tkinter拖动圆点并在非圆点处通过单击创建圆点

本程序演示了鼠标进入，鼠标指针离开，鼠标指针移动等事件。

"""

   本程序演示拖动圆点并在非圆点处通过单击创建圆点

"""

from tkinter import *

class Testclass(Frame):

    def __init__(self, master=None):

        Frame.__init__(self, master)

        Pack.config(self)

        self.createWidgets()
    def createWidgets(self):

        self.QUIT = Button(self, text='QUIT', foreground='red',

                           command=self.quit)

        self.QUIT.pack(side=LEFT, fill=BOTH)

        self.draw = Canvas(self, width="5i", height="5i")

        self.draw.pack(side=LEFT)
        Widget.bind(self.draw, "<1>", self.mouseDown)

        Widget.bind(self.draw, "", self.mouseMove)
    def mouseDown(self, event):

        # 检测鼠标指针是否在一个圆点内，如果时则把它设为tk的当前tag.

        if not event.widget.find_withtag(CURRENT):

            fred = self.draw.create_oval(

                event.x - 10, event.y -10, event.x +10, event.y + 10,

                fill="green", tags=CURRENT)
            self.draw.tag_bind(fred, "", self.mouseEnter)

            self.draw.tag_bind(fred, "", self.mouseLeave)
        self.lastx = event.x

        self.lasty = event.y
    def mouseMove(self, event):

        """鼠标指针移动事件"""

        self.draw.move(CURRENT, event.x - self.lastx, event.y - self.lasty)

        self.lastx = event.x

        self.lasty = event.y
    def mouseEnter(self, event):

        """鼠标指针进入则设为红色"""

        self.draw.itemconfig(CURRENT, fill="red")
    def mouseLeave(self, event):

        """鼠标指针进入则设为蓝色"""

        self.draw.itemconfig(CURRENT, fill="blue")
Testclass = Testclass()

Testclass.mainloop()