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      1 :mod:`curses` --- Terminal handling for character-cell displays
      2 ===============================================================
      3 
      4 .. module:: curses
      5    :synopsis: An interface to the curses library, providing portable terminal
      6               handling.
      7    :platform: Unix
      8 .. sectionauthor:: Moshe Zadka <moshez (a] zadka.site.co.il>
      9 .. sectionauthor:: Eric Raymond <esr (a] thyrsus.com>
     10 
     11 .. versionchanged:: 1.6
     12    Added support for the ``ncurses`` library and converted to a package.
     13 
     14 The :mod:`curses` module provides an interface to the curses library, the
     15 de-facto standard for portable advanced terminal handling.
     16 
     17 While curses is most widely used in the Unix environment, versions are available
     18 for DOS, OS/2, and possibly other systems as well.  This extension module is
     19 designed to match the API of ncurses, an open-source curses library hosted on
     20 Linux and the BSD variants of Unix.
     21 
     22 .. note::
     23 
     24    Since version 5.4, the ncurses library decides how to interpret non-ASCII data
     25    using the ``nl_langinfo`` function.  That means that you have to call
     26    :func:`locale.setlocale` in the application and encode Unicode strings
     27    using one of the system's available encodings.  This example uses the
     28    system's default encoding::
     29 
     30       import locale
     31       locale.setlocale(locale.LC_ALL, '')
     32       code = locale.getpreferredencoding()
     33 
     34    Then use *code* as the encoding for :meth:`str.encode` calls.
     35 
     36 .. seealso::
     37 
     38    Module :mod:`curses.ascii`
     39       Utilities for working with ASCII characters, regardless of your locale settings.
     40 
     41    Module :mod:`curses.panel`
     42       A panel stack extension that adds depth to  curses windows.
     43 
     44    Module :mod:`curses.textpad`
     45       Editable text widget for curses supporting  :program:`Emacs`\ -like bindings.
     46 
     47    :ref:`curses-howto`
     48       Tutorial material on using curses with Python, by Andrew Kuchling and Eric
     49       Raymond.
     50 
     51    The :source:`Demo/curses/` directory in the Python source distribution contains
     52    some example programs using the curses bindings provided by this module.
     53 
     54 
     55 .. _curses-functions:
     56 
     57 Functions
     58 ---------
     59 
     60 The module :mod:`curses` defines the following exception:
     61 
     62 
     63 .. exception:: error
     64 
     65    Exception raised when a curses library function returns an error.
     66 
     67 .. note::
     68 
     69    Whenever *x* or *y* arguments to a function or a method are optional, they
     70    default to the current cursor location. Whenever *attr* is optional, it defaults
     71    to :const:`A_NORMAL`.
     72 
     73 The module :mod:`curses` defines the following functions:
     74 
     75 
     76 .. function:: baudrate()
     77 
     78    Return the output speed of the terminal in bits per second.  On software
     79    terminal emulators it will have a fixed high value. Included for historical
     80    reasons; in former times, it was used to  write output loops for time delays and
     81    occasionally to change interfaces depending on the line speed.
     82 
     83 
     84 .. function:: beep()
     85 
     86    Emit a short attention sound.
     87 
     88 
     89 .. function:: can_change_color()
     90 
     91    Return ``True`` or ``False``, depending on whether the programmer can change the colors
     92    displayed by the terminal.
     93 
     94 
     95 .. function:: cbreak()
     96 
     97    Enter cbreak mode.  In cbreak mode (sometimes called "rare" mode) normal tty
     98    line buffering is turned off and characters are available to be read one by one.
     99    However, unlike raw mode, special characters (interrupt, quit, suspend, and flow
    100    control) retain their effects on the tty driver and calling program.  Calling
    101    first :func:`raw` then :func:`cbreak` leaves the terminal in cbreak mode.
    102 
    103 
    104 .. function:: color_content(color_number)
    105 
    106    Return the intensity of the red, green, and blue (RGB) components in the color
    107    *color_number*, which must be between ``0`` and :const:`COLORS`.  A 3-tuple is
    108    returned, containing the R,G,B values for the given color, which will be between
    109    ``0`` (no component) and ``1000`` (maximum amount of component).
    110 
    111 
    112 .. function:: color_pair(color_number)
    113 
    114    Return the attribute value for displaying text in the specified color.  This
    115    attribute value can be combined with :const:`A_STANDOUT`, :const:`A_REVERSE`,
    116    and the other :const:`A_\*` attributes.  :func:`pair_number` is the counterpart
    117    to this function.
    118 
    119 
    120 .. function:: curs_set(visibility)
    121 
    122    Set the cursor state.  *visibility* can be set to 0, 1, or 2, for invisible,
    123    normal, or very visible.  If the terminal supports the visibility requested, the
    124    previous cursor state is returned; otherwise, an exception is raised.  On many
    125    terminals, the "visible" mode is an underline cursor and the "very visible" mode
    126    is a block cursor.
    127 
    128 
    129 .. function:: def_prog_mode()
    130 
    131    Save the current terminal mode as the "program" mode, the mode when the running
    132    program is using curses.  (Its counterpart is the "shell" mode, for when the
    133    program is not in curses.)  Subsequent calls to :func:`reset_prog_mode` will
    134    restore this mode.
    135 
    136 
    137 .. function:: def_shell_mode()
    138 
    139    Save the current terminal mode as the "shell" mode, the mode when the running
    140    program is not using curses.  (Its counterpart is the "program" mode, when the
    141    program is using curses capabilities.) Subsequent calls to
    142    :func:`reset_shell_mode` will restore this mode.
    143 
    144 
    145 .. function:: delay_output(ms)
    146 
    147    Insert an *ms* millisecond pause in output.
    148 
    149 
    150 .. function:: doupdate()
    151 
    152    Update the physical screen.  The curses library keeps two data structures, one
    153    representing the current physical screen contents and a virtual screen
    154    representing the desired next state.  The :func:`doupdate` ground updates the
    155    physical screen to match the virtual screen.
    156 
    157    The virtual screen may be updated by a :meth:`noutrefresh` call after write
    158    operations such as :meth:`addstr` have been performed on a window.  The normal
    159    :meth:`refresh` call is simply :meth:`noutrefresh` followed by :func:`doupdate`;
    160    if you have to update multiple windows, you can speed performance and perhaps
    161    reduce screen flicker by issuing :meth:`noutrefresh` calls on all windows,
    162    followed by a single :func:`doupdate`.
    163 
    164 
    165 .. function:: echo()
    166 
    167    Enter echo mode.  In echo mode, each character input is echoed to the screen as
    168    it is entered.
    169 
    170 
    171 .. function:: endwin()
    172 
    173    De-initialize the library, and return terminal to normal status.
    174 
    175 
    176 .. function:: erasechar()
    177 
    178    Return the user's current erase character.  Under Unix operating systems this
    179    is a property of the controlling tty of the curses program, and is not set by
    180    the curses library itself.
    181 
    182 
    183 .. function:: filter()
    184 
    185    The :func:`.filter` routine, if used, must be called before :func:`initscr` is
    186    called.  The effect is that, during those calls, :envvar:`LINES` is set to 1; the
    187    capabilities clear, cup, cud, cud1, cuu1, cuu, vpa are disabled; and the home
    188    string is set to the value of cr. The effect is that the cursor is confined to
    189    the current line, and so are screen updates.  This may be used for enabling
    190    character-at-a-time  line editing without touching the rest of the screen.
    191 
    192 
    193 .. function:: flash()
    194 
    195    Flash the screen.  That is, change it to reverse-video and then change it back
    196    in a short interval.  Some people prefer such as 'visible bell' to the audible
    197    attention signal produced by :func:`beep`.
    198 
    199 
    200 .. function:: flushinp()
    201 
    202    Flush all input buffers.  This throws away any  typeahead  that  has been typed
    203    by the user and has not yet been processed by the program.
    204 
    205 
    206 .. function:: getmouse()
    207 
    208    After :meth:`getch` returns :const:`KEY_MOUSE` to signal a mouse event, this
    209    method should be call to retrieve the queued mouse event, represented as a
    210    5-tuple ``(id, x, y, z, bstate)``. *id* is an ID value used to distinguish
    211    multiple devices, and *x*, *y*, *z* are the event's coordinates.  (*z* is
    212    currently unused.)  *bstate* is an integer value whose bits will be set to
    213    indicate the type of event, and will be the bitwise OR of one or more of the
    214    following constants, where *n* is the button number from 1 to 4:
    215    :const:`BUTTONn_PRESSED`, :const:`BUTTONn_RELEASED`, :const:`BUTTONn_CLICKED`,
    216    :const:`BUTTONn_DOUBLE_CLICKED`, :const:`BUTTONn_TRIPLE_CLICKED`,
    217    :const:`BUTTON_SHIFT`, :const:`BUTTON_CTRL`, :const:`BUTTON_ALT`.
    218 
    219 
    220 .. function:: getsyx()
    221 
    222    Return the current coordinates of the virtual screen cursor in y and x.  If
    223    leaveok is currently true, then -1,-1 is returned.
    224 
    225 
    226 .. function:: getwin(file)
    227 
    228    Read window related data stored in the file by an earlier :func:`putwin` call.
    229    The routine then creates and initializes a new window using that data, returning
    230    the new window object.
