第21章 PyQt GUI开发

学习目标

完成本章学习后，读者应能够：

理解Qt框架架构：掌握Qt对象模型、事件循环与父子对象树
精通信号与槽机制：理解Qt的核心通信模式，实现自定义信号与跨线程通信
掌握布局与样式：灵活运用布局管理器与QSS样式表构建专业级界面
实现MVC架构：使用Model/View架构处理数据展示
掌握多文档界面：实现MDI、SDI与停靠窗口
运用多线程：使用QThread与QThreadPool构建响应式GUI
集成Qt Designer：通过UI文件与资源系统加速开发

21.1 Qt框架基础

21.1.1 Qt对象模型

Qt框架的核心是QObject对象模型，提供对象树、信号槽和事件过滤等机制：

┌─────────────────────────────────────────┐
│              QApplication                │
│  ┌─────────────────────────────────┐    │
│  │         QMainWindow             │    │
│  │  ┌──────────┐ ┌──────────────┐  │    │
│  │  │ QMenuBar │ │  QToolBar    │  │    │
│  │  └──────────┘ └──────────────┘  │    │
│  │  ┌────────────────────────────┐ │    │
│  │  │    QWidget (central)       │ │    │
│  │  │  ┌──────┐ ┌─────────────┐ │ │    │
│  │  │  │Label │ │  LineEdit   │ │ │    │
│  │  │  └──────┘ └─────────────┘ │ │    │
│  │  └────────────────────────────┘ │    │
│  │  ┌────────────────────────────┐ │    │
│  │  │      QStatusBar            │ │    │
│  │  └────────────────────────────┘ │    │
│  └─────────────────────────────────┘    │
└─────────────────────────────────────────┘

21.1.2 应用程序架构

python

import sys
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QWidget, QVBoxLayout,
    QLabel, QPushButton, QStatusBar, QMenuBar,
)
from PyQt6.QtCore import Qt, QSize
from PyQt6.QtGui import QAction, QIcon


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("PyQt6 应用程序")
        self.setMinimumSize(QSize(800, 600))

        self._init_menubar()
        self._init_toolbar()
        self._init_central_widget()
        self._init_statusbar()

    def _init_menubar(self):
        file_menu = self.menuBar().addMenu("文件(&F)")

        new_action = QAction("新建(&N)", self)
        new_action.setShortcut("Ctrl+N")
        new_action.setStatusTip("新建文件")
        new_action.triggered.connect(self.on_new)
        file_menu.addAction(new_action)

        open_action = QAction("打开(&O)", self)
        open_action.setShortcut("Ctrl+O")
        open_action.triggered.connect(self.on_open)
        file_menu.addAction(open_action)

        file_menu.addSeparator()

        exit_action = QAction("退出(&Q)", self)
        exit_action.setShortcut("Ctrl+Q")
        exit_action.triggered.connect(self.close)
        file_menu.addAction(exit_action)

    def _init_toolbar(self):
        toolbar = self.addToolBar("主工具栏")
        toolbar.setMovable(False)

        new_btn = QAction("新建", self)
        new_btn.triggered.connect(self.on_new)
        toolbar.addAction(new_btn)

        open_btn = QAction("打开", self)
        open_btn.triggered.connect(self.on_open)
        toolbar.addAction(open_btn)

    def _init_central_widget(self):
        central = QWidget()
        self.setCentralWidget(central)

        layout = QVBoxLayout(central)
        layout.setContentsMargins(20, 20, 20, 20)
        layout.setSpacing(15)

        label = QLabel("欢迎使用 PyQt6")
        label.setAlignment(Qt.AlignmentFlag.AlignCenter)
        label.setStyleSheet("font-size: 24px; font-weight: bold;")
        layout.addWidget(label)

        btn = QPushButton("开始使用")
        btn.setFixedSize(200, 45)
        btn.clicked.connect(self.on_start)
        layout.addWidget(btn, alignment=Qt.AlignmentFlag.AlignCenter)

    def _init_statusbar(self):
        self.statusBar().showMessage("就绪")

    def on_new(self):
        self.statusBar().showMessage("新建文件", 3000)

    def on_open(self):
        self.statusBar().showMessage("打开文件", 3000)

    def on_start(self):
        self.statusBar().showMessage("欢迎使用！", 3000)


def main():
    app = QApplication(sys.argv)
    app.setStyle("Fusion")

    window = MainWindow()
    window.show()
    sys.exit(app.exec())


if __name__ == "__main__":
    main()

