Re: minutes, Tokyo 2013 SVG F2F Day 1, 3 June 2013

On Mon, Jun 3, 2013 at 4:37 PM, Robert O'Callahan <robert@ocallahan.org>wrote:

> Clarification regarding enable-background --- I'm against it not for
> performance reasons but because it creates unnecessary complexity for
> authors. Simple uses of filters with Background should not require special
> CSS in ancestors to work. Especially when applying filters to HTML.
>
> On Mon, Jun 3, 2013 at 8:32 PM, Cameron McCormack <cam@mcc.id.au> wrote:
>
>>    krit: Does FF do transform transitions in hardware? WebKit
>>    doesn't do it yet (all software for SVG), but we want to change
>>    that.
>>
>
>>    heycam: Same.
>>    ... Seems like this will suck.
>>
>
> Actually we do layerize some SVG transforms for GPU compositing, as of
> quite recently. There are some bugs blocking the performance improvements
> from being visible, but they're getting fixed.
>
> I think SVG transforms should cause an isolated group.
>

That's a bit unfortunate since it will require authors to carefully create
their content.
However we can fix that in the future when we add this for HTML.


>
>    krit: We make them isolated groups, and I think FF does too.
>>    ... Also masks and clips are stacking contexts.
>>
>
> Opacity has to create a stacking context, and therefore has to create an
> isolated group.
>
> If people want blending to break out of stacking contexts or other
> isolated groups somehow --- let's see the use-cases for that and see if
> there's any reasonable way to support them.
>

There are definitely use cases for this. If you add some some opacity to a
group, the most natural thing would be that the group's content becomes
transparent and not that its colors change.
This is how Photoshop and Illustrator work for instance (but not Flash
FWIW)


> Getting filter Background and blending/compositing working inside isolated
> groups seems like enough work for now!
>

I agree. Little steps are best. We can do the complex stuff later.