Tkinter DateTime

"""利用tkinter和datetime模組來寫時鐘程式
datetime模組主要用來獲得當前時區的時間。
now = datetime.datetime.now能夠獲得當前時區的時間。
然後利用now.year，now.minute，now.second就分別能得到int類型的數值。
主要難點是利用self.canvas.after(200)，200代表200毫秒，
也就是等待200毫秒後執行後續代碼。
結合while True迴圈和self.canvas.update()，
該代碼會以200毫秒為週期迴圈更新時間。
另外，還要考慮時針和分針轉一圈不僅僅只有60個位置，
可以細化到更為精細的移動。"""

import datetime
import math
from tkinter import *
class CurrentTime:
    def __init__(self):
        window = Tk()
        window.title("Current Time")
        self.canvas = Canvas(window, width = 200, height = 200, bg = "white")
        self.canvas.pack()
        self.canvas.create_text(100,10, text = "CLOCK", font = "bond")
        self.canvas.create_text(100,30, text = "12", font = "bond")
        self.canvas.create_text(135,40, text = "1", font = "bond")
        self.canvas.create_text(160,65, text = "2", font = "bond")
        self.canvas.create_text(170,100, text = "3", font = "bond")
        self.canvas.create_text(160,135, text = "4", font = "bond")
        self.canvas.create_text(135,160, text = "5", font = "bond")
        self.canvas.create_text(100,170, text = "6", font = "bond")
        self.canvas.create_text(65,160, text = "7", font = "bond")
        self.canvas.create_text(40,135, text = "8", font = "bond")
        self.canvas.create_text(30,100, text = "9", font = "bond")
        self.canvas.create_text(40,65, text = "10", font = "bond")
        self.canvas.create_text(65,40, text = "11", font = "bond")
        
        self.canvas.create_oval(20, 20, 180, 180, width = 2)
        
        self.showTime()
        window.mainloop()

    def showTime(self):
        while True:
            self.canvas.delete("time", "line")
            now = datetime.datetime.now()
            self.hour = now.hour
            self.minute = now.minute
            self.second = now.second
            self.canvas.create_text(100,190, text = str(self.hour) + ":" + str(self.minute) \
                                    + ":" + str(self.second), tags = "time")
            self.showLines()
            
            self.canvas.after(200)
            self.canvas.update()
    def showLines(self):
        if self.hour > 12 :
            hour = self.hour - 12
        second = self.second
        minute = self.minute + second/60
        hour += minute/60
        theta1 = - hour / 12 * 2 * math.pi + 0.5 * math.pi
        theta2 = - minute / 60 * 2 * math.pi + 0.5 * math.pi
        theta3 = - second / 60 * 2 * math.pi + 0.5 * math.pi
        tanTheta1 = math.tan(theta1)
        tanTheta2 = math.tan(theta2)
        tanTheta3 = math.tan(theta3)
        r1 = 40
        r2 = 55
        r3 = 65
        x1 = 100 + r1 * math.cos(theta1)
        x2 = 100 + r2 * math.cos(theta2)
        x3 = 100 + r3 * math.cos(theta3)
        y1 = tanTheta1 * x1 + 100 * (1 - tanTheta1)
        y2 = tanTheta2 * x2 + 100 * (1 - tanTheta2)
        y3 = tanTheta3 * x3 + 100 * (1 - tanTheta3)
        y1 = 200 - y1
        y2 = 200 - y2
        y3 = 200 - y3
        if y1 > r1 + 100:
            y1 = -r1 + 100
        if y1 < -r1 + 100:
            y1 = r1 + 100
        if y2 > r2 + 100:
            y2 = -r2 + 100
        if y2 < -r2 + 100:
            y2 = r2 + 100
        if y3 > r3 + 100:
            y3 = -r3 + 100
        if y3 < -r3 + 100:
            y3 = r3 + 100
        self.canvas.create_line(x1, y1, 100, 100, arrow = "first", width = 2, tags = "line")
        self.canvas.create_line(x2, y2, 100, 100, arrow = "first", width = 2, tags = "line")
        self.canvas.create_line(x3, y3, 100, 100, fill = "red", tags = "line")
        
CurrentTime()