > > (100%)
> > > so I added 1, 0, 0% and 300% as well.
> > For what it's worth, this seems to be how -webkit-filter is
> > implemented.  In
> > other words, -webkit-filter: grayscale() applies 100% grayscale
> > filter (in
> > Chrome anyway, haven't tested Safari).
> > 
> > For implementers of the standard property, neither Edge nor Firefox
> > currently support the function without a parameter, so changing the
> > lacuna
> > value would not break anything that isn't already broken.
> > 
> > I also agree that it is more useful/logical to have the default
> > function be
> > complete grayscale.
> Yes, it should be omittable.  All of the functions need similar
> edits.
> 
> I'm not even sure what "the lacuna value for interpolation" *is*.
> First, "Lacuna value" is an SVG-ism defined in that spec; CSS specs
> instead use normal English and talk about what to do when something
> is
> omitted. ^_^  Second, this is the default value *in general*; I don't
> know what this has to do with interpolation.

The SVG 2 spec does not use the term "lacuna".

> ~TJ
>

Received on Tuesday, 15 March 2016 08:01:50 UTC