I think that there is a bright future in using PyQt4 with a QWebView
object for writing basic web tests, and for web automation. My early
experiments suggest that it is a much simpler and faster solution, when
one needs web page browsing with JavaScript enabled, than a heavyweight
technique like running and remotely controlling a separate browser
process.
But though my first few page loads and clicks went well, I quickly found
that sites of any complexity would cause my Python script to crash with
a segmentation fault. Many of my early examples were non-deterministic
- the script would sometimes crash, but sometimes succeed - but I have
now found a test script which always crashes, and that therefore might
serve as a good example of this bug here on the mailing list.
The script is attached to this email. Its output when I run it against
the PyQt4 shipped with Ubuntu Maverick is this:
$ python2.6 qtcrash.py
4.7.0
4.7.4
zsh: segmentation fault python2.6 qtcrash.py
When I download and install the current PyQt4 snapshot instead, this is
the output:
$ ./v/bin/python2.6 qtcrash.py
4.7.0
snapshot-4.8.2-f509333f6b01
zsh: segmentation fault ./v/bin/python2.6 qtcrash.py
Is anyone else able to reproduce this? Where would I get started in
tracking down why this code causes PyQt4 to produce a segmentation
fault? Thanks for any guidance!
"""Routines that actually speak Qt to drive its web views."""
import sys
from PyQt4 import QtCore, QtGui, QtWebKit
print QtCore.QT_VERSION_STR
print QtCore.PYQT_VERSION_STR
class SimpleTest(object):
def __init__(self):
self.current_callback = self.callback1
def step(self):
next = self.current_callback()
if next is not None:
self.current_callback = next
def findAll(self, selector):
return list(self.webview.page().mainFrame().findAllElements(selector))
def click(self, element):
element.evaluateJavaScript(
"var event = document.createEvent('MouseEvents');"
"event.initEvent('click', true, true);"
"this.dispatchEvent(event);"
)
def callback1(self):
self.webview = QtWebKit.QWebView()
self.webview.show()
self.webview.load(QtCore.QUrl(
'http://ec2-184-73-115-78.compute-1.amazonaws.com/simple/'
))
return self.callback2
def callback2(self):
elist = self.findAll('div#content > p > a')
if elist:
self.click(elist[0])
return self.callback3
def callback3(self):
elist = self.findAll('div#ferns-info > h2 > a')
if elist:
self.click(elist[0])
return self.callback4
def callback4(self):
elist = self.findAll('div#lycophytes-info > h2 > a')
if elist:
self.click(elist[0])
return self.callback5
def callback5(self):
pass
# The Qt application itself.
app = QtGui.QApplication(sys.argv)
tester = SimpleTest()
timer = QtCore.QTimer()
timer.timeout.connect(tester.step)
timer.start(50)
sys.exit(app.exec_())
--
Brandon Craig Rhodes [email protected] http://rhodesmill.org/brandon
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