我对Qt一点都不了解,但我正试图厚着脸皮从其他地方借用代码(http://sieral.netmanagers.com.ar/weblog/posts/BB901.html#discus_线程). ;)
我有个问题。当我第一次运行test()时,一切都很顺利。然而,当我第二次运行它时,我得到了令人讨厌的分段错误。我怀疑问题是我没有正确地结束qt。我应该对这个程序做些什么改变才能使它多次工作?提前谢谢!在
from PyQt4 import QtCore, QtGui, QtWebKit
import logging
logging.basicConfig(level=logging.DEBUG)
class Capturer(object):
"""A class to capture webpages as images"""
def __init__(self, url, filename, app):
self.url = url
self.app = app
self.filename = filename
self.saw_initial_layout = False
self.saw_document_complete = False
def loadFinishedSlot(self):
self.saw_document_complete = True
if self.saw_initial_layout and self.saw_document_complete:
self.doCapture()
def initialLayoutSlot(self):
self.saw_initial_layout = True
if self.saw_initial_layout and self.saw_document_complete:
self.doCapture()
def capture(self):
"""Captures url as an image to the file specified"""
self.wb = QtWebKit.QWebPage()
self.wb.mainFrame().setScrollBarPolicy(
QtCore.Qt.Horizontal, QtCore.Qt.ScrollBarAlwaysOff)
self.wb.mainFrame().setScrollBarPolicy(
QtCore.Qt.Vertical, QtCore.Qt.ScrollBarAlwaysOff)
self.wb.loadFinished.connect(self.loadFinishedSlot)
self.wb.mainFrame().initialLayoutCompleted.connect(
self.initialLayoutSlot)
logging.debug("Load %s", self.url)
self.wb.mainFrame().load(QtCore.QUrl(self.url))
def doCapture(self):
logging.debug("Beginning capture")
self.wb.setViewportSize(self.wb.mainFrame().contentsSize())
img = QtGui.QImage(self.wb.viewportSize(), QtGui.QImage.Format_ARGB32)
painter = QtGui.QPainter(img)
self.wb.mainFrame().render(painter)
painter.end()
img.save(self.filename)
self.app.quit()
def test():
"""Run a simple capture"""
app = QtGui.QApplication([])
c = Capturer("http://www.google.com", "google.png", app)
c.capture()
logging.debug("About to run exec_")
app.exec_()
DEBUG:root:Load http://www.google.com
QObject::connect: Cannot connect (null)::configurationAdded(QNetworkConfiguration) to QNetworkConfigurationManager::configurationAdded(QNetworkConfiguration)
QObject::connect: Cannot connect (null)::configurationRemoved(QNetworkConfiguration) to QNetworkConfigurationManager::configurationRemoved(QNetworkConfiguration)
QObject::connect: Cannot connect (null)::configurationUpdateComplete() to QNetworkConfigurationManager::updateCompleted()
QObject::connect: Cannot connect (null)::onlineStateChanged(bool) to QNetworkConfigurationManager::onlineStateChanged(bool)
QObject::connect: Cannot connect (null)::configurationChanged(QNetworkConfiguration) to QNetworkConfigurationManager::configurationChanged(QNetworkConfiguration)
Process Python segmentation fault (this last line is comes from emacs)
QApplication只能初始化一次! 它可以被任意多个捕获实例使用,但是应该在主循环中启动它们。 参见:https://doc.qt.io/qt-4.8/qapplication.html
你也可以试试“del app”应用程序执行_“,但我不确定结果。 (您的原始代码在我的系统上运行良好)
我将使用urllib而不是webkit:
您需要在测试函数之外处理QApplication,有点像singleton(在这里实际上很合适)。在
你能做的就是检查QtCore.qApp是什么(或者如果QApplication.instance应用程序()返回None或其他值),然后才创建qApp,否则,使用全局qApp。在
因为PyQt将应用程序存储在某个地方,所以它不会在test()函数之后被销毁。在
如果您想确保它被正确地处理,只需为它设置一个延迟初始化的singleton。在
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