HTML Canvas performance in the Browse activity

Mihai Sucan mihai.sucan at
Mon Jun 1 05:04:50 EDT 2009

Hello John!

Le Mon, 01 Jun 2009 09:26:20 +0300, John Gilmore <gnu at> a écrit:

>> The XO browser has two problems actually: 1) performance issue caused by
>> scaling everything up; 2) the difference in the scaling logic from a
>> normal Gecko build.
>> Problem 2: Keeping the current 134 DPI value would always require Gecko  
>> to
>> be patched, thus making it different from other Gecko builds. Maybe the
>> browser could use 200 DPI? Perhaps pages would render too big.
> Is there a good reason that the upstream Gecko maintainers wouldn't
> take this a patch, or one like it?  As long as the scale factor is 1
> on ordinary screens (and the code optimizes that path), adding this
> would have little impact on speed or space on non-OLPCs.  (And if
> Pixel Qi succeeds in selling their screens, there are going to be more
> 'unusual' cheap & high performance screens that we'll want good free
> software support for.)

I understand from Robert O'Callahan that it's better to constrain CSS  
pixels to integer device pixels. When the patch is applied, CSS pixels no  
longer map strictly to integer device pixels (IIANM).

Mihai Sucan

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