W3C home > Mailing lists > Public > www-style@w3.org > June 2007

Re: border-image clarifications needed

From: Andrew Smith <asmith15@learn.senecac.on.ca>
Date: Wed, 13 Jun 2007 13:31:42 -0400
To: www-style@w3.org
Message-id: <467029FE.9000605@learn.senecac.on.ca>

I couldn't find Dave Hyatt's email address (would someone email it to 
me?) but I looked at the Safari beta to test the -webkit-border-image 
property. Here's what i found:

Andrew Smith a écrit :
> Regarding http://www.w3.org/TR/css3-background/#the-border-image
> 1) Of the three keywords (stretch, repeat, and round) only two are 
> explaned. If 'repeat' is explained somewhere else, a reference is needed.
In webkit this does not tile the image. For example: on a horisontal 
border the width of the tile is as set by the four numbers used to split 
the source image; the height of the tile is the same as the height set 
by border-width (or the replacement for border-width from border-image). 
In case I'm not explaining it well, here's a screen shot: 

Not sure what you (fantasai) mean by anchoring. The first tile starts 
from the left (or top) and is cut off on the right (or bottom).

Regardless, if it's not explained it's really up to the implementer to 
decide what to do and I think this part could use some consistency, so 
at least a "'repeat' means to simply tile the image as for 
background-image" would do nicely in the spec.

> 2) The sample source image in Example 1 does not break cleanly into 3x3. 
> This is entirely unexpected. The coordinates should be 0-26 for the 
> first diamond, 27-53 for the second, 54-80 for the third. The image the 
> way it is now is hard to use for testing, because of 1 or 2-pixel 
> artifacts. I can make a replacement if you like.
On the webkit blog I found Hyatt saying the same thing. I took a quick 
look again and at least the top left tile is too big: 0-27 in both 
directions, it should be 0-26. I use http://littlesvr.ca/misc/border.png 
for testing instead.

> 3) "If the first keyword is 'round', the top, middle and bottom images 
> are reduced in width" - I assume that means they get squashed 
> horisontally, but on the example it looks like they haven't lost their 
> proportions, which is very unlikely unless the container is sized to 
> accomodate the border image. Should clarify this.
> 4) "If the first keyword is 'round', the top, middle and bottom images 
> are reduced in width, so that exactly a whole number of them fit in the 
> width of the padding box" - if the width of the padding box is a prime 
> number the only way to fit a whole number of images in it is to have 
> them sized to 1 or to the width of the padding area. Should clarify this.
> 5) "X' = W / ceil(W / X)" - this doesn't give me a whole number, is it 
> supposed to? If not, what am I to do with this formula? If it does make 
> sense, a reference to where this is explained would help a lot.
In webkit for 'round' the tiles are increased or decreased in size to 
keep their proportions. Any space left is used up equally on both ends, 
with the tiles cut off on both ends.

Since I can't figure out what the author(s) of the specification meant, 
I propose the following changes: 
http://littlesvr.ca/border-image/border-image-01.pdf If approved, the 
webkit implementation remains mostly valid (except for the 'repeat'). I 
believe that will handle all the expected use cases and I will happily 
implement the same in Mozilla.

> 6) If the width of two consecutive sides isn't the same, what's done to 
> the corner? There are at least three different ways to deal with it. 
> Should clarify this.
In webkit the corner is stretched in both directions. Actually this is 
already explained in step 1 bullet 3, but I moved it in the proposed 
changes document.

Comments please?

Received on Wednesday, 13 June 2007 17:31:46 UTC

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