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使用Python編寫簡單的畫圖板程序的示例教程

更新時間：2015年12月08日 16:37:26 作者：xishui

這篇文章主要介紹了使用Python編寫簡單的畫圖板軟件的示例教程,利用到了經(jīng)常被用來做游戲的pygame模塊,需要的朋友可以參考下

從這次開始，我會由簡單到困難（其實(shí)也不會困難到哪里去）講幾個例程，每一個例程都是我自己寫（或者修改，那樣的話我會提供原始出處）的，都具有一定的操作性和娛樂性。例程中匯盡量覆蓋到以前所講的pygame中方方面面，如果看到哪一步不明白，那就再回去復(fù)習(xí)復(fù)習(xí)，基本沒有人會看一遍什么都記住什么都掌握的，重復(fù)是學(xué)習(xí)之母，實(shí)踐是掌握一門技藝的最好手段！

這次就先從一個最簡單的程序開始，說實(shí)話有些太簡單我都不好意思拿出手了，不過從簡單的開始，容易建立自信培養(yǎng)興趣。興趣是學(xué)習(xí)之母嘛。我們這次做一個畫板，類似Windows里自帶的畫板，還記不記得第一次接觸電腦用畫板時的驚嘆？現(xiàn)在想起來其實(shí)那個真的非常簡陋，不過我們的比那個還要樸素，因?yàn)榇蛩阋黄v完，就不追加很多功能了，等你把這一次講解的都理解了，很容易可以自己給它增加新的機(jī)能。沒準(zhǔn)，你就開發(fā)出一個非常牛X的畫圖工具擊敗了Photoshop，然后日進(jìn)斗金名垂千古（眾：喂，別做夢了?。?/p>

功能樣式

做之前總要有個數(shù)，我們的程序做出來會是個什么樣子。所謂從頂?shù)降谆蛘邚牡椎巾斏兜?，咱就不研究了，這個小程序隨你怎么弄了，而且我們主要是來熟悉pygame，高級的軟件設(shè)計(jì)方法一概不談~

因?yàn)槭浅u畫圖板，也就是鼠標(biāo)按住了能在上面涂涂畫畫就是了，選區(qū)、放大鏡、滴管功能啥的就統(tǒng)統(tǒng)不要了。畫筆的話，基本的鉛筆畫筆總是要的，也可以考慮加一個刷子畫筆，這樣有一點(diǎn)變化；然后顏色應(yīng)該是要的，否則太過單調(diào)了，不過調(diào)色板啥的就暫時免了，提供幾個候選色就好了；然后橡皮……橡皮不就是白色的畫筆么？免了免了！還有啥？似乎夠了。。。 OK，開始吧！

框架

pygame程序的框架都是差不多的，考慮到我們這個程序的實(shí)際作用，大概建立這樣的一個代碼架子就可以了。

import pygame
from pygame.locals import *

class Brush():
 def __init__(self):
  pass

class Painter():
 def __init__(self):
  self.screen = pygame.display.set_mode((800, 600))
  pygame.display.set_caption("Painter")
  self.clock = pygame.time.Clock()

 def run(self):
  self.screen.fill((255, 255, 255))
  while True:
   # max fps limit
   self.clock.tick(30)
   for event in pygame.event.get():
    if event.type == QUIT:
     return
    elif event.type == KEYDOWN:
     pass
    elif event.type == MOUSEBUTTONDOWN:
     pass
    elif event.type == MOUSEMOTION:
     pass
    elif event.type == MOUSEBUTTONUP:
     pass

   pygame.display.update()

if __name__ == '__main__':
 app = Painter()
 app.run()

import pygame
from pygame.locals import *
 
class Brush():
 def __init__(self):
  pass
 
class Painter():
 def __init__(self):
  self.screen = pygame.display.set_mode((800, 600))
  pygame.display.set_caption("Painter")
  self.clock = pygame.time.Clock()
 
 def run(self):
  self.screen.fill((255, 255, 255))
  while True:
   # max fps limit
   self.clock.tick(30)
   for event in pygame.event.get():
    if event.type == QUIT:
     return
    elif event.type == KEYDOWN:
     pass
    elif event.type == MOUSEBUTTONDOWN:
     pass
    elif event.type == MOUSEMOTION:
     pass
    elif event.type == MOUSEBUTTONUP:
     pass
 
   pygame.display.update()
 
if __name__ == '__main__':
 app = Painter()
 app.run()

