Hi,
I've also posted this question as a bug report at qt-project.org
(https://bugreports.qt-project.org/browse/PYSIDE-151), but this is also a PyQt
issue.
QGraphicsView is apparently very slow under Linux and Mac OS X. I've attached
an example program (runs with PySide or PyQt). The signals should be updated
every 25ms; the actual timer intervals are displayed on the console. Now under
Linux and Mac OS X, the graphics get slower with increasing window size. In
full screen, the timer intervals are around 100ms instead of 25ms on my
machines.
This problem does not exist under Windows. Here, the intervals are not affected
by window size, and the intervals stay at the given values. Interestingly, the
program runs perfectly fast even in a Windows inside a VM.
Furthermore, this problem is PySide (or PyQt) specific, because this behavior
does not occur when I use Qt from C+. In C+, the program works as expected on
all three platforms.
Thanks,
Clemens
import sys
from PyQt4 import QtGui, QtCore, QtOpenGL
import random
import math
class SignalItem(QtGui.QGraphicsItem):
def __init__(self, nr):
super(SignalItem, self).__init__()
self.setFlags(QtGui.QGraphicsItem.ItemUsesExtendedStyleOption)
self.nr = nr
self.fr = random.randint(3, 50)
self.bg = QtGui.QColor(random.randint(200,255),random.randint(200,255),random.randint(200,255))
def boundingRect(self):
return QtCore.QRectF(0, self.nr*50, 10000, 50)
def paint(self, painter, option, widget):
painter.fillRect(option.exposedRect, self.bg)
self.prevY = math.sin((int(option.exposedRect.left()) - 1)/float(self.fr))*10 + 25 + self.nr*50
for x in range(int(option.exposedRect.left()), int(option.exposedRect.right())):
y = math.sin(x/float(self.fr))*10 + 25 + self.nr*50
painter.drawLine(x-1, self.prevY, x, y)
self.prevY = y
class Dummy(QtCore.QObject):
def __init__(self):
super(Dummy, self).__init__()
self.scene = QtGui.QGraphicsScene()
for i in range(40):
item = SignalItem(i)
self.scene.addItem(item)
self.view = QtGui.QGraphicsView(self.scene)
self.view.show()
self.startTimer(25)
self.x = 0
self.lastTimerEvent = None
def timerEvent(self,event):
self.x += 1
self.view.horizontalScrollBar().setValue(self.x)
currentTime = QtCore.QTime.currentTime()
if self.lastTimerEvent:
print self.lastTimerEvent.msecsTo(currentTime)
self.lastTimerEvent = currentTime
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
d = Dummy()
sys.exit(app.exec_())
_______________________________________________
PyQt mailing list [email protected]
http://www.riverbankcomputing.com/mailman/listinfo/pyqt
