如何在 PyQt5 中正確使用 setRowStretch

Question

我正在嘗試使用setRowStretch在QGridLayout內垂直拉伸我的按鈕行，但由於某些原因它不想工作。 然而，有趣的是， setColumnStretch對我有用。 我正在學習使用 PyQt5，所以可能有些東西我還不知道。 請參閱附件以獲取我的應用程序的屏幕截圖。 請幫忙。

import PyQt5.QtWidgets as qtw
import PyQt5.QtGui as qtg
import PyQt5.QtCore as qtcore

class MainWindow(qtw.QWidget):
    def __init__(self):
        super().__init__()
            # Add a title
        self.setWindowTitle('Calculator - Anh Nguyen')
        
        
        # Create a label
        my_label = qtw.QLabel("0")
        # Set background color
        my_label.setStyleSheet("background-color: #e3e1da;\
                                border: 1px solid black")
        
        my_label.setMaximumHeight(50)
        
        # Align label text
        my_label.setAlignment(qtcore.Qt.AlignmentFlag.AlignVCenter | qtcore.Qt.AlignmentFlag.AlignRight)        
        
        my_label.setFont(qtg.QFont('Helvetica', 20))
        
        # Add grid layout for calculator buttons
        main_gridlayout = qtw.QGridLayout()
        
        main_gridlayout.addWidget(my_label, 0, 0, 1, 4)
        main_gridlayout.addWidget(qtw.QPushButton('%'), 1, 0)
        main_gridlayout.addWidget(qtw.QPushButton('CE'), 1, 1)
        main_gridlayout.addWidget(qtw.QPushButton('C'), 1, 2)
        main_gridlayout.addWidget(qtw.QPushButton('BKSP'), 1, 3)
        main_gridlayout.addWidget(qtw.QPushButton('7'), 2, 0)
        main_gridlayout.addWidget(qtw.QPushButton('8'), 2, 1)
        main_gridlayout.addWidget(qtw.QPushButton('9'), 2, 2)
        main_gridlayout.addWidget(qtw.QPushButton('/'), 2, 3)
        main_gridlayout.addWidget(qtw.QPushButton('4'), 3, 0)
        main_gridlayout.addWidget(qtw.QPushButton('5'), 3, 1)
        main_gridlayout.addWidget(qtw.QPushButton('6'), 3, 2)
        main_gridlayout.addWidget(qtw.QPushButton('-'), 3, 3)
        main_gridlayout.addWidget(qtw.QPushButton('1'), 4, 0)
        main_gridlayout.addWidget(qtw.QPushButton('2'), 4, 1)
        main_gridlayout.addWidget(qtw.QPushButton('3'), 4, 2)
        main_gridlayout.addWidget(qtw.QPushButton('+'), 4, 3)
        main_gridlayout.addWidget(qtw.QPushButton('+/-'), 5, 0)
        main_gridlayout.addWidget(qtw.QPushButton('0'), 5, 1)
        main_gridlayout.addWidget(qtw.QPushButton('.'), 5, 2)
        main_gridlayout.addWidget(qtw.QPushButton('='), 5, 3)
        
        # This is NOT working:
        main_gridlayout.setRowStretch(1,1)
        
        # This is working
        main_gridlayout.setColumnStretch(2,1)
        
        
        
        self.setLayout(main_gridlayout)
        
        self.show()
        
app = qtw.QApplication([])
mw = MainWindow()

app.exec_()

在此處輸入圖像描述

Answer 1

QPushButtons 大小策略默認設置為占用盡可能多的水平空間。 如果您希望在垂直方向上也是如此，那么您將需要調整按鈕大小策略。

例如

btn = qtw.QPushButton('%')
policy = btn.sizePolicy()
policy.setVerticalPolicy(policy.Policy.Minimum)  # minimum means grow 
                                                 # dont ask me why
btn.setSizePolicy(Policy)

看到你有這么多按鈕，雖然我建議子類化 QPushButton 並在__init__中設置默認值，而不是在每個單獨的按鈕上設置策略。

class Button(qtw.QPushButton):

   def __init__(self, text, parent=None):
       super().__init__(text, parent=parent)
       policy = self.sizePolicy()
       policy.setVerticalPolicy(policy.Policy.Minimum)
       self.setSizePolicy(policy)

然后在主窗口中創建按鈕時

btn = Button("%")