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

• From: Boris Zbarsky <bzbarsky@MIT.EDU>
• Date: Mon, 07 Mar 2011 21:07:55 -0500
• To: Glenn Maynard <glenn@zewt.org>
• CC: Chris Marrin <cmarrin@apple.com>, Web Applications Working Group WG <public-webapps@w3.org>
• Message-ID: <4D758F7B.30307@mit.edu>

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?

-Boris

Received on Tuesday, 8 March 2011 02:09:00 UTC