21.2 信号与槽机制

21.2.1 信号槽原理

信号与槽（Signals and Slots）是Qt的核心通信机制，实现了对象间的松耦合通信：

发送者（Sender）          接收者（Receiver）
┌──────────┐            ┌──────────┐
│          │  信号(Signal)│          │
│  Button  │───────────▶│  Handler │
│          │            │          │
└──────────┘            └──────────┘
     │                       ▲
     │    clicked            │  on_click()
     └───────────────────────┘

python

from PyQt6.QtCore import QObject, pyqtSignal, pyqtSlot
from PyQt6.QtWidgets import QApplication, QMainWindow, QWidget, QVBoxLayout, QPushButton, QLabel


class DataModel(QObject):
    data_changed = pyqtSignal(str)
    progress_updated = pyqtSignal(int)
    error_occurred = pyqtSignal(str)

    def __init__(self):
        super().__init__()
        self._data = ""

    def update_data(self, new_data: str):
        self._data = new_data
        self.data_changed.emit(new_data)

    def set_progress(self, value: int):
        self.progress_updated.emit(value)

    def report_error(self, message: str):
        self.error_occurred.emit(message)


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("信号与槽演示")
        self.setGeometry(100, 100, 500, 300)

        self.model = DataModel()
        self.model.data_changed.connect(self.on_data_changed)
        self.model.progress_updated.connect(self.on_progress)
        self.model.error_occurred.connect(self.on_error)

        central = QWidget()
        self.setCentralWidget(central)
        layout = QVBoxLayout(central)

        self.info_label = QLabel("等待操作...")
        layout.addWidget(self.info_label)

        self.progress_label = QLabel("进度: 0%")
        layout.addWidget(self.progress_label)

        btn1 = QPushButton("更新数据")
        btn1.clicked.connect(lambda: self.model.update_data("新数据内容"))
        layout.addWidget(btn1)

        btn2 = QPushButton("更新进度")
        btn2.clicked.connect(lambda: self.model.set_progress(75))
        layout.addWidget(btn2)

        btn3 = QPushButton("触发错误")
        btn3.clicked.connect(lambda: self.model.report_error("操作失败"))
        layout.addWidget(btn3)

    @pyqtSlot(str)
    def on_data_changed(self, data: str):
        self.info_label.setText(f"数据已更新: {data}")

    @pyqtSlot(int)
    def on_progress(self, value: int):
        self.progress_label.setText(f"进度: {value}%")

    @pyqtSlot(str)
    def on_error(self, message: str):
        self.info_label.setText(f"错误: {message}")
        self.info_label.setStyleSheet("color: red;")


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

21.2.2 自定义信号与跨对象通信

python

from PyQt6.QtCore import QObject, pyqtSignal
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QWidget, QVBoxLayout,
    QHBoxLayout, QPushButton, QLineEdit, QTextEdit, QLabel,
)


class LoginService(QObject):
    login_success = pyqtSignal(str)
    login_failed = pyqtSignal(str)

    def login(self, username: str, password: str):
        if username == "admin" and password == "123456":
            self.login_success.emit(username)
        else:
            self.login_failed.emit("用户名或密码错误")


class LoginWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("用户登录")
        self.setFixedSize(400, 250)

        self.service = LoginService()
        self.service.login_success.connect(self.on_login_success)
        self.service.login_failed.connect(self.on_login_failed)

        central = QWidget()
        self.setCentralWidget(central)
        layout = QVBoxLayout(central)
        layout.setSpacing(15)

        layout.addWidget(QLabel("用户登录系统"))

        self.username_input = QLineEdit()
        self.username_input.setPlaceholderText("请输入用户名")
        layout.addWidget(self.username_input)

        self.password_input = QLineEdit()
        self.password_input.setPlaceholderText("请输入密码")
        self.password_input.setEchoMode(QLineEdit.EchoMode.Password)
        layout.addWidget(self.password_input)

        self.message_label = QLabel("")
        layout.addWidget(self.message_label)

        btn_layout = QHBoxLayout()
        login_btn = QPushButton("登录")
        login_btn.clicked.connect(self.attempt_login)
        btn_layout.addWidget(login_btn)

        cancel_btn = QPushButton("取消")
        cancel_btn.clicked.connect(self.close)
        btn_layout.addWidget(cancel_btn)
        layout.addLayout(btn_layout)

        self.username_input.returnPressed.connect(self.attempt_login)
        self.password_input.returnPressed.connect(self.attempt_login)

    def attempt_login(self):
        username = self.username_input.text().strip()
        password = self.password_input.text().strip()
        if not username or not password:
            self.message_label.setText("请输入用户名和密码")
            self.message_label.setStyleSheet("color: orange;")
            return
        self.service.login(username, password)

    def on_login_success(self, username: str):
        self.message_label.setText(f"欢迎, {username}!")
        self.message_label.setStyleSheet("color: green;")

    def on_login_failed(self, reason: str):
        self.message_label.setText(reason)
        self.message_label.setStyleSheet("color: red;")


