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Re: [css3-background] box-shadow spread radius and rounded corners

From: Brad Kemper <brad.kemper@gmail.com>
Date: Wed, 28 Apr 2010 14:23:44 -0700
Message-Id: <8B4F1165-CDBE-4FBB-B93A-4399679F03FE@gmail.com>
To: Sylvain Galineau <sylvaing@microsoft.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>, Brian Manthos <brianman@microsoft.com>, Prabs Chawla <pchawla@microsoft.com>

On Apr 28, 2010, at 1:06 PM, Sylvain Galineau <sylvaing@microsoft.com>  

> Brad, I don't understand what is 'extreme' about my example or why  
> it's more extreme than your own.

Mine was a little extreme too, but mainly because it is harder to see  
where spread stops and blur starts when using smaller values. Usually  
when I spread shadows in PhotoShop, it is by a few points, usually  
less than the blur amount. When you have a lot of spread and not much  
(or any) blur, it starts looking less like a shadow, and more like  
something else. I can't recall the last time I used more than 10pt of  
spread on anything that was supposed to really look like a shadow.  
Sometimes, when using it as a faux glow, I add

> But by playing
> with increasing spread values in both Opera and Firefox - which, as  
> far as I can tell, implement spread radius as you
> and Elika define it - then I do reach a point where the shadow's  
> shape is very different from that of the box
> being shadowed, as well as that of previous less spread-out shadows.
> For example, using Opera 10.5x and Firefox 3.6.x :
>        #ref {
>            width:50px;
>            height:50px;
>            margin:200px;
>            border: 1px solid black;
>            border-radius: 5px;
>            -moz-border-radius: 5px;
>            box-shadow: 0 0 0 10px blue, 0 0 0 50px green, 0 0 0  
> 160px red;
>            -moz-box-shadow: 0 0 0 10px blue, 0 0 0 50px green, 0 0 0  
> 160px red;
>        }
> From the blue to the green and then the red shadow, is the shadow  
> surface being evenly expanded
> in all directions ? I think the answer is yes and I gather from your  
> feedback that this is what
> spreading is supposed to do. But has the *shape* of the shadow been  
> preserved all along ? I don't
> get that part at all. The outer edge of each of the shadows is  
> visibly different from that of
> any of the other shadows, never mind the outer border edge box being  
> shadowed.
> So it seems I was like Simon: I didn't understand what spreading  
> was. And then inferred it
> from a requirement to preserve shape when a spread radius is  
> applied, requirement I do not see
> being fulfilled with an even surface spread.
> I think an example like the one above annotated with arrows may be  
> helpful in clarifying the meaning
> of spread radius and I can try to produce one. Most importantly,  
> what shape is being preserved, or
> how it is preserved ought to be clarified. Maybe it's just a matter  
> of making it clear that *only* sharp
> corners retain their border-radius ?
Received on Wednesday, 28 April 2010 21:31:39 UTC

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