這個非常簡單，準(zhǔn)備好畫板類，畫筆類，暫時還都是空的，其實(shí)也就是做了一些pygame的初始化工作。如果這樣還不能讀懂的話，您需要把前面22篇從頭再看看，有幾句話不懂就看幾遍：）

這里只有一點(diǎn)要注意一下，我們把幀率控制在了30，沒有人希望在畫畫的時候，CPU風(fēng)扇狂轉(zhuǎn)的。而且只是畫板，沒有自動運(yùn)動的物體，純粹的交互驅(qū)動，我們也不需要很高的刷新率。

第一次的繪圖代碼

按住鼠標(biāo)然后在上面移動就畫東西，我們很容易可以想到這個流程：

按下左鍵 → 繪制flag開
移動鼠標(biāo) → flag開的時候，在移動坐標(biāo)上留下痕跡
放開左鍵 → 繪制flag關(guān)

按下左鍵 → 繪制flag開
移動鼠標(biāo) → flag開的時候，在移動坐標(biāo)上留下痕跡
放開左鍵 → 繪制flag關(guān)
立刻試一試吧：

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False

 def start_draw(self):
  self.drawing = True
 def end_draw(self):
  self.drawing = False

 def draw(self, pos):
  if self.drawing:
   pygame.draw.circle(self.screen, self.color, pos, self.size)

class Painter():
 def __init__(self):
  #*#*#*#*#
  self.brush = Brush(self.screen)

 def run(self):
   #*#*#*#*#
    elif event.type == KEYDOWN:
     # press esc to clear screen
     if event.key == K_ESCAPE:
      self.screen.fill((255, 255, 255))
    elif event.type == MOUSEBUTTONDOWN:
     self.brush.start_draw()
    elif event.type == MOUSEMOTION:
     self.brush.draw(event.pos)
    elif event.type == MOUSEBUTTONUP:
     self.brush.end_draw()

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
 
 def start_draw(self):
  self.drawing = True
 def end_draw(self):
  self.drawing = False
 
 def draw(self, pos):
  if self.drawing:
   pygame.draw.circle(self.screen, self.color, pos, self.size)
 
class Painter():
 def __init__(self):
  #*#*#*#*#
  self.brush = Brush(self.screen)
 
 def run(self):
   #*#*#*#*#
    elif event.type == KEYDOWN:
     # press esc to clear screen
     if event.key == K_ESCAPE:
      self.screen.fill((255, 255, 255))
    elif event.type == MOUSEBUTTONDOWN:
     self.brush.start_draw()
    elif event.type == MOUSEMOTION:
     self.brush.draw(event.pos)
    elif event.type == MOUSEBUTTONUP:
     self.brush.end_draw()

框架中有的代碼我就不貼了，用#*#*#*#*#代替，最后會給出完整代碼的。

這里主要是給Brush類增加了一些功能，也就是上面我們提到的流程想對應(yīng)的功能。留下痕跡，我們是使用了在坐標(biāo)上畫圓的方法，這也是最容易想到的方法。這樣的效果好不好呢？我們試一試：

2015128162649149.jpg (271×170)

哦，太糟糕了，再劣質(zhì)的鉛筆也不會留下這樣斷斷續(xù)續(xù)的筆跡。上面是當(dāng)我們鼠標(biāo)移動的快一些的時候，點(diǎn)之間的間距很大；下面是移動慢一些的時候，勉勉強(qiáng)強(qiáng)顯得比較連續(xù)。從這里我們也可以看到pygame事件響應(yīng)的頻度（這個距離和上面設(shè)置的最大幀率有關(guān)）。

怎么辦？要修改幀率讓pygame平滑的反應(yīng)么？不，那樣做得不償失，換一個角度思考，如果有間隙，我們讓pygame把這個間隙連接起來不好么？

第二次的繪圖代碼

思路還是很簡單，當(dāng)移動的時候，Brush在上一次和這一次的點(diǎn)之間連一條線就好了：

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
  self.last_pos = None  # <--
 
 def start_draw(self, pos):
  self.drawing = True
  self.last_pos = pos # <--
 def end_draw(self):
  self.drawing = False
 
 def draw(self, pos):
  if self.drawing:
   pygame.draw.line(self.screen, self.color,
     self.last_pos, pos, self.size * 2)
   self.last_pos = pos

2015128162728237.jpg (293×247)

