PyQt5按钮布局与菜单功能异常问题求助

Hey there! Let's break down and fix the two issues you're facing with PyQt5 one by one.

1. Button Size & Position Problems #

What's Going Wrong? #

• When using a layout like QGridLayout, the layout takes full control of your widget's size and position. Calls to resize(), setGeometry(), or even adjustSize() will be ignored because the layout overrides these settings.
• Your addWidget call has invalid parameters: layout.addWidget(Import_Deck, 0, 0, 0, -100). The last two arguments are row span and column span—using 0 or negative values breaks the layout's calculation logic.

Fix Steps #

• Use setFixedSize() instead of resize() to lock the button to your desired dimensions (this tells the layout to respect the size).
• Pass valid span values to addWidget. For example, if you want the button to span multiple columns in row 0, use something like 1, 3 (1 row span, 3 column span).

2. Menu Display & AttributeError Issues #

What's Going Wrong? #

• AttributeError: QWidget doesn't have a menuBar() method—this is a built-in feature of QMainWindow, which is designed for standard window layouts with menus, toolbars, etc.
• QToolButton Menu Not Showing: The code snippet you provided doesn't create a QMenu object before calling setMenu(menu)—you need to define the menu and add items to it first.

Fix Steps #

• Change your Window class to inherit from QMainWindow instead of QWidget. This gives you access to menuBar() and proper menu handling.
• Create a QMenu instance, add menu items to it, then attach it to your QToolButton.

Full Fixed Code #

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

class Window(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.setGeometry(0, 0, 2000, 992)
        self.setWindowTitle("MTGCalc")
        
        # Create central widget and layout (required for QMainWindow)
        central_widget = QWidget()
        self.setCentralWidget(central_widget)
        layout = QGridLayout(central_widget)
        
        # Fixed-size Import Deck button
        Import_Deck = QPushButton("Import Deck", self)
        Import_Deck.setFixedSize(150, 50)  # Lock size instead of resize
        layout.addWidget(Import_Deck, 0, 0, 1, 2)  # Valid row/column span
        
        # Add QToolButton with working menu
        formatslider = QToolButton()
        formatslider.setText("Formats")
        
        # Create menu and add items
        menu = QMenu()
        menu.addAction("Standard")
        menu.addAction("Modern")
        menu.addAction("Commander")
        
        formatslider.setMenu(menu)
        formatslider.setPopupMode(QToolButton.MenuButtonPopup)
        layout.addWidget(formatslider, 0, 2)  # Place in column 2
        
        self.mainmenufunc()

    def mainmenufunc(self):
        # Now menuBar() works since we inherit QMainWindow
        mainMenu = self.menuBar()
        fileMenu = mainMenu.addMenu('Decklist')
        editMenu = mainMenu.addMenu('Probability')
        viewMenu = mainMenu.addMenu('Recommended Mana')

app = QApplication(sys.argv)
screen = Window()
screen.show()
sys.exit(app.exec_())

Key Changes Explained #

• Switched from QWidget to QMainWindow and added a central widget (required for QMainWindow to hold layouts).
• Used setFixedSize() for the Import button to enforce dimensions.
• Fixed the addWidget span parameters to valid values.
• Created a proper QMenu with items for the QToolButton.
• Removed redundant imports and the invalid _main_() call at the end.

内容的提问来源于stack exchange，提问作者zettai