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/Lib/curses/textpad.py

http://unladen-swallow.googlecode.com/
Python | 188 lines | 148 code | 7 blank | 33 comment | 28 complexity | f6498c899884787df0cdb7e03a4f9c44 MD5 | raw file
  1"""Simple textbox editing widget with Emacs-like keybindings."""
  2
  3import curses
  4import curses.ascii
  5
  6def rectangle(win, uly, ulx, lry, lrx):
  7    """Draw a rectangle with corners at the provided upper-left
  8    and lower-right coordinates.
  9    """
 10    win.vline(uly+1, ulx, curses.ACS_VLINE, lry - uly - 1)
 11    win.hline(uly, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
 12    win.hline(lry, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
 13    win.vline(uly+1, lrx, curses.ACS_VLINE, lry - uly - 1)
 14    win.addch(uly, ulx, curses.ACS_ULCORNER)
 15    win.addch(uly, lrx, curses.ACS_URCORNER)
 16    win.addch(lry, lrx, curses.ACS_LRCORNER)
 17    win.addch(lry, ulx, curses.ACS_LLCORNER)
 18
 19class Textbox:
 20    """Editing widget using the interior of a window object.
 21     Supports the following Emacs-like key bindings:
 22
 23    Ctrl-A      Go to left edge of window.
 24    Ctrl-B      Cursor left, wrapping to previous line if appropriate.
 25    Ctrl-D      Delete character under cursor.
 26    Ctrl-E      Go to right edge (stripspaces off) or end of line (stripspaces on).
 27    Ctrl-F      Cursor right, wrapping to next line when appropriate.
 28    Ctrl-G      Terminate, returning the window contents.
 29    Ctrl-H      Delete character backward.
 30    Ctrl-J      Terminate if the window is 1 line, otherwise insert newline.
 31    Ctrl-K      If line is blank, delete it, otherwise clear to end of line.
 32    Ctrl-L      Refresh screen.
 33    Ctrl-N      Cursor down; move down one line.
 34    Ctrl-O      Insert a blank line at cursor location.
 35    Ctrl-P      Cursor up; move up one line.
 36
 37    Move operations do nothing if the cursor is at an edge where the movement
 38    is not possible.  The following synonyms are supported where possible:
 39
 40    KEY_LEFT = Ctrl-B, KEY_RIGHT = Ctrl-F, KEY_UP = Ctrl-P, KEY_DOWN = Ctrl-N
 41    KEY_BACKSPACE = Ctrl-h
 42    """
 43    def __init__(self, win, insert_mode=False):
 44        self.win = win
 45        self.insert_mode = insert_mode
 46        (self.maxy, self.maxx) = win.getmaxyx()
 47        self.maxy = self.maxy - 1
 48        self.maxx = self.maxx - 1
 49        self.stripspaces = 1
 50        self.lastcmd = None
 51        win.keypad(1)
 52
 53    def _end_of_line(self, y):
 54        """Go to the location of the first blank on the given line,
 55        returning the index of the last non-blank character."""
 56        last = self.maxx
 57        while True:
 58            if curses.ascii.ascii(self.win.inch(y, last)) != curses.ascii.SP:
 59                last = min(self.maxx, last+1)
 60                break
 61            elif last == 0:
 62                break
 63            last = last - 1
 64        return last
 65
 66    def _insert_printable_char(self, ch):
 67        (y, x) = self.win.getyx()
 68        if y < self.maxy or x < self.maxx:
 69            if self.insert_mode:
 70                oldch = self.win.inch()
 71            # The try-catch ignores the error we trigger from some curses
 72            # versions by trying to write into the lowest-rightmost spot
 73            # in the window.
 74            try:
 75                self.win.addch(ch)
 76            except curses.error:
 77                pass
 78            if self.insert_mode:
 79                (backy, backx) = self.win.getyx()
 80                if curses.ascii.isprint(oldch):
 81                    self._insert_printable_char(oldch)
 82                    self.win.move(backy, backx)
 83
 84    def do_command(self, ch):
 85        "Process a single editing command."
