Lib/curses/textpad.py

   1 """Simple textbox editing widget with Emacs-like keybindings."""
   2
   3 import curses, ascii
   4
   5 def rectangle(win, uly, ulx, lry, lrx):
   6     "Draw a rectangle."
   7     win.vline(uly+1, ulx, curses.ACS_VLINE, lry - uly - 1)
   8     win.hline(uly, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
   9     win.hline(lry, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
  10     win.vline(uly+1, lrx, curses.ACS_VLINE, lry - uly - 1)
  11     win.addch(uly, ulx, curses.ACS_ULCORNER)
  12     win.addch(uly, lrx, curses.ACS_URCORNER)
  13     win.addch(lry, lrx, curses.ACS_LRCORNER)
  14     win.addch(lry, ulx, curses.ACS_LLCORNER)
  15
  16 class Textbox:
  17     """Editing widget using the interior of a window object.
  18      Supports the following Emacs-like key bindings:
  19
  20     Ctrl-A      Go to left edge of window.
  21     Ctrl-B      Cursor left, wrapping to previous line if appropriate.
  22     Ctrl-D      Delete character under cursor.
  23     Ctrl-E      Go to right edge (stripspaces off) or end of line (stripspaces on).
  24     Ctrl-F      Cursor right, wrapping to next line when appropriate.
  25     Ctrl-G      Terminate, returning the window contents.
  26     Ctrl-H      Delete character backward.
  27     Ctrl-J      Terminate if the window is 1 line, otherwise insert newline.
  28     Ctrl-K      If line is blank, delete it, otherwise clear to end of line.
  29     Ctrl-L      Refresh screen.
  30     Ctrl-N      Cursor down; move down one line.
  31     Ctrl-O      Insert a blank line at cursor location.
  32     Ctrl-P      Cursor up; move up one line.
  33
  34     Move operations do nothing if the cursor is at an edge where the movement
  35     is not possible.  The following synonyms are supported where possible:
  36
  37     KEY_LEFT = Ctrl-B, KEY_RIGHT = Ctrl-F, KEY_UP = Ctrl-P, KEY_DOWN = Ctrl-N
  38     KEY_BACKSPACE = Ctrl-h
  39     """
  40     def __init__(self, win):
  41         self.win = win
  42         (self.maxy, self.maxx) = win.getmaxyx()
  43         self.maxy = self.maxy - 1
  44         self.maxx = self.maxx - 1
  45         self.stripspaces = 1
  46         self.lastcmd = None
  47         win.keypad(1)
  48
  49     def _end_of_line(self, y):
  50         "Go to the location of the first blank on the given line."
  51         last = self.maxx
  52         while 1:
  53             if ascii.ascii(self.win.inch(y, last)) != ascii.SP:
  54                 last = last + 1
  55                 break
  56             elif last == 0:
  57                 break
  58             last = last - 1
  59         return last
  60
  61     def do_command(self, ch):
  62         "Process a single editing command."
  63         (y, x) = self.win.getyx()
  64         self.lastcmd = ch
  65         if ascii.isprint(ch):
  66             if y < self.maxy or x < self.maxx:
  67                 # The try-catch ignores the error we trigger from some curses
  68                 # versions by trying to write into the lowest-rightmost spot
  69                 # in the window.
  70                 try:
  71                     self.win.addch(ch)
  72                 except curses.error:
  73                     pass
  74         elif ch == ascii.SOH:                           # ^a
  75             self.win.move(y, 0)
  76         elif ch in (ascii.STX,curses.KEY_LEFT, ascii.BS,curses.KEY_BACKSPACE):
  77             if x > 0:
  78                 self.win.move(y, x-1)
  79             elif y == 0:
  80                 pass
  81             elif self.stripspaces:
  82                 self.win.move(y-1, self._end_of_line(y-1))
  83             else:
  84                 self.win.move(y-1, self.maxx)
  85             if ch in (ascii.BS, curses.KEY_BACKSPACE):
  86                 self.win.delch()
  87         elif ch == ascii.EOT:                           # ^d
  88             self.win.delch()
  89         elif ch == ascii.ENQ:                           # ^e
  90             if self.stripspaces:
  91                 self.win.move(y, self._end_of_line(y))
  92             else:
  93                 self.win.move(y, self.maxx)
  94         elif ch in (ascii.ACK, curses.KEY_RIGHT):       # ^f
  95             if x < self.maxx:
  96                 self.win.move(y, x+1)
  97             elif y == self.maxy:
  98                 pass
  99             else:
 100                 self.win.move(y+1, 0)
 101         elif ch == ascii.BEL:                           # ^g
 102             return 0
 103         elif ch == ascii.NL:                            # ^j
 104             if self.maxy == 0:
 105                 return 0
 106             elif y < self.maxy:
 107                 self.win.move(y+1, 0)
 108         elif ch == ascii.VT:                            # ^k
 109             if x == 0 and self._end_of_line(y) == 0:
 110                 self.win.deleteln()
 111             else:
 112                 self.win.clrtoeol()
 113         elif ch == ascii.FF:                            # ^l
 114             self.win.refresh()
 115         elif ch in (ascii.SO, curses.KEY_DOWN):         # ^n
 116             if y < self.maxy:
 117                 self.win.move(y+1, x)
 118                 if x > self._end_of_line(y+1):
 119                     self.win.move(y+1, self._end_of_line(y+1))
 120         elif ch == ascii.SI:                            # ^o
 121             self.win.insertln()
 122         elif ch in (ascii.DLE, curses.KEY_UP):          # ^p
 123             if y > 0:
 124                 self.win.move(y-1, x)
 125                 if x > self._end_of_line(y-1):
 126                     self.win.move(y-1, self._end_of_line(y-1))
 127         return 1
 128
 129     def gather(self):
 130         "Collect and return the contents of the window."
 131         result = ""
 132         for y in range(self.maxy+1):
 133             self.win.move(y, 0)
 134             stop = self._end_of_line(y)
 135             if stop == 0 and self.stripspaces:
 136                 continue
 137             for x in range(self.maxx+1):
 138                 if self.stripspaces and x == stop:
 139                     break
 140                 result = result + chr(ascii.ascii(self.win.inch(y, x)))
 141             if self.maxy > 0:
 142                 result = result + "\n"
 143         return result
 144
 145     def edit(self, validate=None):
 146         "Edit in the widget window and collect the results."
 147         while 1:
 148             ch = self.win.getch()
 149             if validate:
 150                 ch = validate(ch)
 151             if not ch:
 152                 continue
 153             if not self.do_command(ch):
 154                 break
 155             self.win.refresh()
 156         return self.gather()
 157
 158 if __name__ == '__main__':
 159     def test_editbox(stdscr):
 160         win = curses.newwin(4, 9, 15, 20)
 161         rectangle(stdscr, 14, 19, 19, 29)
 162         stdscr.refresh()
 163         return Textbox(win).edit()
 164
 165     str = curses.wrapper(test_editbox)
 166     print str