W3C home > Mailing lists > Public > whatwg@whatwg.org > December 2009

[whatwg] Canvas pixel manipulation and performance

From: Jason Oster <parasyte@kodewerx.org>
Date: Fri, 04 Dec 2009 10:30:44 -0700
Message-ID: <4B194744.2050601@kodewerx.org>
I guess this suggestion to access the full pixel data in a single array 
element has fallen by the wayside.  Are there any direct objections to 
including additional API to allow this kind of behavior?  It seems most 
developers believe it would be unnecessary, but I haven't heard much in 
the way of reasoning (technical nor personal).

I cannot comment on the "typical uses" of accessing pixel data from 
script; if it is [in general] more important to have each of the R,G,B,A 
components separated for script access, or not.  But for cases involving 
indexed palettes, having the ability to directly treat each pixel as a 
single property is very much desired.

It is not going to provide a huge boost in performance.  At worst, it 
will help make code cleaner.  But at best, it will do that and 
[slightly?] reduce the performance penalty of reading/writing 3 
superfluous (in my eyes) array accesses.  The only negative aspect I can 
think of with additional API functions is the introduction of new 
developer confusion; "Which one do I use?"

Thanks for listening,
Received on Friday, 4 December 2009 09:30:44 UTC

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