    231 
    232 
    233 .. function:: has_colors()
    234 
    235    Return ``True`` if the terminal can display colors; otherwise, return ``False``.
    236 
    237 
    238 .. function:: has_ic()
    239 
    240    Return ``True`` if the terminal has insert- and delete-character capabilities.
    241    This function is included for historical reasons only, as all modern software
    242    terminal emulators have such capabilities.
    243 
    244 
    245 .. function:: has_il()
    246 
    247    Return ``True`` if the terminal has insert- and delete-line capabilities, or can
    248    simulate  them  using scrolling regions. This function is included for
    249    historical reasons only, as all modern software terminal emulators have such
    250    capabilities.
    251 
    252 
    253 .. function:: has_key(ch)
    254 
    255    Take a key value *ch*, and return ``True`` if the current terminal type recognizes
    256    a key with that value.
    257 
    258 
    259 .. function:: halfdelay(tenths)
    260 
    261    Used for half-delay mode, which is similar to cbreak mode in that characters
    262    typed by the user are immediately available to the program. However, after
    263    blocking for *tenths* tenths of seconds, an exception is raised if nothing has
    264    been typed.  The value of *tenths* must be a number between ``1`` and ``255``.  Use
    265    :func:`nocbreak` to leave half-delay mode.
    266 
    267 
    268 .. function:: init_color(color_number, r, g, b)
    269 
    270    Change the definition of a color, taking the number of the color to be changed
    271    followed by three RGB values (for the amounts of red, green, and blue
    272    components).  The value of *color_number* must be between ``0`` and
    273    :const:`COLORS`.  Each of *r*, *g*, *b*, must be a value between ``0`` and
    274    ``1000``.  When :func:`init_color` is used, all occurrences of that color on the
    275    screen immediately change to the new definition.  This function is a no-op on
    276    most terminals; it is active only if :func:`can_change_color` returns ``1``.
    277 
    278 
    279 .. function:: init_pair(pair_number, fg, bg)
    280 
    281    Change the definition of a color-pair.  It takes three arguments: the number of
    282    the color-pair to be changed, the foreground color number, and the background
    283    color number.  The value of *pair_number* must be between ``1`` and
    284    ``COLOR_PAIRS - 1`` (the ``0`` color pair is wired to white on black and cannot
    285    be changed).  The value of *fg* and *bg* arguments must be between ``0`` and
    286    :const:`COLORS`.  If the color-pair was previously initialized, the screen is
    287    refreshed and all occurrences of that color-pair are changed to the new
    288    definition.
    289 
    290 
    291 .. function:: initscr()
    292 
    293    Initialize the library. Return a :class:`WindowObject` which represents the
    294    whole screen.
    295 
    296    .. note::
    297 
    298       If there is an error opening the terminal, the underlying curses library may
    299       cause the interpreter to exit.
    300 
    301 
    302 .. function:: is_term_resized(nlines, ncols)
    303 
    304    Return ``True`` if :func:`resize_term` would modify the window structure,
    305    ``False`` otherwise.
    306 
    307 
    308 .. function:: isendwin()
    309 
    310    Return ``True`` if :func:`endwin` has been called (that is, the  curses library has
    311    been deinitialized).
    312 
    313 
    314 .. function:: keyname(k)
    315 
    316    Return the name of the key numbered *k*.  The name of a key generating printable
    317    ASCII character is the key's character.  The name of a control-key combination
    318    is a two-character string consisting of a caret followed by the corresponding
    319    printable ASCII character.  The name of an alt-key combination (128--255) is a
    320    string consisting of the prefix 'M-' followed by the name of the corresponding
    321    ASCII character.
    322 
    323 
    324 .. function:: killchar()
    325 
    326    Return the user's current line kill character. Under Unix operating systems
    327    this is a property of the controlling tty of the curses program, and is not set
    328    by the curses library itself.
    329 
    330 
    331 .. function:: longname()
    332 
    333    Return a string containing the terminfo long name field describing the current
    334    terminal.  The maximum length of a verbose description is 128 characters.  It is
    335    defined only after the call to :func:`initscr`.
    336 
    337 
    338 .. function:: meta(yes)
    339 
    340    If *yes* is 1, allow 8-bit characters to be input. If *yes* is 0,  allow only
    341    7-bit chars.
    342 
    343 
    344 .. function:: mouseinterval(interval)
    345 
    346    Set the maximum time in milliseconds that can elapse between press and release
    347    events in order for them to be recognized as a click, and return the previous
    348    interval value.  The default value is 200 msec, or one fifth of a second.
    349 
    350 
    351 .. function:: mousemask(mousemask)
    352 
    353    Set the mouse events to be reported, and return a tuple ``(availmask,
    354    oldmask)``.   *availmask* indicates which of the specified mouse events can be
    355    reported; on complete failure it returns 0.  *oldmask* is the previous value of
    356    the given window's mouse event mask.  If this function is never called, no mouse
    357    events are ever reported.
    358 
    359 
    360 .. function:: napms(ms)
    361 
    362    Sleep for *ms* milliseconds.
    363 
    364 
    365 .. function:: newpad(nlines, ncols)
    366 
    367    Create and return a pointer to a new pad data structure with the given number
    368    of lines and columns.  A pad is returned as a window object.
    369 
    370    A pad is like a window, except that it is not restricted by the screen size, and
    371    is not necessarily associated with a particular part of the screen.  Pads can be
    372    used when a large window is needed, and only a part of the window will be on the
    373    screen at one time.  Automatic refreshes of pads (such as from scrolling or
    374    echoing of input) do not occur.  The :meth:`refresh` and :meth:`noutrefresh`
    375    methods of a pad require 6 arguments to specify the part of the pad to be
    376    displayed and the location on the screen to be used for the display. The
    377    arguments are *pminrow*, *pmincol*, *sminrow*, *smincol*, *smaxrow*, *smaxcol*; the *p*
    378    arguments refer to the upper left corner of the pad region to be displayed and
    379    the *s* arguments define a clipping box on the screen within which the pad region
    380    is to be displayed.
    381 
    382 
    383 .. function:: newwin(nlines, ncols)
    384               newwin(nlines, ncols, begin_y, begin_x)
    385 
    386    Return a new window, whose left-upper corner is at  ``(begin_y, begin_x)``, and
    387    whose height/width is  *nlines*/*ncols*.
    388 
    389    By default, the window will extend from the  specified position to the lower
    390    right corner of the screen.
    391 
    392 
    393 .. function:: nl()
    394 
    395    Enter newline mode.  This mode translates the return key into newline on input,
    396    and translates newline into return and line-feed on output. Newline mode is
    397    initially on.
    398 
    399 
    400 .. function:: nocbreak()
    401 
    402    Leave cbreak mode.  Return to normal "cooked" mode with line buffering.
    403 
    404 
    405 .. function:: noecho()
    406 
    407    Leave echo mode.  Echoing of input characters is turned off.
    408 
    409 
    410 .. function:: nonl()
    411 
    412    Leave newline mode.  Disable translation of return into newline on input, and
    413    disable low-level translation of newline into newline/return on output (but this
    414    does not change the behavior of ``addch('\n')``, which always does the
    415    equivalent of return and line feed on the virtual screen).  With translation
    416    off, curses can sometimes speed up vertical motion a little; also, it will be
    417    able to detect the return key on input.
    418 
    419 
    420 .. function:: noqiflush()
    421 
    422    When the :func:`noqiflush` routine is used, normal flush of input and output queues
    423    associated with the INTR, QUIT and SUSP characters will not be done.  You may
    424    want to call :func:`noqiflush` in a signal handler if you want output to
    425    continue as though the interrupt had not occurred, after the handler exits.
    426 
    427 
    428 .. function:: noraw()
    429 
    430    Leave raw mode. Return to normal "cooked" mode with line buffering.
    431 
    432 
    433 .. function:: pair_content(pair_number)
    434 
    435    Return a tuple ``(fg, bg)`` containing the colors for the requested color pair.
    436    The value of *pair_number* must be between ``1`` and ``COLOR_PAIRS - 1``.
    437 
    438 
    439 .. function:: pair_number(attr)
    440 
    441    Return the number of the color-pair set by the attribute value *attr*.
    442    :func:`color_pair` is the counterpart to this function.
    443 
    444 
    445 .. function:: putp(string)
    446 
    447    Equivalent to ``tputs(str, 1, putchar)``; emit the value of a specified
    448    terminfo capability for the current terminal.  Note that the output of :func:`putp`
    449    always goes to standard output.
    450 
    451 
    452 .. function:: qiflush( [flag] )
    453 
    454    If *flag* is ``False``, the effect is the same as calling :func:`noqiflush`. If
    455    *flag* is ``True``, or no argument is provided, the queues will be flushed when
    456    these control characters are read.
    457 
    458 
    459 .. function:: raw()
    460 
    461    Enter raw mode.  In raw mode, normal line buffering and  processing of
    462    interrupt, quit, suspend, and flow control keys are turned off; characters are
    463    presented to curses input functions one by one.
    464 
    465 
    466 .. function:: reset_prog_mode()
    467 
    468    Restore the  terminal  to "program" mode, as previously saved  by
    469    :func:`def_prog_mode`.
    470 
    471 
    472 .. function:: reset_shell_mode()
    473 
    474    Restore the  terminal  to "shell" mode, as previously saved  by
    475    :func:`def_shell_mode`.
    476 
    477 
    478 .. function:: resetty()
    479 
    480    Restore the state of the terminal modes to what it was at the last call to
    481    :func:`savetty`.
