W3C home > Mailing lists > Public > www-style@w3.org > January 2011

Re: 'border-image' confusion

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 26 Jan 2011 13:32:22 -0800
Message-ID: <4D4092E6.5050304@inkedblade.net>
To: Brad Kemper <brad.kemper@gmail.com>
CC: "Eric A. Meyer" <eric@meyerweb.com>, www-style@w3.org
On 01/25/2011 07:45 AM, Brad Kemper wrote:
>
> On Jan 25, 2011, at 7:08 AM, Eric A. Meyer wrote:
>
>> In case that last assertion seems dubious, I put a 'border-image' scenario to the readers of meyerweb[1].  A number of them came up with the right answer but complained about the property being very counter-intuitive.  Others hacked around the problem entirely using other methods because they couldn't figure out how to do what I specified, or couldn't figure out how 'border-image' was supposed to work in the first place.  (And a couple of people got it to work in WebKit, but we're still not sure if that was a bug exploit or not.[2])
>
>> I can't see a good reason why it should behave as it does now, where slices get replaced with transparency if your slices exceed half the height/width of the base image.  Note that WebKit already does this, but other browsers do not.
>
>> [1] http://meyerweb.com/eric/thoughts/2011/01/24/border-imaging/
>> [2] http://meyerweb.com/eric/thoughts/2011/01/24/border-imaging/#comment-531046
>
> The webkit implementation is based on an older and less mature version of the spec. Firefox is doing it correctly according to the spec, as follows:
>
> # The regions given by the ‘border-image-slice’ values may overlap. However if the
> # sum of the right and left widths is equal to or greater than the width of the image,
> # the images for the top and bottom edge and the middle part are empty, which has the
> # same effect as if a nonempty transparent image had been specified for those parts.
> # Analogously for the top and bottom values. [1]
>
> I don't recall exactly why we decided on that.

It was undefined what happened if you overlapped, so I put in a definition that
seemed to make sense? Overlapping sides means negative middles, so I just floored
the middles at zero.

~fantasai
Received on Wednesday, 26 January 2011 21:32:57 GMT

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