16.10. "curses" — Terminal handling for character-cell displays
***************************************************************

======================================================================

The "curses" module provides an interface to the curses library, the
de-facto standard for portable advanced terminal handling.

While curses is most widely used in the Unix environment, versions are
available for Windows, DOS, and possibly other systems as well.  This
extension module is designed to match the API of ncurses, an open-
source curses library hosted on Linux and the BSD variants of Unix.

Note: Since version 5.4, the ncurses library decides how to
  interpret non- ASCII data using the "nl_langinfo" function.  That
  means that you have to call "locale.setlocale()" in the application
  and encode Unicode strings using one of the system’s available
  encodings.  This example uses the system’s default encoding:

     import locale
     locale.setlocale(locale.LC_ALL, '')
     code = locale.getpreferredencoding()

  Then use *code* as the encoding for "str.encode()" calls.

See also:

  Module "curses.ascii"
     Utilities for working with ASCII characters, regardless of your
     locale settings.

  Module "curses.panel"
     A panel stack extension that adds depth to  curses windows.

  Module "curses.textpad"
     Editable text widget for curses supporting  **Emacs**-like
     bindings.

  Curses Programming with Python
     Tutorial material on using curses with Python, by Andrew Kuchling
     and Eric Raymond.

  The Tools/demo/ directory in the Python source distribution contains
  some example programs using the curses bindings provided by this
  module.


16.10.1. Functions
==================

The module "curses" defines the following exception:

exception curses.error

   Exception raised when a curses library function returns an error.

Note: Whenever *x* or *y* arguments to a function or a method are
  optional, they default to the current cursor location. Whenever
  *attr* is optional, it defaults to "A_NORMAL".

The module "curses" defines the following functions:

curses.baudrate()

   Return the output speed of the terminal in bits per second.  On
   software terminal emulators it will have a fixed high value.
   Included for historical reasons; in former times, it was used to
   write output loops for time delays and occasionally to change
   interfaces depending on the line speed.

curses.beep()

   Emit a short attention sound.

curses.can_change_color()

   Return "True" or "False", depending on whether the programmer can
   change the colors displayed by the terminal.

curses.cbreak()

   Enter cbreak mode.  In cbreak mode (sometimes called “rare” mode)
   normal tty line buffering is turned off and characters are
   available to be read one by one. However, unlike raw mode, special
   characters (interrupt, quit, suspend, and flow control) retain
   their effects on the tty driver and calling program.  Calling first
   "raw()" then "cbreak()" leaves the terminal in cbreak mode.

curses.color_content(color_number)

   Return the intensity of the red, green, and blue (RGB) components
   in the color *color_number*, which must be between "0" and
   "COLORS".  A 3-tuple is returned, containing the R,G,B values for
   the given color, which will be between "0" (no component) and
   "1000" (maximum amount of component).

curses.color_pair(color_number)

   Return the attribute value for displaying text in the specified
   color.  This attribute value can be combined with "A_STANDOUT",
   "A_REVERSE", and the other "A_*" attributes.  "pair_number()" is
   the counterpart to this function.

curses.curs_set(visibility)

   Set the cursor state.  *visibility* can be set to 0, 1, or 2, for
   invisible, normal, or very visible.  If the terminal supports the
   visibility requested, the previous cursor state is returned;
   otherwise, an exception is raised.  On many terminals, the
   “visible” mode is an underline cursor and the “very visible” mode
   is a block cursor.

curses.def_prog_mode()

   Save the current terminal mode as the “program” mode, the mode when
   the running program is using curses.  (Its counterpart is the
   “shell” mode, for when the program is not in curses.)  Subsequent
   calls to "reset_prog_mode()" will restore this mode.

curses.def_shell_mode()

   Save the current terminal mode as the “shell” mode, the mode when
   the running program is not using curses.  (Its counterpart is the
   “program” mode, when the program is using curses capabilities.)
   Subsequent calls to "reset_shell_mode()" will restore this mode.

curses.delay_output(ms)

   Insert an *ms* millisecond pause in output.

curses.doupdate()

   Update the physical screen.  The curses library keeps two data
   structures, one representing the current physical screen contents
   and a virtual screen representing the desired next state.  The
   "doupdate()" ground updates the physical screen to match the
   virtual screen.

