PyQt4：重新啓動主循環？

Question

我有一個PyQt4類，它顯示一個html表單並獲取輸入，這要歸功於前面的questions here（一個older one is here）。

現在我想退出主循環，做一些其他的事情，稍後用不同的html表單重新啓動主循環。問題是，我的事件句柄在主循環的第二次執行中不起作用。我究竟做錯了什麼？

問題似乎是由於未提交表單而第二次調用app.exec_()時無法正常工作。

這裏是我的代碼運行，但不提交第二種形式：

import sys 
from urllib import unquote_plus 

from PyQt4 import QtCore, QtGui, QtWebKit 

class MyWebPage(QtWebKit.QWebPage): 
    formSubmitted = QtCore.pyqtSignal(QtCore.QUrl) 

    def acceptNavigationRequest(self, frame, req, nav_type): 
     if nav_type == QtWebKit.QWebPage.NavigationTypeFormSubmitted: 
      self.formSubmitted.emit(req.url()) 
     return super(MyWebPage, self).acceptNavigationRequest(frame, req, nav_type) 



class PsyTML(QtGui.QWidget): 
    def __init__(self): 
     super(PsyTML, self).__init__() 
     self.elements = {} 
     self.view = QtWebKit.QWebView(self) 
     layout = QtGui.QVBoxLayout(self) 
     layout.addWidget(self.view) 
     layout.setContentsMargins(0, 0, 0, 0) 
     self.view.setPage(MyWebPage()) 
     self.view.page().formSubmitted.connect(self.handleFormSubmitted) 

    def viewPsyTML(self, html): 
     self.view.setHtml(html) 
     self.show() 

    def handleFormSubmitted(self, url): 
     elements = self.elements 
     self.close() 
     for key, value in url.encodedQueryItems(): 
      key = unquote_plus(bytes(key)).decode('utf8') 
      value = unquote_plus(bytes(value)).decode('utf8') 
      elements[key] = value 
     # do stuff with elements... 
     for item in elements.iteritems(): 
      print '"%s" = "%s"' % item 
     QtGui.qApp.quit() 


# setup the html form 
html = """ 
<form action="" method="get"> 
Like it? 
<input type="radio" name="like" value="yes"/> Yes 
<input type="radio" name="like" value="no" /> No 
<br/><input type="text" name="text" value="" /> 
<input type="submit" name="submit" value="Send"/> 
</form> 
""" 

html2 = """ 
<form action="" method="get"> 
Choose wisely? 
<input type="radio" name="choose" value="A"/> Yes 
<input type="radio" name="choose" value="B" /> No 
<br/><input type="text" name="text" value="" /> 
<input type="submit" name="submit" value="Send"/> 
</form> 
""" 

def main(): 
    app = QtGui.QApplication(sys.argv) 
    intro = PsyTML() 
    intro.viewPsyTML(html) 
    # now, the html form is displayed nicely and the form elemtns returned 
    app.exec_() 
    # do something else here 

    # in the secomd run, the form is not submitted. 
    intro.viewPsyTML(html2) 
    app.exec_() 



if __name__ == "__main__": 
    main() 

我workinh與Python 2

Answer 1

需要改變你的程序的現有結構。

首先，main函數應儘可能簡單。它應該只是創建一個應用程序對象和一個主窗口，然後運行事件循環。之後，每件事都應該圍繞着信號/事件和他們的處理程序。

目前，只有一箇中心事件：表單提交。發生異步，所以應用程序必須保存其當前狀態，然後等待被動完成每個表單，然後才能轉到下一個任務。

編輯

現在你的規範是清晰的，一個方式來實現你想要的是使用QDialog，它有自己的事件循環。

這是你的腳本的修訂版本，是希望能更接近你想要什麼：

import sys 
from urllib import unquote_plus 

from PyQt4 import QtCore, QtGui, QtWebKit 

class MyWebPage(QtWebKit.QWebPage): 
    formSubmitted = QtCore.pyqtSignal(object) 

    def acceptNavigationRequest(self, frame, req, nav_type): 
     if nav_type == QtWebKit.QWebPage.NavigationTypeFormSubmitted: 
      elements = {} 
      for key, value in req.url().encodedQueryItems(): 
       key = unquote_plus(bytes(key)).decode('utf8') 
       value = unquote_plus(bytes(value)).decode('utf8') 
       elements[key] = value 
      self.formSubmitted.emit(elements) 
     return super(MyWebPage, self).acceptNavigationRequest(frame, req, nav_type) 

class PsyTML(QtGui.QDialog): 
    def __init__(self): 
     super(PsyTML, self).__init__() 
     self.elements = {} 
     self.view = QtWebKit.QWebView(self) 
     layout = QtGui.QVBoxLayout(self) 
     layout.addWidget(self.view) 
     layout.setContentsMargins(0, 0, 0, 0) 
     self.view.setPage(MyWebPage()) 
     self.view.page().formSubmitted.connect(self.handleFormSubmitted) 

    def viewPsyTML(self, html): 
     self.view.setHtml(html) 
     self.exec_() 

    def handleFormSubmitted(self, elements): 
     self.elements = elements 
     self.accept() 

# setup the html form 
html = """ 
<form action="" method="get"> 
Like it? 
<input type="radio" name="like" value="yes"/> Yes 
<input type="radio" name="like" value="no" /> No 
<br/><input type="text" name="text" value="" /> 
<input type="submit" name="submit" value="Send"/> 
</form> 
""" 

html2 = """ 
<form action="" method="get"> 
Choose wisely? 
<input type="radio" name="choose" value="A"/> Yes 
<input type="radio" name="choose" value="B" /> No 
<br/><input type="text" name="text" value="" /> 
<input type="submit" name="submit" value="Send"/> 
</form> 
""" 

def main(): 
    app = QtGui.QApplication(sys.argv) 

    intro = PsyTML() 
    intro.viewPsyTML(html) 

    # do stuff with elements... 
    for item in intro.elements.iteritems(): 
     print '"%s" = "%s"' % item 

    intro = PsyTML() 
    intro.viewPsyTML(html2) 

if __name__ == "__main__": 
    main()