- From: Tab Atkins Jr. <jackalmage@gmail.com>
- Date: Thu, 3 Feb 2011 11:39:06 -0800
On Thu, Feb 3, 2011 at 11:17 AM, Boris Zbarsky <bzbarsky at mit.edu> wrote: > On 2/3/11 1:58 PM, Tab Atkins Jr. wrote: >> >> The alpha value is just a<number>, so whatever we decide on, we >> should make the standard serialization for<number> ?and document it in >> the CSSOM. > > I'm not sure it's that simple. > > In particular, the way browsers actually _store_ the alpha value is not as > an infinite-precision decimal (which is what <number> is in CSS). > > For example, in the case of Gecko the alpha value is stored as an integer in > the range [0,255]. ?When serializing we do a floating-point division by 255 > and then try to make the result not have 6 useless significant figures (in > fact I believe we always output either 2 or 3). > > This is quite different from other <number> uses.... Webkit stores alpha the same way. I don't believe that's a problem here, though - it just means that the <number> has fairly limited precision. There's nothing requiring browsers to store a particular precision for <number>s. (Whether or not there should be is a separate argument.) The serialized value will round-trip as the same thing, right? As long as that's true, then the convenient fiction that you actually store the value you serialize as can be maintained. ~TJ
Received on Thursday, 3 February 2011 11:39:06 UTC