pyqt5中painter鼠标画线完成后弹出一次界面包含文本“请输入长度：”以及文本框可输入后关闭的代码

在PyQt5中，你可以使用`QPainter`来绘制图形，并结合`QInputDialog`来创建一个简单的对话框让用户输入数值。下面是一个简化的示例代码，展示了如何在鼠标画线结束后弹出一个带文本输入框的窗口：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QPainter, QInputDialog, QLineEdit
from PyQt5.QtGui import QPainterPath, QColor, QPen

class MyWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.path = QPainterPath()
        self.pen = QPen(QColor('black'), 2)  # 设置画笔颜色和宽度

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.drawPath(self.path)
        
    def mouseMoveEvent(self, event):
        if not self.path.isEmpty():  # 避免第一次点击就触发绘制
            self.path.lineTo(event.pos())
        self.update()

    def mouseReleaseEvent(self, event):
        line_length = None
        if not self.path.isEmpty():
            self.path.closeSubpath()
            text, ok = QInputDialog.getText(self, "请输入长度", "请输入线条长度:")
            if ok and text.isdigit():
                line_length = int(text)

        if line_length is not None:
            self画画线(line_length)
            self.show_message()  # 显示消息并退出
        else:
            self.update()

    def画画线(self, length):
        painter = QPainter(self)
        painter.setPen(self.pen)
        painter.drawPath(self.path)
        self.path.clear()

    def show_message(self):
        QMessageBox.information(self, '信息', '线条已绘制完成，长度为{}。'.format(length))
        self.close()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = MyWidget()
    widget.setWindowTitle("鼠标画线")
    widget.setGeometry(300, 300, 400, 400)
    widget.show()
    sys.exit(app.exec_())