Cách dùng lớp QStatusBar trong PyQt để tạo thanh status bar

self.status_bar = self.statusBar()

showMessage(text, timeout=0)

addWidget(widget[, stretch=0])

addPermanentWidget(widget[, stretch=0])

import sys
from pathlib import Path
from PyQt6.QtWidgets import QApplication, QMainWindow, QTextEdit, QFileDialog, QMessageBox, QToolBar, QLabel
from PyQt6.QtGui import QIcon, QAction
from PyQt6.QtCore import QSize

class MainWindow(QMainWindow):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.setWindowIcon(QIcon('./assets/editor.png'))
        self.setGeometry(100, 100, 500, 300)

        self.title = 'Editor'
        self.filters = 'Text Files (*.txt)'
        self.set_title()
        self.path = None

        self.text_edit = QTextEdit(self)
        self.text_edit.textChanged.connect(self.text_changed)
        self.setCentralWidget(self.text_edit)

        menu_bar = self.menuBar()
        file_menu = menu_bar.addMenu('&File')
        edit_menu = menu_bar.addMenu('&Edit')
        help_menu = menu_bar.addMenu('&Help')

        # Tạo mục menu mới
        new_action = QAction(QIcon('./assets/new.png'), '&New', self)
        new_action.setStatusTip('Create a new document')
        new_action.setShortcut('Ctrl+N')
        new_action.triggered.connect(self.new_document)
        file_menu.addAction(new_action)

        open_action = QAction(QIcon('./assets/open.png'), '&Open...', self)
        open_action.triggered.connect(self.open_document)
        open_action.setStatusTip('Open a document')
        open_action.setShortcut('Ctrl+O')
        file_menu.addAction(open_action)

        save_action = QAction(QIcon('./assets/save.png'), '&Save', self)
        save_action.setStatusTip('Save the document')
        save_action.setShortcut('Ctrl+S')
        save_action.triggered.connect(self.save_document)
        file_menu.addAction(save_action)

        exit_action = QAction(QIcon('./assets/exit.png'), '&Exit', self)
        exit_action.setStatusTip('Exit')
        exit_action.setShortcut('Alt+F4')
        exit_action.triggered.connect(self.quit)
        file_menu.addAction(exit_action)

        # Toolbar
        toolbar = QToolBar('Main ToolBar')
        self.addToolBar(toolbar)
        toolbar.setIconSize(QSize(16, 16))

        toolbar.addAction(new_action)
        toolbar.addAction(save_action)
        toolbar.addAction(open_action)

        # Status bar
        self.status_bar = self.statusBar()

        # Hiển thị thông báo trong 5 giây
        self.status_bar.showMessage('Ready', 5000)

        # Thêm widget vĩnh viễn hiển thị số ký tự
        self.character_count = QLabel("Length: 0")
        self.status_bar.addPermanentWidget(self.character_count)

        self.show()

    def set_title(self, filename=None):
        title = f"{filename if filename else 'Untitled'} - {self.title}"
        self.setWindowTitle(title)

    def confirm_save(self):
        if not self.text_edit.document().isModified():
            return True

        message = f"Do you want to save changes to {self.path if self.path else 'Untitled'}?"
        MsgBoxBtn = QMessageBox.StandardButton
        MsgBoxBtn = MsgBoxBtn.Save | MsgBoxBtn.Discard | MsgBoxBtn.Cancel

        button = QMessageBox.question(self, self.title, message, buttons=MsgBoxBtn)

        if button == MsgBoxBtn.Cancel:
            return False

        if button == MsgBoxBtn.Save:
            self.save_document()

        return True

    def new_document(self):
        if self.confirm_save():
            self.text_edit.clear()
            self.set_title()

    def write_file(self):
        self.path.write_text(self.text_edit.toPlainText())
        self.statusBar().showMessage('The file has been saved...', 3000)

    def save_document(self):
        if self.path:
            return self.write_file()

        filename, _ = QFileDialog.getSaveFileName(self, 'Save File', filter=self.filters)
        if not filename:
            return

        self.path = Path(filename)
        self.write_file()
        self.set_title(filename)

    def open_document(self):
        filename, _ = QFileDialog.getOpenFileName(self, filter=self.filters)
        if filename:
            self.path = Path(filename)
            self.text_edit.setText(self.path.read_text())
            self.set_title(filename)

    def quit(self):
        if self.confirm_save():
            self.destroy()

    def text_changed(self):
        text = self.text_edit.toPlainText()
        self.character_count.setText(f'Length: {len(text)}')

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec())

self.status_bar = self.statusBar()

self.status_bar.showMessage('Ready', 5000)

self.character_count = QLabel("Length: 0")
self.status_bar.addPermanentWidget(self.character_count)

self.text_edit.textChanged.connect(self.text_changed)

self.statusBar().showMessage('The file has been saved...', 3000)