本节书摘来自异步社区《Python极客项目编程 》一书中的第2章，第2.4节，作者 [美] Mahesh Venkitachalam，王海鹏 译，更多章节内容可以访问云栖社区“异步社区”公众号查看。
2.4 完整代码
下面是完整的万花尺程序。也可以从https://github.com/electronut/pp/blob/master/ spirograph/spiro.py 下载该项目的代码。
import sys, random, argparse
import numpy as np
import math
import turtle
import random
from PIL import Image
from datetime import datetime
from fractions import gcd
# a class that draws a Spirograph
class Spiro:
# constructor
def __init__(self, xc, yc, col, R, r, l):
# create the turtle object
self.t = turtle.Turtle()
# set the cursor shape
self.t.shape('turtle')
# set the step in degrees
self.step = 5
# set the drawing complete flag
self.drawingComplete = False
# set the parameters
self.setparams(xc, yc, col, R, r, l)
# initialize the drawing
self.restart()
# set the parameters
def setparams(self, xc, yc, col, R, r, l):
# the Spirograph parameters
self.xc = xc
self.yc = yc
self.R = int(R)
self.r = int(r)
self.l = l
self.col = col
# reduce r/R to its smallest form by dividing with the GCD
gcdVal = gcd(self.r, self.R)
self.nRot = self.r//gcdVal
# get ratio of radii
self.k = r/float(R)
# set the color
self.t.color(*col)
# store the current angle
self.a = 0
# restart the drawing
def restart(self):
# set the flag
self.drawingComplete = False
# show the turtle
self.t.showturtle()
# go to the first point
self.t.up()
R, k, l = self.R, self.k, self.l
a = 0.0
x = R*((1-k)*math.cos(a) + l*k*math.cos((1-k)*a/k))
y = R*((1-k)*math.sin(a) - l*k*math.sin((1-k)*a/k))
self.t.setpos(self.xc + x, self.yc + y)
self.t.down()
# draw the whole thing
def draw(self):
# draw the rest of the points
R, k, l = self.R, self.k, self.l
for i in range(0, 360*self.nRot + 1, self.step):
a = math.radians(i)
x = R*((1-k)*math.cos(a) + l*k*math.cos((1-k)*a/k))
y = R*((1-k)*math.sin(a) - l*k*math.sin((1-k)*a/k))
self.t.setpos(self.xc + x, self.yc + y)
# drawing is now done so hide the turtle cursor
self.t.hideturtle()
# update by one step
def update(self):
# skip the rest of the steps if done
if self.drawingComplete:
return
# increment the angle
self.a += self.step
# draw a step
R, k, l = self.R, self.k, self.l
# set the angle
a = math.radians(self.a)
x = self.R*((1-k)*math.cos(a) + l*k*math.cos((1-k)*a/k))
y = self.R*((1-k)*math.sin(a) - l*k*math.sin((1-k)*a/k))
self.t.setpos(self.xc + x, self.yc + y)
# if drawing is complete, set the flag
if self.a >= 360*self.nRot:
self.drawingComplete = True
# drawing is now done so hide the turtle cursor
self.t.hideturtle()
# clear everything
def clear(self):
self.t.clear()
# a class for animating Spirographs
class SpiroAnimator:
# constructor
def __init__(self, N):
# set the timer value in milliseconds
self.deltaT = 10
# get the window dimensions
self.width = turtle.window_width()
self.height = turtle.window_height()
# create the Spiro objects
self.spiros = []
for i in range(N):
# generate random parameters
rparams = self.genRandomParams()
# set the spiro parameters
spiro = Spiro(*rparams)
self.spiros.append(spiro)
# call timer
turtle.ontimer(self.update, self.deltaT)
# restart spiro drawing
def restart(self):
for spiro in self.spiros:
# clear
spiro.clear()
# generate random parameters
rparams = self.genRandomParams()
# set the spiro parameters
spiro.setparams(*rparams)
# restart drawing
spiro.restart()
# generate random parameters
def genRandomParams(self):
width, height = self.width, self.height
R = random.randint(50, min(width, height)//2)
r = random.randint(10, 9*R//10)
l = random.uniform(0.1, 0.9)
xc = random.randint(-width//2, width//2)
yc = random.randint(-height//2, height//2)
col = (random.random(),
random.random(),
random.random())
return (xc, yc, col, R, r, l)
def update(self):
# update all spiros
nComplete = 0
for spiro in self.spiros:
# update
spiro.update()
# count completed spiros
if spiro.drawingComplete:
nComplete += 1
# restart if all spiros are complete
if nComplete == len(self.spiros):
self.restart()
# call the timer
turtle.ontimer(self.update, self.deltaT)
# toggle turtle cursor on and off
def toggleTurtles(self):
for spiro in self.spiros:
if spiro.t.isvisible():
spiro.t.hideturtle()
else:
spiro.t.showturtle()
# save drawings as PNG files
def saveDrawing():
# hide the turtle cursor
turtle.hideturtle()
# generate unique filenames
dateStr = (datetime.now()).strftime("%d%b%Y-%H%M%S")
fileName = 'spiro-' + dateStr
print('saving drawing to %s.eps/png' % fileName)
# get the tkinter canvas
canvas = turtle.getcanvas()
# save the drawing as a postscipt image
canvas.postscript(file = fileName + '.eps')
# use the Pillow module to convert the poscript image file to PNG
img = Image.open(fileName + '.eps')
img.save(fileName + '.png', 'png')
# show the turtle cursor
turtle.showturtle()
# main() function
def main():
# use sys.argv if needed
print('generating spirograph...')
# create parser
descStr = """This program draws Spirographs using the Turtle module.
When run with no arguments, this program draws random Spirographs.
Terminology:
R: radius of outer circle
r: radius of inner circle
l: ratio of hole distance to r
"""
parser = argparse.ArgumentParser(description=descStr)
# add expected arguments
parser.add_argument('--sparams', nargs=3, dest='sparams', required=False,
help="The three arguments in sparams: R, r, l.")
# parse args
args = parser.parse_args()
# set the width of the drawing window to 80 percent of the screen width
turtle.setup(width=0.8)
# set the cursor shape to turtle
turtle.shape('turtle')
# set the title to Spirographs!
turtle.title("Spirographs!")
# add the key handler to save our drawings
turtle.onkey(saveDrawing, "s")
# start listening
turtle.listen()
# hide the main turtle cursor
turtle.hideturtle()
# check for any arguments sent to --sparams and draw the Spirograph
if args.sparams:
params = [float(x) for x in args.sparams]
# draw the Spirograph with the given parameters
col = (0.0, 0.0, 0.0)
spiro = Spiro(0, 0, col, *params)
spiro.draw()
else:
# create the animator object
spiroAnim = SpiroAnimator(4)
# add a key handler to toggle the turtle cursor
turtle.onkey(spiroAnim.toggleTurtles, "t")
# add a key handler to restart the animation
turtle.onkey(spiroAnim.restart, "space")
# start the turtle main loop
turtle.mainloop()
# call main
if __name__ == '__main__':
main()
