在Udacity上課時學到了python的turtle方法，這是一個很經典的用來教小孩兒編程的圖形模塊，最早起源于logo語言。python本身內置了這個模塊，其可視化的方法可以幫助小孩兒對編程的一些基本理念有所理解。

在作業提交的論壇里看到很多turtle畫出來的精美圖形，想不出什么要畫的東西，于是決定拿五星紅旗來練練手。

前期準備

五星紅旗繪制參數

Turtle官方文檔

turtle的基本操作

# 初始化屏幕window = turtle.Screen()# 新建turtle對象實例import turtleaTurtle = turtle.Turtle()# 海龜設置aTurtle.hideturtle() # 隱藏箭頭aTurtle.speed(10)  # 設置速度# 前進后退，左轉右轉aTurtle.fd(100)  # 前進100像素aTurtle.right(90) # 右轉90°aTurtle.back(100)aTurtle.left(90)# 填充顏色aTurtle.begin_fill()aTurtle.fillcolor('yellow')DoSomethinghere()aTurtle.end_fill()# 抬起筆和放下筆，這樣進行的操作不會留下痕跡aTurtle.penup()aTurtle.goto(start_pos)aTurtle.fd(radius)aTurtle.pendown()

繪制五星紅旗代碼

github地址：https://gist.github.com/dc11287081ee67075da8

#!/usr/bin/env python   # -*- coding: utf-8 –*-''' 對于turtle類的一些封裝方法，包括畫正多邊形，正多角形和五星紅旗。'''__author__ = 'Hu Wenchao' import turtleimport math def draw_polygon(aTurtle, size=50, n=3):  ''' 繪制正多邊形  args:    aTurtle: turtle對象實例    size: int類型，正多邊形的邊長    n: int類型，是幾邊形      '''  for i in xrange(n):    aTurtle.forward(size)    aTurtle.left(360.0/n) def draw_n_angle(aTurtle, size=50, num=5, color=None):  ''' 繪制正n角形，默認為黃色  args:    aTurtle: turtle對象實例    size: int類型，正多角形的邊長    n: int類型，是幾角形      color: str， 圖形顏色，默認不填色  '''  if color:    aTurtle.begin_fill()    aTurtle.fillcolor(color)  for i in xrange(num):    aTurtle.forward(size)    aTurtle.left(360.0/num)    aTurtle.forward(size)    aTurtle.right(2*360.0/num)  if color:    aTurtle.end_fill() def draw_5_angle(aTurtle=None, start_pos=(0,0), end_pos=(0,10), radius=100, color=None):  ''' 根據起始位置、結束位置和外接圓半徑畫五角星  args:    aTurtle: turtle對象實例    start_pos: int的二元tuple，要畫的五角星的外接圓圓心    end_pos: int的二元tuple，圓心指向的位置坐標點    radius: 五角星外接圓半徑    color: str， 圖形顏色，默認不填色    '''  aTurtle = aTurtle or turtle.Turtle()  size = radius * math.sin(math.pi/5)/math.sin(math.pi*2/5)  aTurtle.left(math.degrees(math.atan2(end_pos[1]-start_pos[1], end_pos[0]-start_pos[0])))  aTurtle.penup()  aTurtle.goto(start_pos)  aTurtle.fd(radius)  aTurtle.pendown()  aTurtle.right(math.degrees(math.pi*9/10))  draw_n_angle(aTurtle, size, 5, color) def draw_5_star_flag(times=20.0):  ''' 繪制五星紅旗  args:    times: 五星紅旗的規格為30*20， times為倍數，默認大小為10倍， 即300*200  '''  width, height = 30*times, 20*times  # 初始化屏幕和海龜  window = turtle.Screen()  aTurtle = turtle.Turtle()  aTurtle.hideturtle()  aTurtle.speed(10)  # 畫紅旗  aTurtle.penup()  aTurtle.goto(-width/2, height/2)  aTurtle.pendown()  aTurtle.begin_fill()  aTurtle.fillcolor('red')  aTurtle.fd(width)  aTurtle.right(90)  aTurtle.fd(height)  aTurtle.right(90)  aTurtle.fd(width)  aTurtle.right(90)  aTurtle.fd(height)  aTurtle.right(90)    aTurtle.end_fill()  # 畫大星星  draw_5_angle(aTurtle, start_pos=(-10*times, 5*times), end_pos=(-10*times, 8*times), radius=3*times, color='yellow')   # 畫四個小星星  stars_start_pos = [(-5, 8), (-3, 6), (-3, 3), (-5, 1)]  for pos in stars_start_pos:    draw_5_angle(aTurtle, start_pos=(pos[0]*times, pos[1]*times), end_pos=(-10*times, 5*times), radius=1*times, color='yellow')   # 點擊關閉窗口  window.exitonclick()if __name__ == '__main__':    draw_5_star_flag()