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使用Python编写简单的画图板程序的示例教程

时间：2022-07-07 17:08 编辑：来源：阅读：
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摘要：使用Python编写简单的画图板程序的示例教程

从这次开始，我会由简单到困难（其实也不会困难到哪里去）讲几个例程，每一个例程都是我自己写（或者修改，那样的话我会提供原始出处）的，都具有一定的操作性和娱乐性。例程中汇尽量覆盖到以前所讲的pygame中方方面面，如果看到哪一步不明白，那就再回去复习复习，基本没有人会看一遍什么都记住什么都掌握的，重复是学习之母，实践是掌握一门技艺的最好手段！这次就先从一个最简单的程序开始，说实话有些太简单我都不好意思拿出手了，不过从简单的开始，容易建立自信培养兴趣。兴趣是学习之母嘛。我们这次做一个画板，类似Windows里自带的画板，还记不记得第一次接触电脑用画板时的惊叹？现在想起来其实那个真的非常简陋，不过我们的比那个还要朴素，因为打算一篇讲完，就不追加很多功能了，等你把这一次讲解的都理解了，很容易可以自己给它增加新的机能。没准，你就开发出一个非常牛X的画图工具击败了Photoshop，然后日进斗金名垂千古（众：喂，别做梦了！）…… [b]功能样式[/b] 做之前总要有个数，我们的程序做出来会是个什么样子。所谓从顶到底或者从底到顶啥的，咱就不研究了，这个小程序随你怎么弄了，而且我们主要是来熟悉pygame，高级的软件设计方法一概不谈~ 因为是抄袭画图板，也就是鼠标按住了能在上面涂涂画画就是了，选区、放大镜、滴管功能啥的就统统不要了。画笔的话，基本的铅笔画笔总是要的，也可以考虑加一个刷子画笔，这样有一点变化；然后颜色应该是要的，否则太过单调了，不过调色板啥的就暂时免了，提供几个候选色就好了；然后橡皮……橡皮不就是白色的画笔么？免了免了！还有啥？似乎够了。。。 OK，开始吧！ [b]框架[/b] pygame程序的框架都是差不多的，考虑到我们这个程序的实际作用，大概建立这样的一个代码架子就可以了。

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()

这个非常简单，准备好画板类，画笔类，暂时还都是空的，其实也就是做了一些pygame的初始化工作。如果这样还不能读懂的话，您需要把前面22篇从头再看看，有几句话不懂就看几遍：）这里只有一点要注意一下，我们把帧率控制在了30，没有人希望在画画的时候，CPU风扇狂转的。而且只是画板，没有自动运动的物体，纯粹的交互驱动，我们也不需要很高的刷新率。 [b]第一次的绘图代码[/b] 按住鼠标然后在上面移动就画东西，我们很容易可以想到这个流程：按下左键 → 绘制flag开移动鼠标 → flag开的时候，在移动坐标上留下痕迹放开左键 → 绘制flag关按下左键 → 绘制flag开移动鼠标 → flag开的时候，在移动坐标上留下痕迹放开左键 → 绘制flag关立刻试一试吧：

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()

框架中有的代码我就不贴了，用#*#*#*#*#代替，最后会给出完整代码的。这里主要是给Brush类增加了一些功能，也就是上面我们提到的流程想对应的功能。留下痕迹，我们是使用了在坐标上画圆的方法，这也是最容易想到的方法。这样的效果好不好呢？我们试一试： [img]http://files.jb51.net/file_images/article/201512/2015128162649149.jpg?201511816271[/img] 哦，太糟糕了，再劣质的铅笔也不会留下这样断断续续的笔迹。上面是当我们鼠标移动的快一些的时候，点之间的间距很大；下面是移动慢一些的时候，勉勉强强显得比较连续。从这里我们也可以看到pygame事件响应的频度（这个距离和上面设置的最大帧率有关）。怎么办？要修改帧率让pygame平滑的反应么？不，那样做得不偿失，换一个角度思考，如果有间隙，我们让pygame把这个间隙连接起来不好么？ [b]第二次的绘图代码[/b] 思路还是很简单，当移动的时候，Brush在上一次和这一次的点之间连一条线就好了：

