Re: Experimental cairo port

[Lars-Peter Clausen <lars metafoo de>]

On 05/30/2012 10:35 AM, John Stowers wrote:
> 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.

As I said the problem is not the filling performance (which is quite good), but
rather submitting all the rectangles to cairo.

> 
> 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.

What gtkdatabox does it not to different from cworth test case in that
blogpost: drawing lots of rectangles.

> Oh, and
>
> git clone git://git.metafoo.de/gtkdatabox/
>
> doesn't work
>

Should be fixed now.