- From: Rik Cabanier <cabanier@gmail.com>
- Date: Thu, 12 Dec 2013 21:36:04 -0800
- To: "Robert O'Callahan" <robert@ocallahan.org>
- Cc: James Robinson <jamesr@google.com>, www-svg <www-svg@w3.org>, www-style list <www-style@w3.org>, "public-fx@w3.org" <public-fx@w3.org>
- Message-ID: <CAGN7qDCtazLfc6+j7Jirn0wVOKU7iaU_f6J_42EPr=NjaTQAfw@mail.gmail.com>
On Thu, Dec 12, 2013 at 9:24 PM, Robert O'Callahan <robert@ocallahan.org>wrote: > On Fri, Dec 13, 2013 at 4:50 PM, Rik Cabanier <cabanier@gmail.com> wrote: > >> On Thu, Dec 12, 2013 at 7:29 PM, Robert O'Callahan <robert@ocallahan.org>wrote: >> >>> On Fri, Dec 13, 2013 at 4:13 PM, Rik Cabanier <cabanier@gmail.com>wrote: >>> >>>> No, the spec should not refer to blogs. Also, this is not 'potentially' >>>> useful as the absence of this description has caused confusion in the past. >>>> >>> >>> I agree with James. Having the spec define behavior that is never used >>> by any Web feature is very confusing. >>> >>> Section 4 is not really needed at all since the HTML5 canvas spec >>> defines the canvas compositing behavior. >>> >> >> Can you point where that is defined in the canvas spec? >> > > > http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#drawing-model > yes, that doesn't describe how you do the compositing. is it 'clip-to-self', or the bounds of the drawing bitmap, or infinite bounds? > >> >>> If you want the Compositing and Blending spec to define new compositing >>> modes for canvas, then define a list of operators that the HTML canvas spec >>> can refer to, but don't define globalCompositeOperation here. Don't even >>> mention canvas here. >>> >> >> It's needed because the canvas spec doesn't say anything about how >> compositing should happen. >> I don't want to break canvas by removing this. >> > > All you need to define for canvas is the per-pixel compositing behavior. > No. What if there are no pixels (ie with 'clear'), you'd still want to clear that area. > > >> >> Another very important reason is also that if this property/behavior is >>>> included in the spec, the W3C patent policy will apply. >>>> >>> >>> Describing something in a W3C spec that is not actually used by any >>> features in that spec, just so we can get the patent policy to apply to it, >>> borders on bad faith. >>> >> >> It *is* being used. >> > > Where? Pointing to "clip to self" saying "don't do this" does not > constitute a use. > > >> Also, future spec might want to refer to this. Another example is the >> proposal for masking in canvas which has an option for clip-to-self. It >> would be unfortunate that we would have to rev the compositing spec to >> progress canvas or filters. >> > > If a future spec will use it, the future spec can define it. > No, we want to avoid defining the same thing over and over again. Filters, blending, canvas, masking all need to build on a common model. This is why we did the compositing and blending spec in the first place: harmonize the different specs. > Any use of clip-to-self will have to define what the clip-to-self region > is for each drawing operation, which is not necessarily easy to do. It > certainly shouldn't be done by saying the clip-to-self region is where > alpha > 0, for the reasons James pointed out near the beginning of this > thread. > That is not what the spec says. clip-to-self=true works on the shape of the element which is independent of its alpha.
Received on Friday, 13 December 2013 05:36:35 UTC