python PyQt实现的手写电子签名程序实例探究

import sys
from PyQt5.QtWidgets import QWidget, QApplication, QLabel, QVBoxLayout
from PyQt5.QtGui import QPixmap, QImage, QColor, QPainter, QPen
from PyQt5.QtCore import Qt
class SignatureWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.setFixedSize(400, 200)  # 设置窗口大小
        self.image = QImage(self.size(), QImage.Format_RGB32)  # 创建图片缓冲区
        self.image.fill(Qt.white)  # 用白色填充
        self.lastPos = None  # 记录上一个位置
        self.pen = QPen(QColor(Qt.black), 3, Qt.SolidLine)  # 设置画笔样式
        self.label = QLabel()
        vbox = QVBoxLayout()
        vbox.addWidget(self.label)
        self.setLayout(vbox)
    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawImage(0, 0, self.image)  # 绘制图片
    def mouseMoveEvent(self, event):
        if event.buttons() == Qt.LeftButton:
            if self.lastPos is not None:
                painter = QPainter(self.image)
                painter.setPen(self.pen)
                painter.drawLine(self.lastPos, event.pos())  # 画线
                self.lastPos = event.pos()  # 记录当前位置
                self.update()  # 刷新窗口
    def mousePressEvent(self, event):
        if event.buttons() == Qt.LeftButton:
            self.lastPos = event.pos()
    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.lastPos = None
    def clear(self):
        self.image.fill(Qt.white)  # 清空图片
        self.update()  # 刷新窗口
    def save(self, filename):
        self.image.save(filename)  # 保存图片
    def get_pixmap(self):
        pixmap = QPixmap(self.image)
        return pixmap
if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = SignatureWidget()
    widget.show()
    sys.exit(app.exec_())