   The virtual screen may be updated by a "noutrefresh()" call after
   write operations such as "addstr()" have been performed on a
   window.  The normal "refresh()" call is simply "noutrefresh()"
   followed by "doupdate()"; if you have to update multiple windows,
   you can speed performance and perhaps reduce screen flicker by
   issuing "noutrefresh()" calls on all windows, followed by a single
   "doupdate()".

curses.echo()

   Enter echo mode.  In echo mode, each character input is echoed to
   the screen as it is entered.

curses.endwin()

   De-initialize the library, and return terminal to normal status.

curses.erasechar()

   Return the user’s current erase character.  Under Unix operating
   systems this is a property of the controlling tty of the curses
   program, and is not set by the curses library itself.

curses.filter()

   The "filter()" routine, if used, must be called before "initscr()"
   is called.  The effect is that, during those calls, "LINES" is set
   to 1; the capabilities clear, cup, cud, cud1, cuu1, cuu, vpa are
   disabled; and the home string is set to the value of cr. The effect
   is that the cursor is confined to the current line, and so are
   screen updates.  This may be used for enabling character-at-a-time
   line editing without touching the rest of the screen.

curses.flash()

   Flash the screen.  That is, change it to reverse-video and then
   change it back in a short interval.  Some people prefer such as
   ‘visible bell’ to the audible attention signal produced by
   "beep()".

curses.flushinp()

   Flush all input buffers.  This throws away any  typeahead  that
   has been typed by the user and has not yet been processed by the
   program.

curses.getmouse()

   After "getch()" returns "KEY_MOUSE" to signal a mouse event, this
   method should be call to retrieve the queued mouse event,
   represented as a 5-tuple "(id, x, y, z, bstate)". *id* is an ID
   value used to distinguish multiple devices, and *x*, *y*, *z* are
   the event’s coordinates.  (*z* is currently unused.)  *bstate* is
   an integer value whose bits will be set to indicate the type of
   event, and will be the bitwise OR of one or more of the following
   constants, where *n* is the button number from 1 to 4:
   "BUTTONn_PRESSED", "BUTTONn_RELEASED", "BUTTONn_CLICKED",
   "BUTTONn_DOUBLE_CLICKED", "BUTTONn_TRIPLE_CLICKED", "BUTTON_SHIFT",
   "BUTTON_CTRL", "BUTTON_ALT".

curses.getsyx()

   Return the current coordinates of the virtual screen cursor in y
   and x.  If leaveok is currently true, then -1,-1 is returned.

curses.getwin(file)

   Read window related data stored in the file by an earlier
   "putwin()" call. The routine then creates and initializes a new
   window using that data, returning the new window object.

curses.has_colors()

   Return "True" if the terminal can display colors; otherwise, return
   "False".

curses.has_ic()

   Return "True" if the terminal has insert- and delete-character
   capabilities. This function is included for historical reasons
   only, as all modern software terminal emulators have such
   capabilities.

curses.has_il()

   Return "True" if the terminal has insert- and delete-line
   capabilities, or can simulate  them  using scrolling regions. This
   function is included for historical reasons only, as all modern
   software terminal emulators have such capabilities.

curses.has_key(ch)

   Take a key value *ch*, and return "True" if the current terminal
   type recognizes a key with that value.

curses.halfdelay(tenths)

   Used for half-delay mode, which is similar to cbreak mode in that
   characters typed by the user are immediately available to the
   program. However, after blocking for *tenths* tenths of seconds, an
   exception is raised if nothing has been typed.  The value of
   *tenths* must be a number between "1" and "255".  Use "nocbreak()"
   to leave half-delay mode.

curses.init_color(color_number, r, g, b)