    482 
    483 
    484 .. function:: resize_term(nlines, ncols)
    485 
    486    Backend function used by :func:`resizeterm`, performing most of the work;
    487    when resizing the windows, :func:`resize_term` blank-fills the areas that are
    488    extended.  The calling application should fill in these areas with
    489    appropriate data.  The :func:`resize_term` function attempts to resize all
    490    windows.  However, due to the calling convention of pads, it is not possible
    491    to resize these without additional interaction with the application.
    492 
    493 
    494 .. function:: resizeterm(nlines, ncols)
    495 
    496    Resize the standard and current windows to the specified dimensions, and
    497    adjusts other bookkeeping data used by the curses library that record the
    498    window dimensions (in particular the SIGWINCH handler).
    499 
    500 
    501 .. function:: savetty()
    502 
    503    Save the current state of the terminal modes in a buffer, usable by
    504    :func:`resetty`.
    505 
    506 
    507 .. function:: setsyx(y, x)
    508 
    509    Set the virtual screen cursor to *y*, *x*. If *y* and *x* are both -1, then
    510    leaveok is set.
    511 
    512 
    513 .. function:: setupterm([termstr, fd])
    514 
    515    Initialize the terminal.  *termstr* is a string giving the terminal name; if
    516    omitted, the value of the :envvar:`TERM` environment variable will be used.  *fd* is the
    517    file descriptor to which any initialization sequences will be sent; if not
    518    supplied, the file descriptor for ``sys.stdout`` will be used.
    519 
    520 
    521 .. function:: start_color()
    522 
    523    Must be called if the programmer wants to use colors, and before any other color
    524    manipulation routine is called.  It is good practice to call this routine right
    525    after :func:`initscr`.
    526 
    527    :func:`start_color` initializes eight basic colors (black, red,  green, yellow,
    528    blue, magenta, cyan, and white), and two global variables in the :mod:`curses`
    529    module, :const:`COLORS` and :const:`COLOR_PAIRS`, containing the maximum number
    530    of colors and color-pairs the terminal can support.  It also restores the colors
    531    on the terminal to the values they had when the terminal was just turned on.
    532 
    533 
    534 .. function:: termattrs()
    535 
    536    Return a logical OR of all video attributes supported by the terminal.  This
    537    information is useful when a curses program needs complete control over the
    538    appearance of the screen.
    539 
    540 
    541 .. function:: termname()
    542 
    543    Return the value of the environment variable :envvar:`TERM`, truncated to 14 characters.
    544 
    545 
    546 .. function:: tigetflag(capname)
    547 
    548    Return the value of the Boolean capability corresponding to the terminfo
    549    capability name *capname*.  The value ``-1`` is returned if *capname* is not a
    550    Boolean capability, or ``0`` if it is canceled or absent from the terminal
    551    description.
    552 
    553 
    554 .. function:: tigetnum(capname)
    555 
    556    Return the value of the numeric capability corresponding to the terminfo
    557    capability name *capname*.  The value ``-2`` is returned if *capname* is not a
    558    numeric capability, or ``-1`` if it is canceled or absent from the terminal
    559    description.
    560 
    561 
    562 .. function:: tigetstr(capname)
    563 
    564    Return the value of the string capability corresponding to the terminfo
    565    capability name *capname*.  ``None`` is returned if *capname* is not a string
    566    capability, or is canceled or absent from the terminal description.
    567 
    568 
    569 .. function:: tparm(str[,...])
    570 
    571    Instantiate the string *str* with the supplied parameters, where *str* should
    572    be a parameterized string obtained from the terminfo database.  E.g.
    573    ``tparm(tigetstr("cup"), 5, 3)`` could result in ``'\033[6;4H'``, the exact
    574    result depending on terminal type.
    575 
    576 
    577 .. function:: typeahead(fd)
    578 
    579    Specify that the file descriptor *fd* be used for typeahead checking.  If *fd*
    580    is ``-1``, then no typeahead checking is done.
    581 
    582    The curses library does "line-breakout optimization" by looking for typeahead
    583    periodically while updating the screen.  If input is found, and it is coming
    584    from a tty, the current update is postponed until refresh or doupdate is called
    585    again, allowing faster response to commands typed in advance. This function
    586    allows specifying a different file descriptor for typeahead checking.
    587 
    588 
    589 .. function:: unctrl(ch)
    590 
    591    Return a string which is a printable representation of the character *ch*.
    592    Control characters are displayed as a caret followed by the character, for
    593    example as ``^C``. Printing characters are left as they are.
    594 
    595 
    596 .. function:: ungetch(ch)
    597 
    598    Push *ch* so the next :meth:`getch` will return it.
    599 
    600    .. note::
    601 
    602       Only one *ch* can be pushed before :meth:`getch` is called.
    603 
    604 
    605 .. function:: ungetmouse(id, x, y, z, bstate)
    606 
    607    Push a :const:`KEY_MOUSE` event onto the input queue, associating the given
    608    state data with it.
    609 
    610 
    611 .. function:: use_env(flag)
    612 
    613    If used, this function should be called before :func:`initscr` or newterm are
    614    called.  When *flag* is ``False``, the values of lines and columns specified in the
    615    terminfo database will be used, even if environment variables :envvar:`LINES`
    616    and :envvar:`COLUMNS` (used by default) are set, or if curses is running in a
    617    window (in which case default behavior would be to use the window size if
    618    :envvar:`LINES` and :envvar:`COLUMNS` are not set).
    619 
    620 
    621 .. function:: use_default_colors()
    622 
    623    Allow use of default values for colors on terminals supporting this feature. Use
    624    this to support transparency in your application.  The default color is assigned
    625    to the color number -1. After calling this function,  ``init_pair(x,
    626    curses.COLOR_RED, -1)`` initializes, for instance, color pair *x* to a red
    627    foreground color on the default background.
    628 
    629 
    630 .. function:: wrapper(func, ...)
    631 
    632    Initialize curses and call another callable object, *func*, which should be the
    633    rest of your curses-using application.  If the application raises an exception,
    634    this function will restore the terminal to a sane state before re-raising the
    635    exception and generating a traceback.  The callable object *func* is then passed
    636    the main window 'stdscr' as its first argument, followed by any other arguments
    637    passed to :func:`wrapper`.  Before calling *func*, :func:`wrapper` turns on
    638    cbreak mode, turns off echo, enables the terminal keypad, and initializes colors
    639    if the terminal has color support.  On exit (whether normally or by exception)
    640    it restores cooked mode, turns on echo, and disables the terminal keypad.
    641 
    642 
    643 .. _curses-window-objects:
    644 
    645 Window Objects
    646 --------------
    647 
    648 Window objects, as returned by :func:`initscr` and :func:`newwin` above, have
    649 the following methods:
    650 
    651 
    652 .. method:: window.addch(ch[, attr])
    653             window.addch(y, x, ch[, attr])
    654 
    655    .. note::
    656 
    657       A *character* means a C character (an ASCII code), rather than a Python
    658       character (a string of length 1). (This note is true whenever the
    659       documentation mentions a character.) The built-in :func:`ord` is handy for
    660       conveying strings to codes.
    661 
    662    Paint character *ch* at ``(y, x)`` with attributes *attr*, overwriting any
    663    character previously painter at that location.  By default, the character
    664    position and attributes are the current settings for the window object.
    665 
    666 
    667 .. method:: window.addnstr(str, n[, attr])
    668             window.addnstr(y, x, str, n[, attr])
    669 
    670    Paint at most *n* characters of the  string *str* at ``(y, x)`` with attributes
    671    *attr*, overwriting anything previously on the display.
    672 
    673 
    674 .. method:: window.addstr(str[, attr])
    675             window.addstr(y, x, str[, attr])
    676 
    677    Paint the string *str* at ``(y, x)`` with attributes *attr*, overwriting
    678    anything previously on the display.
    679 
    680 
    681 .. method:: window.attroff(attr)
    682 
    683    Remove attribute *attr* from the "background" set applied to all writes to the
    684    current window.
    685 
    686 
    687 .. method:: window.attron(attr)
    688 
    689    Add attribute *attr* from the "background" set applied to all writes to the
    690    current window.
    691 
    692 
    693 .. method:: window.attrset(attr)
    694 
    695    Set the "background" set of attributes to *attr*.  This set is initially 0 (no
    696    attributes).
    697 
    698 
    699 .. method:: window.bkgd(ch[, attr])
    700 
    701    Set the background property of the window to the character *ch*, with
    702    attributes *attr*.  The change is then applied to every character position in
    703    that window:
    704 
    705    * The attribute of every character in the window  is changed to the new
    706      background attribute.
    707 
    708    * Wherever  the  former background character appears, it is changed to the new
    709      background character.
    710 
    711 
    712 .. method:: window.bkgdset(ch[, attr])
    713 
    714    Set the window's background.  A window's background consists of a character and
    715    any combination of attributes.  The attribute part of the background is combined
    716    (OR'ed) with all non-blank characters that are written into the window.  Both
    717    the character and attribute parts of the background are combined with the blank
    718    characters.  The background becomes a property of the character and moves with
    719    the character through any scrolling and insert/delete line/character operations.
    720 
    721 
    722 .. method:: window.border([ls[, rs[, ts[, bs[, tl[, tr[, bl[, br]]]]]]]])
    723 
    724    Draw a border around the edges of the window. Each parameter specifies  the
    725    character to use for a specific part of the border; see the table below for more
    726    details.  The characters can be specified as integers or as one-character
    727    strings.
