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Re: [css3-background] background-size and zero length

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 12 May 2010 09:15:07 -0400
Message-ID: <4BEAA9DB.9040501@mit.edu>
To: Brad Kemper <brad.kemper@gmail.com>
CC: Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
> Why don't things less than half a device pixel round to zero (at least for used value)?

That depends on what you mean by "used" values.

In Gecko, you would have the following values for width, say:

1) Specified value (a pair of float and unit).
2) Computed value (an integer in units of 1/60 CSS px).
3) Used value for layout computations (an integer in units of 1/60 CSS
4) Used value for painting (this depends on the device).

1-3 above are device-independent.

It looks to me, at a brief glance, that things less than 1/2 a device 
pixel round to 0 at step 4.  Before that, everything is 
device-independent, so the concept of device pixel doesn't necessarily 
make sense (there are some caveats to that with borders, but it's true 
for most lengths).

Received on Wednesday, 12 May 2010 13:15:42 UTC

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