W3C home > Mailing lists > Public > www-style@w3.org > August 2009

Re: [CSS3] border-radius, border-image and drawing order.

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Sat, 15 Aug 2009 16:28:43 -0500
Message-ID: <dd0fbad0908151428x1932584cve0cc8fc1236fdf84@mail.gmail.com>
To: Andrew Fedoniouk <news@terrainformatica.com>
Cc: "www-style@w3.org" <www-style@w3.org>
On Sat, Aug 15, 2009 at 3:28 PM, Andrew
Fedoniouk<news@terrainformatica.com> wrote:
> Tab Atkins Jr. wrote:
>>
>> On Sat, Aug 15, 2009 at 2:33 PM, Andrew
>> Fedoniouk<news@terrainformatica.com> wrote:
>>>
>>> Consider following style and markup:
>>>
>>> div
>>>   {
>>>     width:100px; height:100px;
>>>     border-width:4px;
>>>     border-color:red;
>>>     border-radius:50%; /* that means border is a
>>>                           perfect circle */
>>>     border-style:solid;
>>>   }
>>>
>>> <div>Some text</div>
>>>
>>> Shall border be drawn on top of the text or behind it?
>>> That is the question.
>>>
>>> If border is a part of background as current spec implies
>>> then text should be drawn on top of the border.
>>
>> Borders are drawn above the background, but under the text.
>>
>>> But what about border-image?
>>> If it is drawn behind the content layer then
>>> this border-image makes almost no practical sense.
>>
>> Border-image is drawn on the same layer as borders.  Borders are
>> hidden while a border-image is in effect.
>>
>> Could you elaborate on why the border-image being drawn below text is
>> a problem?  Is this also a problem for normal borders?
>
> Imagine that text in the third column here:
> http://www.bradclicks.com/cssplay/border-image/Alladins_Lamp_2.png
> will contain couple of more lines. For now they will be drawn on top
> of the lamp that is unexpected.

That's what padding is for.

>>> Why not to use that multi-background feature and
>>> to drop this border-image completely then?
>>
>> One of the original reasons multiple-backgrounds were used *was* to do
>> essentially the same thing as border-image is currently doing.  It's
>> rather nasty when you actually start writing the code, though.  The
>> actual property can get *really* long and complex, you have to design
>> a single image and then slice it into multiple separate images, and it
>> can cause up to 9 network requests.  Border-image solves all of that
>> by letting you create a single image, specify how to slice it in the
>> CSS, and wrap it all up in a relatively simple syntax.
>
> Why not to add such slicing/sectioning to any background image then?

Because, for the most part, that would be useless for background
images.  It's only really useful when you are specifically making a
fancy border for a box.

> I suspect that we need either
> 1) multi-background images or
> 2) single background image and the border-image
>
> But not both.
>
> We have multiple features that serve the same purpose -
> drawing image(s) on the background in various ways.
>
> Usually such feature redundancy is one of ringing bells of
> bad design.

But they don't serve the same purpose.  Border-image *replaces the
border*.  Background images are independent of the border.  You use
border-image specifically when you want a border on a box, but want to
use a fancy image rather than one of the built-in styles.

>> Another benefit of the current border-image proposal is that it allows
>> you to paint outside of the actual box geometry.  The benefits of this
>> are clearly explain with a great example over at Brad's site:
>>
>> http://www.bradclicks.com/cssplay/border-image/Thinking_Outside_The_Box.html
>>
>
> "to paint outside of the actual box geometry"
>
> That simply means that borders of the element are drawn on top of its
> siblings but not on top of its children. That makes the logic even worse.

Elaborate, please?

~TJ
Received on Saturday, 15 August 2009 21:29:45 GMT

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