    728 
    729    .. note::
    730 
    731       A ``0`` value for any parameter will cause the default character to be used for
    732       that parameter.  Keyword parameters can *not* be used.  The defaults are listed
    733       in this table:
    734 
    735    +-----------+---------------------+-----------------------+
    736    | Parameter | Description         | Default value         |
    737    +===========+=====================+=======================+
    738    | *ls*      | Left side           | :const:`ACS_VLINE`    |
    739    +-----------+---------------------+-----------------------+
    740    | *rs*      | Right side          | :const:`ACS_VLINE`    |
    741    +-----------+---------------------+-----------------------+
    742    | *ts*      | Top                 | :const:`ACS_HLINE`    |
    743    +-----------+---------------------+-----------------------+
    744    | *bs*      | Bottom              | :const:`ACS_HLINE`    |
    745    +-----------+---------------------+-----------------------+
    746    | *tl*      | Upper-left corner   | :const:`ACS_ULCORNER` |
    747    +-----------+---------------------+-----------------------+
    748    | *tr*      | Upper-right corner  | :const:`ACS_URCORNER` |
    749    +-----------+---------------------+-----------------------+
    750    | *bl*      | Bottom-left corner  | :const:`ACS_LLCORNER` |
    751    +-----------+---------------------+-----------------------+
    752    | *br*      | Bottom-right corner | :const:`ACS_LRCORNER` |
    753    +-----------+---------------------+-----------------------+
    754 
    755 
    756 .. method:: window.box([vertch, horch])
    757 
    758    Similar to :meth:`border`, but both *ls* and *rs* are *vertch* and both *ts* and
    759    *bs* are *horch*.  The default corner characters are always used by this function.
    760 
    761 
    762 .. method:: window.chgat(attr)
    763             window.chgat(num, attr)
    764             window.chgat(y, x, attr)
    765             window.chgat(y, x, num, attr)
    766 
    767    Set the attributes of *num* characters at the current cursor position, or at
    768    position ``(y, x)`` if supplied. If no value of *num* is given or *num* = -1,
    769    the attribute will  be set on all the characters to the end of the line.  This
    770    function does not move the cursor. The changed line will be touched using the
    771    :meth:`touchline` method so that the contents will be redisplayed by the next
    772    window refresh.
    773 
    774 
    775 .. method:: window.clear()
    776 
    777    Like :meth:`erase`, but also cause the whole window to be repainted upon next
    778    call to :meth:`refresh`.
    779 
    780 
    781 .. method:: window.clearok(yes)
    782 
    783    If *yes* is 1, the next call to :meth:`refresh` will clear the window
    784    completely.
    785 
    786 
    787 .. method:: window.clrtobot()
    788 
    789    Erase from cursor to the end of the window: all lines below the cursor are
    790    deleted, and then the equivalent of :meth:`clrtoeol` is performed.
    791 
    792 
    793 .. method:: window.clrtoeol()
    794 
    795    Erase from cursor to the end of the line.
    796 
    797 
    798 .. method:: window.cursyncup()
    799 
    800    Update the current cursor position of all the ancestors of the window to
    801    reflect the current cursor position of the window.
    802 
    803 
    804 .. method:: window.delch([y, x])
    805 
    806    Delete any character at ``(y, x)``.
    807 
    808 
    809 .. method:: window.deleteln()
    810 
    811    Delete the line under the cursor. All following lines are moved up by one line.
    812 
    813 
    814 .. method:: window.derwin(begin_y, begin_x)
    815             window.derwin(nlines, ncols, begin_y, begin_x)
    816 
    817    An abbreviation for "derive window", :meth:`derwin` is the same as calling
    818    :meth:`subwin`, except that *begin_y* and *begin_x* are relative to the origin
    819    of the window, rather than relative to the entire screen.  Return a window
    820    object for the derived window.
    821 
    822 
    823 .. method:: window.echochar(ch[, attr])
    824 
    825    Add character *ch* with attribute *attr*, and immediately  call :meth:`refresh`
    826    on the window.
    827 
    828 
    829 .. method:: window.enclose(y, x)
    830 
    831    Test whether the given pair of screen-relative character-cell coordinates are
    832    enclosed by the given window, returning ``True`` or ``False``.  It is useful for
    833    determining what subset of the screen windows enclose the location of a mouse
    834    event.
    835 
    836 
    837 .. method:: window.erase()
    838 
    839    Clear the window.
    840 
    841 
    842 .. method:: window.getbegyx()
    843 
    844    Return a tuple ``(y, x)`` of co-ordinates of upper-left corner.
    845 
    846 
    847 .. method:: window.getbkgd()
    848 
    849    Return the given window's current background character/attribute pair.
    850 
    851 
    852 .. method:: window.getch([y, x])
    853 
    854    Get a character. Note that the integer returned does *not* have to be in ASCII
    855    range: function keys, keypad keys and so on return numbers higher than 256. In
    856    no-delay mode, -1 is returned if there is no input, else :func:`getch` waits
    857    until a key is pressed.
    858 
    859 
    860 .. method:: window.getkey([y, x])
    861 
    862    Get a character, returning a string instead of an integer, as :meth:`getch`
    863    does. Function keys, keypad keys and so on return a multibyte string containing
    864    the key name.  In no-delay mode, an exception is raised if there is no input.
    865 
    866 
    867 .. method:: window.getmaxyx()
    868 
    869    Return a tuple ``(y, x)`` of the height and width of the window.
    870 
    871 
    872 .. method:: window.getparyx()
    873 
    874    Return the beginning coordinates of this window relative to its parent window
    875    into two integer variables y and x.  Return ``-1, -1`` if this window has no
    876    parent.
    877 
    878 
    879 .. method:: window.getstr([y, x])
    880 
    881    Read a string from the user, with primitive line editing capacity.
    882 
    883 
    884 .. method:: window.getyx()
    885 
    886    Return a tuple ``(y, x)`` of current cursor position  relative to the window's
    887    upper-left corner.
    888 
    889 
    890 .. method:: window.hline(ch, n)
    891             window.hline(y, x, ch, n)
    892 
    893    Display a horizontal line starting at ``(y, x)`` with length *n* consisting of
    894    the character *ch*.
    895 
    896 
    897 .. method:: window.idcok(flag)
    898 
    899    If *flag* is ``False``, curses no longer considers using the hardware insert/delete
    900    character feature of the terminal; if *flag* is ``True``, use of character insertion
    901    and deletion is enabled.  When curses is first initialized, use of character
    902    insert/delete is enabled by default.
    903 
    904 
    905 .. method:: window.idlok(yes)
    906 
    907    If called with *yes* equal to 1, :mod:`curses` will try and use hardware line
    908    editing facilities. Otherwise, line insertion/deletion are disabled.
    909 
    910 
    911 .. method:: window.immedok(flag)
    912 
    913    If *flag* is ``True``, any change in the window image automatically causes the
    914    window to be refreshed; you no longer have to call :meth:`refresh` yourself.
    915    However, it may degrade performance considerably, due to repeated calls to
    916    wrefresh.  This option is disabled by default.
    917 
    918 
    919 .. method:: window.inch([y, x])
    920 
    921    Return the character at the given position in the window. The bottom 8 bits are
    922    the character proper, and upper bits are the attributes.
    923 
    924 
    925 .. method:: window.insch(ch[, attr])
    926             window.insch(y, x, ch[, attr])
    927 
    928    Paint character *ch* at ``(y, x)`` with attributes *attr*, moving the line from
    929    position *x* right by one character.
    930 
    931 
    932 .. method:: window.insdelln(nlines)
    933 
    934    Insert *nlines* lines into the specified window above the current line.  The
    935    *nlines* bottom lines are lost.  For negative *nlines*, delete *nlines* lines
    936    starting with the one under the cursor, and move the remaining lines up.  The
    937    bottom *nlines* lines are cleared.  The current cursor position remains the
    938    same.
    939 
    940 
    941 .. method:: window.insertln()
    942 
    943    Insert a blank line under the cursor. All following lines are moved down by one
    944    line.
    945 
    946 
    947 .. method:: window.insnstr(str, n[, attr])
    948             window.insnstr(y, x, str, n[, attr])
    949 
    950    Insert a character string (as many characters as will fit on the line) before
    951    the character under the cursor, up to *n* characters.   If *n* is zero or
    952    negative, the entire string is inserted. All characters to the right of the
    953    cursor are shifted right, with the rightmost characters on the line being lost.
    954    The cursor position does not change (after moving to *y*, *x*, if specified).
    955 
    956 
    957 .. method:: window.insstr(str[, attr])
    958             window.insstr(y, x, str[, attr])
    959 
    960    Insert a character string (as many characters as will fit on the line) before
    961    the character under the cursor.  All characters to the right of the cursor are
    962    shifted right, with the rightmost characters on the line being lost.  The cursor
    963    position does not change (after moving to *y*, *x*, if specified).
    964 
    965 
    966 .. method:: window.instr([n])
    967             window.instr(y, x[, n])
    968 
    969    Return a string of characters, extracted from the window starting at the
    970    current cursor position, or at *y*, *x* if specified. Attributes are stripped
    971    from the characters.  If *n* is specified, :meth:`instr` returns a string
    972    at most *n* characters long (exclusive of the trailing NUL).
