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.