Overriding paintEvent in PyQt5 and PySide2
我使用PyQt和PySide已有一段时间了。今天，我偶然发现了一个奇怪的行为：重新实现paintEvent似乎在Qt5的Python版本中不起作用。我在Qt4中从未遇到过此问题。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | from PySide2 import QtWidgets, QtCore, QtGui # use pyside # from PyQt5 import QtWidgets, QtCore, QtGui # use pyqt import sys class TagWidget(QtWidgets.QWidget): def __init__(self, parent): super().__init__(parent) print("__init__") def paintEvent(self, e): # this is called or not # depends (see below) print("paintEvent") raise(AssertionError) class MyGui(QtWidgets.QMainWindow): def __init__(self,parent=None): super(MyGui, self).__init__() self.setupUi() def setupUi(self): self.setGeometry(QtCore.QRect(100,100,500,500)) self.w=QtWidgets.QWidget(self) self.setCentralWidget(self.w) self.lay = QtWidgets.QHBoxLayout(self.w) self.image = TagWidget(self.w) self.lay.addWidget(self.image) # return # exit here, and TagWidget.paintEvent # is still being called self.file_list = QtWidgets.QListWidget(self.w) # return # exit here, and TagWidget.paintEvent # is still being called self.lay.addWidget(self.file_list) # .. but if we reach all the way here, # TagWidget.paintEvent is never called ! def main(): app=QtWidgets.QApplication(["test_app"]) mg=MyGui() mg.show() app.exec_() if (__name__=="__main__"): main() |
因此，我们只是测试是否调用paintEvent(通过在调用它时引发AssertionError)。
一旦将另一个小部件添加到TagWidget所在的相同布局中，paintEvent将不再有效。
太奇怪了。感谢帮助。
如果需要重绘，则
因此解决方案是设置适当的
1 2 3 4 5 6 7 8 | class TagWidget(QtWidgets.QWidget): def paintEvent(self, e): print("paintEvent") raise(AssertionError) def sizeHint(self): print("default sizeHint:", super(TagWidget, self).sizeHint()) return QtCore.QSize(640, 480) |
我用