   Change the definition of a color, taking the number of the color to
   be changed followed by three RGB values (for the amounts of red,
   green, and blue components).  The value of *color_number* must be
   between "0" and "COLORS".  Each of *r*, *g*, *b*, must be a value
   between "0" and "1000".  When "init_color()" is used, all
   occurrences of that color on the screen immediately change to the
   new definition.  This function is a no-op on most terminals; it is
   active only if "can_change_color()" returns "1".

curses.init_pair(pair_number, fg, bg)

   Change the definition of a color-pair.  It takes three arguments:
   the number of the color-pair to be changed, the foreground color
   number, and the background color number.  The value of
   *pair_number* must be between "1" and "COLOR_PAIRS - 1" (the "0"
   color pair is wired to white on black and cannot be changed).  The
   value of *fg* and *bg* arguments must be between "0" and "COLORS".
   If the color-pair was previously initialized, the screen is
   refreshed and all occurrences of that color-pair are changed to the
   new definition.

curses.initscr()

   Initialize the library. Return a window object which represents the
   whole screen.

   Note: If there is an error opening the terminal, the underlying
     curses library may cause the interpreter to exit.

curses.is_term_resized(nlines, ncols)

   Return "True" if "resize_term()" would modify the window structure,
   "False" otherwise.

curses.isendwin()

   Return "True" if "endwin()" has been called (that is, the  curses
   library has been deinitialized).

curses.keyname(k)

   Return the name of the key numbered *k*.  The name of a key
   generating printable ASCII character is the key’s character.  The
   name of a control-key combination is a two-character string
   consisting of a caret followed by the corresponding printable ASCII
   character.  The name of an alt-key combination (128–255) is a
   string consisting of the prefix ‘M-‘ followed by the name of the
   corresponding ASCII character.

curses.killchar()

   Return the user’s current line kill character. Under Unix operating
   systems this is a property of the controlling tty of the curses
   program, and is not set by the curses library itself.

curses.longname()

   Return a string containing the terminfo long name field describing
   the current terminal.  The maximum length of a verbose description
   is 128 characters.  It is defined only after the call to
   "initscr()".

curses.meta(yes)

   If *yes* is 1, allow 8-bit characters to be input. If *yes* is 0,
   allow only 7-bit chars.

curses.mouseinterval(interval)

   Set the maximum time in milliseconds that can elapse between press
   and release events in order for them to be recognized as a click,
   and return the previous interval value.  The default value is 200
   msec, or one fifth of a second.

curses.mousemask(mousemask)

   Set the mouse events to be reported, and return a tuple
   "(availmask, oldmask)".   *availmask* indicates which of the
   specified mouse events can be reported; on complete failure it
   returns 0.  *oldmask* is the previous value of the given window’s
   mouse event mask.  If this function is never called, no mouse
   events are ever reported.

curses.napms(ms)

   Sleep for *ms* milliseconds.

curses.newpad(nlines, ncols)

   Create and return a pointer to a new pad data structure with the
   given number of lines and columns.  A pad is returned as a window
   object.

   A pad is like a window, except that it is not restricted by the
   screen size, and is not necessarily associated with a particular
   part of the screen.  Pads can be used when a large window is
   needed, and only a part of the window will be on the screen at one
   time.  Automatic refreshes of pads (such as from scrolling or
   echoing of input) do not occur.  The "refresh()" and
   "noutrefresh()" methods of a pad require 6 arguments to specify the
   part of the pad to be displayed and the location on the screen to
   be used for the display. The arguments are *pminrow*, *pmincol*,
   *sminrow*, *smincol*, *smaxrow*, *smaxcol*; the *p* arguments refer
   to the upper left corner of the pad region to be displayed and the
   *s* arguments define a clipping box on the screen within which the
   pad region is to be displayed.

curses.newwin(nlines, ncols)
curses.newwin(nlines, ncols, begin_y, begin_x)

   Return a new window, whose left-upper corner is at  "(begin_y,
   begin_x)", and whose height/width is  *nlines*/*ncols*.

