用pyqt5写一个简单的绘图软件

好的，以下是一个简单的绘图软件的示例代码，它使用 PyQt5 库编写：

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QAction, QFileDialog, QColorDialog
from PyQt5.QtGui import QPainter, QPen, QColor
from PyQt5.QtCore import Qt


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setGeometry(100, 100, 800, 600)
        self.setWindowTitle("Simple Paint")
        self.image = None
        self.last_point = None
        self.color = Qt.black
        self.pen_size = 1
        self.init_ui()

    def init_ui(self):
        menubar = self.menuBar()
        file_menu = menubar.addMenu("File")
        new_action = QAction("New", self)
        new_action.setShortcut("Ctrl+N")
        new_action.triggered.connect(self.new_image)
        file_menu.addAction(new_action)
        open_action = QAction("Open", self)
        open_action.setShortcut("Ctrl+O")
        open_action.triggered.connect(self.open_image)
        file_menu.addAction(open_action)
        save_action = QAction("Save", self)
        save_action.setShortcut("Ctrl+S")
        save_action.triggered.connect(self.save_image)
        file_menu.addAction(save_action)
        color_menu = menubar.addMenu("Color")
        color_action = QAction("Choose Color", self)
        color_action.triggered.connect(self.choose_color)
        color_menu.addAction(color_action)
        pen_menu = menubar.addMenu("Pen")
        pen_size_menu = pen_menu.addMenu("Pen Size")
        size1_action = QAction("Size 1", self)
        size1_action.triggered.connect(lambda: self.set_pen_size(1))
        pen_size_menu.addAction(size1_action)
        size3_action = QAction("Size 3", self)
        size3_action.triggered.connect(lambda: self.set_pen_size(3))
        pen_size_menu.addAction(size3_action)
        size5_action = QAction("Size 5", self)
        size5_action.triggered.connect(lambda: self.set_pen_size(5))
        pen_size_menu.addAction(size5_action)

    def new_image(self):
        self.image = None
        self.update()

    def open_image(self):
        file_path, _ = QFileDialog.getOpenFileName(self, "Open Image", "", "Images (*.png *.jpg *.bmp)")
        if file_path:
            self.image = file_path
            self.update()

    def save_image(self):
        if self.image:
            file_path, _ = QFileDialog.getSaveFileName(self, "Save Image", "", "Images (*.png *.jpg *.bmp)")
            if file_path:
                painter = QPainter(self.image)
                self.draw(painter)
                self.image.save(file_path)

    def choose_color(self):
        self.color = QColorDialog.getColor(self.color, self)
        if not self.color.isValid():
            self.color = Qt.black

    def set_pen_size(self, size):
        self.pen_size = size

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.last_point = event.pos()

    def mouseMoveEvent(self, event):
        if event.buttons() == Qt.LeftButton:
            painter = QPainter(self.image)
            self.draw(painter, event.pos())
            self.update()
            self.last_point = event.pos()

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setPen(QPen(self.color, self.pen_size, Qt.SolidLine))
        if self.image:
            painter.drawImage(0, 0, self.image)

    def draw(self, painter, end_point=None):
        if not self.image:
            self.image = QImage(self.width(), self.height(), QImage.Format_RGB32)
            self.image.fill(Qt.white)
        painter.drawLine(self.last_point, end_point or self.last_point)


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

这个简单的绘图软件可以实现以下功能：

1. 新建、打开、保存图片；
2. 选择画笔颜色和大小；
3. 用鼠标绘制图形。

希望能帮到你！