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Re: Drop-Shadow proposal

From: Brad Kemper <brad.kemper@gmail.com>
Date: Mon, 14 Sep 2009 22:55:50 -0700
Cc: www-style list <www-style@w3.org>
Message-Id: <7AED7C9A-9504-4903-A379-4B59A78CDC44@gmail.com>
To: Andrew Fedoniouk <news@terrainformatica.com>

On Sep 14, 2009, at 7:59 PM, Andrew Fedoniouk wrote:

>> This might help show what is going on a little more clearly:
>> http://www.bradclicks.com/cssplay/concentric.html
>
> Brad, am I correct that element with background-color:transparent;
> placed on another one with background-color: rgba(214,0,0,0.5); will
> produce the following: http://terrainformatica.com/w3/inner-shadow.png
> ?

No, the shadow goes under the transparent areas, it does not use the  
transparency of one layer to cut out another. It does not alter the  
transparency of the original images or fills. It does cast into the  
opaque areas instead of the transparent areas when you use the 'inset'  
keyword.

So, if you had a solid white rounded-corner rectangle background-image  
with a background-color: rgba(214,0,0,0.5) on the same element, and  
you flattened them into using a single transparency map for the shadow  
to cast through/into, then you could have something like that with  
'drop-shadow: inset apply-to(background-color+background-image) <x- 
offset><y-offset><blur-radius><shadow-color>'.

The inner shadow created with 'inset' casts the shadow into the areas  
of opacity (more opacity = more shadow, so the white box in the middle  
would need to start out as rgba(255,255,255,1).
Received on Tuesday, 15 September 2009 05:56:44 GMT

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