   By default, the window will extend from the  specified position to
   the lower right corner of the screen.

curses.nl()

   Enter newline mode.  This mode translates the return key into
   newline on input, and translates newline into return and line-feed
   on output. Newline mode is initially on.

curses.nocbreak()

   Leave cbreak mode.  Return to normal “cooked” mode with line
   buffering.

curses.noecho()

   Leave echo mode.  Echoing of input characters is turned off.

curses.nonl()

   Leave newline mode.  Disable translation of return into newline on
   input, and disable low-level translation of newline into
   newline/return on output (but this does not change the behavior of
   "addch('\n')", which always does the equivalent of return and line
   feed on the virtual screen).  With translation off, curses can
   sometimes speed up vertical motion a little; also, it will be able
   to detect the return key on input.

curses.noqiflush()

   When the "noqiflush()" routine is used, normal flush of input and
   output queues associated with the INTR, QUIT and SUSP characters
   will not be done.  You may want to call "noqiflush()" in a signal
   handler if you want output to continue as though the interrupt had
   not occurred, after the handler exits.

curses.noraw()

   Leave raw mode. Return to normal “cooked” mode with line buffering.

curses.pair_content(pair_number)

   Return a tuple "(fg, bg)" containing the colors for the requested
   color pair. The value of *pair_number* must be between "1" and
   "COLOR_PAIRS - 1".

curses.pair_number(attr)

   Return the number of the color-pair set by the attribute value
   *attr*. "color_pair()" is the counterpart to this function.

curses.putp(string)

   Equivalent to "tputs(str, 1, putchar)"; emit the value of a
   specified terminfo capability for the current terminal.  Note that
   the output of "putp()" always goes to standard output.

curses.qiflush([flag])

   If *flag* is "False", the effect is the same as calling
   "noqiflush()". If *flag* is "True", or no argument is provided, the
   queues will be flushed when these control characters are read.

curses.raw()

   Enter raw mode.  In raw mode, normal line buffering and  processing
   of interrupt, quit, suspend, and flow control keys are turned off;
   characters are presented to curses input functions one by one.

curses.reset_prog_mode()

   Restore the  terminal  to “program” mode, as previously saved  by
   "def_prog_mode()".

curses.reset_shell_mode()

   Restore the  terminal  to “shell” mode, as previously saved  by
   "def_shell_mode()".

curses.resetty()

   Restore the state of the terminal modes to what it was at the last
   call to "savetty()".

curses.resize_term(nlines, ncols)

   Backend function used by "resizeterm()", performing most of the
   work; when resizing the windows, "resize_term()" blank-fills the
   areas that are extended.  The calling application should fill in
   these areas with appropriate data.  The "resize_term()" function
   attempts to resize all windows.  However, due to the calling
   convention of pads, it is not possible to resize these without
   additional interaction with the application.

curses.resizeterm(nlines, ncols)

   Resize the standard and current windows to the specified
   dimensions, and adjusts other bookkeeping data used by the curses
   library that record the window dimensions (in particular the
   SIGWINCH handler).

curses.savetty()

   Save the current state of the terminal modes in a buffer, usable by
   "resetty()".

curses.setsyx(y, x)

   Set the virtual screen cursor to *y*, *x*. If *y* and *x* are both
   -1, then leaveok is set.

curses.setupterm([termstr, fd])

   Initialize the terminal.  *termstr* is a string giving the terminal
   name; if omitted, the value of the "TERM" environment variable will
   be used.  *fd* is the file descriptor to which any initialization
   sequences will be sent; if not supplied, the file descriptor for
   "sys.stdout" will be used.

curses.start_color()

   Must be called if the programmer wants to use colors, and before
   any other color manipulation routine is called.  It is good
   practice to call this routine right after "initscr()".

