For reference, here is a prototype patch which implements <canvas opaque>: https://bugs.webkit.org/show_bug.cgi?id=112624 And one which implements getContext('2d', { alpha: none }): https://bugs.webkit.org/show_bug.cgi?id=112628
I believe this represents the bulk of the cross-port work that would be required; there is further port-specific work required, but this should be mostly in platform/graphics/*. Stephen On Thu, Mar 14, 2013 at 5:23 PM, Dean Jackson <[email protected]> wrote: > > On 15/03/2013, at 8:06 AM, Gregg Tavares <[email protected]> wrote: > > > Because it's not the same as fillRect(0, 0, width, height) on an empty > canvas. The canvas itself has alpha (unless we add the option to not have > it as has been proposed). The contents of the canvas has to stay as the > user created it. If I draw with rgba(255,255,0, 0.5) I expect if I read > data out of the canvas or draw that canvas into another canvas I'll get > that color, not the color blended with the css background. > > Yes, this is what I said in another email. Maybe I'm misunderstanding > this, but if the main concern is to guarantee nice subpixel-antialiased > text in canvas (but not anywhere else, such as the 99.99% of places where > people draw text) then.... well, I'm still not convinced opaque is a great > idea :) Especially not as an HTML attribute. > > There are obviously ways to get around the problems you mentioned above > (e.g. two buffers + two draws, or keeping a display list until someone > wants to read out, etc) and, even more obviously, they have significant > problems. It just seems to me that we're trying to address the issue of > wanting nice looking text with a very specific solution on one element. > Maybe we should consider what we could do across the platform? > > Dean > > > > So, the canvas has to be blended if there's alpha. There's no magic > getting around that. The only way around it is to give the user a way to > say "no alpha". > > > > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev >
_______________________________________________ webkit-dev mailing list [email protected] https://lists.webkit.org/mailman/listinfo/webkit-dev