 86        (y, x) = self.win.getyx()
 87        self.lastcmd = ch
 88        if curses.ascii.isprint(ch):
 89            if y < self.maxy or x < self.maxx:
 90                self._insert_printable_char(ch)
 91        elif ch == curses.ascii.SOH:                           # ^a
 92            self.win.move(y, 0)
 93        elif ch in (curses.ascii.STX,curses.KEY_LEFT, curses.ascii.BS,curses.KEY_BACKSPACE):
 94            if x > 0:
 95                self.win.move(y, x-1)
 96            elif y == 0:
 97                pass
 98            elif self.stripspaces:
 99                self.win.move(y-1, self._end_of_line(y-1))
100            else:
101                self.win.move(y-1, self.maxx)
102            if ch in (curses.ascii.BS, curses.KEY_BACKSPACE):
103                self.win.delch()
104        elif ch == curses.ascii.EOT:                           # ^d
105            self.win.delch()
106        elif ch == curses.ascii.ENQ:                           # ^e
107            if self.stripspaces:
108                self.win.move(y, self._end_of_line(y))
109            else:
110                self.win.move(y, self.maxx)
111        elif ch in (curses.ascii.ACK, curses.KEY_RIGHT):       # ^f
112            if x < self.maxx:
113                self.win.move(y, x+1)
114            elif y == self.maxy:
115                pass
116            else:
117                self.win.move(y+1, 0)
118        elif ch == curses.ascii.BEL:                           # ^g
119            return 0
120        elif ch == curses.ascii.NL:                            # ^j
121            if self.maxy == 0:
122                return 0
123            elif y < self.maxy:
124                self.win.move(y+1, 0)
125        elif ch == curses.ascii.VT:                            # ^k
126            if x == 0 and self._end_of_line(y) == 0:
127                self.win.deleteln()
128            else:
129                # first undo the effect of self._end_of_line
130                self.win.move(y, x)
131                self.win.clrtoeol()
132        elif ch == curses.ascii.FF:                            # ^l
133            self.win.refresh()
134        elif ch in (curses.ascii.SO, curses.KEY_DOWN):         # ^n
135            if y < self.maxy:
136                self.win.move(y+1, x)
137                if x > self._end_of_line(y+1):
138                    self.win.move(y+1, self._end_of_line(y+1))
139        elif ch == curses.ascii.SI:                            # ^o
140            self.win.insertln()
141        elif ch in (curses.ascii.DLE, curses.KEY_UP):          # ^p
142            if y > 0:
143                self.win.move(y-1, x)
144                if x > self._end_of_line(y-1):
145                    self.win.move(y-1, self._end_of_line(y-1))
146        return 1
147
148    def gather(self):
149        "Collect and return the contents of the window."
150        result = ""
151        for y in range(self.maxy+1):
152            self.win.move(y, 0)
153            stop = self._end_of_line(y)
154            if stop == 0 and self.stripspaces:
155                continue
156            for x in range(self.maxx+1):
157                if self.stripspaces and x > stop:
158                    break
159                result = result + chr(curses.ascii.ascii(self.win.inch(y, x)))
160            if self.maxy > 0:
161                result = result + "\n"
162        return result
163
164    def edit(self, validate=None):
165        "Edit in the widget window and collect the results."
166        while 1:
167            ch = self.win.getch()
168            if validate:
169                ch = validate(ch)
170            if not ch:
171                continue
172            if not self.do_command(ch):
173                break
174            self.win.refresh()
175        return self.gather()
176
177if __name__ == '__main__':
178    def test_editbox(stdscr):
179        ncols, nlines = 9, 4
180        uly, ulx = 15, 20
181        stdscr.addstr(uly-2, ulx, "Use Ctrl-G to end editing.")
182        win = curses.newwin(nlines, ncols, uly, ulx)
183        rectangle(stdscr, uly-1, ulx-1, uly + nlines, ulx + ncols)
184        stdscr.refresh()
185        return Textbox(win).edit()
186
187    str = curses.wrapper(test_editbox)
188    print 'Contents of text box:', repr(str)