QWidget:必须在 QPaintDevice 之前构造一个 QApplication [英] QWidget: Must construct a QApplication before a QPaintDevice

问题描述

首先，出于兼容性原因，我使用 Windows 7-64 位和 PyQwt5.2.0、PyQt4.5.4、NumPy1.3.0、python2.6.2 32 位.

First, I use Windows 7-64 bit with PyQwt5.2.0, PyQt4.5.4, NumPy1.3.0, python2.6.2 32-bit for compatibility reasons.

在运行我的脚本时出现:

While runnning my script this appears:

QWidget: Must construct a QApplication before a QPaintDevice

在网上冲浪，寻找修复它的方法，我发现 QWidget 继承了 QObject 和 QPaintDevice(它是继承的，再见几乎我使用的每个对象)，并且 QMainWindow 继承了 QWidget.我还了解到某些静态函数正在尝试使用某个类，但我不太明白这意味着什么.

Surfing the net, looking for some way to fix it, I got that QWidget inherits QObject and QPaintDevice (and it is inherited bye almost every object I use), and QMainWindow inherits QWidget. I also got that some static function is trying to use some class, but I do not really understand what it means.

如果有人能解释一下，我将不胜感激.

If someone could please explain this, I would really appreciate it.

PS:如有翻译错误，请见谅.

PS: Sorry for any translation mistakes.

推荐答案

从代码来看，错误是由于第 102 行.在那里，在加载模块时，您创建了一个 QWidget(更多正好是一个 QMainWindow).这发生在之前QApplication被创建.

From the code, the error is due to line 102. There, while the module is loaded, you create a QWidget (more precisely a QMainWindow). And this happens before the QApplication is created.

另外，我不知道为什么你在那里有这个起始变量，因为它似乎没有被使用.

Also, I don't know why you have this start variable there, as it doesn't seem to be used.

如果要使用 HelloBegin 对象创建它，请将其移动到 __init__ 方法中.

If you want to create it with the HelloBegin object, move it in the __init__ method.

如果您想在加载模块时显示启动画面，您需要由一个小型轻量级模块启动应用程序.在本模块中，您将:

If you want to display a splash screen while your modules are loading, you need the application to be started by a small, lightweight, module. In this module, you will:

1. 创建 QApplication
2. 打开启动画面/消息框
3. 然后才加载其他模块

为了一切顺利，我会在一个单独的函数中导入模块，并使用一个小技巧来确保它只在 GUI 准备好后才启动.代码将如下所示:

For everything to work smoothly, I would import the modules in a separate function, and use a small trick to make sure it's started only once the GUI is ready. The code will look like this:

from PyQt4.QtGui import QApplication
from PyQt4.QtCore import QTimer
def startApp():
    import m1
    import m2
    wnd = createWindow()
    wnd.show()
import sys
app = QApplication(sys.argv)
splash = createSplashScreen()
splash.show()
QTimer.singleShot(1, startApp) # call startApp only after the GUI is ready
sys.exit(app.exec_())

其中 createSplashScreen 是创建启动画面的函数

where createSplashScreen is the function that creates your splash screen

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