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = LoginWindow()
    window.show()
    sys.exit(app.exec())

21.3 布局与样式

21.3.1 布局管理器

python

from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QWidget, QVBoxLayout, QHBoxLayout,
    QGridLayout, QFormLayout, QGroupBox, QLabel, QLineEdit,
    QPushButton, QSplitter, QTextEdit, QFrame,
)
from PyQt6.QtCore import Qt


class LayoutDemo(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("布局演示")
        self.setGeometry(100, 100, 900, 600)

        central = QWidget()
        self.setCentralWidget(central)
        main_layout = QHBoxLayout(central)

        left_panel = self._create_form_panel()
        main_layout.addWidget(left_panel)

        splitter = QSplitter(Qt.Orientation.Horizontal)
        splitter.addWidget(self._create_editor())
        splitter.addWidget(self._create_preview())
        splitter.setStretchFactor(0, 2)
        splitter.setStretchFactor(1, 1)
        main_layout.addWidget(splitter, stretch=1)

    def _create_form_panel(self) -> QGroupBox:
        group = QGroupBox("表单")
        form_layout = QFormLayout(group)
        form_layout.setSpacing(10)

        form_layout.addRow("姓名:", QLineEdit())
        form_layout.addRow("邮箱:", QLineEdit())

        btn_layout = QHBoxLayout()
        btn_layout.addWidget(QPushButton("提交"))
        btn_layout.addWidget(QPushButton("重置"))
        form_layout.addRow(btn_layout)

        group.setFixedWidth(250)
        return group

    def _create_editor(self) -> QWidget:
        widget = QWidget()
        layout = QVBoxLayout(widget)

        toolbar = QHBoxLayout()
        toolbar.addWidget(QPushButton("B"))
        toolbar.addWidget(QPushButton("I"))
        toolbar.addWidget(QPushButton("U"))
        toolbar.addStretch()
        layout.addLayout(toolbar)

        editor = QTextEdit()
        editor.setPlaceholderText("在此输入内容...")
        layout.addWidget(editor)

        return widget

    def _create_preview(self) -> QWidget:
        widget = QWidget()
        layout = QVBoxLayout(widget)
        layout.addWidget(QLabel("预览区域"))
        preview = QTextEdit()
        preview.setReadOnly(True)
        layout.addWidget(preview)
        return widget


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = LayoutDemo()
    window.show()
    sys.exit(app.exec())

21.3.2 QSS样式表

python

DARK_STYLE = """
QMainWindow {
    background-color: #1e1e2e;
}

QWidget {
    color: #cdd6f4;
    font-family: "Microsoft YaHei", "Segoe UI", sans-serif;
    font-size: 13px;
}

QGroupBox {
    border: 1px solid #45475a;
    border-radius: 6px;
    margin-top: 12px;
    padding-top: 16px;
    font-weight: bold;
}

QGroupBox::title {
    subcontrol-origin: margin;
    left: 12px;
    padding: 0 6px;
}

QLineEdit, QTextEdit {
    background-color: #313244;
    border: 1px solid #45475a;
    border-radius: 4px;
    padding: 6px 10px;
    selection-background-color: #585b70;
}

QLineEdit:focus, QTextEdit:focus {
    border-color: #89b4fa;
}

QPushButton {
    background-color: #45475a;
    border: 1px solid #585b70;
    border-radius: 4px;
    padding: 8px 20px;
    min-width: 80px;
}

QPushButton:hover {
    background-color: #585b70;
}

QPushButton:pressed {
    background-color: #313244;
}

QLabel {
    background: transparent;
    border: none;
}

QMenuBar {
    background-color: #181825;
    border-bottom: 1px solid #313244;
}

QMenuBar::item:selected {
    background-color: #45475a;
}

QMenu {
    background-color: #1e1e2e;
    border: 1px solid #45475a;
}

QMenu::item:selected {
    background-color: #45475a;
}

QStatusBar {
    background-color: #181825;
    border-top: 1px solid #313244;
}

QSplitter::handle {
    background-color: #45475a;
    width: 2px;
}

QScrollBar:vertical {
    background: #1e1e2e;
    width: 10px;
    border: none;
}

QScrollBar::handle:vertical {
    background: #45475a;
    border-radius: 5px;
    min-height: 30px;
}

