pyqt5中painter鼠标画线完成后弹出界面包含文本“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`进行绘图，结合`QDialog`来创建一个简单的交互式界面。以下是一个示例代码，展示如何在鼠标画线结束后弹出一个窗口，让用户输入长度，然后关闭窗口：

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

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.init_ui()

    def init_ui(self):
        self.setGeometry(100, 100, 400, 400)
        self.setWindowTitle('Paint and Input')

        self.canvas = QWidget()
        self.setCentralWidget(self.canvas)

        self.path = QPainterPath()
        self.connect_mouse_move_and_paint()

    def connect_mouse_move_and_paint(self):
        self.canvas.mouseMoveEvent = self.on_mouse_move
        self.canvas.paintEvent = self.on_paint

    def on_mouse_move(self, event):
        if event.buttons() & Qt.LeftButton:
            self.path.lineTo(event.pos())
            self.update_canvas()

    def on_paint(self, event):
        painter = QPainter(self.canvas)
        painter.drawPath(self.path)

    def update_canvas(self):
        painter = QPainter(self.canvas)
        painter.drawPath(self.path)
        self.canvas.repaint()

    def draw_input_popup(self):
        # 创建一个模态对话框
        input_dialog = QDialog(self)
        input_dialog.setWindowTitle("请输入长度")
        layout = QVBoxLayout(input_dialog)

        # 添加一个文本输入框
        input_line_edit = QLineEdit()
        layout.addWidget(input_line_edit)

        # 提交按钮
        ok_button = QPushButton("确定")
        ok_button.clicked.connect(lambda: self.input_popup_closed(input_line_edit.text()))
        layout.addWidget(ok_button)

        # 关闭按钮
        cancel_button = QPushButton("取消")
        cancel_button.clicked.connect(input_dialog.reject)
        layout.addWidget(cancel_button)

        # 设置大小和显示
        input_dialog.resize(200, 100)
        result = input_dialog.exec_()

        # 如果用户点击了确认，获取输入并关闭对话框
        if result == QDialog.Accepted:
            print(f"输入的长度：{input_line_edit.text()}")

    def input_popup_closed(self, length):
        self.close_popup()
        print(f"已保存长度：{length}")

    def close_popup(self):
        self.draw_input_popup.hide()

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

在这个例子中，当用户在窗口上拖动鼠标绘制线条时，`on_paint`函数会被触发，显示绘制的路径。当鼠标绘制结束（例如，松开左键），会调用`draw_input_popup`打开一个对话框让用户输入长度。输入后，对话框会消失，并打印输入的内容。