Basis for a general PyQT app

basicapp.py

import os
import sys
import ctypes
import traceback
import logging
log = logging.getLogger()

from QtBinding import QtCore, QtGui

def remove_window_context_help_button(qwindow):
        #http://stackoverflow.com/questions/81627/how-can-i-hide-delete-the-help-button-on-the-title-bar-of-a-qt-dialog
        icon = qwindow.windowIcon()
        flags = qwindow.windowFlags() & ~QtCore.Qt.WindowContextHelpButtonHint
        qwindow.setWindowFlags(flags)
        qwindow.setWindowIcon(icon)

class BasicQApplication(QtGui.QApplication):
    remove_input_hook = True
    def __init__(self, argv, install_excepthook=True):
        if len(argv) == 0:
            argv = ['']
        super(BasicQApplication, self).__init__(argv)
        self.setWindowIcon(self._loadIcon())
        if install_excepthook:
            sys.excepthook = self.on_unhandled_exception
    
    def get_toplevel_window(self, allow_hidden=True):
        top = self.activeWindow()
        if not top:
            others = []
            for w in self.topLevelWidgets():
                if not w.isHidden():
                    top = w
                    break
                if allow_hidden:
                    others.append(w)
            else:
                if others:
                    top = others[0]
                else:
                    top = None
        return top

    @QtCore.pyqtSlot(unicode, unicode, unicode, int)
    def _main_thread_msgbox(self, title, text, details, icon):
        top = self.get_toplevel_window()
        mb = QtGui.QMessageBox(icon, title, text, QtGui.QMessageBox.Ok, top)
        if details:
            mb.setDetailedText(details)
        mb.exec_()

    @QtCore.pyqtSlot(unicode, unicode, unicode, int)
    def _main_thread_msgbox_and_exit(self, title, text, details, icon):
        top = self.get_toplevel_window()
        mb = QtGui.QMessageBox(icon, title, text, QtGui.QMessageBox.Ok, top)
        if details:
            mb.setDetailedText(details)
        mb.exec_()
        self._main_thread_exit(1)
        
    @QtCore.pyqtSlot(int)
    def _main_thread_exit(self, exitcode):
        self.exit(exitcode)
        
    #Threadsafe
    def on_unhandled_exception(self, type, value, tb):
        msg = u"Unhandled Exception %s: %s"%(type.__name__, unicode(value))
        log.error(msg, exc_info=(type, value, tb))
        tbinfo = ''.join(traceback.format_exception(type, value, tb))
        sys.stderr.write(tbinfo + '\n')
        
        QtCore.QMetaObject.invokeMethod(self, "_main_thread_msgbox", QtCore.Qt.AutoConnection,
            QtCore.Q_ARG("QString", u"Unhandled Exception"),
            QtCore.Q_ARG("QString", u"An error has occured:\n\n%s: %s"%(type.__name__, unicode(value))),
            QtCore.Q_ARG("QString", tbinfo),
            QtCore.Q_ARG("int", QtGui.QMessageBox.Critical),
        )

    #Threadsafe
    def queue_exit(self, exitcode):
        QtCore.QMetaObject.invokeMethod(self, "_main_thread_exit", QtCore.Qt.AutoConnection,
            QtCore.Q_ARG("int", exitcode),
        )
        
    def _loadIcon(self):
        #TODO: Make this not depend on win32gui
        import win32gui
        icons = win32gui.ExtractIconEx(sys.executable, 0, 1)
        # should call win32gui.DestroyIcon on all the icons returned by ExtractIconEx
        info = win32gui.GetIconInfo(icons[0][0])
        pixmap = QtGui.QPixmap.fromWinHBITMAP(int(info[4]), 2)
        icon = QtGui.QIcon(pixmap)
        info[3].close()
        info[4].close()
        return icon

    def exec_(self):
        super(BasicQApplication, self).exec_()
        if self.remove_input_hook:
            QtCore.pyqtRemoveInputHook()

class DemoApp(BasicQApplication):
    def exit_me(self):
        print "Bye!"
        self.queue_exit(0)
        
    def exec_(self):
        print "DemoApp.exec()"
        QtCore.QTimer.singleShot(2000, self.exit_me)
        super(DemoApp, self).exec_()
        print "DemoApp.exec() complete"


if __name__ == '__main__':
    app = DemoApp(sys.argv)
    sys.exit(app.exec_())

This is a simple BasicQApplication class for Qt that does a number of handy things:

1. Installs a sys.excepthook that will pop up an error dialog parented to the current window
2. This excepthook works even from separate threads
3. Removes pyqt input hook so you can use pdb (from any thread)
4. Basic cross thread communicaton for showing errors