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Re: Using ArrayBuffer as payload for binary data to/from Web Workers

From: Chris Marrin <cmarrin@apple.com>
Date: Wed, 09 Mar 2011 10:24:39 -0800
Cc: Glenn Maynard <glenn@zewt.org>, Web Applications Working Group WG <public-webapps@w3.org>
Message-id: <A5E36528-24DA-4135-B5B7-CA58CDC3B9C5@apple.com>
To: Boris Zbarsky <bzbarsky@MIT.EDU>

On Mar 7, 2011, at 6:07 PM, Boris Zbarsky wrote:

> On 3/7/11 8:55 PM, Glenn Maynard wrote:
>> I'd expect CanvasPixelArray to allow optimizations that ArrayBuffer
>> doesn't, since the implementation can use the native surface format,
>> translating to RGBA for the script transparently.  This can matter for
>> streaming textures to OpenGL/D3D, too; creating BGRA textures on nVidia
>> hardware is typically much faster than RGBA ones.
> 
> But modifying the ImageData is not supposed to modify what the graphics card sees, right?  So you have to make a copy here on putImageData (or on the next write to the image data), right?
> 
>> I don't recall if this has been brought up: are there cases where
>> explicit zero-copy messaging is better than transparent copy-on-write?
> 
> Transparent copy on write requires that each write do a "should I copy?" check, right?

Yeah, nothing's free, unless you have copy-on-write hardware or something. 

-----
~Chris
cmarrin@apple.com
Received on Wednesday, 9 March 2011 18:25:14 GMT

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