On Thu, Mar 14, 2013 at 1:38 PM, Ryosuke Niwa <[email protected]> wrote:
> On Thu, Mar 14, 2013 at 12:55 PM, Dean Jackson <[email protected]> wrote: > >> >> On 15/03/2013, at 6:50 AM, Dana Jansens <[email protected]> wrote: >> >> On Thu, Mar 14, 2013 at 3:46 PM, Dean Jackson <[email protected]> wrote: >> >>> I'm not sure I like this proposal. Why is canvas special? Why doesn't >>> <img> get an opaque attribute (or flag)? Why not every element? >>> >> >> There is ongoing work to infer opaqueness in every other kind of element >> when possible. See for example >> https://bugs.webkit.org/show_bug.cgi?id=70634 >> >> >> Yes, I'd prefer to infer it rather than specify it. For example, I could >> infer that a canvas is opaque if it has a non-transparent CSS >> background-color. >> > The content of the canvas has to be blended with the background color so that doesn't help optimization. If there's a background color you first have to do a full blend of the contents of the canvas with the background color. Where as if the canvas has no alpha then that step can be avoided. > > I like this approach. It means that developers don't have to explicitly > use this feature to get the performance benefits. > > In fact, this is the preferred performance optimization approach on the > Web. We don't provide explicit APIs to optimize performance. We make > sensible APIs which allows us to implement more optimizations on common > cases behind the scene. > > - R. Niwa > > > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev > >
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