W3C home > Mailing lists > Public > public-css-testsuite@w3.org > November 2012

Need for better, other images for testing background-size (Apostrophy cat image)

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Wed, 14 Nov 2012 20:59:32 -0500
Message-ID: <87b194891427c3faf42bd8d9a91eef6f.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Public CSS testsuite mailing list@w3.org" <public-css-testsuite@w3.org>

> background-size-021: the image should be scaled from 98px wide by 99px
> tall to 100px wide and 100px tall. There is a rounding of fractional
> pixels: it's actually difficult to figure out what happens with
> calculations here. When I set 'background-size: 99% 99%' in that test,
> then I should see a 1px wide red vertical line at the right of the cat
> with a 1px tall red horizontal line below the cat but this is not
> happening in Opera 12.10. So, the failure in Chrome 23.0.1271.64 is most
> likely only due to rounding effects of a fraction in the calculation.
> The way to work around this difficulty would be to create an image whose
> dimensions won't be subject to fraction when being scaled. The cat image
> does not have ideal dimensions for scaling: 98px wide by 99px height.
> NeedsWork=Precision

> best is to use an image dimensions
> that will scale without creating fractional pixel and [when!]
> rounding up or down

> to use an image which, when
> scaled up or down, will not involve fractions

It seems that the original cat image from Ian "Hixie" Hickson was 62px
by 65px:


and there are other versions with 1:1 ratio, like 64px by 64px or 200px
by 200px.

We should use/copy some of these images and maybe we should be looking
for other images with an intrinsic ratio of 1:1 and with an intrinsic
ratio of 2:1 which could be more reliably rescaled without causing
unneedlessly fractions. Also, if such images could fill both dimensions,
this would be a plus. The cat image has some blank areas.

Contributions to the CSS 2.1 test suite:

CSS 2.1 Test suite RC6, March 23rd 2011:

CSS 2.1 test suite harness:

Contributing to to CSS 2.1 test suite:
Received on Thursday, 15 November 2012 02:00:05 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:13:25 UTC