   "start_color()" initializes eight basic colors (black, red,  green,
   yellow, blue, magenta, cyan, and white), and two global variables
   in the "curses" module, "COLORS" and "COLOR_PAIRS", containing the
   maximum number of colors and color-pairs the terminal can support.
   It also restores the colors on the terminal to the values they had
   when the terminal was just turned on.

curses.termattrs()

   Return a logical OR of all video attributes supported by the
   terminal.  This information is useful when a curses program needs
   complete control over the appearance of the screen.

curses.termname()

   Return the value of the environment variable "TERM", truncated to
   14 characters.

curses.tigetflag(capname)

   Return the value of the Boolean capability corresponding to the
   terminfo capability name *capname*.  The value "-1" is returned if
   *capname* is not a Boolean capability, or "0" if it is canceled or
   absent from the terminal description.

curses.tigetnum(capname)

   Return the value of the numeric capability corresponding to the
   terminfo capability name *capname*.  The value "-2" is returned if
   *capname* is not a numeric capability, or "-1" if it is canceled or
   absent from the terminal description.

curses.tigetstr(capname)

   Return the value of the string capability corresponding to the
   terminfo capability name *capname*.  "None" is returned if
   *capname* is not a string capability, or is canceled or absent from
   the terminal description.

curses.tparm(str[, ...])

   Instantiate the string *str* with the supplied parameters, where
   *str* should be a parameterized string obtained from the terminfo
   database.  E.g. "tparm(tigetstr("cup"), 5, 3)" could result in
   "b'\033[6;4H'", the exact result depending on terminal type.

curses.typeahead(fd)

   Specify that the file descriptor *fd* be used for typeahead
   checking.  If *fd* is "-1", then no typeahead checking is done.

   The curses library does “line-breakout optimization” by looking for
   typeahead periodically while updating the screen.  If input is
   found, and it is coming from a tty, the current update is postponed
   until refresh or doupdate is called again, allowing faster response
   to commands typed in advance. This function allows specifying a
   different file descriptor for typeahead checking.

curses.unctrl(ch)

   Return a string which is a printable representation of the
   character *ch*. Control characters are displayed as a caret
   followed by the character, for example as "^C". Printing characters
   are left as they are.

curses.ungetch(ch)

   Push *ch* so the next "getch()" will return it.

   Note: Only one *ch* can be pushed before "getch()" is called.

curses.update_lines_cols()

   Update "LINES" and "COLS". Useful for detecting manual screen
   resize.

   New in version 3.5.

curses.unget_wch(ch)

   Push *ch* so the next "get_wch()" will return it.

   Note: Only one *ch* can be pushed before "get_wch()" is called.

   New in version 3.3.

curses.ungetmouse(id, x, y, z, bstate)

   Push a "KEY_MOUSE" event onto the input queue, associating the
   given state data with it.

curses.use_env(flag)

   If used, this function should be called before "initscr()" or
   newterm are called.  When *flag* is "False", the values of lines
   and columns specified in the terminfo database will be used, even
   if environment variables "LINES" and "COLUMNS" (used by default)
   are set, or if curses is running in a window (in which case default
   behavior would be to use the window size if "LINES" and "COLUMNS"
   are not set).

curses.use_default_colors()

   Allow use of default values for colors on terminals supporting this
   feature. Use this to support transparency in your application.  The
   default color is assigned to the color number -1. After calling
   this function,  "init_pair(x, curses.COLOR_RED, -1)" initializes,
   for instance, color pair *x* to a red foreground color on the
   default background.

curses.wrapper(func, ...)

   Initialize curses and call another callable object, *func*, which
   should be the rest of your curses-using application.  If the
   application raises an exception, this function will restore the
   terminal to a sane state before re-raising the exception and
   generating a traceback.  The callable object *func* is then passed
   the main window ‘stdscr’ as its first argument, followed by any
   other arguments passed to "wrapper()".  Before calling *func*,
   "wrapper()" turns on cbreak mode, turns off echo, enables the
   terminal keypad, and initializes colors if the terminal has color
   support.  On exit (whether normally or by exception) it restores
   cooked mode, turns on echo, and disables the terminal keypad.


16.10.2. Window Objects
=======================

Window objects, as returned by "initscr()" and "newwin()" above, have
the following methods and attributes:

window.addch(ch[, attr])
window.addch(y, x, ch[, attr])

   Note: A *character* means a C character (an ASCII code), rather
     than a Python character (a string of length 1). (This note is
     true whenever the documentation mentions a character.) The built-
     in "ord()" is handy for conveying strings to codes.

