Re: Experimental cairo port

[John Stowers <john stowers lists gmail com>]

On Wed, May 30, 2012 at 9:14 AM, Lars-Peter Clausen <lars metafoo de> wrote:
> On 05/30/2012 07:07 AM, John Stowers wrote:
>>> On the negative side though it is almost a magnitude of order slower. This is
>>> especially noticeable if many datapoints are drawn like in the rulers example.
>>> A simple solution I've tried is to filter the points and skip points which
>>> wouldn't be visible anyway, because they are identical to their predecessor.
>>> Part of the problem though is that cairo requires a function for each point
>>> which should be drawn. This results in a huge overhead, so another solution
>>> would be to use a cairo image surface and implement our own drawing functions
>>> and do raw pixel access.

Strange, rectangle filling performance seems to regularly be a
problem; for example

http://cworth.org/exa/understanding_rectangles/

But I thought this had been fixed (the slow filling at least). I
wonder if doing it on an image surface would be faster.

I still suggest posting on the cairo mailing list, they might like the
cairo trace for performance tuning even if they can't fix the problem
immediately.

John