QScrollBar::handle:vertical:hover {
    background: #585b70;
}
"""


class StyledApp(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("QSS样式演示")
        self.setGeometry(100, 100, 700, 500)

        central = QWidget()
        self.setCentralWidget(central)
        layout = QVBoxLayout(central)
        layout.setSpacing(15)
        layout.setContentsMargins(30, 30, 30, 30)

        title = QLabel("暗色主题应用")
        title.setStyleSheet("font-size: 28px; font-weight: bold; color: #89b4fa;")
        title.setAlignment(Qt.AlignmentFlag.AlignCenter)
        layout.addWidget(title)

        form = QGroupBox("用户信息")
        form_layout = QFormLayout(form)
        form_layout.addRow("用户名:", QLineEdit())
        form_layout.addRow("邮箱:", QLineEdit())
        layout.addWidget(form)

        btn_layout = QHBoxLayout()
        btn_layout.addStretch()
        btn_layout.addWidget(QPushButton("提交"))
        btn_layout.addWidget(QPushButton("取消"))
        layout.addLayout(btn_layout)

        self.statusBar().showMessage("就绪")


if __name__ == "__main__":
    app = QApplication(sys.argv)
    app.setStyleSheet(DARK_STYLE)
    window = StyledApp()
    window.show()
    sys.exit(app.exec())

21.4 Model/View架构

21.4.1 自定义模型

python

from PyQt6.QtCore import Qt, QAbstractTableModel, QModelIndex
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QTableView, QVBoxLayout, QWidget,
    QPushButton, QHBoxLayout, QInputDialog, QMessageBox,
)
from dataclasses import dataclass


@dataclass
class Student:
    id: int
    name: str
    age: int
    score: float


class StudentTableModel(QAbstractTableModel):
    HEADERS = ["ID", "姓名", "年龄", "成绩", "等级"]

    def __init__(self, students: list[Student] = None):
        super().__init__()
        self._students = students or []

    def rowCount(self, parent=QModelIndex()):
        return len(self._students)

    def columnCount(self, parent=QModelIndex()):
        return len(self.HEADERS)

    def data(self, index: QModelIndex, role=Qt.ItemDataRole.DisplayRole):
        if not index.isValid() or not (0 <= index.row() < len(self._students)):
            return None

        student = self._students[index.row()]
        col = index.column()

        if role == Qt.ItemDataRole.DisplayRole:
            if col == 0: return student.id
            if col == 1: return student.name
            if col == 2: return student.age
            if col == 3: return f"{student.score:.1f}"
            if col == 4:
                if student.score >= 90: return "优秀"
                if student.score >= 80: return "良好"
                if student.score >= 60: return "及格"
                return "不及格"

        elif role == Qt.ItemDataRole.TextAlignmentRole:
            if col in (0, 2, 3, 4):
                return Qt.AlignmentFlag.AlignCenter
            return Qt.AlignmentFlag.AlignLeft | Qt.AlignmentFlag.AlignVCenter

        elif role == Qt.ItemDataRole.ForegroundRole:
            if col == 4:
                if student.score < 60:
                    from PyQt6.QtGui import QColor
                    return QColor("#f38ba8")
                if student.score >= 90:
                    from PyQt6.QtGui import QColor
                    return QColor("#a6e3a1")

        return None

    def headerData(self, section, orientation, role=Qt.ItemDataRole.DisplayRole):
        if role == Qt.ItemDataRole.DisplayRole and orientation == Qt.Orientation.Horizontal:
            return self.HEADERS[section]
        return None

    def add_student(self, student: Student):
        self.beginInsertRows(QModelIndex(), len(self._students), len(self._students))
        self._students.append(student)
        self.endInsertRows()

    def remove_student(self, row: int):
        if 0 <= row < len(self._students):
            self.beginRemoveRows(QModelIndex(), row, row)
            self._students.pop(row)
            self.endRemoveRows()

    def get_student(self, row: int) -> Student | None:
        if 0 <= row < len(self._students):
            return self._students[row]
        return None


class StudentManager(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("学生成绩管理")
        self.setGeometry(100, 100, 700, 500)

        self.model = StudentTableModel([
            Student(1, "张三", 20, 92.5),
            Student(2, "李四", 21, 78.0),
            Student(3, "王五", 19, 55.0),
        ])

        central = QWidget()
        self.setCentralWidget(central)
        layout = QVBoxLayout(central)

        toolbar = QHBoxLayout()
        add_btn = QPushButton("添加")
        add_btn.clicked.connect(self.add_student)
        toolbar.addWidget(add_btn)

        del_btn = QPushButton("删除")
        del_btn.clicked.connect(self.delete_student)
        toolbar.addWidget(del_btn)

        toolbar.addStretch()
        layout.addLayout(toolbar)

        self.table = QTableView()
        self.table.setModel(self.model)
        self.table.setSelectionBehavior(QTableView.SelectionBehavior.SelectRows)
        self.table.setSelectionMode(QTableView.SelectionMode.SingleSelection)
        self.table.setAlternatingRowColors(True)
        self.table.horizontalHeader().setStretchLastSection(True)
        layout.addWidget(self.table)

