Python3使用PyQt5制作简单的画板/手写板

好的，我可以帮你解答这个问题。下面是一个简单的Python3程序，使用PyQt5模块制作一个画板/手写板。

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


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setGeometry(100, 100, 800, 600)
        self.setWindowTitle("画板")
        self.image = QImage(self.size(), QImage.Format_RGB32)
        self.image.fill(Qt.white)
        self.drawing = False
        self.brush_size = 2
        self.brush_color = Qt.black
        self.last_point = QPoint()

        main_menu = self.menuBar()
        file_menu = main_menu.addMenu("文件")
        brush_menu = main_menu.addMenu("画笔")
        color_menu = main_menu.addMenu("颜色")

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

        clear_action = QAction("清空", self)
        clear_action.setShortcut("Ctrl+C")
        clear_action.triggered.connect(self.clear)
        file_menu.addAction(clear_action)

        size_action_1 = QAction("小", self)
        size_action_1.setShortcut("Ctrl+1")
        size_action_1.triggered.connect(self.set_small_brush)
        brush_menu.addAction(size_action_1)

        size_action_2 = QAction("中", self)
        size_action_2.setShortcut("Ctrl+2")
        size_action_2.triggered.connect(self.set_medium_brush)
        brush_menu.addAction(size_action_2)

        size_action_3 = QAction("大", self)
        size_action_3.setShortcut("Ctrl+3")
        size_action_3.triggered.connect(self.set_large_brush)
        brush_menu.addAction(size_action_3)

        color_action = QAction("选择颜色", self)
        color_action.setShortcut("Ctrl+Shift+C")
        color_action.triggered.connect(self.choose_color)
        color_menu.addAction(color_action)

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

    def mouseMoveEvent(self, event):
        if (event.buttons() & Qt.LeftButton) and self.drawing:
            painter = QPainter(self.image)
            painter.setPen(QPen(self.brush_color, self.brush_size, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
            painter.drawLine(self.last_point, event.pos())
            self.last_point = event.pos()
            self.update()

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.drawing = False

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(self.rect(), self.image, self.image.rect())

    def save(self):
        file_name, _ = QFileDialog.getSaveFileName(self, "保存画板", "", "PNG(*.png);;JPEG(*.jpg *.jpeg);;All Files(*.*)")
        if file_name == "":
            return
        self.image.save(file_name)

    def clear(self):
        self.image.fill(Qt.white)
        self.update()

    def set_small_brush(self):
        self.brush_size = 2

    def set_medium_brush(self):
        self.brush_size = 5

    def set_large_brush(self):
        self.brush_size = 10

    def choose_color(self):
        color = QColorDialog.getColor()
        if color.isValid():
            self.brush_color = color


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

你可以将这个程序保存为一个.py文件，然后使用Python3解释器执行它。当你打开这个程序时，你将看到一个带有菜单栏和一个空白区域的窗口。菜单栏中有文件、画笔和颜色三个菜单，你可以在这里选择不同的选项来操作画板。在画板上，你可以使用鼠标左键绘制图形，使用菜单栏中的选项来选择画笔的大小和颜色，以及保存或清空画板。

希望这个简单的例子能够帮到你！