在__init__和start_draw中各加了一句，用來存儲上一個點(diǎn)的位置，然后draw也由剛剛的話圓變成畫線，效果如何？我們來試試。嗯，好多了，如果你動作能溫柔一些的話，線條已經(jīng)很圓潤了，至少沒有斷斷續(xù)續(xù)的存在了。

滿足了么？我希望你的回答是“NO”，為什么，如果你劃線很快的話，你就能明顯看出棱角來，就好像左圖上半部分，還是能看出是由幾個線段組合的。只有永不滿足，我們才能不停進(jìn)步。

不過對我們這個例程而言，差不多了，一般人在真正畫東西的時候，也不會動那么快的：）

那么這個就是我們最終的繪圖機(jī)制了么？回頭看看我們的樣式，好用還需要加一個筆刷……所謂筆刷，不僅僅是很粗，而且是由很多細(xì)小的毛組成，畫出來的線是給人一種一縷一縷的感覺，用這個方法可以實(shí)現(xiàn)么？好像非常非常的困難。。。孜孜不倦的我們再次進(jìn)入了沉思……

這個時候，如果沒有頭緒，就得借鑒一下前輩的經(jīng)驗(yàn)了。看看人家是如何實(shí)現(xiàn)的？

2015128162744801.jpg (550×125)

如果你的Photoshop不錯，應(yīng)該知道它里面復(fù)雜的筆刷設(shè)定，而Photoshop畫出來的筆畫，并不是真正一直線的，而是由無數(shù)細(xì)小的點(diǎn)組成的，這些點(diǎn)之間的間距是如此的密，以至于我們誤會它是一直線……所以說，我們還得回到第一種方法上，把它發(fā)揚(yáng)光大一下~ 這沒有什么不好意思的，放棄第二種方法并不意味著我們是多么的愚蠢，而是說明我們從自己身上又學(xué)到了很多！

(公元前1800年）醫(yī)生：來，試試吃點(diǎn)兒這種草根，感謝偉大的部落守護(hù)神賜與我們神藥！
(公元900年）醫(yī)生：別再吃那種草根，簡直是野蠻不開化不尊重上帝，這是一篇祈禱詞，每天虔誠地向上帝祈禱一次，不久就會治愈你的疾病。
(公元1650年）醫(yī)生：祈禱？！封建迷信?。?！來，只要喝下這種藥水，什么病都能治好！
(公元1960年）醫(yī)生：什么藥水？早就不用了！別喝那騙人的”萬靈藥”，還是這種藥片的療效快！
(公元1995年）醫(yī)生：哪個庸醫(yī)給你開的處方？那種藥片吃半瓶也抵不上這一粒，來來來，試試科技新成果—抗生素
(公元2003年）醫(yī)生:據(jù)最新科學(xué)研究，抗生素副作用太強(qiáng)，畢竟是人造的東西呀……來，試試吃點(diǎn)兒這種草根！早在公元前1800年，文獻(xiàn)就有記載了。
返璞歸真，大抵如此了。

第三次的繪圖代碼

這次我們考慮的更多，希望在點(diǎn)與點(diǎn)之間充滿我們的筆畫，很自然的我們就需要一個循環(huán)來做這樣的事情。我們的筆畫有兩種，普通的實(shí)心和刷子，實(shí)心的話，用circle來畫也不失為一個好主意；刷子的話，我們可能需要一個刷子的圖案來填充了。

下面是我們新的Brush類：

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
  self.last_pos = None
  self.space = 1
  # if style is True, normal solid brush
  # if style is False, png brush
  self.style = False
  # load brush style png
  self.brush = pygame.image.load("brush.png").convert_alpha()
  # set the current brush depends on size
  self.brush_now = self.brush.subsurface((0,0), (1, 1))

 def start_draw(self, pos):
  self.drawing = True
  self.last_pos = pos
 def end_draw(self):
  self.drawing = False

 def set_brush_style(self, style):
  print "* set brush style to", style
  self.style = style
 def get_brush_style(self):
  return self.style

 def set_size(self, size):
  if size < 0.5: size = 0.5
  elif size > 50: size = 50
  print "* set brush size to", size
  self.size = size
  self.brush_now = self.brush.subsurface((0,0), (size*2, size*2))
 def get_size(self):
  return self.size

 def draw(self, pos):
  if self.drawing:
   for p in self._get_points(pos):
    # draw eveypoint between them
    if self.style == False:
     pygame.draw.circle(self.screen,
       self.color, p, self.size)
    else:
     self.screen.blit(self.brush_now, p)

