Python Tkinter 鼠标事件

from tkinter import * # Import tkinter

class EnlargeShrinkCircle:
    def __init__(self):
        self.radius = 50 # 半径50
        window = Tk() # 创建窗体 Create a window
        window.title("Control Circle Demo") # 窗体标题 Set a title
        self.canvas = Canvas(window, bg = "white",
                             width = 200, height = 200) # Canvas为画布；背景白色；宽度200像素；高度200像素
        self.canvas.pack() # 画布放置并显示
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius,
            100 + self.radius, 100 + self.radius, tags = "oval")# 创建椭圆（包括圆）
        # 左上角为 100-50,100-50, 右下角为 100+50,100+50，
        # Bind canvas with mouse events
        self.canvas.bind("<Button-1>", self.increaseCircle) # Tkinter Canvas 消息绑定， <Button-1>  鼠标左键单击 https://www.cnblogs.com/emanlee/p/16180742.html
        self.canvas.bind("<Button-3>", self.decreaseCircle) # <Button-3>  鼠标右键单击
        window.mainloop() # Create an event loop

    def increaseCircle(self, event):
        self.canvas.delete("oval") # Canvas delete方法可以清除canvas画布上已绘制的对象
        if self.radius < 100:
            self.radius += 2 # 改变半径
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius,
            100 + self.radius, 100 + self.radius, tags = "oval") # 绘制圆

    def decreaseCircle(self, event):
        self.canvas.delete("oval") # Canvas delete方法可以清除canvas画布上已绘制的对象
        if self.radius > 2:
            self.radius -= 2 # 改变半径
        self.canvas.create_oval(
            100 - self.radius, 100 - self.radius,
            100 + self.radius, 100 + self.radius, tags = "oval") # 绘制圆

EnlargeShrinkCircle() # Create GUI