PyQt5: chapter10-在两次鼠标单击之间绘制矩形

实例

1. 创建基于Dialog without Buttons模板窗口
2. 添加Label部件，其text为Click the mouse and drag it to draw a  rectangle of the desired size
3. 保存为demoDrawRectangle.ui
4. 使用pyuic生成demoDrawRectangle.py
5. 创建callDrawRectangle.py

import sys
from PyQt5.QtWidgets import QDialog, QApplication
from PyQt5.QtGui import QPainter
from cookbook_200505.demoDrawRectangle import *

class MyForm(QDialog):
    def __init__(self):
        super().__init__()
        self.ui = Ui_Dialog()
        self.ui.setupUi(self)
        self.pos1 = [0,0]
        self.pos2 = [0,0]
        self.show()
    def paintEvent(self, event):
        width = self.pos2[0]-self.pos1[0]
        height = self.pos2[1] - self.pos1[1]
        qp = QPainter()
        qp.begin(self)
        qp.drawRect(self.pos1[0], self.pos1[1], width, height)
        qp.end()
    def mousePressEvent(self, event):
        if event.buttons() & QtCore.Qt.LeftButton:
            self.pos1[0], self.pos1[1] = event.pos().x(),event.pos().y()
    def mouseReleaseEvent(self, event):
        self.pos2[0], self.pos2[1] = event.pos().x(),event.pos().y()
        self.update()
if __name__=="__main__":
    app = QApplication(sys.argv)
    w = MyForm()
    w.show()
    sys.exit(app.exec_())