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

[img]http://files.jb51.net/file_images/article/201512/2015128162728237.jpg?2015118162736[/img] 在__init__和start_draw中各加了一句，用来存储上一个点的位置，然后draw也由刚刚的话圆变成画线，效果如何？我们来试试。嗯，好多了，如果你动作能温柔一些的话，线条已经很圆润了，至少没有断断续续的存在了。满足了么？我希望你的回答是“NO”，为什么，如果你划线很快的话，你就能明显看出棱角来，就好像左图上半部分，还是能看出是由几个线段组合的。只有永不满足，我们才能不停进步。不过对我们这个例程而言，差不多了，一般人在真正画东西的时候，也不会动那么快的：）那么这个就是我们最终的绘图机制了么？回头看看我们的样式，好用还需要加一个笔刷……所谓笔刷，不仅仅是很粗，而且是由很多细小的毛组成，画出来的线是给人一种一缕一缕的感觉，用这个方法可以实现么？好像非常非常的困难。。。孜孜不倦的我们再次进入了沉思…… 这个时候，如果没有头绪，就得借鉴一下前辈的经验了。看看人家是如何实现的？ [img]http://files.jb51.net/file_images/article/201512/2015128162744801.jpg?2015118162752[/img] 如果你的Photoshop不错，应该知道它里面复杂的笔刷设定，而Photoshop画出来的笔画，并不是真正一直线的，而是由无数细小的点组成的，这些点之间的间距是如此的密，以至于我们误会它是一直线……所以说，我们还得回到第一种方法上，把它发扬光大一下~ 这没有什么不好意思的，放弃第二种方法并不意味着我们是多么的愚蠢，而是说明我们从自己身上又学到了很多！ (公元前1800年）医生：来，试试吃点儿这种草根，感谢伟大的部落守护神赐与我们神药！ (公元900年）医生：别再吃那种草根，简直是野蛮不开化不尊重上帝，这是一篇祈祷词，每天虔诚地向上帝祈祷一次，不久就会治愈你的疾病。 (公元1650年）医生：祈祷？！封建迷信！！！来，只要喝下这种药水，什么病都能治好！ (公元1960年）医生：什么药水？早就不用了！别喝那骗人的”万灵药”，还是这种药片的疗效快！ (公元1995年）医生：哪个庸医给你开的处方？那种药片吃半瓶也抵不上这一粒，来来来，试试科技新成果—抗生素 (公元2003年）医生:据最新科学研究，抗生素副作用太强，毕竟是人造的东西呀……来，试试吃点儿这种草根！早在公元前1800年，文献就有记载了。返璞归真，大抵如此了。 [b]第三次的绘图代码[/b] 这次我们考虑的更多，希望在点与点之间充满我们的笔画，很自然的我们就需要一个循环来做这样的事情。我们的笔画有两种，普通的实心和刷子，实心的话，用circle来画也不失为一个好主意；刷子的话，我们可能需要一个刷子的图案来填充了。下面是我们新的Brush类：

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))

我们增加了几个方法，_get_points()返回上一个点到现在点之间所有的点（这话听着真别扭），draw根据这些点填充。同时我们把get_size()、set_size()也加上了，用来设定当前笔刷的大小。而变化最大的，则是set_style()和get_style()，我们现在载入一个PNG图片作为笔刷的样式，当style==True的时候，draw不再使用circle填充，而是使用这个PNG样式，当然，这个样式大小也是应该可调的，所有我们在set_size()中，会根据size大小实时的调整PNG笔刷。当然，我们得在主循环中调用set方法，才能让这些东西工作起来~ 过一会儿再讲。再回顾下我们的样式，还有什么？颜色……我们马上把颜色设置代码也加进去吧，太简单了！我这里就先偷偷懒了~ [b]控制代码[/b] 到现在，我们已经完成了绘图部分的所有功能了。现在已经可以在屏幕上自由发挥了，但是笔刷的颜色和大小好像不能改啊……我们有这样的接口你却不调用，浪费了。趁热打铁赶快把我们这个画板完成吧~ [img]http://files.jb51.net/file_images/article/201512/2015128163600970.jpg?201511816368[/img]

现在实际写的时候才发现，因为我们设置了颜色需要对刷子也有效，所以实际上set_color方法还有一点点收尾工作需要做：

 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,))

也就是在设定color的时候，顺便把笔刷的颜色也改了，但是要保留原来的alpha值，其实也很简单就是了…… [b]按钮菜单部分[/b] 上图可以看到，按钮部分分别为铅笔、毛笔、尺寸大小、（当前样式）、颜色选择者几个组成。我们只以笔刷选择为例讲解一下，其他的都是类似的。

# 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)

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

# 点击判断部分
  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)
 
# 绘制部分
  for (i, img) in enumerate(self.pens):
   self.screen.blit(img, self.pens_rect[i].topleft)
 
# 点击判断部分
  for (i, rect) in enumerate(self.pens_rect):
   if rect.collidepoint(pos):
    self.brush.set_brush_style(bool(i))
    return True

这些代码实际上是我这个例子最想给大家说明的地方，按钮式我们从未接触过的东西，然而游戏中按钮的应用我都不必说。不过这代码也都不困难，基本都是我们学过的东西，只不过变换了一下组合而已，我稍微说明一下：初始化部分：读入图标，并给每个图标一个Rect 绘制部分：根据图表的Rect绘制图表点击判断部分：根据点击的位置，依靠“碰撞”来判断这个按钮是否被点击，若点击了，则做相应的操作（这里是设置样式）后返回True。这里的collidepoint()是新内容，也就是Rect的“碰撞”函数，它接收一个坐标，如果在Rect内部，就返回True，否则False。好像也就如此，有了一定的知识积累后，新东西的学习也变得易如反掌了。在这个代码中，为了明晰，我把各个按钮按照功能都分成了好几组，在实际应用中按钮数量很多的时候可能并不合适，请自己斟酌。 [b]完整代码[/b] OK，这就结束了~ 下面把整个代码贴出来。不过，我是一边写代码一遍写文章，思路不是很连贯，而且python也好久不用了……如果有哪里写的有问题（没有就怪了），还请不吝指出！

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，注释也不是很多，因为在这两篇文章里都讲了，有哪里不明白的请留言，我会根据实际情况再改改。本次使用的资源文件打包这次的pygame知识点： [list] [*]屏幕Surface和图像Surface[/*] [*]图像绘制和图形绘制（是不是有人不明白“图像”和“图形”的区别？简单的说，图像指的是那些图片文件，图形指的是用命令画出来形状）[/*] [*]按钮的实现（新内容）[/*] [/list] 认真的朋友一定发现了本次没有涉及到动画和声音，毕竟这次只是简单的例子，太复杂了不免让人生畏。

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