        self.statusBar().showMessage(f"共 {self.model.rowCount()} 条记录")

    def add_student(self):
        name, ok = QInputDialog.getText(self, "添加学生", "姓名:")
        if ok and name:
            from random import randint
            student = Student(
                id=self.model.rowCount() + 1,
                name=name,
                age=randint(18, 25),
                score=round(randint(40, 100) + randint(0, 9) / 10, 1),
            )
            self.model.add_student(student)
            self.statusBar().showMessage(f"已添加: {name}")

    def delete_student(self):
        indexes = self.table.selectionModel().selectedRows()
        if not indexes:
            return
        row = indexes[0].row()
        student = self.model.get_student(row)
        if student and QMessageBox.question(
            self, "确认", f"确定删除 {student.name}？",
        ) == QMessageBox.StandardButton.Yes:
            self.model.remove_student(row)
            self.statusBar().showMessage("已删除")


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = StudentManager()
    window.show()
    sys.exit(app.exec())

21.5 多线程GUI

21.5.1 QThread与工作对象

python

from PyQt6.QtCore import QThread, pyqtSignal, QObject, Qt
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QWidget, QVBoxLayout,
    QPushButton, QProgressBar, QLabel, QTextEdit,
)
import time


class Worker(QObject):
    progress = pyqtSignal(int)
    finished = pyqtSignal(str)
    error = pyqtSignal(str)

    def __init__(self, total: int = 100):
        super().__init__()
        self._total = total
        self._is_cancelled = False

    def run(self):
        try:
            for i in range(self._total + 1):
                if self._is_cancelled:
                    self.finished.emit("任务已取消")
                    return
                time.sleep(0.03)
                self.progress.emit(i)
            self.finished.emit(f"任务完成！处理了 {self._total} 个项目")
        except Exception as e:
            self.error.emit(str(e))

    def cancel(self):
        self._is_cancelled = True


class AsyncTaskWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("异步任务演示")
        self.setGeometry(100, 100, 500, 350)

        self._thread = None
        self._worker = None

        central = QWidget()
        self.setCentralWidget(central)
        layout = QVBoxLayout(central)
        layout.setSpacing(15)

        self.progress_bar = QProgressBar()
        self.progress_bar.setRange(0, 100)
        layout.addWidget(self.progress_bar)

        self.status_label = QLabel("就绪")
        self.status_label.setAlignment(Qt.AlignmentFlag.AlignCenter)
        layout.addWidget(self.status_label)

        self.log_edit = QTextEdit()
        self.log_edit.setReadOnly(True)
        self.log_edit.setMaximumHeight(120)
        layout.addWidget(self.log_edit)

        btn_layout = QVBoxLayout()
        self.start_btn = QPushButton("开始任务")
        self.start_btn.clicked.connect(self.start_task)
        btn_layout.addWidget(self.start_btn)

        self.cancel_btn = QPushButton("取消任务")
        self.cancel_btn.setEnabled(False)
        self.cancel_btn.clicked.connect(self.cancel_task)
        btn_layout.addWidget(self.cancel_btn)
        layout.addLayout(btn_layout)

    def start_task(self):
        self._worker = Worker(total=100)
        self._thread = QThread()
        self._worker.moveToThread(self._thread)

        self._thread.started.connect(self._worker.run)
        self._worker.progress.connect(self.on_progress)
        self._worker.finished.connect(self.on_finished)
        self._worker.error.connect(self.on_error)
        self._worker.finished.connect(self._thread.quit)
        self._worker.finished.connect(self._worker.deleteLater)
        self._thread.finished.connect(self._thread.deleteLater)

        self.start_btn.setEnabled(False)
        self.cancel_btn.setEnabled(True)
        self.progress_bar.setValue(0)
        self.status_label.setText("执行中...")
        self._thread.start()

    def cancel_task(self):
        if self._worker:
            self._worker.cancel()
        self.cancel_btn.setEnabled(False)

    def on_progress(self, value: int):
        self.progress_bar.setValue(value)
        self.status_label.setText(f"进度: {value}%")

    def on_finished(self, message: str):
        self.start_btn.setEnabled(True)
        self.cancel_btn.setEnabled(False)
        self.status_label.setText(message)
        self.log_edit.append(message)

    def on_error(self, message: str):
        self.start_btn.setEnabled(True)
        self.cancel_btn.setEnabled(False)
        self.status_label.setText(f"错误: {message}")
        self.log_edit.append(f"错误: {message}")

    def closeEvent(self, event):
        if self._thread and self._thread.isRunning():
            self._worker.cancel()
            self._thread.quit()
            self._thread.wait(3000)
        event.accept()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = AsyncTaskWindow()
    window.show()
    sys.exit(app.exec())