   Paint character *ch* at "(y, x)" with attributes *attr*,
   overwriting any character previously painter at that location.  By
   default, the character position and attributes are the current
   settings for the window object.

window.addnstr(str, n[, attr])
window.addnstr(y, x, str, n[, attr])

   Paint at most *n* characters of the  string *str* at "(y, x)" with
   attributes *attr*, overwriting anything previously on the display.

window.addstr(str[, attr])
window.addstr(y, x, str[, attr])

   Paint the string *str* at "(y, x)" with attributes *attr*,
   overwriting anything previously on the display.

window.attroff(attr)

   Remove attribute *attr* from the “background” set applied to all
   writes to the current window.

window.attron(attr)

   Add attribute *attr* from the “background” set applied to all
   writes to the current window.

window.attrset(attr)

   Set the “background” set of attributes to *attr*.  This set is
   initially 0 (no attributes).

window.bkgd(ch[, attr])

   Set the background property of the window to the character *ch*,
   with attributes *attr*.  The change is then applied to every
   character position in that window:

   * The attribute of every character in the window  is changed to
     the new background attribute.

   * Wherever  the  former background character appears, it is
     changed to the new background character.

window.bkgdset(ch[, attr])

   Set the window’s background.  A window’s background consists of a
   character and any combination of attributes.  The attribute part of
   the background is combined (OR’ed) with all non-blank characters
   that are written into the window.  Both the character and attribute
   parts of the background are combined with the blank characters.
   The background becomes a property of the character and moves with
   the character through any scrolling and insert/delete
   line/character operations.

window.border([ls[, rs[, ts[, bs[, tl[, tr[, bl[, br]]]]]]]])

   Draw a border around the edges of the window. Each parameter
   specifies  the character to use for a specific part of the border;
   see the table below for more details.  The characters can be
   specified as integers or as one-character strings.

   Note: A "0" value for any parameter will cause the default
     character to be used for that parameter.  Keyword parameters can
     *not* be used.  The defaults are listed in this table:

   +-------------+-----------------------+-------------------------+
   | Parameter   | Description           | Default value           |
   +=============+=======================+=========================+
   | *ls*        | Left side             | "ACS_VLINE"             |
   +-------------+-----------------------+-------------------------+
   | *rs*        | Right side            | "ACS_VLINE"             |
   +-------------+-----------------------+-------------------------+
   | *ts*        | Top                   | "ACS_HLINE"             |
   +-------------+-----------------------+-------------------------+
   | *bs*        | Bottom                | "ACS_HLINE"             |
   +-------------+-----------------------+-------------------------+
   | *tl*        | Upper-left corner     | "ACS_ULCORNER"          |
   +-------------+-----------------------+-------------------------+
   | *tr*        | Upper-right corner    | "ACS_URCORNER"          |
   +-------------+-----------------------+-------------------------+
   | *bl*        | Bottom-left corner    | "ACS_LLCORNER"          |
   +-------------+-----------------------+-------------------------+
   | *br*        | Bottom-right corner   | "ACS_LRCORNER"          |
   +-------------+-----------------------+-------------------------+

window.box([vertch, horch])

   Similar to "border()", but both *ls* and *rs* are *vertch* and both
   *ts* and *bs* are *horch*.  The default corner characters are
   always used by this function.

window.chgat(attr)
window.chgat(num, attr)
window.chgat(y, x, attr)
window.chgat(y, x, num, attr)

   Set the attributes of *num* characters at the current cursor
   position, or at position "(y, x)" if supplied. If no value of *num*
   is given or *num* = -1, the attribute will  be set on all the
   characters to the end of the line.  This function does not move the
   cursor. The changed line will be touched using the "touchline()"
   method so that the contents will be redisplayed by the next window
   refresh.

window.clear()

   Like "erase()", but also cause the whole window to be repainted
   upon next call to "refresh()".

