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Re: hit testing and retained graphics

From: Charles Pritchard <chuck@jumis.com>
Date: Thu, 30 Jun 2011 23:24:12 -0700
Message-Id: <33E5F3E9-85B4-4919-BD0F-103D03C543F4@jumis.com>
Cc: "Blessing, Kimberly" <Kimberly_Blessing@Comcast.com>, Paul Bakaus <pbakaus@zynga.com>, "Tab Atkins Jr." <jackalmage@gmail.com>, John Foliot <jfoliot@stanford.edu>, Charles McCathieNevile <chaals@opera.com>, Richard Schwerdtfeger <schwer@us.ibm.com>, Cameron McCormack <cam@mcc.id.au>, Cynthia Shelly <cyns@microsoft.com>, "david.bolter@gmail.com" <david.bolter@gmail.com>, Frank Olivier <Frank.Olivier@microsoft.com>, "Mike@w3.org" <Mike@w3.org>, "public-canvas-api@w3.org" <public-canvas-api@w3.org>, "public-html@w3.org" <public-html@w3.org>, "public-html-a11y@w3.org" <public-html-a11y@w3.org>
To: Maciej Stachowiak <mjs@apple.com>




On Jun 30, 2011, at 11:09 PM, Maciej Stachowiak <mjs@apple.com> wrote:

> 
> On Jun 29, 2011, at 7:23 AM, Blessing, Kimberly wrote:
> 
>>> -----Original Message-----
>>> From: Paul Bakaus
>>> Sent: Wednesday, June 29, 2011 9:33 AM
>>> 
>>> Mostly, today's canvas applications are game
>>> demos and drawing apps.
>> 
>> <snip>
>> 
>>> Finally, I want to end this little rant by reiterating that canvas is
>>> absolutely *not* used much in the wild.
>> 
>> I have heard similar comments from other developers and wanted to address the points Paul raised.
>> 
>> Canvas is targeted as the near-future development platform for set-top boxes -- which would impact a very large number of people. Consumer electronics manufacturers are buying in to HTML5 and my understanding is that canvas could be used to render not just the on-screen guides but even the video streams.
> 
> 
> This sounds unlikely to me. Rendering HD video via canvas on the relatively underpowered hardware of a set top box is not feasible.
> 
> Regards,
> Maciej
> 
> 

Consider canvas as an overlay, and that fillRect/drawImage are easily optimized.

They can all be managed reasonably well on the gpu in constrained environments.

One common mistake for example, is in filtering for a chroma key.

If a small video feed, such as a sign language translation is to be used, it can be filtered and placed into a small canvas, and that canvas positioned via CSS over a larger video element. The gpu can take care of the final composition step.

These constraints and efficiency techniques have been around a long time.

GPUs are quite helpful in understanding how and where rendering can happen. Some of the ultramodern GPUs have some neat things on them, but overall, things are the same as they were a decade ago.

-Charles
Received on Friday, 1 July 2011 06:24:44 UTC

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