    973 
    974 
    975 .. method:: window.is_linetouched(line)
    976 
    977    Return ``True`` if the specified line was modified since the last call to
    978    :meth:`refresh`; otherwise return ``False``.  Raise a :exc:`curses.error`
    979    exception if *line* is not valid for the given window.
    980 
    981 
    982 .. method:: window.is_wintouched()
    983 
    984    Return ``True`` if the specified window was modified since the last call to
    985    :meth:`refresh`; otherwise return ``False``.
    986 
    987 
    988 .. method:: window.keypad(yes)
    989 
    990    If *yes* is 1, escape sequences generated by some keys (keypad,  function keys)
    991    will be interpreted by :mod:`curses`. If *yes* is 0, escape sequences will be
    992    left as is in the input stream.
    993 
    994 
    995 .. method:: window.leaveok(yes)
    996 
    997    If *yes* is 1, cursor is left where it is on update, instead of being at "cursor
    998    position."  This reduces cursor movement where possible. If possible the cursor
    999    will be made invisible.
   1000 
   1001    If *yes* is 0, cursor will always be at "cursor position" after an update.
   1002 
   1003 
   1004 .. method:: window.move(new_y, new_x)
   1005 
   1006    Move cursor to ``(new_y, new_x)``.
   1007 
   1008 
   1009 .. method:: window.mvderwin(y, x)
   1010 
   1011    Move the window inside its parent window.  The screen-relative parameters of
   1012    the window are not changed.  This routine is used to display different parts of
   1013    the parent window at the same physical position on the screen.
   1014 
   1015 
   1016 .. method:: window.mvwin(new_y, new_x)
   1017 
   1018    Move the window so its upper-left corner is at ``(new_y, new_x)``.
   1019 
   1020 
   1021 .. method:: window.nodelay(yes)
   1022 
   1023    If *yes* is ``1``, :meth:`getch` will be non-blocking.
   1024 
   1025 
   1026 .. method:: window.notimeout(yes)
   1027 
   1028    If *yes* is ``1``, escape sequences will not be timed out.
   1029 
   1030    If *yes* is ``0``, after a few milliseconds, an escape sequence will not be
   1031    interpreted, and will be left in the input stream as is.
   1032 
   1033 
   1034 .. method:: window.noutrefresh()
   1035 
   1036    Mark for refresh but wait.  This function updates the data structure
   1037    representing the desired state of the window, but does not force an update of
   1038    the physical screen.  To accomplish that, call  :func:`doupdate`.
   1039 
   1040 
   1041 .. method:: window.overlay(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])
   1042 
   1043    Overlay the window on top of *destwin*. The windows need not be the same size,
   1044    only the overlapping region is copied. This copy is non-destructive, which means
   1045    that the current background character does not overwrite the old contents of
   1046    *destwin*.
   1047 
   1048    To get fine-grained control over the copied region, the second form of
   1049    :meth:`overlay` can be used. *sminrow* and *smincol* are the upper-left
   1050    coordinates of the source window, and the other variables mark a rectangle in
   1051    the destination window.
   1052 
   1053 
   1054 .. method:: window.overwrite(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])
   1055 
   1056    Overwrite the window on top of *destwin*. The windows need not be the same size,
   1057    in which case only the overlapping region is copied. This copy is destructive,
   1058    which means that the current background character overwrites the old contents of
   1059    *destwin*.
   1060 
   1061    To get fine-grained control over the copied region, the second form of
   1062    :meth:`overwrite` can be used. *sminrow* and *smincol* are the upper-left
   1063    coordinates of the source window, the other variables mark a rectangle in the
   1064    destination window.
   1065 
   1066 
   1067 .. method:: window.putwin(file)
   1068 
   1069    Write all data associated with the window into the provided file object.  This
   1070    information can be later retrieved using the :func:`getwin` function.
   1071 
   1072 
   1073 .. method:: window.redrawln(beg, num)
   1074 
   1075    Indicate that the *num* screen lines, starting at line *beg*, are corrupted and
   1076    should be completely redrawn on the next :meth:`refresh` call.
   1077 
   1078 
   1079 .. method:: window.redrawwin()
   1080 
   1081    Touch the entire window, causing it to be completely redrawn on the next
   1082    :meth:`refresh` call.
   1083 
   1084 
   1085 .. method:: window.refresh([pminrow, pmincol, sminrow, smincol, smaxrow, smaxcol])
   1086 
   1087    Update the display immediately (sync actual screen with previous
   1088    drawing/deleting methods).
   1089 
   1090    The 6 optional arguments can only be specified when the window is a pad created
   1091    with :func:`newpad`.  The additional parameters are needed to indicate what part
   1092    of the pad and screen are involved. *pminrow* and *pmincol* specify the upper
   1093    left-hand corner of the rectangle to be displayed in the pad.  *sminrow*,
   1094    *smincol*, *smaxrow*, and *smaxcol* specify the edges of the rectangle to be
   1095    displayed on the screen.  The lower right-hand corner of the rectangle to be
   1096    displayed in the pad is calculated from the screen coordinates, since the
   1097    rectangles must be the same size.  Both rectangles must be entirely contained
   1098    within their respective structures.  Negative values of *pminrow*, *pmincol*,
   1099    *sminrow*, or *smincol* are treated as if they were zero.
   1100 
   1101 
   1102 .. method:: window.resize(nlines, ncols)
   1103 
   1104    Reallocate storage for a curses window to adjust its dimensions to the
   1105    specified values.  If either dimension is larger than the current values, the
   1106    window's data is filled with blanks that have the current background
   1107    rendition (as set by :meth:`bkgdset`) merged into them.
   1108 
   1109 
   1110 .. method:: window.scroll([lines=1])
   1111 
   1112    Scroll the screen or scrolling region upward by *lines* lines.
   1113 
   1114 
   1115 .. method:: window.scrollok(flag)
   1116 
   1117    Control what happens when the cursor of a window is moved off the edge of the
   1118    window or scrolling region, either as a result of a newline action on the bottom
   1119    line, or typing the last character of the last line.  If *flag* is false, the
   1120    cursor is left on the bottom line.  If *flag* is true, the window is scrolled up
   1121    one line.  Note that in order to get the physical scrolling effect on the
   1122    terminal, it is also necessary to call :meth:`idlok`.
   1123 
   1124 
   1125 .. method:: window.setscrreg(top, bottom)
   1126 
   1127    Set the scrolling region from line *top* to line *bottom*. All scrolling actions
   1128    will take place in this region.
   1129 
   1130 
   1131 .. method:: window.standend()
   1132 
   1133    Turn off the standout attribute.  On some terminals this has the side effect of
   1134    turning off all attributes.
   1135 
   1136 
   1137 .. method:: window.standout()
   1138 
   1139    Turn on attribute *A_STANDOUT*.
   1140 
   1141 
   1142 .. method:: window.subpad(begin_y, begin_x)
   1143             window.subpad(nlines, ncols, begin_y, begin_x)
   1144 
   1145    Return a sub-window, whose upper-left corner is at ``(begin_y, begin_x)``, and
   1146    whose width/height is *ncols*/*nlines*.
   1147 
   1148 
   1149 .. method:: window.subwin(begin_y, begin_x)
   1150             window.subwin(nlines, ncols, begin_y, begin_x)
   1151 
   1152    Return a sub-window, whose upper-left corner is at ``(begin_y, begin_x)``, and
   1153    whose width/height is *ncols*/*nlines*.
   1154 
   1155    By default, the sub-window will extend from the specified position to the lower
   1156    right corner of the window.
   1157 
   1158 
   1159 .. method:: window.syncdown()
   1160 
   1161    Touch each location in the window that has been touched in any of its ancestor
   1162    windows.  This routine is called by :meth:`refresh`, so it should almost never
   1163    be necessary to call it manually.
   1164 
   1165 
   1166 .. method:: window.syncok(flag)
   1167 
   1168    If called with *flag* set to ``True``, then :meth:`syncup` is called automatically
   1169    whenever there is a change in the window.
   1170 
   1171 
   1172 .. method:: window.syncup()
   1173 
   1174    Touch all locations in ancestors of the window that have been changed in  the
   1175    window.
   1176 
   1177 
   1178 .. method:: window.timeout(delay)
   1179 
   1180    Set blocking or non-blocking read behavior for the window.  If *delay* is
   1181    negative, blocking read is used (which will wait indefinitely for input).  If
   1182    *delay* is zero, then non-blocking read is used, and -1 will be returned by
   1183    :meth:`getch` if no input is waiting.  If *delay* is positive, then
   1184    :meth:`getch` will block for *delay* milliseconds, and return -1 if there is
   1185    still no input at the end of that time.
   1186 
   1187 
   1188 .. method:: window.touchline(start, count[, changed])
   1189 
   1190    Pretend *count* lines have been changed, starting with line *start*.  If
   1191    *changed* is supplied, it specifies whether the affected lines are marked as
   1192    having been changed (*changed*\ =1) or unchanged (*changed*\ =0).
   1193 
   1194 
   1195 .. method:: window.touchwin()
   1196 
   1197    Pretend the whole window has been changed, for purposes of drawing
   1198    optimizations.
   1199 
   1200 
   1201 .. method:: window.untouchwin()
   1202 
   1203    Mark all lines in  the  window  as unchanged since the last call to
   1204    :meth:`refresh`.