window.clearok(yes)

   If *yes* is 1, the next call to "refresh()" will clear the window
   completely.

window.clrtobot()

   Erase from cursor to the end of the window: all lines below the
   cursor are deleted, and then the equivalent of "clrtoeol()" is
   performed.

window.clrtoeol()

   Erase from cursor to the end of the line.

window.cursyncup()

   Update the current cursor position of all the ancestors of the
   window to reflect the current cursor position of the window.

window.delch([y, x])

   Delete any character at "(y, x)".

window.deleteln()

   Delete the line under the cursor. All following lines are moved up
   by one line.

window.derwin(begin_y, begin_x)
window.derwin(nlines, ncols, begin_y, begin_x)

   An abbreviation for “derive window”, "derwin()" is the same as
   calling "subwin()", except that *begin_y* and *begin_x* are
   relative to the origin of the window, rather than relative to the
   entire screen.  Return a window object for the derived window.

window.echochar(ch[, attr])

   Add character *ch* with attribute *attr*, and immediately  call
   "refresh()" on the window.

window.enclose(y, x)

   Test whether the given pair of screen-relative character-cell
   coordinates are enclosed by the given window, returning "True" or
   "False".  It is useful for determining what subset of the screen
   windows enclose the location of a mouse event.

window.encoding

   Encoding used to encode method arguments (Unicode strings and
   characters). The encoding attribute is inherited from the parent
   window when a subwindow is created, for example with
   "window.subwin()". By default, the locale encoding is used (see
   "locale.getpreferredencoding()").

   New in version 3.3.

window.erase()

   Clear the window.

window.getbegyx()

   Return a tuple "(y, x)" of co-ordinates of upper-left corner.

window.getbkgd()

   Return the given window’s current background character/attribute
   pair.

window.getch([y, x])

   Get a character. Note that the integer returned does *not* have to
   be in ASCII range: function keys, keypad keys and so on return
   numbers higher than 256. In no-delay mode, -1 is returned if there
   is no input, else "getch()" waits until a key is pressed.

window.get_wch([y, x])

   Get a wide character. Return a character for most keys, or an
   integer for function keys, keypad keys, and other special keys.

   New in version 3.3.

window.getkey([y, x])

   Get a character, returning a string instead of an integer, as
   "getch()" does. Function keys, keypad keys and other special keys
   return a multibyte string containing the key name.  In no-delay
   mode, an exception is raised if there is no input.

window.getmaxyx()

   Return a tuple "(y, x)" of the height and width of the window.

window.getparyx()

   Return the beginning coordinates of this window relative to its
   parent window into two integer variables y and x.  Return "-1, -1"
   if this window has no parent.

window.getstr([y, x])

   Read a string from the user, with primitive line editing capacity.

window.getyx()

   Return a tuple "(y, x)" of current cursor position  relative to the
   window’s upper-left corner.

window.hline(ch, n)
window.hline(y, x, ch, n)

   Display a horizontal line starting at "(y, x)" with length *n*
   consisting of the character *ch*.

window.idcok(flag)

   If *flag* is "False", curses no longer considers using the hardware
   insert/delete character feature of the terminal; if *flag* is
   "True", use of character insertion and deletion is enabled.  When
   curses is first initialized, use of character insert/delete is
   enabled by default.

window.idlok(yes)

   If called with *yes* equal to 1, "curses" will try and use hardware
   line editing facilities. Otherwise, line insertion/deletion are
   disabled.

window.immedok(flag)

   If *flag* is "True", any change in the window image automatically
   causes the window to be refreshed; you no longer have to call
   "refresh()" yourself. However, it may degrade performance
   considerably, due to repeated calls to wrefresh.  This option is
   disabled by default.

window.inch([y, x])

   Return the character at the given position in the window. The
   bottom 8 bits are the character proper, and upper bits are the
   attributes.

window.insch(ch[, attr])
window.insch(y, x, ch[, attr])

   Paint character *ch* at "(y, x)" with attributes *attr*, moving the
   line from position *x* right by one character.