21.6 Qt Designer集成

21.6.1 使用UI文件

python

from PyQt6.QtWidgets import QApplication, QMainWindow
from PyQt6.uic import loadUi


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        loadUi("mainwindow.ui", self)

        self.submitButton.clicked.connect(self.on_submit)
        self.cancelButton.clicked.connect(self.close)

    def on_submit(self):
        name = self.nameInput.text()
        email = self.emailInput.text()
        print(f"提交: {name}, {email}")


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

21.6.2 资源系统

python

from PyQt6.QtGui import QIcon
from PyQt6.QtWidgets import QApplication, QMainWindow, QPushButton

import resources_rc


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("资源系统演示")

        btn = QPushButton(QIcon(":/icons/save.png"), "保存", self)
        btn.clicked.connect(lambda: print("保存"))
        self.setCentralWidget(btn)

资源文件 resources.qrc：

xml

<RCC>
    <qresource prefix="/">
        <file>icons/save.png</file>
        <file>icons/open.png</file>
        <file>icons/new.png</file>
    </qresource>
</RCC>

编译资源文件：

bash

pyside6-rcc resources.qrc -o resources_rc.py

21.7 综合实例：Markdown编辑器

python

import sys
import markdown
from pathlib import Path

from PyQt6.QtCore import Qt, QThread, pyqtSignal
from PyQt6.QtGui import QAction, QFont, QTextCursor
from PyQt6.QtWidgets import (
    QApplication, QMainWindow, QSplitter, QTextEdit,
    QFileDialog, QMessageBox, QLabel,
)


class MarkdownPreviewer(QThread):
    preview_ready = pyqtSignal(str)

    def __init__(self, text: str):
        super().__init__()
        self._text = text

    def run(self):
        html = markdown.markdown(
            self._text,
            extensions=["tables", "fenced_code", "toc", "nl2br"],
        )
        self.preview_ready.emit(html)


class MarkdownEditor(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Markdown 编辑器")
        self.setGeometry(100, 100, 1000, 700)
        self._current_file = None
        self._previewer = None

        self._init_ui()
        self._update_preview()

    def _init_ui(self):
        self._init_menubar()
        self._init_toolbar()
        self._init_editor()
        self._init_statusbar()

    def _init_menubar(self):
        file_menu = self.menuBar().addMenu("文件(&F)")

        new_action = QAction("新建(&N)", self)
        new_action.setShortcut("Ctrl+N")
        new_action.triggered.connect(self.new_file)
        file_menu.addAction(new_action)

        open_action = QAction("打开(&O)", self)
        open_action.setShortcut("Ctrl+O")
        open_action.triggered.connect(self.open_file)
        file_menu.addAction(open_action)

        save_action = QAction("保存(&S)", self)
        save_action.setShortcut("Ctrl+S")
        save_action.triggered.connect(self.save_file)
        file_menu.addAction(save_action)

        saveas_action = QAction("另存为(&A)", self)
        saveas_action.setShortcut("Ctrl+Shift+S")
        saveas_action.triggered.connect(self.save_file_as)
        file_menu.addAction(saveas_action)

        file_menu.addSeparator()
        exit_action = QAction("退出(&Q)", self)
        exit_action.setShortcut("Ctrl+Q")
        exit_action.triggered.connect(self.close)
        file_menu.addAction(exit_action)

    def _init_toolbar(self):
        toolbar = self.addToolBar("格式")
        toolbar.setMovable(False)

        for text, prefix, shortcut in [
            ("B", "**", "Ctrl+B"),
            ("I", "*", "Ctrl+I"),
            ("Code", "`", "Ctrl+K"),
        ]:
            action = QAction(text, self)
            action.setShortcut(shortcut)
            action.triggered.connect(lambda checked, p=prefix: self._insert_format(p))
            toolbar.addAction(action)

    def _init_editor(self):
        splitter = QSplitter(Qt.Orientation.Horizontal)

        self.editor = QTextEdit()
        self.editor.setFont(QFont("Consolas", 12))
        self.editor.textChanged.connect(self._on_text_changed)
        splitter.addWidget(self.editor)

        self.preview = QTextEdit()
        self.preview.setReadOnly(True)
        self.preview.setFont(QFont("Microsoft YaHei", 12))
        splitter.addWidget(self.preview)

        splitter.setStretchFactor(0, 1)
        splitter.setStretchFactor(1, 1)
        self.setCentralWidget(splitter)

    def _init_statusbar(self):
        self._status_label = QLabel("就绪")
        self.statusBar().addPermanentWidget(self._status_label)

