PyQT4：为什么当setVisible（false）时QDialog从exec_（）返回

Question

我正在使用 Python 2.7 和 PyQT4。

我想隐藏一个模态 QDialog 实例，然后再显示它。然而，当 dialog.setVisible(false) 被调用（例如，使用 QTimer）时，dialog.exec_() 调用返回（带有 QDialog.Rejected 返回值）。

然而，根据http://pyqt.sourceforge.net/Docs/PyQt4/qdialog.html#exec，_exec() 调用应该阻塞，直到用户关闭对话框。

有没有办法在不返回 _exec() 的情况下隐藏对话框？

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
import os
from PyQt4 import QtGui, QtCore


class MyDialog(QtGui.QDialog):
    def __init__(self, parent):
        QtGui.QDialog.__init__(self, parent)

    def closeEvent(self, QCloseEvent):
        print "Close Event"

    def hideEvent(self, QHideEvent):
        print "Hide Event"


class MyWindow(QtGui.QMainWindow):
    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.setWindowTitle("Main Window")
        button = QtGui.QPushButton("Press me", self)
        button.clicked.connect(self.run_dialog)

    def run_dialog(self):
        self.dialog = MyDialog(self)
        self.dialog.setModal(True)
        self.dialog.show()
        QtCore.QTimer.singleShot(1000, self.hide_dialog)
        status = self.dialog.exec_()
        print "Dialog exited with status {}".format(status), "::", QtGui.QDialog.Accepted, QtGui.QDialog.Rejected

    def hide_dialog(self):
        self.dialog.setVisible(False)
        # self.dialog.setHidden(True)


if __name__ == '__main__':
    app = QtGui.QApplication([])
    w = MyWindow()
    w.show()
    sys.exit(app.exec_())

PS1：此代码打印以下输出：

Hide Event
Dialog exited with status 0 :: 1 0

（不调用关闭事件）。

PS2：对于上下文，我正在尝试实现一个 SystemTrayIcon，它允许隐藏和恢复 QMainWindow（这部分很好）和可能的模式 QDialog，而无需关闭对话框。

谢谢！

Answer 1

您可以通过调用基类方法来绕过QDialog.setVisible（隐式关闭对话框）的正常行为：

    def hide_dialog(self):
        # self.dialog.setVisible(False)
        QtGui.QWidget.setVisible(self.dialog, False)

但是，最好连接到对话框的finished() 信号，而不是使用exec()，并在其closeEvent 中明确地reject() 对话框。

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
import os
from PyQt4 import QtGui, QtCore

class MyDialog(QtGui.QDialog):
    def __init__(self, parent):
        QtGui.QDialog.__init__(self, parent)
        layout = QtGui.QHBoxLayout(self)
        for title, slot in ('Ok', self.accept), ('Cancel', self.reject):
            button = QtGui.QPushButton(title)
            button.clicked.connect(slot)
            layout.addWidget(button)

    def closeEvent(self, QCloseEvent):
        print "Close Event"
        self.reject()

    def hideEvent(self, QHideEvent):
        print "Hide Event"

class MyWindow(QtGui.QMainWindow):
    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        self.setWindowTitle("Main Window")
        button = QtGui.QPushButton("Press me", self)
        button.clicked.connect(self.run_dialog)

    def run_dialog(self):
        self.dialog = MyDialog(self)
        self.dialog.finished.connect(self.dialog_finished)
        self.dialog.setModal(True)
        self.dialog.show()
        QtCore.QTimer.singleShot(3000, self.dialog.hide)

    def dialog_finished(self, status):
        print "Dialog exited with status:", status

if __name__ == '__main__':

    app = QtGui.QApplication([])
    w = MyWindow()
    w.show()
    sys.exit(app.exec_())

Answer 2

如果有人感兴趣，下面的代码为我提供了一种快速而简单的方法来规避问题，尽管它并不能真正回答问题。

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Extension of the QDialog class so that exec_() does not exit when hidden.

Dialogs inheriting will only exit exec_() via close(), reject() or accept()
"""

from PyQt4 import QtGui, QtCore
from PyQt4.QtGui import *
from PyQt4.QtCore import *

class HideableQDialog(QDialog):
    def __init__(self, *args, **kwargs):
        super(HideableQDialog, self).__init__(*args, **kwargs)
        self._mutex = QMutex()
        self._is_finished = False
        self._finished_condition = QWaitCondition()
        self.finished.connect(self._finish_dialog)

    def _finish_dialog(self):
        self._is_finished = True
        self._finished_condition.wakeOne()

    def close(self):
        super(HideableQDialog, self).close()
        self._finish_dialog()

    def reject(self):
        super(HideableQDialog, self).reject()
        self._finish_dialog()

    def accept(self):
        super(HideableQDialog, self).accept()
        self._finish_dialog()

    def exec_(self):
        status = super(HideableQDialog, self).exec_()
        self._mutex.lock()
        condition_succedeed = False
        while not condition_succedeed and not self._is_finished:
            condition_succedeed = self._finished_condition.wait(self._mutex, 10)
            QApplication.processEvents()
        self._mutex.unlock()