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

Gradients and background-repeat (Was: Re: Automatic spec annotations)

From: Simon Fraser <smfr@me.com>
Date: Wed, 11 May 2011 11:07:54 -0700
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-id: <00C83B80-A99A-460B-AFAD-9A58867B526D@me.com>
To: Brad Kemper <brad.kemper@gmail.com>
What does this have to do with the subject line?

On May 11, 2011, at 10:24 AM, Brad Kemper wrote:

> On May 10, 2011, at 2:07 PM, Tab Atkins Jr. wrote:
>> On Tue, May 10, 2011 at 11:34 AM, Brad Kemper <brad.kemper@gmail.com> wrote:
>>> BK:
>>> I disagree that using a special version of linear-gradient to make
>>> backgrounds repeat is "the obvious" way. The obvious way to repeat
>>> backgrounds is with background-repeat. And that is what most of the ones I
>>> looked at did.
>> Like I said, mostly for bandwidth savings, as the point of the
>> patterns gallery is to create images that are smaller than the
>> equivalent PNG would be.
> I don't know what makes you so sure you know the minds of the authors there. It seems more likely to me that they used background-repeat because that is the obvious and familiar way to repeat a background, whether it is a stripe, a star, a wave, or whatever.

As I've said before, I think background-repeat should only ever affect axis-aligned, tiled backgrounds (i.e. repeating a rectangular image on an x-y grid). Because of this, it's not suitable for repeating gradients, which may be linear at an angle, or radial.

>> For argyle, the two layers that use background-repeat *cannot* be
>> replaced by repeating-linear-gradient - they're setting up the
>> checkerboard, which employs a completely different technique.
> The bigger question is whether any of the few using 'repeating-linear-gradient' cannot be replaced by 'background-repeat'., since I am not questioning whether or not 'background-repeat' is necessary; I am questioning whether or not  'repeating-linear-gradient'  is really necessary.
> I think that angles other that are not multiples of 45deg are harder to do with 'background-repeat'. But for the hard cases of repeating arbitrary gradient angles via the familiar background-repeat (and related properties), I would prefer to see something like 'background-rotate: [<angle> | auto]', where 'auto' means rotate the background by the gradient angle and make the actual gradient in the image vertical. That seems more useful and forward looking than to have a separate special version of linear-gradient that does repeating in a new different way than what we are familiar with already in backgrounds.
>> Otherwise, the patterns that can potentially use repeating gradients
>> are tartan, madras, blueprint grid, tablecloth, and the three stripes.
>> Of those, blueprint grid, tablecloth, and horizontal and vertical
>> stripes can also potentially use background-repeat, and they do.  
> I think all of those could use background-repeat, actually. On some of them, using repeating-linear-gradient might save some bytes, but so would the stripe generator you are considering, and so would 'background-rotate' (which is desirable for other reasons as well). I just don't see a strong need for 'repeating-linear-gradient'. And of course, there is considerably less need for 'repeating-radial-gradient', other than for symmetry and consistency of properties if you do have a repeating-linear-gradient property.
>> That said, on Chrome Linux at least, blueprint grid has messed up
>> spacing, and I think it would be a lot easier to understand in general
>> if it just used four repeating linear gradients (if we had a stripe
>> generator, doing it as two would be reasonable, but it's too verbose
>> to do that with the gradient generator).
> Well, sure, a stripe generator would be a more reasonable way of generating stripes than a gradient generator. But then your use cases for 'repeating-linear-gradient' from this site go away. I don't find the rule for "blueprint grid" difficult to decipher. It is one of the easier to read patterns of that site. And Safari's Webkit nightly on Mac renders it fine.

Received on Wednesday, 11 May 2011 23:14:15 UTC

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