kicad-developers team mailing list archive

["emmedics4" <marco.serantoni@...>]

> > Good, but no application would use only one Path (means 1 thichness andcolor), using 10 changes something ?
> Yes. If you look at source code for wxGraphicsContext, you will see
> that wxGCDC::DrawLine() ends up creating and destroying a
> wxGraphicsPath() for each line drawn. This is why your initial test saw
> a large improvement on OSX. It was only using 10 paths when drawing
> with wxGraphicsContext compared to 200,000 paths (indirectly) when
> drawing with wxDC. See wxWidget's source file common/graphcmn.cpp. I
> believe that this is what Dick was talking about when using a proper
> wxGraphicsContext implementation instead of wxGCDC. There must be some
> significant overhead when constantly calling the graphics context for
> each line.
I mean if on platform you have tested there is a difference of performance with 1 versus 10 Path ? 
I've used that number because a number near at the need of pcbnew.
 
> >> On gtk/cairo and msw/gdi+ the story is
> >> different. Although there is an order of magnitude performance
> >> decrease, gtk/cairo is probably usable. However, the the msw/gdi+
> >> situation is bleak. I cannot see how msw/gdi+ could ever be made usable
> >> for Kicad (or anything else for that matter). The msw/cairo combination
> >> still needs to be investigated. I'll try to test this over the next
> >> week or two when I get some free time. I may also try to modify the
> >> example to use SFML if it isn't too much of a hassle to see if it lives
> >> up to it's name.
> > Which CAIRO backend are you using and with which driver on linux ?
> I'm using the AMD64 version of Debian testing (sqeeze) with the NVidia
> proprietary drivers and cairo version 1.8.8.
Be sure to being using glitz and have OpenGL enabled on the driver.

> >> It's looking like Manveru was correct about GDI+ performance. It is
> >> also looking like I may have wasted my time moving the coordinate
> >> transforms to wxDC if we can't use wxGraphicsContext due to performance.
> > First test are for NO GO for me too, but better doing more deep tests before thrash all.
> I don't know about that. The gtk/cairo difference of 0.04s to 0.5s can
> probably be improved enough with some clever programming. I seriously
> doubt that you are going to overcome the 0.124s to 17.985s difference on
> msw/gdi+ with careful programming unless this test is the completely
> wrong approach to using wxGraphicsContext.

I was suggesting from the beginning the escape of msw/cairo for this reason, moreover
GDI+ was dumped in the latest windows releases as the standard is now Direct2D: (http://msdn.microsoft.com/en-us/library/dd370990(VS.85).aspx) HW accelerated, so users are cut in two slices with a cut between XP and Vista.

--
Marco