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"""Simple textbox editing widget with Emacs-like keybindings."""
import curses
import curses.ascii
def rectangle(win, uly, ulx, lry, lrx):
"""Draw a rectangle with corners at the provided upper-left
and lower-right coordinates.
"""
win.vline(uly+1, ulx, curses.ACS_VLINE, lry - uly - 1)
win.hline(uly, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
win.hline(lry, ulx+1, curses.ACS_HLINE, lrx - ulx - 1)
win.vline(uly+1, lrx, curses.ACS_VLINE, lry - uly - 1)
win.addch(uly, ulx, curses.ACS_ULCORNER)
win.addch(uly, lrx, curses.ACS_URCORNER)
win.addch(lry, lrx, curses.ACS_LRCORNER)
win.addch(lry, ulx, curses.ACS_LLCORNER)
class Textbox:
"""Editing widget using the interior of a window object.
Supports the following Emacs-like key bindings:
Ctrl-A Go to left edge of window.
Ctrl-B Cursor left, wrapping to previous line if appropriate.
Ctrl-D Delete character under cursor.
Ctrl-E Go to right edge (stripspaces off) or end of line (stripspaces on).
Ctrl-F Cursor right, wrapping to next line when appropriate.
Ctrl-G Terminate, returning the window contents.
Ctrl-H Delete character backward.
Ctrl-J Terminate if the window is 1 line, otherwise insert newline.
Ctrl-K If line is blank, delete it, otherwise clear to end of line.
Ctrl-L Refresh screen.
Ctrl-N Cursor down; move down one line.
Ctrl-O Insert a blank line at cursor location.
Ctrl-P Cursor up; move up one line.
Move operations do nothing if the cursor is at an edge where the movement
is not possible. The following synonyms are supported where possible:
KEY_LEFT = Ctrl-B, KEY_RIGHT = Ctrl-F, KEY_UP = Ctrl-P, KEY_DOWN = Ctrl-N
KEY_BACKSPACE = Ctrl-h
"""
def __init__(self, win, insert_mode=False):
self.win = win
self.insert_mode = insert_mode
self._update_max_yx()
self.stripspaces = 1
self.lastcmd = None
win.keypad(1)
def _update_max_yx(self):
maxy, maxx = self.win.getmaxyx()
self.maxy = maxy - 1
self.maxx = maxx - 1
def _end_of_line(self, y):
"""Go to the location of the first blank on the given line,
returning the index of the last non-blank character."""
self._update_max_yx()
last = self.maxx
while True:
if curses.ascii.ascii(self.win.inch(y, last)) != curses.ascii.SP:
last = min(self.maxx, last+1)
break
elif last == 0:
break
last = last - 1
return last
def _insert_printable_char(self, ch):
self._update_max_yx()
(y, x) = self.win.getyx()
backyx = None
while y < self.maxy or x < self.maxx:
if self.insert_mode:
oldch = self.win.inch()
# The try-catch ignores the error we trigger from some curses
# versions by trying to write into the lowest-rightmost spot
# in the window.
try:
self.win.addch(ch)
except curses.error:
pass
if not self.insert_mode or not curses.ascii.isprint(oldch):
break
ch = oldch
(y, x) = self.win.getyx()
# Remember where to put the cursor back since we are in insert_mode
if backyx is None:
backyx = y, x
if backyx is not None:
self.win.move(*backyx)
def do_command(self, ch):
"Process a single editing command."
self._update_max_yx()
(y, x) = self.win.getyx()
self.lastcmd = ch
if curses.ascii.isprint(ch):
if y < self.maxy or x < self.maxx:
self._insert_printable_char(ch)
elif ch == curses.ascii.SOH: # ^a
self.win.move(y, 0)
elif ch in (curses.ascii.STX,curses.KEY_LEFT, curses.ascii.BS,curses.KEY_BACKSPACE):
if x > 0:
self.win.move(y, x-1)
elif y == 0:
pass
elif self.stripspaces:
self.win.move(y-1, self._end_of_line(y-1))
else:
self.win.move(y-1, self.maxx)
if ch in (curses.ascii.BS, curses.KEY_BACKSPACE):
self.win.delch()
elif ch == curses.ascii.EOT: # ^d
self.win.delch()
elif ch == curses.ascii.ENQ: # ^e
if self.stripspaces:
self.win.move(y, self._end_of_line(y))
else:
self.win.move(y, self.maxx)
elif ch in (curses.ascii.ACK, curses.KEY_RIGHT): # ^f
if x < self.maxx:
self.win.move(y, x+1)
elif y == self.maxy:
pass
else:
self.win.move(y+1, 0)
elif ch == curses.ascii.BEL: # ^g
return 0
elif ch == curses.ascii.NL: # ^j
if self.maxy == 0:
return 0
elif y < self.maxy:
self.win.move(y+1, 0)
elif ch == curses.ascii.VT: # ^k
if x == 0 and self._end_of_line(y) == 0:
self.win.deleteln()
else:
# first undo the effect of self._end_of_line
self.win.move(y, x)
self.win.clrtoeol()
elif ch == curses.ascii.FF: # ^l
self.win.refresh()
elif ch in (curses.ascii.SO, curses.KEY_DOWN): # ^n
if y < self.maxy:
self.win.move(y+1, x)
if x > self._end_of_line(y+1):
self.win.move(y+1, self._end_of_line(y+1))
elif ch == curses.ascii.SI: # ^o
self.win.insertln()
elif ch in (curses.ascii.DLE, curses.KEY_UP): # ^p
if y > 0:
self.win.move(y-1, x)
if x > self._end_of_line(y-1):
self.win.move(y-1, self._end_of_line(y-1))
return 1
def gather(self):
"Collect and return the contents of the window."
result = ""
self._update_max_yx()
for y in range(self.maxy+1):
self.win.move(y, 0)
stop = self._end_of_line(y)
if stop == 0 and self.stripspaces:
continue
for x in range(self.maxx+1):
if self.stripspaces and x > stop:
break
result = result + chr(curses.ascii.ascii(self.win.inch(y, x)))
if self.maxy > 0:
result = result + "\n"
return result
def edit(self, validate=None):
"Edit in the widget window and collect the results."
while 1:
ch = self.win.getch()
if validate:
ch = validate(ch)
if not ch:
continue
if not self.do_command(ch):
break
self.win.refresh()
return self.gather()
if __name__ == '__main__':
def test_editbox(stdscr):
ncols, nlines = 9, 4
uly, ulx = 15, 20
stdscr.addstr(uly-2, ulx, "Use Ctrl-G to end editing.")
win = curses.newwin(nlines, ncols, uly, ulx)
rectangle(stdscr, uly-1, ulx-1, uly + nlines, ulx + ncols)
stdscr.refresh()
return Textbox(win).edit()
str = curses.wrapper(test_editbox)
print('Contents of text box:', repr(str))