   self.last_pos = pos

 def _get_points(self, pos):
  """ Get all points between last_point ~ now_point. """
  points = [ (self.last_pos[0], self.last_pos[1]) ]
  len_x = pos[0] - self.last_pos[0]
  len_y = pos[1] - self.last_pos[1]
  length = math.sqrt(len_x ** 2 + len_y ** 2)
  step_x = len_x / length
  step_y = len_y / length
  for i in xrange(int(length)):
   points.append(
     (points[-1][0] + step_x, points[-1][1] + step_y))
  points = map(lambda x:(int(0.5+x[0]), int(0.5+x[1])), points)
  # return light-weight, uniq list
  return list(set(points))

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
  self.last_pos = None
  self.space = 1
  # if style is True, normal solid brush
  # if style is False, png brush
  self.style = False
  # load brush style png
  self.brush = pygame.image.load("brush.png").convert_alpha()
  # set the current brush depends on size
  self.brush_now = self.brush.subsurface((0,0), (1, 1))
 
 def start_draw(self, pos):
  self.drawing = True
  self.last_pos = pos
 def end_draw(self):
  self.drawing = False
 
 def set_brush_style(self, style):
  print "* set brush style to", style
  self.style = style
 def get_brush_style(self):
  return self.style
 
 def set_size(self, size):
  if size < 0.5: size = 0.5
  elif size > 50: size = 50
  print "* set brush size to", size
  self.size = size
  self.brush_now = self.brush.subsurface((0,0), (size*2, size*2))
 def get_size(self):
  return self.size
 
 def draw(self, pos):
  if self.drawing:
   for p in self._get_points(pos):
    # draw eveypoint between them
    if self.style == False:
     pygame.draw.circle(self.screen,
       self.color, p, self.size)
    else:
     self.screen.blit(self.brush_now, p)
 
   self.last_pos = pos
 
 def _get_points(self, pos):
  """ Get all points between last_point ~ now_point. """
  points = [ (self.last_pos[0], self.last_pos[1]) ]
  len_x = pos[0] - self.last_pos[0]
  len_y = pos[1] - self.last_pos[1]
  length = math.sqrt(len_x ** 2 + len_y ** 2)
  step_x = len_x / length
  step_y = len_y / length
  for i in xrange(int(length)):
   points.append(
     (points[-1][0] + step_x, points[-1][1] + step_y))
  points = map(lambda x:(int(0.5+x[0]), int(0.5+x[1])), points)
  # return light-weight, uniq list
  return list(set(points))

我們增加了幾個方法，_get_points()返回上一個點(diǎn)到現(xiàn)在點(diǎn)之間所有的點(diǎn)（這話聽著真別扭），draw根據(jù)這些點(diǎn)填充。
同時我們把get_size()、set_size()也加上了，用來設(shè)定當(dāng)前筆刷的大小。
而變化最大的，則是set_style()和get_style()，我們現(xiàn)在載入一個PNG圖片作為筆刷的樣式，當(dāng)style==True的時候，draw不再使用circle填充，而是使用這個PNG樣式，當(dāng)然，這個樣式大小也是應(yīng)該可調(diào)的，所有我們在set_size()中，會根據(jù)size大小實(shí)時的調(diào)整PNG筆刷。

當(dāng)然，我們得在主循環(huán)中調(diào)用set方法，才能讓這些東西工作起來~ 過一會兒再講。再回顧下我們的樣式，還有什么？顏色……我們馬上把顏色設(shè)置代碼也加進(jìn)去吧，太簡單了！我這里就先偷偷懶了~

控制代碼

到現(xiàn)在，我們已經(jīng)完成了繪圖部分的所有功能了?，F(xiàn)在已經(jīng)可以在屏幕上自由發(fā)揮了，但是筆刷的顏色和大小好像不能改啊……我們有這樣的接口你卻不調(diào)用，浪費(fèi)了。
趁熱打鐵趕快把我們這個畫板完成吧~

2015128163600970.jpg (550×430)

現(xiàn)在實(shí)際寫的時候才發(fā)現(xiàn)，因?yàn)槲覀冊O(shè)置了顏色需要對刷子也有效，所以實(shí)際上set_color方法還有一點(diǎn)點(diǎn)收尾工作需要做：

 def set_color(self, color):
  self.color = color
  for i in xrange(self.brush.get_width()):
   for j in xrange(self.brush.get_height()):
    self.brush.set_at((i, j),
      color + (self.brush.get_at((i, j)).a,))

 def set_color(self, color):
  self.color = color
  for i in xrange(self.brush.get_width()):
   for j in xrange(self.brush.get_height()):
    self.brush.set_at((i, j),
      color + (self.brush.get_at((i, j)).a,))

