Re: [css-compositing] Isolation groups

On Tue, Dec 10, 2013 at 5:30 AM, Tavmjong Bah <tavmjong@free.fr> wrote:

> On Mon, 2013-12-09 at 09:40 -0800, Rik Cabanier wrote:
> >
> >
> >
> > On Mon, Dec 9, 2013 at 6:07 AM, Tavmjong Bah <tavmjong@free.fr> wrote:
> >
> >         Hi,
> >
> >         I have a few questions about the spec:
> >
> >         Section 3.3: I don't understand how blending creates an
> >         isolation group.
> >         If I set 'mix-mode-blend' on a circle and the circle gets
> >         blended with
> >         the background, what is the isolation group? An example would
> >         really
> >         help.
> >
> >
> > there's an example in the section on
> > isolation: http://dev.w3.org/fxtf/compositing-1/#isolationblending
> > It is the circle that becomes the isolated group so if there's
> > blending inside the content that has the blend-mode, it will be
> > isolated to that content.
>
> In the example, 'isolation' is a property of the group, correct?. What I
> don't understand is how an SVG circle can have blending inside.


that is true. A circle is drawn atomically, so in that case, it doesn't
matter if it's isolated.
If in the future we would allow just the stroke to blend, this would make a
difference.


> It seems
> to me that the 'isolation' property is not applicable to SVG graphics
> elements (unless or until we allow graphics elements to contain other
> elements... and maybe <text> which can wrap <tspan>s which could
> overlap).
>

Correct. In that case, if both <text> and <tspan>s had blend modes, the
<tspan>s would not blend with the backdrop of <text>

>         Example 4: It appears that the three circles are being blended
> >         in one
> >         isolation group and then put over the gray background. What is
> >         causing
> >         the circles to be isolated? If the SVG is referenced from an
> >         <img> then
> >         it should be isolated but if it is included inline then it
> >         should not
> >         be(?). If I try the SVG in Chrome the circles are never
> >         isolated, no
> >         matter what I do (stand-alone SVG, external SVG, inline). Is
> >         this due to
> >         a lack of isolation support in Chrome?
> >
> >
> > Can you post your example online (codepen, jsfiddle)?
> > There should be a difference since if you link them using <img>, the
> > SVG should be rasterized.
>
> See: http://tavmjong.free.fr/SVG/BLENDING/blending.html
>
> Tav
>
>
>
>
>