W3C home > Mailing lists > Public > whatwg@whatwg.org > June 2014

Re: [whatwg] High-density canvases

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 20 Jun 2014 11:02:23 +1200
Message-ID: <CAOp6jLbb938vtVFRQpd5iXY8F3mDH95w5ZV-P70YoYBK6eSNPQ@mail.gmail.com>
To: Stephen White <senorblanco@chromium.org>
Cc: Ian Hickson <ian@hixie.ch>, Dean Jackson <dino@apple.com>, Rik Cabanier <cabanier@gmail.com>, WHAT Working Group <whatwg@whatwg.org>
On Fri, Jun 20, 2014 at 2:54 AM, Stephen White <senorblanco@chromium.org>
wrote:

> I assume that the size change event would fire:
>
>    - on browser page zoom
>    - on pinch-zoom
>    - when a CSS animation (e.g., scale) changes the canvas size in CSS
>    pixels
>
> For browsers that implement the latter two off the main thread, perhaps
> they should only fire at end-of-gesture or end-of-animation, to avoid the
> rendered size being out-of-sync with scaled size by the time the canvas
> gets composited.
>

We should queue a task to fire the event every time the attributes change.
The question is when the attributes should change.

I think we should leave some flexibility here for the UA both for
controlling the timing and exact values of the attributes. For example, it
would be reasonable for a UA to change the device pixel size attributes
exactly when it re-rasterizes the surrounding Web content, and set the
canvas device pixel size to match the pixel size at which the canvas'
content-rect would be rasterized (if it had a solid color background, say).
That's the way I'd want to implement this in Gecko. But the timing and
rasterized resolution are controlled by quite complex algorithms. So I'm
not sure what normative text to put in the spec.

I agree with Mark that the names need work.
>

I don't care what the name is as long as we reach a consensus and stick to
it :-).

Rob
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Received on Thursday, 19 June 2014 23:02:48 UTC

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