也就是在設(shè)定color的時候，順便把筆刷的顏色也改了，但是要保留原來的alpha值，其實(shí)也很簡單就是了……

按鈕菜單部分

上圖可以看到，按鈕部分分別為鉛筆、毛筆、尺寸大小、（當(dāng)前樣式）、顏色選擇者幾個組成。我們只以筆刷選擇為例講解一下，其他的都是類似的。

# 初始化部分
  self.sizes = [
    pygame.image.load("big.png").convert_alpha(),
    pygame.image.load("small.png").convert_alpha()
   ]
  self.sizes_rect = []
  for (i, img) in enumerate(self.sizes):
   rect = pygame.Rect(10 + i * 32, 138, 32, 32)
   self.sizes_rect.append(rect)

# 繪制部分
  for (i, img) in enumerate(self.pens):
   self.screen.blit(img, self.pens_rect[i].topleft)

# 點(diǎn)擊判斷部分
  for (i, rect) in enumerate(self.pens_rect):
   if rect.collidepoint(pos):
    self.brush.set_brush_style(bool(i))
    return True

# 初始化部分
  self.sizes = [
    pygame.image.load("big.png").convert_alpha(),
    pygame.image.load("small.png").convert_alpha()
   ]
  self.sizes_rect = []
  for (i, img) in enumerate(self.sizes):
   rect = pygame.Rect(10 + i * 32, 138, 32, 32)
   self.sizes_rect.append(rect)
 
# 繪制部分
  for (i, img) in enumerate(self.pens):
   self.screen.blit(img, self.pens_rect[i].topleft)
 
# 點(diǎn)擊判斷部分
  for (i, rect) in enumerate(self.pens_rect):
   if rect.collidepoint(pos):
    self.brush.set_brush_style(bool(i))
    return True

這些代碼實(shí)際上是我這個例子最想給大家說明的地方，按鈕式我們從未接觸過的東西，然而游戲中按鈕的應(yīng)用我都不必說。

不過這代碼也都不困難，基本都是我們學(xué)過的東西，只不過變換了一下組合而已，我稍微說明一下：

初始化部分：讀入圖標(biāo)，并給每個圖標(biāo)一個Rect
繪制部分：根據(jù)圖表的Rect繪制圖表
點(diǎn)擊判斷部分：根據(jù)點(diǎn)擊的位置，依靠“碰撞”來判斷這個按鈕是否被點(diǎn)擊，若點(diǎn)擊了，則做相應(yīng)的操作（這里是設(shè)置樣式）后返回True。這里的collidepoint()是新內(nèi)容，也就是Rect的“碰撞”函數(shù)，它接收一個坐標(biāo)，如果在Rect內(nèi)部，就返回True，否則False。

好像也就如此，有了一定的知識積累后，新東西的學(xué)習(xí)也變得易如反掌了。

在這個代碼中，為了明晰，我把各個按鈕按照功能都分成了好幾組，在實(shí)際應(yīng)用中按鈕數(shù)量很多的時候可能并不合適，請自己斟酌。

完整代碼

OK，這就結(jié)束了~ 下面把整個代碼貼出來。不過，我是一邊寫代碼一遍寫文章，思路不是很連貫，而且python也好久不用了……如果有哪里寫的有問題（沒有就怪了），還請不吝指出！

import pygame
from pygame.locals import *
import math

# 2011/08/27 Version 1, first imported

class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
  self.last_pos = None
  self.space = 1
  # if style is True, normal solid brush
  # if style is False, png brush
  self.style = False
  # load brush style png
  self.brush = pygame.image.load("brush.png").convert_alpha()
  # set the current brush depends on size
  self.brush_now = self.brush.subsurface((0,0), (1, 1))

 def start_draw(self, pos):
  self.drawing = True
  self.last_pos = pos
 def end_draw(self):
  self.drawing = False

 def set_brush_style(self, style):
  print "* set brush style to", style
  self.style = style
 def get_brush_style(self):
  return self.style

 def get_current_brush(self):
  return self.brush_now

 def set_size(self, size):
  if size < 0.5: size = 0.5
  elif size > 32: size = 32
  print "* set brush size to", size
  self.size = size
  self.brush_now = self.brush.subsurface((0,0), (size*2, size*2))
 def get_size(self):
  return self.size

