Re: [css-compositing] why general blending is confusing

On 12 Oct 2013, at 9:20 pm, Robert O'Callahan <robert@ocallahan.org> wrote:

> It will depend on what the specification requires, but it will be hard to implement
> something that produces the same output for examples 3 and 4 in my test.
> 
> According to the spec they should produce different output. In example 4 the CSS transform makes the blendingbg element a stacking context, therefore an isolated group, and therefore the 'content' element does not blend into the page background (it blends into the transparent black background of the isolated group instead).
> 
> Mostly this, yes. I don’t think an author will understand when layers are created,
> and why behaviour changes dramatically when they are.
> 
> The implicit creation of an isolated group for every stacking context may be confusing, but it's much easier to implement, more performant, and probably less confusing in edge cases than any other proposal on the table.

OK. I’ll go ahead and land the implementation then.

Dean