    def _on_text_changed(self):
        self._update_preview()
        self._update_status()

    def _update_preview(self):
        text = self.editor.toPlainText()
        if self._previewer and self._previewer.isRunning():
            return
        self._previewer = MarkdownPreviewer(text)
        self._previewer.preview_ready.connect(self._set_preview)
        self._previewer.start()

    def _set_preview(self, html: str):
        self.preview.setHtml(f"""
        <html>
        <head>
        <style>
            body {{ font-family: "Microsoft YaHei", sans-serif; padding: 20px; }}
            code {{ background: #f0f0f0; padding: 2px 6px; border-radius: 3px; }}
            pre {{ background: #f5f5f5; padding: 12px; border-radius: 6px; overflow-x: auto; }}
            table {{ border-collapse: collapse; width: 100%; }}
            th, td {{ border: 1px solid #ddd; padding: 8px; text-align: left; }}
            blockquote {{ border-left: 4px solid #ddd; margin: 0; padding-left: 16px; color: #666; }}
        </style>
        </head>
        <body>{html}</body>
        </html>
        """)

    def _update_status(self):
        text = self.editor.toPlainText()
        chars = len(text)
        words = len(text.split())
        lines = text.count("\n") + 1
        filename = Path(self._current_file).name if self._current_file else "未命名"
        self._status_label.setText(f"{filename} | {lines} 行 | {words} 词 | {chars} 字符")

    def _insert_format(self, prefix: str):
        cursor = self.editor.textCursor()
        selected = cursor.selectedText()
        if selected:
            cursor.insertText(f"{prefix}{selected}{prefix}")
        else:
            cursor.insertText(f"{prefix}文本{prefix}")
            cursor.movePosition(QTextCursor.MoveOperation.Left, QTextCursor.MoveMode.MoveAnchor, len(prefix) + 2)
            cursor.movePosition(QTextCursor.MoveOperation.Right, QTextCursor.MoveMode.KeepAnchor, 2)
            self.editor.setTextCursor(cursor)

    def new_file(self):
        self.editor.clear()
        self._current_file = None
        self._update_status()

    def open_file(self):
        filepath, _ = QFileDialog.getOpenFileName(
            self, "打开文件", "", "Markdown (*.md);;所有文件 (*)",
        )
        if filepath:
            try:
                text = Path(filepath).read_text(encoding="utf-8")
                self.editor.setPlainText(text)
                self._current_file = filepath
                self._update_status()
            except Exception as e:
                QMessageBox.critical(self, "错误", f"无法打开文件: {e}")

    def save_file(self):
        if self._current_file:
            try:
                Path(self._current_file).write_text(
                    self.editor.toPlainText(), encoding="utf-8",
                )
                self.statusBar().showMessage("文件已保存", 3000)
            except Exception as e:
                QMessageBox.critical(self, "错误", f"无法保存文件: {e}")
        else:
            self.save_file_as()

    def save_file_as(self):
        filepath, _ = QFileDialog.getSaveFileName(
            self, "保存文件", "", "Markdown (*.md);;所有文件 (*)",
        )
        if filepath:
            self._current_file = filepath
            self.save_file()

    def closeEvent(self, event):
        if self._previewer and self._previewer.isRunning():
            self._previewer.quit()
            self._previewer.wait()
        event.accept()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MarkdownEditor()
    window.show()
    sys.exit(app.exec())

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21.8 前沿技术动态

21.8.1 PyQt6新特性

高DPI支持：自动缩放，无需手动处理
Python类型提示：完整的类型注解支持
QML与Python：通过PyQt6绑定QML前端
Qt for WebAssembly：浏览器中运行Qt应用

21.8.2 替代框架对比

特性	PyQt6	PySide6	Tkinter
许可证	GPL/商业	LGPL	Python
控件丰富度	★★★★★	★★★★★	★★★
样式定制	QSS	QSS	有限
设计器	Qt Designer	Qt Designer	无
文档	丰富	官方	一般
打包体积	大	大	小
学习曲线	陡	陡	平缓

21.9 本章小结

本章系统阐述了PyQt6 GUI开发的核心知识体系：

Qt框架基础：QObject对象模型、事件循环与父子对象树
信号与槽：Qt核心通信机制、自定义信号与跨对象通信
布局与样式：布局管理器、QSplitter与QSS样式表
Model/View架构：自定义表格模型与数据展示
多线程GUI：QThread工作对象模式与线程安全通信
Qt Designer集成：UI文件加载与资源系统
综合实例：Markdown编辑器的完整实现

