How to remove widget from the layout in PySide

I’d like to add close button to the single widget and remove the widget from the parent layout when the close button pressed.

GOAL

To remove single widget with close button as below.

Environment

Windows 10
Python 3.8.7
PySide2 5.15.2

Method

1. Create a widget with close button and set it in the layout

I create ItemWidget with close button and put the item and add button on the main window. Check “How To Insert Widget To The Layout Counting From The End” for detail about the implement of add button.

import sys
from PySide2.QtWidgets import *

class ItemWidget(QWidget):
    def __init__(self, id_str="", parent=None):
        super(ItemWidget, self).__init__(parent)
        self.id_str = id_str
        self._generateUI()
    def _generateUI(self):
        main_layout = QGridLayout()
        self.setLayout(main_layout)
        title = QLabel("title" + self.id_str)
        main_layout.addWidget(title, 0, 0, 1, 3)
        close_button = QPushButton("-")
        close_button.setFixedWidth(30)
        main_layout.addWidget(close_button, 0, 3, 1, 1)
        spinbox = QSpinBox()
        main_layout.addWidget(spinbox, 1, 0, 1, 4)

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self.id_num = 1
        self._generateUI()
    def _generateUI(self):
        main_widget = QWidget()
        self.main_layout = QVBoxLayout()
        main_widget.setLayout(self.main_layout)
        self.setCentralWidget(main_widget)
        item = ItemWidget(str(self.id_num))
        self.main_layout.addWidget(item)
        add_button = QPushButton("+")
        add_button.clicked.connect(self._addItem)
        self.main_layout.addWidget(add_button)
    def _addItem(self):
        self.id_num += 1
        item = ItemWidget(str(self.id_num))
        self.main_layout.insertWidget(self.main_layout.count()-1, item)

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    app.exec_()

launch()

2. Connect close function to the signal “clicked” of the close button

Use deleteLater() to delete widget.

class ItemWidget(QWidget):
    def __init__(self, id_str="", parent=None):
        super(ItemWidget, self).__init__(parent)
        self.id_str = id_str
        self._generateUI()
    def _generateUI(self):
        main_layout = QGridLayout()
        self.setLayout(main_layout)
        title = QLabel("title" + self.id_str)
        main_layout.addWidget(title, 0, 0, 1, 3)
        close_button = QPushButton("-")
        close_button.setFixedWidth(30)
        close_button.clicked.connect(self._close_widget) # add to close the widget
        main_layout.addWidget(close_button, 0, 3, 1, 1)
        spinbox = QSpinBox()
        main_layout.addWidget(spinbox, 1, 0, 1, 4)
    def _close_widget(self):
        self.deleteLater() # main function to close widget

* There are many ways to remove widget from the parent layout. For example, some people use setParent(None) or something. However don’t use removeWidget() because it just removes widget without destroying it. Please refer to the discussion below.

• Is deleteLater() necessary in PyQt/PySide? in stackoverflow.com
• pyqt: how to remove a widget? in stackoverflow.com

3. Resize the parent widget when the child removed

The function deleteLater() just delete the widget without changing the size. So I changed size manually with adjustSize() as below.
Related article: How to detect the child widget destroy?

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self.id_num = 1
        self._generateUI()
    def _generateUI(self):
        main_widget = QWidget()
        self.main_layout = QVBoxLayout()
        main_widget.setLayout(self.main_layout)
        self.setCentralWidget(main_widget)
        item = ItemWidget(str(self.id_num))
        self.main_layout.addWidget(item)
        add_button = QPushButton("+")
        add_button.clicked.connect(self._addItem)
        self.main_layout.addWidget(add_button)
    def _addItem(self):
        self.id_num += 1
        item = ItemWidget(str(self.id_num))
        self.main_layout.insertWidget(self.main_layout.count()-1, item)
    def _deletedItem(self, item):
        self.id_num -= 1
        for i in range(3):
            QApplication.processEvents()
        self.adjustSize()

I don’t know why but adjustSize() doesn’t work correctly until some events are processed in the event loop. So I called QApplication.processEvents() in the for loop. Please let me know if you have any idea about this

Reference: PySide: What is the best way to resize the main window if one widget is hidden? in stackoverflow.com

How to detect the child widget destroy?

GOAL

To do some functions when the child widget is deleted.

