PyQt5：QLineEdit 正在大规模扩展并破坏我的网格布局

Question

Excuse the probably quite simple question, I'm very new to PyQt5 and am really struggling to understand how it works.

I'm trying to make a rough and ready options menu for my program, and as part of that, I'd like to add a few small text boxes for user inputs. I've been using a grid layout system to make things easier for myself, but it seems like the QLineEdit text boxes are trying to expand horizontally and squash everything else.

What my window looks like without the text box

What my window looks like with the text box

I've seen talk about using setHorizontalPolicy, but I don't understand the documentation (and trying to work it out by hand isn't working).

(Ideally, I'd want my window to look something like this:

_______________________________________________
|          [title         |      [title]      |
|                         |[label] [text box] |
|                         |[label] [text box] |
|      checkboxes         |[label] [text box] |
|                         |[label] [text box] |
|                         |                   |
|                         |                   |
|                         |  [some buttons]   |
|_________________________|___________________|

)

Here are the most relevant bits of my code if it helps.

class label_and_qle(QWidget):

def __init__(self, label):
    
    super().__init__()
    self.label = label
    self.initUI()

def initUI(self):
    
    grid = QGridLayout()
    self.setLayout(grid)

    qle = QLineEdit(self)
    qle_label = set_labels()  
    qle.setFixedWidth(80)
    qle_label.set_label_dynamic(self.label)
    # qle.textChanged[str].connect(self.change_options)
    
    grid.addWidget(qle_label, 0, 0, 1, 2)
    grid.addWidget(qle, 0, 2, 1, 1)

class misc_options_gui(QWidget):
    
def __init__(self):
    
    super().__init__()
    self.initUI()
    
def initUI(self):
    
    grid = QGridLayout()
    self.setLayout(grid)
    
    #Set the section title
    lab_title = set_labels()
    lab_title.set_label_title(data_options.misc_options_title)
    grid.addWidget(lab_title, 0, 0)
    
    error_tol = label_and_qle("Error tolerance", data_options.error_tolerance)
    grid.addWidget(error_tol, 5, 0)
    
    #Creat a button to set Folder destination
    set_path =  QPushButton('set folder', self)
    set_path.clicked.connect(self.get_folder)
    grid.addWidget(set_path, 12, 0)
    
    #Create button to launch iMMPY program
    run_button = QPushButton('Run iMMPY script', self)
    run_button.clicked.connect(self.run_iMMPY)
    grid.addWidget(run_button, 14, 0)

def run_iMMPY(self):
    
    if data_options.path == []:
        self.get_folder()
    
    self.showMinimized()
    run_iMMPY()
    self.close()
    
def get_folder(self):
    
    folder = QFileDialog.getExistingDirectory(parent = None, caption = "Select folder")
    data_options.path = folder

class Example(QMainWindow):
'''
This object is the main window of the options menu
'''

def __init__(self):
    
    super().__init__()
    self.initUI()
 
def initUI(self):
    '''
    Initialise main window's UI
    '''
    
    #Create central widget
    self.central_widget = QWidget()               
    self.setCentralWidget(self.central_widget) 
    
    #Define grid layout
    self.grid = QGridLayout()
    self.centralWidget().setLayout(self.grid)
    
    checkboxes = checkboxes_gui(data_options.checkboxes_title, data_options.names_list, data_options.defaults_list)

    misc_options = misc_options_gui()
    

    
    self.grid.addWidget(checkboxes, 0, 0, 1, 3)
    self.grid.addWidget(misc_options, 0, 3, 1, 1)
    checkboxes.resize(500, 750)
    misc_options.resize(250, 750)
    
    #Set window properties
    self.setGeometry(600, 200, 750, 750)
    self.setWindowTitle('Options menu')
    self.show()

Thanks for any help you can give

Answer 1

The expanding labels are a bit confusing using Qt. I've dealt with layout issues a lot. A couple things you could try. It looks like your label that reads "Error tolerance" is causing the issue. It is expanding horizontally more than you would like it seems. If you are using Qt Designer to design the GUI, you can change the "Horizontal Policy" to "Maximum" in the Property editor. This seems counter intuitive but Maximum will make your label expand only as much as the space that the text actually takes up. To do this without Qt Designer and just using code, I think this might work:

    sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Maximum, QtWidgets.QSizePolicy.Preferred)
    self.label.setSizePolicy(sizePolicy)

replace 'label' with the label Widget that you want to modify.