W3C home > Mailing lists > Public > www-style@w3.org > August 2009

Re: Shadows vs. layout

From: fantasai <fantasai.lists@inkedblade.net>
Date: Mon, 03 Aug 2009 14:57:54 -0700
Message-ID: <4A775D62.2050801@inkedblade.net>
To: David Hyatt <hyatt@apple.com>
CC: W3C style mailing list <www-style@w3.org>
David Hyatt wrote:
> 
> Having two types of overflow means that when it comes time to calculate 
> scroll dimensions, you have to omit the shadow information.  This means 
> that overflow information that is propagated to containers now has to 
> come in two flavors...  the overflow information *has* to be cached for 
> efficient dirty rect intersection testing on repaints, so you're left 
> with the choice of either caching two sets of propagated numbers or just 
> not using the cached numbers when computing scroll information.   The 
> first solution will impact memory.  The second solution will impact 
> performance.  Neither solution makes me very happy as an implementor.

Usually both sets will coincide. If you've got free state bits, you can
store the more unusual data in a property-table and only look it up when
needed. Gecko does this for certain types of overflow data.

~fantasai
Received on Monday, 3 August 2009 22:58:39 GMT

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