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Re: [CSS3-color] [css3-images] [css3-transitions] transparent transitions

From: Chris Lilley <chris@w3.org>
Date: Mon, 27 Jun 2011 22:53:45 +0200
Message-ID: <11810555235.20110627225345@w3.org>
To: fantasai <fantasai.lists@inkedblade.net>
CC: www-style@w3.org, Tantek Çelik <tantek@cs.stanford.edu>
On Monday, June 27, 2011, 7:46:42 PM, fantasai wrote:

f> On 01/12/2011 12:26 PM, Tab Atkins Jr. wrote:

>> What you're seeing is the fact that transitions from opaque colors to
>> transparent in non-premultiplied space get darker as they progress.
>> Try doing a transition from opaque white to transparent over a white
>> background, and you'll see it very clearly - you'll get an image that
>> starts white, darkens to gray, and then lightens to white again.

f> Is there a way to avoid things like this? It seems to me that having
f> 'transparent' mean 'transparent black' means you almost never get what
f> you want, which is the opacity fading without the color itself changing.
f> I think that's a common enough use case that it should be easy to do.

This is why its better to have dolour and opacity as two separate properties.

Making them be one value gives situations like this where you want to animate one while keeping the other the same; so you need a magic "lower opacity but same colour" keyword.




-- 
 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Monday, 27 June 2011 20:54:31 GMT

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