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Re: [css3-background] CSS Drop Shadows

From: Erik Dahlström <ed@opera.com>
Date: Wed, 19 Dec 2007 11:22:27 +0100
To: ~:'' ありがとうございました。 <j.chetwynd@btinternet.com>, fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org
Message-ID: <op.t3ku3pawdhsuf5@gnorps.palace.opera.no>

Hi Jonathan,

On Tue, 18 Dec 2007 15:19:10 +0100, ~:'' ありがとうございました。  
<j.chetwynd@btinternet.com> wrote:

>
> fantasai,
>
> not quite an answer to what you're requesting, but had you considered  
> how CSS drop shadows will be implemented in SVG?

There is no notion of a box in svg except for boundingboxes, and those are  
non-transformed geometric boundingboxes. There are several types of  
boundingboxes for graphical shapes, and it may be useful to specify which  
of them to use - but it's unlikely to be defined fully until SVG 1.2 Full.  
The drop-shadow functionality (and more) is already offered by svg filters.

> including SVG fonts I guess?

Maybe you mean the 'text-shadow' property? That could be supported for  
text in svg, but again the functionality is already covered by SVG  
filters. The 'text-shadow' property is a rather nice shorthand though, and  
personally I wouldn't mind if more of CSS was usable in SVG.

> my concern being that the absence of 'border's in SVG creates  
> significant accessibility barriers for authors and viewers. whilst it is  
> true there are a multiplicity of possibilities, this would have been a  
> good place to start, had it been included. as it is it's extremely rare  
> to find any visual indication of focus in the wild.

That may be something that the CSS and SVG WG:s should work out together,  
but it's rather far-reaching since SVG doesn't use the box model for  
layout. This means that CSS would have to be more open to allowing other  
languages to define what is meant by "box" (or various types of boxes). I  
don't think that's an easy task, since CSS is currently very much geared  
towards the box model (HTML).

> could CSS drop shadows help?

Same thing as for other types of borders or anything using the box model.

> regards
>
> Jonathan Chetwynd
> Accessibility Consultant on Media Literacy and the Internet
>
>
>
> On 17 Dec 2007, at 16:16, fantasai wrote:
>
>
> I'm working on the CSS3 Backgrounds and Borders [1] module with Bert  
> Bos, and
> I'd like to start a new Q&A series because I think we need some help:  
> This
> time I'll ask the questions, and you give me answers. Ok? :) The first
> issue is a complicated one, so I'll start with an easy question. The  
> topic
> is drop shadows.
>
> In the latest public working draft [2] we have a <code>box-shadow</code>  
> [3]
> property. The point is, obviously, to be able to draw a drop-shadow for a
> CSS box. It starts to get complicated once you ask "what happens when  
> there
> are semi-transparent parts of the box?" At first we figured 'box-shadow'
> should just draw the shadow as if the box was opaque. Then Dave Hyatt,  
> who
> had started implementing this, started questioning that logic. We've got
> proposals for a 'border-shadow' property to shadow just the border and a
> 'background-shadow' property to shadow just the background color (but not
> the image?), etc. We could also just "shadow everything drawn in this  
> element".
> This all sounds rather complicated to me so I want to step back and ask:
>
> What do you, as a web designer, want to *do* with shadows? What's the end
> result you want to get?
>
> Show me. Post a few links to stuff from your portfolio that uses anything
> beyond pure text shadows, even if it's all done with pure Photoshop(/ 
> Painter/GIMP)
> graphics. Draw (or explain) a picture of what you want to achieve. Then
> maybe we can figure out how best to make it happen in CSS.
>
> [1] http://www.w3.org/TR/css3-background/
> [2] http://www.w3.org/TR/2005/WD-css3-background-20050216/
> [3] http://www.w3.org/TR/2005/WD-css3-background-20050216/#the-box-shadow

-- 
Erik Dahlstrom, Core Technology Developer, Opera Software
http://my.opera.com/macdev_ed
Received on Wednesday, 19 December 2007 10:25:09 GMT

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