Re: Integration of HTM

On Tue, Feb 9, 2010 at 1:25 PM, Maciej Stachowiak <mjs@apple.com> wrote:

> I am concerned however about overlaying the canvas with 0.01 opacity divs.
> I expect this will have a negative impact on canvas rendering performance,
> especially if there are significant animations. Because even though 0.01
> opacity likely won't draw anything visible, the browser still has to render
> and composite the content on top of the canvas.
>

In the future we can probably expect most browsers to use graphics hardware
in a way that makes the compositing cheap/free. However, opacity:epsilon
does seem rather ugly. Wouldn't opacity:0 work here? In Gecko at least that
would optimize away almost all rendering (while still catching events).

I am also wondering how this technique can be extended to control target
> areas that are not rectangles.
>

I'm wondering that too. I wonder if it would make sense to add some kind of
canvas API that lets you associate an element with the current path. Mmm,
sounds like image maps :-).

Rob
-- 
"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
53:5-6]