 def set_color(self, color):
  self.color = color
  for i in xrange(self.brush.get_width()):
   for j in xrange(self.brush.get_height()):
    self.brush.set_at((i, j),
      color + (self.brush.get_at((i, j)).a,))
 def get_color(self):
  return self.color

 def draw(self, pos):
  if self.drawing:
   for p in self._get_points(pos):
    # draw eveypoint between them
    if self.style == False:
     pygame.draw.circle(self.screen, self.color, p, self.size)
    else:
     self.screen.blit(self.brush_now, p)

   self.last_pos = pos

 def _get_points(self, pos):
  """ Get all points between last_point ~ now_point. """
  points = [ (self.last_pos[0], self.last_pos[1]) ]
  len_x = pos[0] - self.last_pos[0]
  len_y = pos[1] - self.last_pos[1]
  length = math.sqrt(len_x ** 2 + len_y ** 2)
  step_x = len_x / length
  step_y = len_y / length
  for i in xrange(int(length)):
   points.append(
     (points[-1][0] + step_x, points[-1][1] + step_y))
  points = map(lambda x:(int(0.5+x[0]), int(0.5+x[1])), points)
  # return light-weight, uniq integer point list
  return list(set(points))

class Menu():
 def __init__(self, screen):
  self.screen = screen
  self.brush = None
  self.colors = [
    (0xff, 0x00, 0xff), (0x80, 0x00, 0x80),
    (0x00, 0x00, 0xff), (0x00, 0x00, 0x80),
    (0x00, 0xff, 0xff), (0x00, 0x80, 0x80),
    (0x00, 0xff, 0x00), (0x00, 0x80, 0x00),
    (0xff, 0xff, 0x00), (0x80, 0x80, 0x00),
    (0xff, 0x00, 0x00), (0x80, 0x00, 0x00),
    (0xc0, 0xc0, 0xc0), (0xff, 0xff, 0xff),
    (0x00, 0x00, 0x00), (0x80, 0x80, 0x80),
   ]
  self.colors_rect = []
  for (i, rgb) in enumerate(self.colors):
   rect = pygame.Rect(10 + i % 2 * 32, 254 + i / 2 * 32, 32, 32)
   self.colors_rect.append(rect)

  self.pens = [
    pygame.image.load("pen1.png").convert_alpha(),
    pygame.image.load("pen2.png").convert_alpha()
   ]
  self.pens_rect = []
  for (i, img) in enumerate(self.pens):
   rect = pygame.Rect(10, 10 + i * 64, 64, 64)
   self.pens_rect.append(rect)

  self.sizes = [
    pygame.image.load("big.png").convert_alpha(),
    pygame.image.load("small.png").convert_alpha()
   ]
  self.sizes_rect = []
  for (i, img) in enumerate(self.sizes):
   rect = pygame.Rect(10 + i * 32, 138, 32, 32)
   self.sizes_rect.append(rect)

 def set_brush(self, brush):
  self.brush = brush

 def draw(self):
  # draw pen style button
  for (i, img) in enumerate(self.pens):
   self.screen.blit(img, self.pens_rect[i].topleft)
  # draw < > buttons
  for (i, img) in enumerate(self.sizes):
   self.screen.blit(img, self.sizes_rect[i].topleft)
  # draw current pen / color
  self.screen.fill((255, 255, 255), (10, 180, 64, 64))
  pygame.draw.rect(self.screen, (0, 0, 0), (10, 180, 64, 64), 1)
  size = self.brush.get_size()
  x = 10 + 32
  y = 180 + 32
  if self.brush.get_brush_style():
   x = x - size
   y = y - size
   self.screen.blit(self.brush.get_current_brush(), (x, y))
  else:
   pygame.draw.circle(self.screen,
     self.brush.get_color(), (x, y), size)
  # draw colors panel
  for (i, rgb) in enumerate(self.colors):
   pygame.draw.rect(self.screen, rgb, self.colors_rect[i])

 def click_button(self, pos):
  # pen buttons
  for (i, rect) in enumerate(self.pens_rect):
   if rect.collidepoint(pos):
    self.brush.set_brush_style(bool(i))
    return True
  # size buttons
  for (i, rect) in enumerate(self.sizes_rect):
   if rect.collidepoint(pos):
    if i: # i == 1, size down
     self.brush.set_size(self.brush.get_size() - 0.5)
    else:
     self.brush.set_size(self.brush.get_size() + 0.5)
    return True
  # color buttons
  for (i, rect) in enumerate(self.colors_rect):
   if rect.collidepoint(pos):
    self.brush.set_color(self.colors[i])
    return True
  return False

