小部件在添加到佈局時沒有獲得適當的大小

Question

當它動態添加到佈局時，我需要獲取小部件的真實寬度（），因爲我需要根據小部件的寬度對小部件進行繪製（ ）。但是下面的代碼不能像我預期的那樣工作：w.width（）總是640，這顯然不是真正的寬度。 有什麼想法？

# -*- coding: utf-8 -*- 
import os, sys 
from PyQt4 import QtGui, QtCore 
from PyQt4.QtGui import * 
from PyQt4.QtCore import * 

class MainWidget(QWidget): 
    def __init__(self, parent=None): 
     super(MainWidget, self).__init__(parent) 

     self.setupUI() 

    def setupUI(self): 
     self.mainLayout = QVBoxLayout(self) 

class MyWidget(QWidget): 
    def __init__(self, parent=None): 
     super(MyWidget, self).__init__(parent) 

     layout = QVBoxLayout(self) 
     layout.addWidget(QLabel('label')) 

    def minimunSizeHint(self): 
     return QSize(30, 30) 

    def sizeHint(self): 
     return QSize(100, 100) 

if __name__ == '__main__': 
    app = QtGui.QApplication(sys.argv) 
    main = MainWidget() 
    main.show() 

    l = QGridLayout() 
    l.addWidget(MyWidget(), 0, 0) 
    l.addWidget(MyWidget(), 0, 1) 
    l.addWidget(MyWidget(), 1, 0) 
    l.addWidget(MyWidget(), 1, 1) 
    main.mainLayout.addLayout(l) 

    w = l.itemAtPosition(0, 0).widget() 
    print w.width(), w.height() 


    sys.exit(app.exec_()) 

Answer 1

只需重新實現resizeEvent（）並在大小更改時重新繪製。

# -*- coding: utf-8 -*- 
import os, sys 
from PyQt4 import QtGui, QtCore 
from PyQt4.QtGui import * 
from PyQt4.QtCore import * 

class MainWidget(QWidget): 
    def __init__(self, parent=None): 
     super(MainWidget, self).__init__(parent) 

     self.setupUI() 

    def setupUI(self): 
     self.mainLayout = QVBoxLayout(self) 

class MyWidget(QWidget): 
    def __init__(self, parent=None): 
     super(MyWidget, self).__init__(parent) 

     layout = QVBoxLayout(self) 
     layout.addWidget(QLabel('label')) 

    def minimunSizeHint(self): 
     return QSize(30, 30) 

    def sizeHint(self): 
     return QSize(100, 100) 

    def resizeEvent(self, event): 
     print self.width(), self.height() 
     # call painting here 

if __name__ == '__main__': 
    app = QtGui.QApplication(sys.argv) 
    main = MainWidget() 
    main.show() 

    l = QGridLayout() 
    l.addWidget(MyWidget(), 0, 0) 
    l.addWidget(MyWidget(), 0, 1) 
    l.addWidget(MyWidget(), 1, 0) 
    l.addWidget(MyWidget(), 1, 1) 
    main.mainLayout.addLayout(l) 

    w = l.itemAtPosition(0, 0).widget() 

    sys.exit(app.exec_())