21.10 习题与项目练习

基础题

使用PyQt6创建一个登录窗口，包含用户名、密码输入框，实现表单验证与信号槽通信。
实现一个支持加减乘除的计算器，使用QGridLayout布局。
创建一个文本编辑器，支持新建、打开、保存功能，使用QSS设置暗色主题。

进阶题

使用QAbstractTableModel实现一个可排序、可过滤的数据表格，支持CSV导入导出。
实现一个多线程文件搜索工具，搜索过程中界面保持响应，实时显示进度和结果。
使用QSplitter实现一个双面板文件管理器，左侧目录树，右侧文件列表。

综合项目

数据库管理工具：构建一个SQLite数据库管理GUI应用，包含：
- 数据库连接管理
- 表结构浏览与编辑
- SQL查询编辑器与结果展示
- 数据导入/导出（CSV、JSON）
- 使用Model/View架构
RSS阅读器：构建一个桌面RSS阅读器，包含：
- RSS订阅管理（增删改查）
- 文章列表与内容预览
- 多线程后台刷新
- 收藏与标记已读
- 搜索与过滤功能

思考题

PyQt6的信号槽机制与回调函数相比有何优势？在大型项目中如何避免信号槽连接导致的内存泄漏？
QThread的moveToThread模式与继承QThread重写run()方法有何区别？为什么推荐使用前者？

21.11 延伸阅读

21.11.1 Qt官方资源

Qt官方文档 (https://doc.qt.io/qt-6/) — Qt 6权威指南
PyQt6文档 (https://www.riverbankcomputing.com/static/Docs/PyQt6/) — Python绑定文档
PySide6文档 (https://doc.qt.io/qtforpython/) — Qt官方Python绑定

21.11.2 进阶书籍

《Rapid GUI Programming with Python and Qt》 (Mark Summerfield) — Qt经典教程
《Qt 6 C++ GUI Programming Cookbook》 — Qt实战技巧
《Mastering GUI Programming with Python》 — PyQt6高级教程

21.11.3 工具与资源

Qt Designer (https://doc.qt.io/qt-6/qtdesigner-manual.html) — 可视化界面设计器
Qt Creator (https://www.qt.io/product/development-tools) — 集成开发环境
QSS样式参考 (https://doc.qt.io/qt-6/stylesheet-reference.html) — 样式表参考

21.11.4 社区与生态

Qt Forum (https://forum.qt.io/) — Qt社区论坛
Qt Examples (https://doc.qt.io/qt-6/qtexamplesandtutorials.html) — 官方示例
Qt Blog (https://www.qt.io/blog) — Qt官方博客

下一章：第22章测试驱动开发

第21章 PyQt GUI开发 ​

学习目标 ​

21.1 Qt框架基础 ​

21.1.1 Qt对象模型 ​

21.1.2 应用程序架构 ​

21.2 信号与槽机制 ​

21.2.1 信号槽原理 ​

21.2.2 自定义信号与跨对象通信 ​

21.3 布局与样式 ​

21.3.1 布局管理器 ​

21.3.2 QSS样式表 ​

21.4 Model/View架构 ​

21.4.1 自定义模型 ​

21.5 多线程GUI ​

21.5.1 QThread与工作对象 ​

21.6 Qt Designer集成 ​

21.6.1 使用UI文件 ​

21.6.2 资源系统 ​

21.7 综合实例：Markdown编辑器 ​

21.8 前沿技术动态 ​

21.8.1 PyQt6新特性 ​

21.8.2 替代框架对比 ​

21.9 本章小结 ​

21.10 习题与项目练习 ​

基础题 ​

进阶题 ​

综合项目 ​

思考题 ​

21.11 延伸阅读 ​

21.11.1 Qt官方资源 ​

21.11.2 进阶书籍 ​

21.11.3 工具与资源 ​

21.11.4 社区与生态 ​

第21章 PyQt GUI开发

学习目标

21.1 Qt框架基础

21.1.1 Qt对象模型

21.1.2 应用程序架构

21.2 信号与槽机制

21.2.1 信号槽原理

21.2.2 自定义信号与跨对象通信

21.3 布局与样式

21.3.1 布局管理器

21.3.2 QSS样式表

21.4 Model/View架构

21.4.1 自定义模型

21.5 多线程GUI

21.5.1 QThread与工作对象

21.6 Qt Designer集成

21.6.1 使用UI文件

21.6.2 资源系统

21.7 综合实例：Markdown编辑器

21.8 前沿技术动态

21.8.1 PyQt6新特性

21.8.2 替代框架对比

21.9 本章小结

21.10 习题与项目练习

基础题

进阶题

综合项目

思考题

21.11 延伸阅读

21.11.1 Qt官方资源

21.11.2 进阶书籍

21.11.3 工具与资源

21.11.4 社区与生态