/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
 20import random, string, traceback
 21import curses
 22
 23class 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
133def 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
140def 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
148def 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
211def main(stdscr):
212    keyloop(stdscr)                    # Enter the main loop
213
214
215if __name__ == '__main__':
216    curses.wrapper(main)