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

From: Brian Manthos <brianman@microsoft.com>
Date: Wed, 12 May 2010 08:39:32 +0000
To: Brad Kemper <brad.kemper@gmail.com>
CC: Boris Zbarsky <bzbarsky@MIT.EDU>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <FA122FEC823D524CB516E4E0374D9DCF014FAA16@TK5EX14MBXC136.redmond.corp.microsoft.com>
Would you expect the background color to show through on-screen if the image is opaque and is 96/1200ths of a pixel wide?


-----Original Message-----
From: Brad Kemper [mailto:brad.kemper@gmail.com] 
Sent: Wednesday, May 12, 2010 1:34 AM
To: Brian Manthos
Cc: Boris Zbarsky; www-style@w3.org
Subject: Re: [css3-background] background-size and zero length

On May 12, 2010, at 1:20 AM, Brian Manthos wrote:

>>> On 5/11/10 1:49 PM, Brian Manthos wrote:
>>>> For values below 0.00833333331px, Firefox continues to show no image.
>>> Right.  Lengths in Gecko are stored as integers in units that are 1/60 of a CSS px.
>>> The number above is about 1/120.  So things smaller than that would would round to 0.
>> Why don't things less than half a device pixel round to zero (at least for used value)?
>> That is what I would expect (unless you were going to simulate a 60th of a pixel by
>> averaging the colors of the subpixels, the way anti-aliasing or image size interpolation
>> does). I assume you have a perfectly logical reason, but I cannot guess what it is.
> Half a device pixel before or after zooming?

Before. Multiplied by zoom factor. When I zoom out in Safari, 1-pixel black lines against a white background become gray lines.

> How should it behave when printed to a 1200dpi device?  Should lines "appear" that don't appear in the on-screen/monitor rendering?

Of course. If I specify a line that is 1/1200 of an inch, I'd expect a faint hairline on the paper, but not much of anything on the screen (or maybe a very faint line simulating the thinness of it). I wouldn't want it to look 13 times bigger on my 96dpi screen.
Received on Wednesday, 12 May 2010 08:40:13 UTC

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