tkinter 练习之画笔（重置、撤销、还原）

import tkinter as tk

import sys

import os

class App(tk.Tk):

    b1 = "up"

    xold, yold = None, None

    color = "black"

    linesize = 2

    counter = 1  # keeps track of the current working line, is incremented as soon as line is finished

    undone = []  # keeps a list of coordinate lists on undone items

    def __init__(self):

        tk.Tk.__init__(self)

        self.drawing_area = tk.Canvas(self, width=600, height=600, background="white")

        self.drawing_area.pack()

        self.drawing_area.bind("<Motion>", self.motion)

        self.drawing_area.bind("<ButtonPress-1>", self.b1down)

        self.drawing_area.bind("<ButtonRelease-1>", self.b1up)

        self.button1 = tk.Button(self, text="Reset", command=self.blank_canvas, anchor=tk.N)

        self.button1.configure(width=3, background="#FFFFFF", relief=tk.FLAT)

        self.button1.pack(side="left")

        self.button2 = tk.Button(self, text="Undo", command=self.undo, anchor=tk.N)

        self.button2.configure(width=3, background="#FFFFFF", relief=tk.FLAT)

        self.button2.pack(side="left")

        self.button3 = tk.Button(self, text="Redo", command=self.redo, anchor=tk.N)

        self.button3.configure(width=3, background="#FFFFFF", relief=tk.FLAT)

        self.button3.pack(side="left")

    def blank_canvas(self):

        self.drawing_area.delete("line")

    def undo(self):

        self.counter -= 1  # decrements the counter to look at the previous item

        currentlist = []  # creates a list to store the coordinates in

        for item in self.drawing_area.find_withtag(

                "line" + str(self.counter)):  # find all sub lines from the previous line

            currentlist.append(self.drawing_area.coords(item))  # get and add the coordinates to the working list

        self.drawing_area.delete("line" + str(self.counter))  # delete all items of the current line

        self.undone.append(currentlist)  # add the working list to the stored list

    def redo(self):

        try:

            currentlist = self.undone.pop()  # fetch and remove last set of coordinates

            for coords in currentlist:  # for set of coordinates redraw subline

                self.drawing_area.create_line(coords, smooth=tk.TRUE, fill=self.color, width=self.linesize,

                                              tags=["line", "line" + str(self.counter)])

            self.counter += 1  # re increment counter

        except IndexError:

            pass  # occurs if list is empty

    def b1down(self, event):

        self.b1 = "down"

    def b1up(self, event):

        self.b1 = "up"

        self.xold = None

        self.yold = None

        self.counter += 1

    def motion(self, event):

        if self.b1 == "down":

            if self.xold is not None and self.yold is not None:

                event.widget.create_line(self.xold, self.yold, event.x, event.y, smooth=tk.TRUE, fill=self.color,

                                         width=self.linesize, tags=["line", "line" + str(self.counter)])

            self.xold = event.x

            self.yold = event.y

if __name__ == "__main__":

    app = App()

    app.mainloop()