Re: [gradients] basics

On Nov 8, 2009, at 1:12 PM, Simon Fraser wrote:

>> Any UA that supports 'background-repeat', 'background-size', and  
>> Tab's 'linear-gradient()' should support tiling a properly sized  
>> gradient with 'background-repeat'. What Gecko does that goes beyond  
>> this is to adjust the tiling so that the gradients in each tile  
>> line up with each other. Thus, if you had a 30deg gradient, the  
>> tiles of 'background-repeat' are not in rows and columns as they  
>> normally are, but presumably shift each column (or row?) so that  
>> the colors of the gradient in each tile will line up with its  
>> neighbor. Although, that doesn't precisely describe how something  
>> like 'repeat-x' would work with a gradient that includes, say, a  
>> 10deg gradient or even a top-left to lower-right gradient.
>
> I don't think this can be construed as "adjusting the tiling so that  
> the gradients line up with eachother", since Gecko also makes radial  
> gradients repeat, and that can't be described by adjusting the tiles.

Agreed. I was limiting myself to talking about linear gradients, and I  
admitted that my explanation didn't exactly cover what was happening.

> What they do is to simply repeat the color stops along the gradient  
> axis for as long as is necessary to fill the box.

Ah, yes. That is a much better way to describe what is happening there.

>> That is kind of nice behavior, even though it seems like a somewhat  
>> uncommon need. Perhaps we could eventually add a note to  
>> 'background-repeat' to explain how to tile generated images like  
>> gradients that can have a more seamless joining of tiles as with  
>> Gecko.
>
> If we want background-repeat to have this magic effect on gradients,  
> we should just say that it's achieved by repeating the color stops.  
> However, Tab's approach was to have two more gradient functions  
> (repeating-linear-gradient, repeating-radial-gradient), which I  
> think is a bit more honest.

That really seems unnecessary. I don't see a strong use case for  
repeating gradients at all, and much less so for 'list-image', 'border- 
image', etc. And for those few times that you do want to have a  
gradient repeat as a background, you would pretty much always want it  
to repeat in the most intelligent way possible, and it is pretty clear  
what that would be: magic. I can't see ANY reason why someone would  
want a repeating background gradient in which there were sharp  
divisions between the tiles because the colors didn't line up, so that  
is where it makes sense for the magic to happen.