Demo/curses/life.py

   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={} ; self.scr=scr
  48         Y, X = self.scr.getmaxyx()
  49         self.X, self.Y = X-2, Y-2-1
  50         self.char = char
  51         self.scr.clear()
  52
  53         # Draw a border around the board
  54         border_line='+'+(self.X*'-')+'+'
  55         self.scr.addstr(0, 0, border_line)
  56         self.scr.addstr(self.Y+1,0, border_line)
  57         for y in range(0, self.Y):
  58             self.scr.addstr(1+y, 0, '|')
  59             self.scr.addstr(1+y, self.X+1, '|')
  60         self.scr.refresh()
  61
  62     def set(self, y, x):
  63         """Set a cell to the live state"""
  64         if x<0 or self.X<=x or y<0 or self.Y<=y:
  65             raise ValueError, "Coordinates out of range %i,%i"% (y,x)
  66         self.state[x,y] = 1
  67
  68     def toggle(self, y, x):
  69         """Toggle a cell's state between live and dead"""
  70         if x<0 or self.X<=x or y<0 or self.Y<=y:
  71             raise ValueError, "Coordinates out of range %i,%i"% (y,x)
  72         if self.state.has_key( (x,y) ):
  73             del self.state[x,y]
  74             self.scr.addch(y+1, x+1, ' ')
  75         else:
  76             self.state[x,y]=1
  77             self.scr.addch(y+1, x+1, self.char)
  78         self.scr.refresh()
  79
  80     def erase(self):
  81         """Clear the entire board and update the board display"""
  82         self.state={}
  83         self.display(update_board=0)
  84
  85     def display(self, update_board=1):
  86         """Display the whole board, optionally computing one generation"""
  87         M,N = self.X, self.Y
  88         if not update_board:
  89             for i in range(0, M):
  90                 for j in range(0, N):
  91                         if self.state.has_key( (i,j) ):
  92                             self.scr.addch(j+1, i+1, self.char)
  93                         else:
  94                             self.scr.addch(j+1, i+1, ' ')
  95             self.scr.refresh()
  96             return
  97
  98         d={} ; self.boring=1
  99         for i in range(0, M):
 100             L=range( max(0, i-1), min(M, i+2) )
 101             for j in range(0, N):
 102                 s=0
 103                 live=self.state.has_key( (i,j) )
 104                 for k in range( max(0, j-1), min(N, j+2) ):
 105                     for l in L:
 106                         if self.state.has_key( (l,k) ):
 107                             s=s+1
 108                 s=s-live
 109                 if s==3:
 110                     # Birth
 111                     d[i,j]=1
 112                     self.scr.addch(j+1, i+1, self.char)
 113                     if not live: self.boring=0
 114                 elif s==2 and live: d[i,j]=1       # Survival
 115                 elif live:
 116                     # Death
 117                     self.scr.addch(j+1, i+1, ' ')
 118                     self.boring=0
 119         self.state=d
 120         self.scr.refresh()
 121
 122     def makeRandom(self):
 123         "Fill the board with a random pattern"
 124         self.state={}
 125         for i in range(0, self.X):
 126             for j in range(0, self.Y):
 127                 if random.random() > 0.5: self.set(j,i)
 128
 129
 130 def erase_menu(stdscr, menu_y):
 131     "Clear the space where the menu resides"
 132     stdscr.move(menu_y, 0) ; stdscr.clrtoeol()
 133     stdscr.move(menu_y+1, 0) ; stdscr.clrtoeol()
 134
 135 def display_menu(stdscr, menu_y):
 136     "Display the menu of possible keystroke commands"
 137     erase_menu(stdscr, menu_y)
 138     stdscr.addstr(menu_y, 4,
 139                   'Use the cursor keys to move, and space or Enter to toggle a cell.')
 140     stdscr.addstr(menu_y+1, 4,
 141                   'E)rase the board, R)andom fill, S)tep once or C)ontinuously, Q)uit')
 142
 143 def main(stdscr):
 144
 145     # Clear the screen and display the menu of keys
 146     stdscr.clear()
 147     stdscr_y, stdscr_x = stdscr.getmaxyx()
 148     menu_y=(stdscr_y-3)-1
 149     display_menu(stdscr, menu_y)
 150
 151     # Allocate a subwindow for the Life board and create the board object
 152     subwin=stdscr.subwin(stdscr_y-3, stdscr_x, 0, 0)
 153     board=LifeBoard(subwin, char=ord('*'))
 154     board.display(update_board=0)
 155
 156     # xpos, ypos are the cursor's position
 157     xpos, ypos = board.X/2, board.Y/2
 158
 159     # Main loop:
 160     while (1):
 161         stdscr.move(1+ypos, 1+xpos)     # Move the cursor
 162         c=stdscr.getch()                # Get a keystroke
 163         if 0<c<256:
 164             c=chr(c)
 165             if c in ' \n':
 166                 board.toggle(ypos, xpos)
 167             elif c in 'Cc':
 168                 erase_menu(stdscr, menu_y)
 169                 stdscr.addstr(menu_y, 6, ' Hit any key to stop continuously '
 170                               'updating the screen.')
 171                 stdscr.refresh()
 172                 # Activate nodelay mode; getch() will return -1
 173                 # if no keystroke is available, instead of waiting.
 174                 stdscr.nodelay(1)
 175                 while (1):
 176                     c=stdscr.getch()
 177                     if c!=-1: break
 178                     stdscr.addstr(0,0, '/'); stdscr.refresh()
 179                     board.display()
 180                     stdscr.addstr(0,0, '+'); stdscr.refresh()
 181
 182                 stdscr.nodelay(0)       # Disable nodelay mode
 183                 display_menu(stdscr, menu_y)
 184
 185             elif c in 'Ee': board.erase()
 186             elif c in 'Qq': break
 187             elif c in 'Rr':
 188                 board.makeRandom()
 189                 board.display(update_board=0)
 190             elif c in 'Ss':
 191                 board.display()
 192             else: pass                  # Ignore incorrect keys
 193         elif c==curses.KEY_UP and ypos>0:            ypos=ypos-1
 194         elif c==curses.KEY_DOWN and ypos<board.Y-1:  ypos=ypos+1
 195         elif c==curses.KEY_LEFT and xpos>0:          xpos=xpos-1
 196         elif c==curses.KEY_RIGHT and xpos<board.X-1: xpos=xpos+1
 197         else: pass                      # Ignore incorrect keys
 198
 199 if __name__=='__main__':
 200     try:
 201         # Initialize curses
 202         stdscr=curses.initscr()
 203         # Turn off echoing of keys, and enter cbreak mode,
 204         # where no buffering is performed on keyboard input
 205         curses.noecho() ; curses.cbreak()
 206
 207         # In keypad mode, escape sequences for special keys
 208         # (like the cursor keys) will be interpreted and
 209         # a special value like curses.KEY_LEFT will be returned
 210         stdscr.keypad(1)
 211         main(stdscr)                    # Enter the main loop
 212         # Set everything back to normal
 213         stdscr.keypad(0)
 214         curses.echo() ; curses.nocbreak()
 215         curses.endwin()                 # Terminate curses
 216     except:
 217         # In the event of an error, restore the terminal
 218         # to a sane state.
 219         stdscr.keypad(0)
 220         curses.echo() ; curses.nocbreak()
 221         curses.endwin()
 222         traceback.print_exc()           # Print the exception
 223