#!/usr/bin/env python """ A Dumb full-screen editor. This example program makes use of many context manager methods: :meth:`~.Terminal.hidden_cursor`, :meth:`~.Terminal.raw`, :meth:`~.Terminal.location`, :meth:`~.Terminal.fullscreen`, and :meth:`~.Terminal.keypad`. Early curses work focused namely around writing screen editors, naturally any serious editor would make liberal use of special modes. Actions: - ``Ctrl - L`` refresh - ``F2`` quit - ``F1`` save - ``LEFT MOUSE BUTTON`` move cursor """ # std imports import collections # local from blessed import Terminal def echo(text): """Display ``text`` and flush output.""" print(text, end='', flush=True) def input_filter(keystroke): """ For given keystroke, return whether it should be allowed as input. This somewhat requires that the interface use special application keys to perform functions, as alphanumeric input intended for persisting could otherwise be interpreted as a command sequence. """ if keystroke.is_sequence: # Namely, deny multi-byte sequences (such as '\x1b[A'), return False if ord(keystroke) < ord(' '): # or control characters (such as ^L), return False return True def echo_yx(cursor, text): """Move to ``cursor`` and display ``text``.""" echo(cursor.term.move_yx(cursor.y, cursor.x) + text) Cursor = collections.namedtuple('Cursor', ('y', 'x', 'term')) def readline(term, width=20): """A rudimentary readline implementation.""" text = '' while True: inp = term.inkey() if inp.code == term.KEY_ENTER: break elif inp.code == term.KEY_ESCAPE or inp == chr(3): text = None break elif not inp.is_sequence and len(text) < width: text += inp echo(inp) elif inp.code in (term.KEY_BACKSPACE, term.KEY_DELETE): text = text[:-1] # https://utcc.utoronto.ca/~cks/space/blog/unix/HowUnixBackspaces # # "When you hit backspace, the kernel tty line discipline rubs out # your previous character by printing (in the simple case) # Ctrl-H, a space, and then another Ctrl-H." echo('\b \b') return text def save(screen, fname): """Save screen contents to file.""" if not fname: return with open(fname, 'w') as fout: cur_row = cur_col = 0 for (row, col) in sorted(screen): char = screen[(row, col)] while row != cur_row: cur_row += 1 cur_col = 0 fout.write('\n') while col > cur_col: cur_col += 1 fout.write(' ') fout.write(char) cur_col += 1 fout.write('\n') def redraw(term, screen, start=None, end=None): """Redraw the screen.""" if start is None and end is None: echo(term.clear) start, end = (Cursor(y=min(y for (y, x) in screen or [(0, 0)]), x=min(x for (y, x) in screen or [(0, 0)]), term=term), Cursor(y=max(y for (y, x) in screen or [(0, 0)]), x=max(x for (y, x) in screen or [(0, 0)]), term=term)) lastcol, lastrow = -1, -1 for row, col in sorted(screen): if start.y <= row <= end.y and start.x <= col <= end.x: if col >= term.width or row >= term.height: # out of bounds continue if row != lastrow or col != lastcol + 1: # use cursor movement echo_yx(Cursor(row, col, term), screen[row, col]) else: # just write past last one echo(screen[row, col]) def main(): """Program entry point.""" def above(csr, offset): return Cursor(y=max(0, csr.y - offset), x=csr.x, term=csr.term) def below(csr, offset): return Cursor(y=min(csr.term.height - 1, csr.y + offset), x=csr.x, term=csr.term) def right_of(csr, offset): return Cursor(y=csr.y, x=min(csr.term.width - 1, csr.x + offset), term=csr.term) def left_of(csr, offset): return Cursor(y=csr.y, x=max(0, csr.x - offset), term=csr.term) def home(csr): return Cursor(y=csr.y, x=0, term=csr.term) def end(csr): return Cursor(y=csr.y, x=csr.term.width - 1, term=csr.term) def bottom(csr): return Cursor(y=csr.term.height - 1, x=csr.x, term=csr.term) def center(csr): return Cursor(csr.term.height // 2, csr.term.width // 2, csr.term) def lookup_move(inp_code, csr): return { # arrows, including angled directionals csr.term.KEY_END: below(left_of(csr, 1), 1), csr.term.KEY_KP_1: below(left_of(csr, 1), 1), csr.term.KEY_DOWN: below(csr, 1), csr.term.KEY_KP_2: below(csr, 1), csr.term.KEY_PGDOWN: below(right_of(csr, 1), 1), csr.term.KEY_LR: below(right_of(csr, 1), 1), csr.term.KEY_KP_3: below(right_of(csr, 1), 1), csr.term.KEY_LEFT: left_of(csr, 1), csr.term.KEY_KP_4: left_of(csr, 1), csr.term.KEY_CENTER: center(csr), csr.term.KEY_KP_5: center(csr), csr.term.KEY_RIGHT: right_of(csr, 1), csr.term.KEY_KP_6: right_of(csr, 1), csr.term.KEY_HOME: above(left_of(csr, 1), 1), csr.term.KEY_KP_7: above(left_of(csr, 1), 1), csr.term.KEY_UP: above(csr, 1), csr.term.KEY_KP_8: above(csr, 1), csr.term.KEY_PGUP: above(right_of(csr, 1), 1), csr.term.KEY_KP_9: above(right_of(csr, 1), 1), # shift + arrows csr.term.KEY_SLEFT: left_of(csr, 10), csr.term.KEY_SRIGHT: right_of(csr, 10), csr.term.KEY_SDOWN: below(csr, 10), csr.term.KEY_SUP: above(csr, 10), # carriage return csr.term.KEY_ENTER: home(below(csr, 1)), }.get(inp_code, csr) term = Terminal() csr = Cursor(0, 0, term) screen = {} with term.hidden_cursor(), \ term.raw(), \ term.location(), \ term.fullscreen(), \ term.keypad(), \ term.mouse_enabled(): inp = None while True: echo_yx(csr, term.reverse(screen.get((csr.y, csr.x), ' '))) inp = term.inkey() if inp.name == 'KEY_F2': break elif inp.name == 'KEY_F1': # ^s saves echo_yx(home(bottom(csr)), term.ljust(term.bold_white('Filename: '))) echo_yx(right_of(home(bottom(csr)), len('Filename: ')), '') save(screen, readline(term)) echo_yx(home(bottom(csr)), term.clear_eol) redraw(term=term, screen=screen, start=home(bottom(csr)), end=end(bottom(csr))) continue elif inp == chr(12): # ^l refreshes redraw(term=term, screen=screen) elif inp.is_mouse_left(): # Handle left mouse button press csr = Cursor(inp.y - 1, inp.x - 1, term) continue else: n_csr = lookup_move(inp.code, csr) if n_csr != csr: # erase old cursor, echo_yx(csr, screen.get((csr.y, csr.x), ' ')) csr = n_csr elif input_filter(inp): echo_yx(csr, inp) screen[(csr.y, csr.x)] = inp.__str__() n_csr = right_of(csr, 1) if n_csr == csr: # wrap around margin n_csr = home(below(csr, 1)) csr = n_csr if __name__ == '__main__': main()