删除 PyQt5 中的小部件时如何删除黑色空间

Question

I have a code to generate a GUI with PyQt5 that enables a user to create multiple buttons (QPushButton) based on an entry (QLineEdit), and to delete these buttons when pressing an "X" button (deleteLater()).

My problem is that when deleting some of these buttons by pressing the associated X-button, this leaves a small empty space where the buttons were initially, and I therefore wonder how to remove these spaces?

Image of the empty spaces

from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QLineEdit, QWidget, QVBoxLayout, QHBoxLayout, QGridLayout, QGroupBox, QScrollArea, QLabel
from PyQt5.QtCore import Qt
import sys


class MyWindow(QMainWindow):
    def __init__(self):
        super(MyWindow, self).__init__()
        self.setWindowTitle("My Program")
        self.setGeometry(100, 100, 1500, 1500)
        self.initUI()

    def initUI(self):
        widgets = MainWidgets()
        self.setCentralWidget(widgets)


class MainWidgets(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.grid = QGridLayout()
        self.grid.setColumnStretch(0, 1)
        self.grid.setColumnStretch(1, 1)
        self.grid.setColumnStretch(2, 1)
        self.grid.setColumnStretch(3, 1)
        self.grid.setColumnStretch(4, 1)

        self.groupBox = QGroupBox("Labels")
        self.groupBox.setStyleSheet('''
            QGroupBox::title {
                subcontrol-position: top center;
            }
        ''')

        right_column_layout = QVBoxLayout(self.groupBox)
        scrollArea = QScrollArea()
        scrollArea.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
        scrollArea.setWidgetResizable(True)
        right_column_layout.addWidget(scrollArea)
        scrollArea.setWidget(RightColWidgets())

        self.grid.addWidget(self.groupBox, 0, 5, 1, 5)
        self.setLayout(self.grid)


class RightColWidgets(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.layout = QVBoxLayout(self)

        self.labelEntry = QLineEdit(self)

        self.addLabelButton = QPushButton(self)
        self.addLabelButton.setText("Add Label")
        self.addLabelButton.clicked.connect(self.addNewLabel)

        self.emptyspace = QLabel(self)

        self.layout.addWidget(self.labelEntry, stretch=0)
        self.layout.addWidget(self.addLabelButton, stretch=0)
        self.layout.addWidget(self.emptyspace, stretch=1)

    def addNewLabel(self):
        labelname = self.labelEntry.text()
        newLabelItems = Labels(self, labelname)

        self.layout.insertWidget(2, newLabelItems)


class Labels(QWidget):
    def __init__(self, parent, labelname, *args, **kwargs):
        super().__init__(parent, *args, **kwargs)
        self.mylabelname = labelname
        self.initUI()

    def initUI(self):
        self.labelButton = QPushButton(self)
        self.labelButton.setText(str(self.mylabelname))
        self.labelButton.setStyleSheet("""
            QPushButton {border: 1px solid back; background: rgba(103, 186, 181, 0.5); padding-top: 10px; padding-bottom: 10px}
        """)
        self.labelButton.clicked.connect(self.printbutton)
        self.buttonErase = QPushButton(self)
        self.buttonErase.setText("X")
        self.buttonErase.setStyleSheet("""
            QPushButton {border: 1px solid back; padding-right: 5 px; padding-left: 5 px; padding-top: 10px; padding-bottom: 10px}
        """)
        self.buttonErase.clicked.connect(self.erasebutton)

        layout = QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.addWidget(self.labelButton, stretch=1)
        layout.addWidget(self.buttonErase, stretch=0)

    def printbutton(self):
        print('clicked:', self.labelButton.text())

    def erasebutton(self):
        self.labelButton.deleteLater()
        self.buttonErase.deleteLater()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    # app.setStyle('Fusion')
    window = MyWindow()
    window.showMaximized()
    sys.exit(app.exec_())

Answer 1

Deleting the children does not delete the container, so what you see is the empty Labels widget with the spacing of its layout contentsMargins() .

A simple solution could be to directly connect the button with its own deleteLeter() , which automatically deletes its children:

        self.buttonErase.clicked.connect(self.deleteLater)

A better solution would be to connect the signal to the parent and let it do everything necessary in a cleaner way, as you might need to keep track of the existing widgets (for instance, to remove them from the list of currently existing labels):

class RightColWidgets(QWidget):
    # ...

    def addNewLabel(self):
        labelname = self.labelEntry.text()
        newLabelItems = Labels(self, labelname)

        self.layout.insertWidget(2, newLabelItems)
        newLabelItems.buttonErase.clicked.connect(
            lambda: self.deleteLabel(newLabelItems))

    def deleteLabel(self, widget):
        self.layout.removeWidget(widget)
        widget.deleteLater()

Obviously, in this case you don't need to connect the clicked signal in the initUi of the Label class anymore.

Note that layout() is an existing (and dynamic ) property of any QWidget, so you should not overwrite it.