   1205 
   1206 
   1207 .. method:: window.vline(ch, n)
   1208             window.vline(y, x, ch, n)
   1209 
   1210    Display a vertical line starting at ``(y, x)`` with length *n* consisting of the
   1211    character *ch*.
   1212 
   1213 
   1214 Constants
   1215 ---------
   1216 
   1217 The :mod:`curses` module defines the following data members:
   1218 
   1219 
   1220 .. data:: ERR
   1221 
   1222    Some curses routines  that  return  an integer, such as  :func:`getch`, return
   1223    :const:`ERR` upon failure.
   1224 
   1225 
   1226 .. data:: OK
   1227 
   1228    Some curses routines  that  return  an integer, such as  :func:`napms`, return
   1229    :const:`OK` upon success.
   1230 
   1231 
   1232 .. data:: version
   1233 
   1234    A string representing the current version of the module.  Also available as
   1235    :const:`__version__`.
   1236 
   1237 Several constants are available to specify character cell attributes:
   1238 
   1239 +------------------+-------------------------------+
   1240 | Attribute        | Meaning                       |
   1241 +==================+===============================+
   1242 | ``A_ALTCHARSET`` | Alternate character set mode. |
   1243 +------------------+-------------------------------+
   1244 | ``A_BLINK``      | Blink mode.                   |
   1245 +------------------+-------------------------------+
   1246 | ``A_BOLD``       | Bold mode.                    |
   1247 +------------------+-------------------------------+
   1248 | ``A_DIM``        | Dim mode.                     |
   1249 +------------------+-------------------------------+
   1250 | ``A_NORMAL``     | Normal attribute.             |
   1251 +------------------+-------------------------------+
   1252 | ``A_REVERSE``    | Reverse background and        |
   1253 |                  | foreground colors.            |
   1254 +------------------+-------------------------------+
   1255 | ``A_STANDOUT``   | Standout mode.                |
   1256 +------------------+-------------------------------+
   1257 | ``A_UNDERLINE``  | Underline mode.               |
   1258 +------------------+-------------------------------+
   1259 
   1260 Keys are referred to by integer constants with names starting with  ``KEY_``.
   1261 The exact keycaps available are system dependent.
   1262 
   1263 .. XXX this table is far too large! should it be alphabetized?
   1264 
   1265 +-------------------+--------------------------------------------+
   1266 | Key constant      | Key                                        |
   1267 +===================+============================================+
   1268 | ``KEY_MIN``       | Minimum key value                          |
   1269 +-------------------+--------------------------------------------+
   1270 | ``KEY_BREAK``     | Break key (unreliable)                     |
   1271 +-------------------+--------------------------------------------+
   1272 | ``KEY_DOWN``      | Down-arrow                                 |
   1273 +-------------------+--------------------------------------------+
   1274 | ``KEY_UP``        | Up-arrow                                   |
   1275 +-------------------+--------------------------------------------+
   1276 | ``KEY_LEFT``      | Left-arrow                                 |
   1277 +-------------------+--------------------------------------------+
   1278 | ``KEY_RIGHT``     | Right-arrow                                |
   1279 +-------------------+--------------------------------------------+
   1280 | ``KEY_HOME``      | Home key (upward+left arrow)               |
   1281 +-------------------+--------------------------------------------+
   1282 | ``KEY_BACKSPACE`` | Backspace (unreliable)                     |
   1283 +-------------------+--------------------------------------------+
   1284 | ``KEY_F0``        | Function keys.  Up to 64 function keys are |
   1285 |                   | supported.                                 |
   1286 +-------------------+--------------------------------------------+
   1287 | ``KEY_Fn``        | Value of function key *n*                  |
   1288 +-------------------+--------------------------------------------+
   1289 | ``KEY_DL``        | Delete line                                |
   1290 +-------------------+--------------------------------------------+
   1291 | ``KEY_IL``        | Insert line                                |
   1292 +-------------------+--------------------------------------------+
   1293 | ``KEY_DC``        | Delete character                           |
   1294 +-------------------+--------------------------------------------+
   1295 | ``KEY_IC``        | Insert char or enter insert mode           |
   1296 +-------------------+--------------------------------------------+
   1297 | ``KEY_EIC``       | Exit insert char mode                      |
   1298 +-------------------+--------------------------------------------+
   1299 | ``KEY_CLEAR``     | Clear screen                               |
   1300 +-------------------+--------------------------------------------+
   1301 | ``KEY_EOS``       | Clear to end of screen                     |
   1302 +-------------------+--------------------------------------------+
   1303 | ``KEY_EOL``       | Clear to end of line                       |
   1304 +-------------------+--------------------------------------------+
   1305 | ``KEY_SF``        | Scroll 1 line forward                      |
   1306 +-------------------+--------------------------------------------+
   1307 | ``KEY_SR``        | Scroll 1 line backward (reverse)           |
   1308 +-------------------+--------------------------------------------+
   1309 | ``KEY_NPAGE``     | Next page                                  |
   1310 +-------------------+--------------------------------------------+
   1311 | ``KEY_PPAGE``     | Previous page                              |
   1312 +-------------------+--------------------------------------------+
   1313 | ``KEY_STAB``      | Set tab                                    |
   1314 +-------------------+--------------------------------------------+
   1315 | ``KEY_CTAB``      | Clear tab                                  |
   1316 +-------------------+--------------------------------------------+
   1317 | ``KEY_CATAB``     | Clear all tabs                             |
   1318 +-------------------+--------------------------------------------+
   1319 | ``KEY_ENTER``     | Enter or send (unreliable)                 |
   1320 +-------------------+--------------------------------------------+
   1321 | ``KEY_SRESET``    | Soft (partial) reset (unreliable)          |
   1322 +-------------------+--------------------------------------------+
   1323 | ``KEY_RESET``     | Reset or hard reset (unreliable)           |
   1324 +-------------------+--------------------------------------------+
   1325 | ``KEY_PRINT``     | Print                                      |
   1326 +-------------------+--------------------------------------------+
   1327 | ``KEY_LL``        | Home down or bottom (lower left)           |
   1328 +-------------------+--------------------------------------------+
   1329 | ``KEY_A1``        | Upper left of keypad                       |
   1330 +-------------------+--------------------------------------------+
   1331 | ``KEY_A3``        | Upper right of keypad                      |
   1332 +-------------------+--------------------------------------------+
   1333 | ``KEY_B2``        | Center of keypad                           |
   1334 +-------------------+--------------------------------------------+
   1335 | ``KEY_C1``        | Lower left of keypad                       |
   1336 +-------------------+--------------------------------------------+
   1337 | ``KEY_C3``        | Lower right of keypad                      |
   1338 +-------------------+--------------------------------------------+
   1339 | ``KEY_BTAB``      | Back tab                                   |
   1340 +-------------------+--------------------------------------------+
   1341 | ``KEY_BEG``       | Beg (beginning)                            |
   1342 +-------------------+--------------------------------------------+
   1343 | ``KEY_CANCEL``    | Cancel                                     |
   1344 +-------------------+--------------------------------------------+
   1345 | ``KEY_CLOSE``     | Close                                      |
   1346 +-------------------+--------------------------------------------+
   1347 | ``KEY_COMMAND``   | Cmd (command)                              |
   1348 +-------------------+--------------------------------------------+
   1349 | ``KEY_COPY``      | Copy                                       |
   1350 +-------------------+--------------------------------------------+
   1351 | ``KEY_CREATE``    | Create                                     |
   1352 +-------------------+--------------------------------------------+
   1353 | ``KEY_END``       | End                                        |
   1354 +-------------------+--------------------------------------------+
   1355 | ``KEY_EXIT``      | Exit                                       |
   1356 +-------------------+--------------------------------------------+
   1357 | ``KEY_FIND``      | Find                                       |
   1358 +-------------------+--------------------------------------------+
   1359 | ``KEY_HELP``      | Help                                       |
   1360 +-------------------+--------------------------------------------+
   1361 | ``KEY_MARK``      | Mark                                       |
   1362 +-------------------+--------------------------------------------+
   1363 | ``KEY_MESSAGE``   | Message                                    |
   1364 +-------------------+--------------------------------------------+
   1365 | ``KEY_MOVE``      | Move                                       |
   1366 +-------------------+--------------------------------------------+
   1367 | ``KEY_NEXT``      | Next                                       |
   1368 +-------------------+--------------------------------------------+
   1369 | ``KEY_OPEN``      | Open                                       |
   1370 +-------------------+--------------------------------------------+
   1371 | ``KEY_OPTIONS``   | Options                                    |
   1372 +-------------------+--------------------------------------------+
   1373 | ``KEY_PREVIOUS``  | Prev (previous)                            |
   1374 +-------------------+--------------------------------------------+
   1375 | ``KEY_REDO``      | Redo                                       |
   1376 +-------------------+--------------------------------------------+
   1377 | ``KEY_REFERENCE`` | Ref (reference)                            |
   1378 +-------------------+--------------------------------------------+
   1379 | ``KEY_REFRESH``   | Refresh                                    |
   1380 +-------------------+--------------------------------------------+
   1381 | ``KEY_REPLACE``   | Replace                                    |
   1382 +-------------------+--------------------------------------------+