class Painter():
 def __init__(self):
  self.screen = pygame.display.set_mode((800, 600))
  pygame.display.set_caption("Painter")
  self.clock = pygame.time.Clock()
  self.brush = Brush(self.screen)
  self.menu = Menu(self.screen)
  self.menu.set_brush(self.brush)

 def run(self):
  self.screen.fill((255, 255, 255))
  while True:
   # max fps limit
   self.clock.tick(30)
   for event in pygame.event.get():
    if event.type == QUIT:
     return
    elif event.type == KEYDOWN:
     # press esc to clear screen
     if event.key == K_ESCAPE:
      self.screen.fill((255, 255, 255))
    elif event.type == MOUSEBUTTONDOWN:
     # <= 74, coarse judge here can save much time
     if ((event.pos)[0] <= 74 and
       self.menu.click_button(event.pos)):
      # if not click on a functional button, do drawing
      pass
     else:
      self.brush.start_draw(event.pos)
    elif event.type == MOUSEMOTION:
     self.brush.draw(event.pos)
    elif event.type == MOUSEBUTTONUP:
     self.brush.end_draw()

   self.menu.draw()
   pygame.display.update()

if __name__ == '__main__':
 app = Painter()
 app.run()

import pygame
from pygame.locals import *
import math
 
# 2011/08/27 Version 1, first imported
 
class Brush():
 def __init__(self, screen):
  self.screen = screen
  self.color = (0, 0, 0)
  self.size = 1
  self.drawing = False
  self.last_pos = None
  self.space = 1
  # if style is True, normal solid brush
  # if style is False, png brush
  self.style = False
  # load brush style png
  self.brush = pygame.image.load("brush.png").convert_alpha()
  # set the current brush depends on size
  self.brush_now = self.brush.subsurface((0,0), (1, 1))
 
 def start_draw(self, pos):
  self.drawing = True
  self.last_pos = pos
 def end_draw(self):
  self.drawing = False
 
 def set_brush_style(self, style):
  print "* set brush style to", style
  self.style = style
 def get_brush_style(self):
  return self.style
 
 def get_current_brush(self):
  return self.brush_now
 
 def set_size(self, size):
  if size < 0.5: size = 0.5
  elif size > 32: size = 32
  print "* set brush size to", size
  self.size = size
  self.brush_now = self.brush.subsurface((0,0), (size*2, size*2))
 def get_size(self):
  return self.size
 
 def set_color(self, color):
  self.color = color
  for i in xrange(self.brush.get_width()):
   for j in xrange(self.brush.get_height()):
    self.brush.set_at((i, j),
      color + (self.brush.get_at((i, j)).a,))
 def get_color(self):
  return self.color
 
 def draw(self, pos):
  if self.drawing:
   for p in self._get_points(pos):
    # draw eveypoint between them
    if self.style == False:
     pygame.draw.circle(self.screen, self.color, p, self.size)
    else:
     self.screen.blit(self.brush_now, p)
 
   self.last_pos = pos
 
 def _get_points(self, pos):
  """ Get all points between last_point ~ now_point. """
  points = [ (self.last_pos[0], self.last_pos[1]) ]
  len_x = pos[0] - self.last_pos[0]
  len_y = pos[1] - self.last_pos[1]
  length = math.sqrt(len_x ** 2 + len_y ** 2)
  step_x = len_x / length
  step_y = len_y / length
  for i in xrange(int(length)):
   points.append(
     (points[-1][0] + step_x, points[-1][1] + step_y))
  points = map(lambda x:(int(0.5+x[0]), int(0.5+x[1])), points)
  # return light-weight, uniq integer point list
  return list(set(points))
 