Environment

Windows 10
Python 3.8.7
PySide2 5.15.2

Method

Connect the function to child’s signal “destroyed” as below.

import sys
from PySide2.QtWidgets import *

class ItemWidget(QWidget):
    def __init__(self, id_str="", parent=None):
        super(ItemWidget, self).__init__(parent)
        self._generateUI()
    def _generateUI(self):
        main_layout = QGridLayout()
        self.setLayout(main_layout)
        title = QLabel("title")
        main_layout.addWidget(title, 0, 0, 1, 3)
        close_button = QPushButton("×")
        close_button.setFixedWidth(30)
        close_button.clicked.connect(self._close_widget)
        main_layout.addWidget(close_button, 0, 3, 1, 1)
    def _close_widget(self):
        self.deleteLater()

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self._generateUI()
    def _generateUI(self):
        main_widget = QWidget()
        self.main_layout = QVBoxLayout()
        main_widget.setLayout(self.main_layout)
        self.setCentralWidget(main_widget)
        item = ItemWidget(str(self.id_num))
        item.destroyed.connect(self._deletedItemFunc) # connect the function to execute
        self.main_layout.addWidget(item)
    def _deletedItemFunc(self):
        print("deleted") # when the item deleted, the message "deleted" is displayed

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    app.exec_()

launch()

When click × button, the child widget deleted and the message “deleted” is displayed.

Appendix

If the child is removed from the parent layout. You can add function at the same time.

self.main_layout.removeWIdget(item)
self._deletedItemFunc()

How To Insert Widget To The Layout Counting From The End

GOAL

To insert widget to the layout counting from the end. For example, I’d like to create the add button to add widget at the second position from the end as below.

How to select one column of QTreeWidgetItem in PySide2

GOAL

To allow users to select one column from the QTreeWidget as below. (If you’d like to know how to generate tree widget, check “How to use QTreeWidget() in PySide2” first.)

Environment

Windows 10
Python 3.8.7
PySide2 5.15.2

Method

Use SelectionBehavior.

How to change the default size of PySide window

GOAL

To change the default size that is initial size of the window in PySide2.

Environment

Windows 10
Python 3.8.7
PySide2 5.15.2

Method

I create a simple window as below.

import sys
from PySide2.QtWidgets import *

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self._generateUI()

    def _generateUI(self):
        main_widget = QWidget()
        main_layout = QVBoxLayout()
        main_widget.setLayout(main_layout)
        self.setCentralWidget(main_widget)
        button = QPushButton("Button")
        main_layout.addWidget(button)

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    app.exec_()

launch()

How to change the variable size

Use resize() function at first to change the default size.

from PySide2 import QtCore

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self._generateUI()
        self.resize(200, 300)

How to change the variable width and height

You can change only width or height of the window using height() or width() to get current size.

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    widget.resize(250, widget.height())

Because the window size is adjusted to the contents of the window, resize after showing the window.

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self._generateUI()
        print(self.width(), self.height())
        # output => 640 480

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    print(widget.width(), widget.height())
    # output => 200 100

Appendix

How to change the fixed size

Use setFixedSize() to fix the size of window. (You can’t resize the window after using this function.)

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self.setFixedSize(200, 300)
        self._generateUI()

How to change the fixed height and width.

Use setFixedWidth() and setFixedHeight(). If you use setFixedWidth(), you can still change the height of the window.

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self.setFixedWidth(250)
        self._generateUI()

How to use QTreeWidget() in PySide2

GOAL

To create tree widget in my GUI program with PySide2.

Environment

Windows 10
Python 3.8.7
PySide2 5.15.2

Related Classes

Reference: PySide.QtGui / Qt Widgets C++ Classes

• QTreeWidget: Tree view that uses a predefined tree model
• QTreeWidgetItem: Item for use with the QTreeWidget convenience class
• QTreeWidgetItemIterator: Way to iterate over the items in a QTreeWidget instance

Examples

I created sample window and 4 types of tree widgets and 2 functions. The below is the template.

import sys
from PySide2.QtWidgets import *

class MyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self._generateUI()
        #self._simple_tree_widget()
        self._tree_widget1()
        
    def _generateUI(self):
        main_widget = QWidget()
        main_layout = QVBoxLayout()
        main_widget.setLayout(main_layout)
        self.setCentralWidget(main_widget)
        self.tree_widget = QTreeWidget()
        main_layout.addWidget(self.tree_widget)
    def _tree_widget1(self):
        ...
    def _tree_widget2(self):
        ...

def launch():
    app = QApplication.instance()
    if not app:
        app = QApplication(sys.argv)
    widget = MyMainWindow()
    widget.show()
    app.exec_()

launch()

Example 1. Simple tree widget