| Olivier Deprez | f4ef2d0 | 2021-04-20 13:36:24 +0200 | [diff] [blame] | 1 | """Simple textbox editing widget with Emacs-like keybindings.""" |
| 2 | |
| 3 | import curses |
| 4 | import curses.ascii |
| 5 | |
| 6 | def 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 | |
| 19 | class 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._update_max_yx() |
| 47 | self.stripspaces = 1 |
| 48 | self.lastcmd = None |
| 49 | win.keypad(1) |
| 50 | |
| 51 | def _update_max_yx(self): |
| 52 | maxy, maxx = self.win.getmaxyx() |
| 53 | self.maxy = maxy - 1 |
| 54 | self.maxx = maxx - 1 |
| 55 | |
| 56 | def _end_of_line(self, y): |
| 57 | """Go to the location of the first blank on the given line, |
| 58 | returning the index of the last non-blank character.""" |
| 59 | self._update_max_yx() |
| 60 | last = self.maxx |
| 61 | while True: |
| 62 | if curses.ascii.ascii(self.win.inch(y, last)) != curses.ascii.SP: |
| 63 | last = min(self.maxx, last+1) |
| 64 | break |
| 65 | elif last == 0: |
| 66 | break |
| 67 | last = last - 1 |
| 68 | return last |
| 69 | |
| 70 | def _insert_printable_char(self, ch): |
| 71 | self._update_max_yx() |
| 72 | (y, x) = self.win.getyx() |
| 73 | backyx = None |
| 74 | while y < self.maxy or x < self.maxx: |
| 75 | if self.insert_mode: |
| 76 | oldch = self.win.inch() |
| 77 | # The try-catch ignores the error we trigger from some curses |
| 78 | # versions by trying to write into the lowest-rightmost spot |
| 79 | # in the window. |
| 80 | try: |
| 81 | self.win.addch(ch) |
| 82 | except curses.error: |
| 83 | pass |
| 84 | if not self.insert_mode or not curses.ascii.isprint(oldch): |
| 85 | break |
| 86 | ch = oldch |
| 87 | (y, x) = self.win.getyx() |
| 88 | # Remember where to put the cursor back since we are in insert_mode |
| 89 | if backyx is None: |
| 90 | backyx = y, x |
| 91 | |
| 92 | if backyx is not None: |
| 93 | self.win.move(*backyx) |
| 94 | |
| 95 | def do_command(self, ch): |
| 96 | "Process a single editing command." |
| 97 | self._update_max_yx() |
| 98 | (y, x) = self.win.getyx() |
| 99 | self.lastcmd = ch |
| 100 | if curses.ascii.isprint(ch): |
| 101 | if y < self.maxy or x < self.maxx: |
| 102 | self._insert_printable_char(ch) |
| 103 | elif ch == curses.ascii.SOH: # ^a |
| 104 | self.win.move(y, 0) |
| 105 | elif ch in (curses.ascii.STX,curses.KEY_LEFT, curses.ascii.BS,curses.KEY_BACKSPACE): |
| 106 | if x > 0: |
| 107 | self.win.move(y, x-1) |
| 108 | elif y == 0: |
| 109 | pass |
| 110 | elif self.stripspaces: |
| 111 | self.win.move(y-1, self._end_of_line(y-1)) |
| 112 | else: |
| 113 | self.win.move(y-1, self.maxx) |
| 114 | if ch in (curses.ascii.BS, curses.KEY_BACKSPACE): |
| 115 | self.win.delch() |
| 116 | elif ch == curses.ascii.EOT: # ^d |
| 117 | self.win.delch() |
| 118 | elif ch == curses.ascii.ENQ: # ^e |
| 119 | if self.stripspaces: |
| 120 | self.win.move(y, self._end_of_line(y)) |
| 121 | else: |
| 122 | self.win.move(y, self.maxx) |
| 123 | elif ch in (curses.ascii.ACK, curses.KEY_RIGHT): # ^f |
| 124 | if x < self.maxx: |
| 125 | self.win.move(y, x+1) |
| 126 | elif y == self.maxy: |
| 127 | pass |
| 128 | else: |
| 129 | self.win.move(y+1, 0) |
| 130 | elif ch == curses.ascii.BEL: # ^g |
| 131 | return 0 |
| 132 | elif ch == curses.ascii.NL: # ^j |
| 133 | if self.maxy == 0: |
| 134 | return 0 |
| 135 | elif y < self.maxy: |
| 136 | self.win.move(y+1, 0) |
| 137 | elif ch == curses.ascii.VT: # ^k |
| 138 | if x == 0 and self._end_of_line(y) == 0: |
| 139 | self.win.deleteln() |
| 140 | else: |
| 141 | # first undo the effect of self._end_of_line |
| 142 | self.win.move(y, x) |
| 143 | self.win.clrtoeol() |
| 144 | elif ch == curses.ascii.FF: # ^l |
| 145 | self.win.refresh() |
| 146 | elif ch in (curses.ascii.SO, curses.KEY_DOWN): # ^n |
| 147 | if y < self.maxy: |
| 148 | self.win.move(y+1, x) |
| 149 | if x > self._end_of_line(y+1): |
| 150 | self.win.move(y+1, self._end_of_line(y+1)) |
| 151 | elif ch == curses.ascii.SI: # ^o |
| 152 | self.win.insertln() |
| 153 | elif ch in (curses.ascii.DLE, curses.KEY_UP): # ^p |
| 154 | if y > 0: |
| 155 | self.win.move(y-1, x) |
| 156 | if x > self._end_of_line(y-1): |
| 157 | self.win.move(y-1, self._end_of_line(y-1)) |
| 158 | return 1 |
| 159 | |
| 160 | def gather(self): |
| 161 | "Collect and return the contents of the window." |
| 162 | result = "" |
| 163 | self._update_max_yx() |
| 164 | for y in range(self.maxy+1): |
| 165 | self.win.move(y, 0) |
| 166 | stop = self._end_of_line(y) |
| 167 | if stop == 0 and self.stripspaces: |
| 168 | continue |
| 169 | for x in range(self.maxx+1): |
| 170 | if self.stripspaces and x > stop: |
| 171 | break |
| 172 | result = result + chr(curses.ascii.ascii(self.win.inch(y, x))) |
| 173 | if self.maxy > 0: |
| 174 | result = result + "\n" |
| 175 | return result |
| 176 | |
| 177 | def edit(self, validate=None): |
| 178 | "Edit in the widget window and collect the results." |
| 179 | while 1: |
| 180 | ch = self.win.getch() |
| 181 | if validate: |
| 182 | ch = validate(ch) |
| 183 | if not ch: |
| 184 | continue |
| 185 | if not self.do_command(ch): |
| 186 | break |
| 187 | self.win.refresh() |
| 188 | return self.gather() |
| 189 | |
| 190 | if __name__ == '__main__': |
| 191 | def test_editbox(stdscr): |
| 192 | ncols, nlines = 9, 4 |
| 193 | uly, ulx = 15, 20 |
| 194 | stdscr.addstr(uly-2, ulx, "Use Ctrl-G to end editing.") |
| 195 | win = curses.newwin(nlines, ncols, uly, ulx) |
| 196 | rectangle(stdscr, uly-1, ulx-1, uly + nlines, ulx + ncols) |
| 197 | stdscr.refresh() |
| 198 | return Textbox(win).edit() |
| 199 | |
| 200 | str = curses.wrapper(test_editbox) |
| 201 | print('Contents of text box:', repr(str)) |