class Menu():
 def __init__(self, screen):
  self.screen = screen
  self.brush = None
  self.colors = [
    (0xff, 0x00, 0xff), (0x80, 0x00, 0x80),
    (0x00, 0x00, 0xff), (0x00, 0x00, 0x80),
    (0x00, 0xff, 0xff), (0x00, 0x80, 0x80),
    (0x00, 0xff, 0x00), (0x00, 0x80, 0x00),
    (0xff, 0xff, 0x00), (0x80, 0x80, 0x00),
    (0xff, 0x00, 0x00), (0x80, 0x00, 0x00),
    (0xc0, 0xc0, 0xc0), (0xff, 0xff, 0xff),
    (0x00, 0x00, 0x00), (0x80, 0x80, 0x80),
   ]
  self.colors_rect = []
  for (i, rgb) in enumerate(self.colors):
   rect = pygame.Rect(10 + i % 2 * 32, 254 + i / 2 * 32, 32, 32)
   self.colors_rect.append(rect)
 
  self.pens = [
    pygame.image.load("pen1.png").convert_alpha(),
    pygame.image.load("pen2.png").convert_alpha()
   ]
  self.pens_rect = []
  for (i, img) in enumerate(self.pens):
   rect = pygame.Rect(10, 10 + i * 64, 64, 64)
   self.pens_rect.append(rect)
 
  self.sizes = [
    pygame.image.load("big.png").convert_alpha(),
    pygame.image.load("small.png").convert_alpha()
   ]
  self.sizes_rect = []
  for (i, img) in enumerate(self.sizes):
   rect = pygame.Rect(10 + i * 32, 138, 32, 32)
   self.sizes_rect.append(rect)
 
 def set_brush(self, brush):
  self.brush = brush
 
 def draw(self):
  # draw pen style button
  for (i, img) in enumerate(self.pens):
   self.screen.blit(img, self.pens_rect[i].topleft)
  # draw < > buttons
  for (i, img) in enumerate(self.sizes):
   self.screen.blit(img, self.sizes_rect[i].topleft)
  # draw current pen / color
  self.screen.fill((255, 255, 255), (10, 180, 64, 64))
  pygame.draw.rect(self.screen, (0, 0, 0), (10, 180, 64, 64), 1)
  size = self.brush.get_size()
  x = 10 + 32
  y = 180 + 32
  if self.brush.get_brush_style():
   x = x - size
   y = y - size
   self.screen.blit(self.brush.get_current_brush(), (x, y))
  else:
   pygame.draw.circle(self.screen,
     self.brush.get_color(), (x, y), size)
  # draw colors panel
  for (i, rgb) in enumerate(self.colors):
   pygame.draw.rect(self.screen, rgb, self.colors_rect[i])
 
 def click_button(self, pos):
  # pen buttons
  for (i, rect) in enumerate(self.pens_rect):
   if rect.collidepoint(pos):
    self.brush.set_brush_style(bool(i))
    return True
  # size buttons
  for (i, rect) in enumerate(self.sizes_rect):
   if rect.collidepoint(pos):
    if i: # i == 1, size down
     self.brush.set_size(self.brush.get_size() - 0.5)
    else:
     self.brush.set_size(self.brush.get_size() + 0.5)
    return True
  # color buttons
  for (i, rect) in enumerate(self.colors_rect):
   if rect.collidepoint(pos):
    self.brush.set_color(self.colors[i])
    return True
  return False
 
class Painter():
 def __init__(self):
  self.screen = pygame.display.set_mode((800, 600))
  pygame.display.set_caption("Painter")
  self.clock = pygame.time.Clock()
  self.brush = Brush(self.screen)
  self.menu = Menu(self.screen)
  self.menu.set_brush(self.brush)
 
 def run(self):
  self.screen.fill((255, 255, 255))
  while True:
   # max fps limit
   self.clock.tick(30)
   for event in pygame.event.get():
    if event.type == QUIT:
     return
    elif event.type == KEYDOWN:
     # press esc to clear screen
     if event.key == K_ESCAPE:
      self.screen.fill((255, 255, 255))
    elif event.type == MOUSEBUTTONDOWN:
     # <= 74, coarse judge here can save much time
     if ((event.pos)[0] <= 74 and
       self.menu.click_button(event.pos)):
      # if not click on a functional button, do drawing
      pass
     else:
      self.brush.start_draw(event.pos)
    elif event.type == MOUSEMOTION:
     self.brush.draw(event.pos)
    elif event.type == MOUSEBUTTONUP:
     self.brush.end_draw()
 
   self.menu.draw()
   pygame.display.update()
 
if __name__ == '__main__':
 app = Painter()
 app.run()

200行左右，注釋也不是很多，因?yàn)樵谶@兩篇文章里都講了，有哪里不明白的請留言，我會根據(jù)實(shí)際情況再改改。

本次使用的資源文件打包

這次的pygame知識點(diǎn)：