Re: Utility of background-composite and background-blend-mode?

On Thu, Mar 14, 2013 at 12:06 PM, L. David Baron <dbaron@dbaron.org> wrote:

> On Thursday 2013-03-14 11:21 -0700, Rik Cabanier wrote:
> > On Thu, Mar 14, 2013 at 11:04 AM, Simon Fraser <smfr@me.com> wrote:
> > > I'm confused about background-blend-mode, and the spec <
> > >
> https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#background-blend-mode
> >
> > > is not helping.
> > >
> > > Does it blend with anything in other elements, or only between the
> > > background images/background color of the element to which it's
> applied?
> > >
> > > The spec's use of "the background images at a lower z-index." is
> confusing
> > > here. Is that "the background images of elements at a lower z-index",
> or
> > > "later  background images of the element"?
> > >
> > > If it's only within elements and not between them, I don't see why it
> > > matters whether position:fixed creates a group.
> > >
> > >
> > From the spec:
> >
> > Each background image will blend with the element's background and the
> > background images at a lower z-index
> >
> >
> > So, it will blend between elements.
>
> Pointing to one piece of the spec to say another piece of the spec
> is wrong isn't sufficient here.  If you want people to review the
> concepts you're proposing, the spec needs to be clear about what
> those concepts are.


I'm unsure what those 2 pieces are. The whole spec text is:

This attribute sets the blending mode of each background image and the
background color.
Each background image will blend with the element's background and the
background images at a lower z-index. This must follow the CSS drawing
model<http://www.w3.org/TR/CSS21/zindex.html>
.


I will reword it so it's more clear:

Each background image will blend with the element's background and the *
element's* background images at a lower z-index.