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Re: [whatwg] High-density canvases

From: Justin Novosad <junov@google.com>
Date: Fri, 20 Jun 2014 08:58:08 -0400
Message-ID: <CABpaAqSKQOD1ej4ao3GOUi6PnXhKc=ZH=kxVryBgECNeBC3kew@mail.gmail.com>
To: "Robert O'Callahan" <robert@ocallahan.org>
Cc: Stephen White <senorblanco@chromium.org>, Ian Hickson <ian@hixie.ch>, Dean Jackson <dino@apple.com>, Rik Cabanier <cabanier@gmail.com>, WHAT Working Group <whatwg@whatwg.org>
On Thu, Jun 19, 2014 at 7:03 PM, Robert O'Callahan <robert@ocallahan.org>

> On Fri, Jun 20, 2014 at 7:32 AM, Justin Novosad <junov@google.com> wrote:
>> +1 from me too. But I have one concern in terms of future proofing,
>> because
>> I would like to keep the door open for auto-resizing as a possible future
>> improvement. In an eventual auto-resize proposal, we will want to make
>> the "preferredsizechange"
>> event cancelable.
> Why?

Because apps may want to use the auto resizing feature to delegate the
resize math to the browser (and possibly the re-rendering too, in the case
of a command-buffer backed implementation), but still retain some control
over when the auto-resizing kicks in.  A simple way to provide that control
is to allow the app to inhibit an auto-resize by cancelling the
preferredsizechange event.  It could be done differently, but I think
making the event cancelable would be the most natural and succinct way to
expose that control.

Examples of how this might be used:
* If the CSS size of the canvas is being animated, the app may want to only
allow the backing store to be auto-resized at the end of the animation, so
that the animation stays fluid.
* The app may want to allow auto-resize to kick-in only when the preferred
vs actual size ratio exceeds a certain threshold.


> Rob
> --
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Received on Friday, 20 June 2014 12:58:37 UTC

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