1 #!/usr/bin/env python
2 # life.py -- A curses-based version of Conway's Game of Life.
3 # Contributed by AMK
4 #
5 # An empty board will be displayed, and the following commands are available:
6 #  E : Erase the board
7 #  R : Fill the board randomly
8 #  S : Step for a single generation
9 #  C : Update continuously until a key is struck
10 #  Q : Quit
11 #  Cursor keys :  Move the cursor around the board
12 #  Space or Enter : Toggle the contents of the cursor's position
13 #
14 # TODO :
15 #   Support the mouse
16 #   Use colour if available
17 #   Make board updates faster
18 #
19 
20 import random, string, traceback
21 import curses
22 
23 class LifeBoard:
24     """Encapsulates a Life board
25 
26     Attributes:
27     X,Y : horizontal and vertical size of the board
28     state : dictionary mapping (x,y) to 0 or 1
29 
30     Methods:
31     display(update_board) -- If update_board is true, compute the
32                              next generation.  Then display the state
33                              of the board and refresh the screen.
34     erase() -- clear the entire board
35     makeRandom() -- fill the board randomly
36     set(y,x) -- set the given cell to Live; doesn't refresh the screen
37     toggle(y,x) -- change the given cell from live to dead, or vice
38                    versa, and refresh the screen display
39 
40     """
41     def __init__(self, scr, char=ord('*')):
42         """Create a new LifeBoard instance.
43 
44         scr -- curses screen object to use for display
45         char -- character used to render live cells (default: '*')
46         """
47         self.state = {}
48         self.scr = scr
49         Y, X = self.scr.getmaxyx()
50         self.X, self.Y = X-2, Y-2-1
51         self.char = char
52         self.scr.clear()
53 
54         # Draw a border around the board
55         border_line = '+'+(self.X*'-')+'+'
56         self.scr.addstr(0, 0, border_line)
57         self.scr.addstr(self.Y+1,0, border_line)
58         for y in range(0, self.Y):
59             self.scr.addstr(1+y, 0, '|')
60             self.scr.addstr(1+y, self.X+1, '|')
61         self.scr.refresh()
62 
63     def set(self, y, x):
64         """Set a cell to the live state"""
65         if x<0 or self.X<=x or y<0 or self.Y<=y:
66             raise ValueError, "Coordinates out of range %i,%i"% (y,x)
67         self.state[x,y] = 1
68 
69     def toggle(self, y, x):
70         """Toggle a cell's state between live and dead"""
71         if x<0 or self.X<=x or y<0 or self.Y<=y:
72             raise ValueError, "Coordinates out of range %i,%i"% (y,x)
73         if self.state.has_key( (x,y) ):
74             del self.state[x,y]
75             self.scr.addch(y+1, x+1, ' ')
76         else:
77             self.state[x,y] = 1
78             self.scr.addch(y+1, x+1, self.char)
79         self.scr.refresh()
80 
81     def erase(self):
82         """Clear the entire board and update the board display"""
83         self.state = {}
84         self.display(update_board=False)
85 
86     def display(self, update_board=True):
87         """Display the whole board, optionally computing one generation"""
88         M,N = self.X, self.Y
89         if not update_board:
90             for i in range(0, M):
91                 for j in range(0, N):
92                     if self.state.has_key( (i,j) ):
93                         self.scr.addch(j+1, i+1, self.char)
94                     else:
95                         self.scr.addch(j+1, i+1, ' ')
96             self.scr.refresh()
97             return
98 
99         d = {}
100         self.boring = 1
101         for i in range(0, M):
102             L = range( max(0, i-1), min(M, i+2) )
103             for j in range(0, N):
104                 s = 0
105                 live = self.state.has_key( (i,j) )
106                 for k in range( max(0, j-1), min(N, j+2) ):
107                     for l in L:
108                         if self.state.has_key( (l,k) ):
109                             s += 1
110                 s -= live
111                 if s == 3:
112                     # Birth
113                     d[i,j] = 1
114                     self.scr.addch(j+1, i+1, self.char)
115                     if not live: self.boring = 0
116                 elif s == 2 and live: d[i,j] = 1       # Survival
117                 elif live:
118                     # Death
119                     self.scr.addch(j+1, i+1, ' ')
120                     self.boring = 0
121         self.state = d
122         self.scr.refresh()
123 
124     def makeRandom(self):
125         "Fill the board with a random pattern"
126         self.state = {}
127         for i in range(0, self.X):
128             for j in range(0, self.Y):
129                 if random.random() > 0.5:
130                     self.set(j,i)
131 
132 
133 def erase_menu(stdscr, menu_y):
134     "Clear the space where the menu resides"
135     stdscr.move(menu_y, 0)
136     stdscr.clrtoeol()
137     stdscr.move(menu_y+1, 0)
138     stdscr.clrtoeol()
139 
140 def display_menu(stdscr, menu_y):
141     "Display the menu of possible keystroke commands"
142     erase_menu(stdscr, menu_y)
143     stdscr.addstr(menu_y, 4,
144                   'Use the cursor keys to move, and space or Enter to toggle a cell.')