   1383 | ``KEY_RESTART``   | Restart                                    |
   1384 +-------------------+--------------------------------------------+
   1385 | ``KEY_RESUME``    | Resume                                     |
   1386 +-------------------+--------------------------------------------+
   1387 | ``KEY_SAVE``      | Save                                       |
   1388 +-------------------+--------------------------------------------+
   1389 | ``KEY_SBEG``      | Shifted Beg (beginning)                    |
   1390 +-------------------+--------------------------------------------+
   1391 | ``KEY_SCANCEL``   | Shifted Cancel                             |
   1392 +-------------------+--------------------------------------------+
   1393 | ``KEY_SCOMMAND``  | Shifted Command                            |
   1394 +-------------------+--------------------------------------------+
   1395 | ``KEY_SCOPY``     | Shifted Copy                               |
   1396 +-------------------+--------------------------------------------+
   1397 | ``KEY_SCREATE``   | Shifted Create                             |
   1398 +-------------------+--------------------------------------------+
   1399 | ``KEY_SDC``       | Shifted Delete char                        |
   1400 +-------------------+--------------------------------------------+
   1401 | ``KEY_SDL``       | Shifted Delete line                        |
   1402 +-------------------+--------------------------------------------+
   1403 | ``KEY_SELECT``    | Select                                     |
   1404 +-------------------+--------------------------------------------+
   1405 | ``KEY_SEND``      | Shifted End                                |
   1406 +-------------------+--------------------------------------------+
   1407 | ``KEY_SEOL``      | Shifted Clear line                         |
   1408 +-------------------+--------------------------------------------+
   1409 | ``KEY_SEXIT``     | Shifted Dxit                               |
   1410 +-------------------+--------------------------------------------+
   1411 | ``KEY_SFIND``     | Shifted Find                               |
   1412 +-------------------+--------------------------------------------+
   1413 | ``KEY_SHELP``     | Shifted Help                               |
   1414 +-------------------+--------------------------------------------+
   1415 | ``KEY_SHOME``     | Shifted Home                               |
   1416 +-------------------+--------------------------------------------+
   1417 | ``KEY_SIC``       | Shifted Input                              |
   1418 +-------------------+--------------------------------------------+
   1419 | ``KEY_SLEFT``     | Shifted Left arrow                         |
   1420 +-------------------+--------------------------------------------+
   1421 | ``KEY_SMESSAGE``  | Shifted Message                            |
   1422 +-------------------+--------------------------------------------+
   1423 | ``KEY_SMOVE``     | Shifted Move                               |
   1424 +-------------------+--------------------------------------------+
   1425 | ``KEY_SNEXT``     | Shifted Next                               |
   1426 +-------------------+--------------------------------------------+
   1427 | ``KEY_SOPTIONS``  | Shifted Options                            |
   1428 +-------------------+--------------------------------------------+
   1429 | ``KEY_SPREVIOUS`` | Shifted Prev                               |
   1430 +-------------------+--------------------------------------------+
   1431 | ``KEY_SPRINT``    | Shifted Print                              |
   1432 +-------------------+--------------------------------------------+
   1433 | ``KEY_SREDO``     | Shifted Redo                               |
   1434 +-------------------+--------------------------------------------+
   1435 | ``KEY_SREPLACE``  | Shifted Replace                            |
   1436 +-------------------+--------------------------------------------+
   1437 | ``KEY_SRIGHT``    | Shifted Right arrow                        |
   1438 +-------------------+--------------------------------------------+
   1439 | ``KEY_SRSUME``    | Shifted Resume                             |
   1440 +-------------------+--------------------------------------------+
   1441 | ``KEY_SSAVE``     | Shifted Save                               |
   1442 +-------------------+--------------------------------------------+
   1443 | ``KEY_SSUSPEND``  | Shifted Suspend                            |
   1444 +-------------------+--------------------------------------------+
   1445 | ``KEY_SUNDO``     | Shifted Undo                               |
   1446 +-------------------+--------------------------------------------+
   1447 | ``KEY_SUSPEND``   | Suspend                                    |
   1448 +-------------------+--------------------------------------------+
   1449 | ``KEY_UNDO``      | Undo                                       |
   1450 +-------------------+--------------------------------------------+
   1451 | ``KEY_MOUSE``     | Mouse event has occurred                   |
   1452 +-------------------+--------------------------------------------+
   1453 | ``KEY_RESIZE``    | Terminal resize event                      |
   1454 +-------------------+--------------------------------------------+
   1455 | ``KEY_MAX``       | Maximum key value                          |
   1456 +-------------------+--------------------------------------------+
   1457 
   1458 On VT100s and their software emulations, such as X terminal emulators, there are
   1459 normally at least four function keys (:const:`KEY_F1`, :const:`KEY_F2`,
   1460 :const:`KEY_F3`, :const:`KEY_F4`) available, and the arrow keys mapped to
   1461 :const:`KEY_UP`, :const:`KEY_DOWN`, :const:`KEY_LEFT` and :const:`KEY_RIGHT` in
   1462 the obvious way.  If your machine has a PC keyboard, it is safe to expect arrow
   1463 keys and twelve function keys (older PC keyboards may have only ten function
   1464 keys); also, the following keypad mappings are standard:
   1465 
   1466 +------------------+-----------+
   1467 | Keycap           | Constant  |
   1468 +==================+===========+
   1469 | :kbd:`Insert`    | KEY_IC    |
   1470 +------------------+-----------+
   1471 | :kbd:`Delete`    | KEY_DC    |
   1472 +------------------+-----------+
   1473 | :kbd:`Home`      | KEY_HOME  |
   1474 +------------------+-----------+
   1475 | :kbd:`End`       | KEY_END   |
   1476 +------------------+-----------+
   1477 | :kbd:`Page Up`   | KEY_PPAGE |
   1478 +------------------+-----------+
   1479 | :kbd:`Page Down` | KEY_NPAGE |
   1480 +------------------+-----------+
   1481 
   1482 The following table lists characters from the alternate character set. These are
   1483 inherited from the VT100 terminal, and will generally be  available on software
   1484 emulations such as X terminals.  When there is no graphic available, curses
   1485 falls back on a crude printable ASCII approximation.
   1486 
   1487 .. note::
   1488 
   1489    These are available only after :func:`initscr` has  been called.
   1490 
   1491 +------------------+------------------------------------------+
   1492 | ACS code         | Meaning                                  |
   1493 +==================+==========================================+
   1494 | ``ACS_BBSS``     | alternate name for upper right corner    |
   1495 +------------------+------------------------------------------+
   1496 | ``ACS_BLOCK``    | solid square block                       |
   1497 +------------------+------------------------------------------+
   1498 | ``ACS_BOARD``    | board of squares                         |
   1499 +------------------+------------------------------------------+
   1500 | ``ACS_BSBS``     | alternate name for horizontal line       |
   1501 +------------------+------------------------------------------+
   1502 | ``ACS_BSSB``     | alternate name for upper left corner     |
   1503 +------------------+------------------------------------------+
   1504 | ``ACS_BSSS``     | alternate name for top tee               |
   1505 +------------------+------------------------------------------+
   1506 | ``ACS_BTEE``     | bottom tee                               |
   1507 +------------------+------------------------------------------+
   1508 | ``ACS_BULLET``   | bullet                                   |
   1509 +------------------+------------------------------------------+
   1510 | ``ACS_CKBOARD``  | checker board (stipple)                  |
   1511 +------------------+------------------------------------------+
   1512 | ``ACS_DARROW``   | arrow pointing down                      |
   1513 +------------------+------------------------------------------+
   1514 | ``ACS_DEGREE``   | degree symbol                            |
   1515 +------------------+------------------------------------------+
   1516 | ``ACS_DIAMOND``  | diamond                                  |
   1517 +------------------+------------------------------------------+
   1518 | ``ACS_GEQUAL``   | greater-than-or-equal-to                 |
   1519 +------------------+------------------------------------------+
   1520 | ``ACS_HLINE``    | horizontal line                          |
   1521 +------------------+------------------------------------------+
   1522 | ``ACS_LANTERN``  | lantern symbol                           |
   1523 +------------------+------------------------------------------+
   1524 | ``ACS_LARROW``   | left arrow                               |
   1525 +------------------+------------------------------------------+
   1526 | ``ACS_LEQUAL``   | less-than-or-equal-to                    |
   1527 +------------------+------------------------------------------+
   1528 | ``ACS_LLCORNER`` | lower left-hand corner                   |
   1529 +------------------+------------------------------------------+
   1530 | ``ACS_LRCORNER`` | lower right-hand corner                  |
   1531 +------------------+------------------------------------------+
   1532 | ``ACS_LTEE``     | left tee                                 |
   1533 +------------------+------------------------------------------+
   1534 | ``ACS_NEQUAL``   | not-equal sign                           |
   1535 +------------------+------------------------------------------+
   1536 | ``ACS_PI``       | letter pi                                |
   1537 +------------------+------------------------------------------+
   1538 | ``ACS_PLMINUS``  | plus-or-minus sign                       |
   1539 +------------------+------------------------------------------+
   1540 | ``ACS_PLUS``     | big plus sign                            |
   1541 +------------------+------------------------------------------+
   1542 | ``ACS_RARROW``   | right arrow                              |
   1543 +------------------+------------------------------------------+
   1544 | ``ACS_RTEE``     | right tee                                |
   1545 +------------------+------------------------------------------+
   1546 | ``ACS_S1``       | scan line 1                              |
