PyQt5 Drawing points(绘制点) 学习

A point is the most simple graphics object that can be drawn. It is a small spot on the window.

代码：

# coding='utf-8'

from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtGui import QPainter
from PyQt5.QtCore import Qt
import sys, random


class Gui(QWidget):
    def __init__(self):
        super(Gui, self).__init__()
        self.start()

    def start(self):
        self.setGeometry(300, 300, 300, 190)
        self.setWindowTitle('绘制点')
        self.show()

    # 触发绘图的slot
    # Each time we resize the window, a paint event is generated. 
    def paintEvent(self, event) -> None:
        # QPainter实例对象负责绘制所有低等级的绘图功能
        qp = QPainter()
        # 所有的绘图功能都得从QPainter实例对象的begin方法开始,\
        #     一直到它的end方法结束.
        # begin的参数:begin(self, QPaintDevice) -> bool
        #     注意begin比end多一个参数: 将图形绘制到哪里
        qp.begin(self)
        # 具体的绘制过程被我们放到了我们自定义的函数里面
        self.draw_points(event, qp)
        qp.end()

    def draw_points(self, event, qp):
        # 设置绘图颜色为红色
        qp.setPen(Qt.red)
        # 得到主窗体的大小(宽,长)的二元组
        size = self.size()
        # 绘制1000个点
        for i in range(1000):
            # 在主窗体范围内随机区域绘制点
            x = random.randint(1, size.width()-1)
            y = random.randint(1, size.height()-1)
            qp.drawPoint(x, y)


app = QApplication(sys.argv)
gui = Gui()
sys.exit(app.exec_())