145     stdscr.addstr(menu_y+1, 4,
146                   'E)rase the board, R)andom fill, S)tep once or C)ontinuously, Q)uit')
147 
148 def keyloop(stdscr):
149     # Clear the screen and display the menu of keys
150     stdscr.clear()
151     stdscr_y, stdscr_x = stdscr.getmaxyx()
152     menu_y = (stdscr_y-3)-1
153     display_menu(stdscr, menu_y)
154 
155     # Allocate a subwindow for the Life board and create the board object
156     subwin = stdscr.subwin(stdscr_y-3, stdscr_x, 0, 0)
157     board = LifeBoard(subwin, char=ord('*'))
158     board.display(update_board=False)
159 
160     # xpos, ypos are the cursor's position
161     xpos, ypos = board.X//2, board.Y//2
162 
163     # Main loop:
164     while (1):
165         stdscr.move(1+ypos, 1+xpos)     # Move the cursor
166         c = stdscr.getch()                # Get a keystroke
167         if 0<c<256:
168             c = chr(c)
169             if c in ' \n':
170                 board.toggle(ypos, xpos)
171             elif c in 'Cc':
172                 erase_menu(stdscr, menu_y)
173                 stdscr.addstr(menu_y, 6, ' Hit any key to stop continuously '
174                               'updating the screen.')
175                 stdscr.refresh()
176                 # Activate nodelay mode; getch() will return -1
177                 # if no keystroke is available, instead of waiting.
178                 stdscr.nodelay(1)
179                 while (1):
180                     c = stdscr.getch()
181                     if c != -1:
182                         break
183                     stdscr.addstr(0,0, '/')
184                     stdscr.refresh()
185                     board.display()
186                     stdscr.addstr(0,0, '+')
187                     stdscr.refresh()
188 
189                 stdscr.nodelay(0)       # Disable nodelay mode
190                 display_menu(stdscr, menu_y)
191 
192             elif c in 'Ee':
193                 board.erase()
194             elif c in 'Qq':
195                 break
196             elif c in 'Rr':
197                 board.makeRandom()
198                 board.display(update_board=False)
199             elif c in 'Ss':
200                 board.display()
201             else: pass                  # Ignore incorrect keys
202         elif c == curses.KEY_UP and ypos>0:            ypos -= 1
203         elif c == curses.KEY_DOWN and ypos<board.Y-1:  ypos += 1
204         elif c == curses.KEY_LEFT and xpos>0:          xpos -= 1
205         elif c == curses.KEY_RIGHT and xpos<board.X-1: xpos += 1
206         else:
207             # Ignore incorrect keys
208             pass
209 
210 
211 def main(stdscr):
212     keyloop(stdscr)                    # Enter the main loop
213 
214 
215 if __name__ == '__main__':
216     curses.wrapper(main)
217