   1547 +------------------+------------------------------------------+
   1548 | ``ACS_S3``       | scan line 3                              |
   1549 +------------------+------------------------------------------+
   1550 | ``ACS_S7``       | scan line 7                              |
   1551 +------------------+------------------------------------------+
   1552 | ``ACS_S9``       | scan line 9                              |
   1553 +------------------+------------------------------------------+
   1554 | ``ACS_SBBS``     | alternate name for lower right corner    |
   1555 +------------------+------------------------------------------+
   1556 | ``ACS_SBSB``     | alternate name for vertical line         |
   1557 +------------------+------------------------------------------+
   1558 | ``ACS_SBSS``     | alternate name for right tee             |
   1559 +------------------+------------------------------------------+
   1560 | ``ACS_SSBB``     | alternate name for lower left corner     |
   1561 +------------------+------------------------------------------+
   1562 | ``ACS_SSBS``     | alternate name for bottom tee            |
   1563 +------------------+------------------------------------------+
   1564 | ``ACS_SSSB``     | alternate name for left tee              |
   1565 +------------------+------------------------------------------+
   1566 | ``ACS_SSSS``     | alternate name for crossover or big plus |
   1567 +------------------+------------------------------------------+
   1568 | ``ACS_STERLING`` | pound sterling                           |
   1569 +------------------+------------------------------------------+
   1570 | ``ACS_TTEE``     | top tee                                  |
   1571 +------------------+------------------------------------------+
   1572 | ``ACS_UARROW``   | up arrow                                 |
   1573 +------------------+------------------------------------------+
   1574 | ``ACS_ULCORNER`` | upper left corner                        |
   1575 +------------------+------------------------------------------+
   1576 | ``ACS_URCORNER`` | upper right corner                       |
   1577 +------------------+------------------------------------------+
   1578 | ``ACS_VLINE``    | vertical line                            |
   1579 +------------------+------------------------------------------+
   1580 
   1581 The following table lists the predefined colors:
   1582 
   1583 +-------------------+----------------------------+
   1584 | Constant          | Color                      |
   1585 +===================+============================+
   1586 | ``COLOR_BLACK``   | Black                      |
   1587 +-------------------+----------------------------+
   1588 | ``COLOR_BLUE``    | Blue                       |
   1589 +-------------------+----------------------------+
   1590 | ``COLOR_CYAN``    | Cyan (light greenish blue) |
   1591 +-------------------+----------------------------+
   1592 | ``COLOR_GREEN``   | Green                      |
   1593 +-------------------+----------------------------+
   1594 | ``COLOR_MAGENTA`` | Magenta (purplish red)     |
   1595 +-------------------+----------------------------+
   1596 | ``COLOR_RED``     | Red                        |
   1597 +-------------------+----------------------------+
   1598 | ``COLOR_WHITE``   | White                      |
   1599 +-------------------+----------------------------+
   1600 | ``COLOR_YELLOW``  | Yellow                     |
   1601 +-------------------+----------------------------+
   1602 
   1603 
   1604 :mod:`curses.textpad` --- Text input widget for curses programs
   1605 ===============================================================
   1606 
   1607 .. module:: curses.textpad
   1608    :synopsis: Emacs-like input editing in a curses window.
   1609 .. moduleauthor:: Eric Raymond <esr (a] thyrsus.com>
   1610 .. sectionauthor:: Eric Raymond <esr (a] thyrsus.com>
   1611 
   1612 
   1613 .. versionadded:: 1.6
   1614 
   1615 The :mod:`curses.textpad` module provides a :class:`Textbox` class that handles
   1616 elementary text editing in a curses window, supporting a set of keybindings
   1617 resembling those of Emacs (thus, also of Netscape Navigator, BBedit 6.x,
   1618 FrameMaker, and many other programs).  The module also provides a
   1619 rectangle-drawing function useful for framing text boxes or for other purposes.
   1620 
   1621 The module :mod:`curses.textpad` defines the following function:
   1622 
   1623 
   1624 .. function:: rectangle(win, uly, ulx, lry, lrx)
   1625 
   1626    Draw a rectangle.  The first argument must be a window object; the remaining
   1627    arguments are coordinates relative to that window.  The second and third
   1628    arguments are the y and x coordinates of the upper left hand corner of the
   1629    rectangle to be drawn; the fourth and fifth arguments are the y and x
   1630    coordinates of the lower right hand corner. The rectangle will be drawn using
   1631    VT100/IBM PC forms characters on terminals that make this possible (including
   1632    xterm and most other software terminal emulators).  Otherwise it will be drawn
   1633    with ASCII  dashes, vertical bars, and plus signs.
   1634 
   1635 
   1636 .. _curses-textpad-objects:
   1637 
   1638 Textbox objects
   1639 ---------------
   1640 
   1641 You can instantiate a :class:`Textbox` object as follows:
   1642 
   1643 
   1644 .. class:: Textbox(win)
   1645 
   1646    Return a textbox widget object.  The *win* argument should be a curses
   1647    :class:`WindowObject` in which the textbox is to be contained. The edit cursor
   1648    of the textbox is initially located at the upper left hand corner of the
   1649    containing window, with coordinates ``(0, 0)``. The instance's
   1650    :attr:`stripspaces` flag is initially on.
   1651 
   1652    :class:`Textbox` objects have the following methods:
   1653 
   1654 
   1655    .. method:: edit([validator])
   1656 
   1657       This is the entry point you will normally use.  It accepts editing
   1658       keystrokes until one of the termination keystrokes is entered.  If
   1659       *validator* is supplied, it must be a function.  It will be called for
   1660       each keystroke entered with the keystroke as a parameter; command dispatch
   1661       is done on the result. This method returns the window contents as a
   1662       string; whether blanks in the window are included is affected by the
   1663       :attr:`stripspaces` attribute.
   1664 
   1665 
   1666    .. method:: do_command(ch)
   1667 
   1668       Process a single command keystroke.  Here are the supported special
   1669       keystrokes:
   1670 
   1671       +------------------+-------------------------------------------+
   1672       | Keystroke        | Action                                    |
   1673       +==================+===========================================+
   1674       | :kbd:`Control-A` | Go to left edge of window.                |
   1675       +------------------+-------------------------------------------+
   1676       | :kbd:`Control-B` | Cursor left, wrapping to previous line if |
   1677       |                  | appropriate.                              |
   1678       +------------------+-------------------------------------------+
   1679       | :kbd:`Control-D` | Delete character under cursor.            |
   1680       +------------------+-------------------------------------------+
   1681       | :kbd:`Control-E` | Go to right edge (stripspaces off) or end |
   1682       |                  | of line (stripspaces on).                 |
   1683       +------------------+-------------------------------------------+
   1684       | :kbd:`Control-F` | Cursor right, wrapping to next line when  |
   1685       |                  | appropriate.                              |
   1686       +------------------+-------------------------------------------+
   1687       | :kbd:`Control-G` | Terminate, returning the window contents. |
   1688       +------------------+-------------------------------------------+
   1689       | :kbd:`Control-H` | Delete character backward.                |
   1690       +------------------+-------------------------------------------+
   1691       | :kbd:`Control-J` | Terminate if the window is 1 line,        |
   1692       |                  | otherwise insert newline.                 |
   1693       +------------------+-------------------------------------------+
   1694       | :kbd:`Control-K` | If line is blank, delete it, otherwise    |
   1695       |                  | clear to end of line.                     |
   1696       +------------------+-------------------------------------------+
   1697       | :kbd:`Control-L` | Refresh screen.                           |
   1698       +------------------+-------------------------------------------+
   1699       | :kbd:`Control-N` | Cursor down; move down one line.          |
   1700       +------------------+-------------------------------------------+
   1701       | :kbd:`Control-O` | Insert a blank line at cursor location.   |
   1702       +------------------+-------------------------------------------+
   1703       | :kbd:`Control-P` | Cursor up; move up one line.              |
   1704       +------------------+-------------------------------------------+
   1705 
   1706       Move operations do nothing if the cursor is at an edge where the movement
   1707       is not possible.  The following synonyms are supported where possible:
   1708 
   1709       +------------------------+------------------+
   1710       | Constant               | Keystroke        |
   1711       +========================+==================+
   1712       | :const:`KEY_LEFT`      | :kbd:`Control-B` |
   1713       +------------------------+------------------+
   1714       | :const:`KEY_RIGHT`     | :kbd:`Control-F` |
   1715       +------------------------+------------------+
   1716       | :const:`KEY_UP`        | :kbd:`Control-P` |
   1717       +------------------------+------------------+
   1718       | :const:`KEY_DOWN`      | :kbd:`Control-N` |
   1719       +------------------------+------------------+
   1720       | :const:`KEY_BACKSPACE` | :kbd:`Control-h` |
   1721       +------------------------+------------------+
   1722 
   1723       All other keystrokes are treated as a command to insert the given
   1724       character and move right (with line wrapping).
   1725 
   1726 
   1727    .. method:: gather()
   1728 
   1729       Return the window contents as a string; whether blanks in the
   1730       window are included is affected by the :attr:`stripspaces` member.
   1731 
   1732 
   1733    .. attribute:: stripspaces
   1734 
   1735       This attribute is a flag which controls the interpretation of blanks in
   1736       the window.  When it is on, trailing blanks on each line are ignored; any
   1737       cursor motion that would land the cursor on a trailing blank goes to the
   1738       end of that line instead, and trailing blanks are stripped when the window
   1739       contents are gathered.
   1740 
   1741