On 04/03/2013 05:09 PM, Andreas Pakulat wrote:
As I said, with Qt4.8 I don't see this here on Linux at all, once the
window is at a certain size the timer fires every 25 ms again. This is
on a somewhat new system with Debians standard Qt/PyQt packages. So its
not necessarily a general problem with Linux/PyQt, but might be limited
to the systems you've used so far to reproduce this or a configuration
thing etc.
Strange. I tried it on my Arch Linux as well as on openSUSE (inside
VirtualBox), and I never get 25ms... I do get 25ms on Windows inside
VirtualBox though. Plus I do get 25ms on all platforms when I run the
C++ version.
It could also be the fact that the various helpers inside your paint are
slower in Python on *nix for whatever reason. Did you try further
simplifying the paint function, for example simply painting 1 line
across the whole rect in multiple steps? Or try out a single step? That
way you'd be able to get rid of all the math which could affect the
result too.
[...]
I doubt there's much difference in the PyQt/PySide code between Windows
and *nix, after all the C API of CPython is the same on both platforms.
One difference though is the compiler being used for both - at least
usually it is a different one - and of course the platform itself. Does
a fixed-length sleep instead of the paint() function produce a different
result on Linux? Meaning, does it matter what exactly happens in paint
or that its just not a noop?
It does depend on how much I draw. If I only fill the backgrounds, I get
25ms. However, if I get rid of all the math functions and just paint a
constant line, the program gets slower when this line is visible:
def paint(self, painter, option, widget):
painter.fillRect(option.exposedRect, self.bg)
for x in range(int(option.exposedRect.left()),
int(option.exposedRect.right())):
painter.drawLine(x-1, 20, x, 40)
I will talk about the output of perf in my reply to Hans-Peter's post.
Clemens
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