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Re: [css-images] Negative implications of linear gradient color space choice in CSS

From: Rik Cabanier <cabanier@gmail.com>
Date: Mon, 25 Jan 2016 16:11:40 -0800
Message-ID: <CAGN7qDC-FaK-hG3TKjga_X=UWegRPJ4awdc=LJFkBP8zKT+GZQ@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: Xidorn Quan <quanxunzhen@gmail.com>, Simon Fraser <smfr@me.com>, Mark Straver <mark@wolfbeast.com>, www-style list <www-style@w3.org>
On Mon, Jan 25, 2016 at 3:48 PM, Tab Atkins Jr. <jackalmage@gmail.com>
wrote:

> On Mon, Jan 25, 2016 at 3:29 PM, Xidorn Quan <quanxunzhen@gmail.com>
> wrote:
> > On Tue, Jan 26, 2016 at 6:22 AM, Tab Atkins Jr. <jackalmage@gmail.com>
> wrote:
> >> On Mon, Jan 25, 2016 at 11:17 AM, Rik Cabanier <cabanier@gmail.com>
> wrote:
> >>> On Mon, Jan 25, 2016 at 10:58 AM, Tab Atkins Jr. <jackalmage@gmail.com
> >
> >>> wrote:
> >>>> On Mon, Jan 25, 2016 at 10:53 AM, Rik Cabanier <cabanier@gmail.com>
> wrote:
> >>>> > Are you worried about the computed value of the 'transparent'
> keyword in
> >>>> > the
> >>>> > gradient? If so, that one doesn't resolve to an rgba color.
> >>>>
> >>>> Sure it does.  (Or it should be doing so, for consistency - colors
> >>>> should be computed in computed values.)
> >>>
> >>> It does not. I tried Edge, Safari 9, latest Chrome and Firefox.
> >>
> >> Then that's a bug, either in the specs or the implementations.  There
> >> is absolutely no reason a color should serialize differently based on
> >> whether it's bare or wrapped in a gradient function.
> >
> > Given all impls current agree with the same behavior here, I guess we
> > can probably make 'transparent' a keyword value in gradient function
> > to simulate premultiplied effect, and revert the general cases to
> > non-premultiplied...
>
> If and only if there's not a significant number of gradients out there
> that currently write out transparent with rgba() syntax, or that use
> near-transparent colors that'll significant change behavior here.
>

Given that a major browser has a different implementation and no bug
reports, that number is likely small.
Also, when we made the change in the other browsers, there were no user
reported bugs that we closed.


> And we (Blink) must store the input string somewhere so we can output
> it back literally, because I *know* that we parse that into an
> #AARRGGBB 4-byte int and operate on it like that.  So it doesn't
> matter whether you type "transparent" or "rgba(0,0,0,0)", you get
> 0x00000000 either way.


It looks like Safari, Edge and Chrome return the original CSS input string.
Firefox resolves color names to their rgba equivalents, but not
'transparent'
Received on Tuesday, 26 January 2016 00:12:19 UTC

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