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For specific opacity properties (was Re: Opacity 0-1: Bad Idea?)

From: Etan Wexler <ewexler@stickdog.com>
Date: Tue, 13 Nov 2001 18:07:01 -0500
To: Web style list <www-style@w3.org>
Message-Id: <20011113230823.853695DCB@server3.safepages.com>
Chris Lilley wrote:

> Andy wrote:
>> 
>> I'd personally like to see separate control over text opacity[...]
>> Indeed I can see that ideally one would define:
>> 
>> background-opacity, text-opacity and border-opacity
> 
> Yes.

I'm glad that there is some support within the W3C for this good idea. 
 Opaque text with a semi-transparent background is a useful 
combination and is seen regularly in printed materials and on 
television.  Any overlay of text on images cries out for the text to 
have a semi-transparent background.

> So for CSS3 it makes sense to be able to control the background 
opacity
> as one can with the background color, and also the border opacity as 
one
> can with border color (problem though, would we need 
border-top-opacity
> and all that stuff too) and the text color opacity (color-opacity?).

An opacity property for each of the four borders is desirable.  The 
property 'border-opacity' can then become a shorthand like 
'border-color'.

The specification should stipulate that a specified value of 
'transparent' for a border color computes as 'black' for the border 
color and as 0 for the corresponding border opacity property.  (What 
happens if a border opacity declaration conflicts?  Is the effective 
opacity value 0 or the one from the opacity declaration?)

My suggestion for the name of the text opacity property is 
'foreground-opacity'.  Should this property affect replaced content?

Should we add 'outline-opacity'?

> Note that the introduction of opacity on background requires 
definition
> of ther color of the canvas before the roor element is painted. In 
SVG
> we went for white.

I feel strongly that the color of the canvas is an issue best left 
between consenting adults and their user agent of choice.

-- 
Etan Wexler
Received on Tuesday, 13 November 2001 18:08:25 GMT

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