python编程之 模拟时钟

运用画圆，画线的方法，以及一些数学知识做的一个demo。 对教材里的例子里的画时针的部分修改了下。

需要注意的是远点选择在中央，而数字时钟的十二点位于远点的正上方。所以如果用三角函数来计算时针分针秒针的位置的时候需要对角度进行旋转。根据sin, cos函数的特点，将对应的角度-90 读得到的是所需要的结果。比如说位于第一象限,相对于远点，sin值要为负，cos值为正; 第二象限，sin 为正， cos依旧为正; 第三象限，sin为正， cos 为负;第四象限，sin为负，cos为负。正好是sin(x-90),cos(x-90)。再一点，为了保证角度不超过360（时钟对应只有十二个小时）,所取角度对360取余数。

代码：

  

# -*- coding: utf-8 -*-
"""
Created on Tue Jul  7 15:07:20 2015

@author: liuchang
"""

import sys,random,math,pygame
from pygame.locals import * 
from datetime import datetime,date,time



def print_text(font,x,y,text,color=(255,255,255)):
    imgText=font.render(text,True,color)
    screen.blit(imgText,(x,y))

def wrap_angle(angle):
    return angle%360
    
    

pygame.init()
screen = pygame.display.set_mode((600,500))
pygame.display.set_caption("clock")
font = pygame.font.Font(None,60)
orange= 220,180,0
white = 255,255,255
yellow = 255,255,0
pink = 255,100,100

pos_x = 300
pos_y = 250
radius = 250
angle = 360


while True:
   
    for event in pygame.event.get():
        if event.type== QUIT:
            sys.exit()
        keys = pygame.key.get_pressed()
        if keys[K_ESCAPE]:
            sys.exit()
    screen.fill((0,0,100))
    pygame.draw.circle(screen,white,(pos_x,pos_y),radius,6)
    #draw clock number
    for n in range(1,13):
        angle = math.radians(n*(360/12)-90)
        x = math.cos(angle)*(radius-28)-18
        y = math.sin(angle)*(radius-28)-18
        print_text(font,pos_x+x,pos_y+y,str(n))
    # time 
    today = datetime.today()
    hours = today.hour%12
    minutes = today.minute
    seconds = today.second
    
    #draw  seconds hands
    seconds_angle = wrap_angle(seconds*(360/60)-90)
    seconds_angle = math.radians(seconds_angle)
    second_x = math.cos(seconds_angle)*(radius-40)
    second_y = math.sin(seconds_angle)*(radius-40)
    target= (pos_x+second_x,pos_y+second_y)
    
    pygame.draw.line(screen,white,(pos_x,pos_y),target,10)
    
    #minute hand
    minute_angle = wrap_angle(minutes*(360/60)-90)
    #add the angle affected by the minute hand
    add_angle = minutes
    minute_angle = math.radians(minute_angle)
    minute_x = math.cos(minute_angle)*(radius-60)
    minute_y = math.sin(minute_angle)*(radius-60)
    target= (pos_x+minute_x,pos_y+minute_y)
    
    pygame.draw.line(screen,orange,(pos_x,pos_y),target,10)    
    
    
    
    #hour hand
    hour_angle = wrap_angle(hours*(360/12)-90)
    #化弧度制用于计算
    add_angle= (add_angle/60)*(360/12)
    hour_angle = math.radians(hour_angle+add_angle)
    hour_x = math.cos(hour_angle)*(radius-80)
    hour_y = math.sin(hour_angle)*(radius-80)
    
    target= (pos_x+hour_x,pos_y+hour_y)
    
    pygame.draw.line(screen,pink,(pos_x,pos_y),target,25)
    
    

    
    pygame.display.update()        


   

截图：