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Re: [CSS4 color][CSS4 transition] color pre-multiplied vs non pre-multiplied

From: Rik Cabanier <cabanier@gmail.com>
Date: Thu, 31 Jan 2013 21:35:07 -0800
Message-ID: <CAGN7qDDYszo-2+_i5iE3fh_TkjhYk4cMgEghVZZZ7oe+ftWJFg@mail.gmail.com>
To: Alan Gresley <alan@css-class.com>
Cc: fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
On Thu, Jan 31, 2013 at 9:28 PM, Alan Gresley <alan@css-class.com> wrote:

> On 1/02/2013 3:48 PM, Rik Cabanier wrote:
>
>> On Thu, Jan 31, 2013 at 8:31 PM, Alan Gresley <alan@css-class.com> wrote:
>>
>>  On 1/02/2013 2:25 PM, Rik Cabanier wrote:
>>>
>>>  So, can we fix the spec?
>>>>
>>>>
>>> Yes. Changing the part here [1] regarding example 23 and the second note
>>> that discusses premultiplied color space.
>>>
>>> Giving an example of how to create a gradient from color to
>>> transparent-color like so:
>>>
>>>    linear-gradient(red, rgba(255,0,0,0))
>>>
>>>    linear-gradient(red, rgba(255,0,0,0) 50%, rgba(0,0,255,0) 50%, blue)
>>>
>>>
>>> Possibly consider a new way to trigger transparent-color:
>>>
>>>    linear-gradient(red, pre-transparent)
>>>
>>>    linear-gradient(red, pre-transparent, blue)
>>>
>>>
>>>   I volunteer to fix the implementation in FF and WK.
>>>
>>>>
>>>>
>>>
>>> What would you fix in FF and what is WK?
>>>
>>>
>> FF = mozilla :-)
>> WK = WebKit
>>
>> I would fix that transparent has a special meaning (meaning a transparent
>> version of the previous and next stop color)
>>
>
> Well then there is nothing to fix in regards to those implementations. FF
> (with prefix and un-prefixed) and WebKit all show gradients in non
> pre-multiplied colorspace [1] (check in both Chrome and Safari). It's Opera
> and IE10 that does different.
>
> It is the spec that needs to be changed.
>

True.
However, those browsers are not treating 'transparent' special. This means
that if you go to transparent you will transition to rgba(0,0,0,0) which
will make your gradient washed out.

Can you update your example with a couple of gradients that are just using
'transparent' as a stop color?


>
>
> Regarding transitioning, I happy for the ship to have sailed.
>
>
> 1. http://css-class.com/test/**temp/color-transparent.htm<http://css-class.com/test/temp/color-transparent.htm>
>
>
>
> --
> Alan Gresley
> http://css-3d.org/
> http://css-class.com/
>
Received on Friday, 1 February 2013 05:35:34 GMT

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