window.insdelln(nlines)

   Insert *nlines* lines into the specified window above the current
   line.  The *nlines* bottom lines are lost.  For negative *nlines*,
   delete *nlines* lines starting with the one under the cursor, and
   move the remaining lines up.  The bottom *nlines* lines are
   cleared.  The current cursor position remains the same.

window.insertln()

   Insert a blank line under the cursor. All following lines are moved
   down by one line.

window.insnstr(str, n[, attr])
window.insnstr(y, x, str, n[, attr])

   Insert a character string (as many characters as will fit on the
   line) before the character under the cursor, up to *n* characters.
   If *n* is zero or negative, the entire string is inserted. All
   characters to the right of the cursor are shifted right, with the
   rightmost characters on the line being lost. The cursor position
   does not change (after moving to *y*, *x*, if specified).

window.insstr(str[, attr])
window.insstr(y, x, str[, attr])

   Insert a character string (as many characters as will fit on the
   line) before the character under the cursor.  All characters to the
   right of the cursor are shifted right, with the rightmost
   characters on the line being lost.  The cursor position does not
   change (after moving to *y*, *x*, if specified).

window.instr([n])
window.instr(y, x[, n])

   Return a string of characters, extracted from the window starting
   at the current cursor position, or at *y*, *x* if specified.
   Attributes are stripped from the characters.  If *n* is specified,
   "instr()" returns a string at most *n* characters long (exclusive
   of the trailing NUL).

window.is_linetouched(line)

   Return "True" if the specified line was modified since the last
   call to "refresh()"; otherwise return "False".  Raise a
   "curses.error" exception if *line* is not valid for the given
   window.

window.is_wintouched()

   Return "True" if the specified window was modified since the last
   call to "refresh()"; otherwise return "False".

window.keypad(yes)

   If *yes* is 1, escape sequences generated by some keys (keypad,
   function keys) will be interpreted by "curses". If *yes* is 0,
   escape sequences will be left as is in the input stream.

window.leaveok(yes)

   If *yes* is 1, cursor is left where it is on update, instead of
   being at “cursor position.”  This reduces cursor movement where
   possible. If possible the cursor will be made invisible.

   If *yes* is 0, cursor will always be at “cursor position” after an
   update.

window.move(new_y, new_x)

   Move cursor to "(new_y, new_x)".

window.mvderwin(y, x)

   Move the window inside its parent window.  The screen-relative
   parameters of the window are not changed.  This routine is used to
   display different parts of the parent window at the same physical
   position on the screen.

window.mvwin(new_y, new_x)

   Move the window so its upper-left corner is at "(new_y, new_x)".

window.nodelay(yes)

   If *yes* is "1", "getch()" will be non-blocking.

window.notimeout(yes)

   If *yes* is "1", escape sequences will not be timed out.

   If *yes* is "0", after a few milliseconds, an escape sequence will
   not be interpreted, and will be left in the input stream as is.

window.noutrefresh()

   Mark for refresh but wait.  This function updates the data
   structure representing the desired state of the window, but does
   not force an update of the physical screen.  To accomplish that,
   call  "doupdate()".

window.overlay(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])

   Overlay the window on top of *destwin*. The windows need not be the
   same size, only the overlapping region is copied. This copy is non-
   destructive, which means that the current background character does
   not overwrite the old contents of *destwin*.

   To get fine-grained control over the copied region, the second form
   of "overlay()" can be used. *sminrow* and *smincol* are the upper-
   left coordinates of the source window, and the other variables mark
   a rectangle in the destination window.

window.overwrite(destwin[, sminrow, smincol, dminrow, dmincol, dmaxrow, dmaxcol])

   Overwrite the window on top of *destwin*. The windows need not be
   the same size, in which case only the overlapping region is copied.
   This copy is destructive, which means that the current background
   character overwrites the old contents of *destwin*.

   To get fine-grained control over the copied region, the second form
   of "overwrite()" can be used. *sminrow* and *smincol* are the
   upper-left coordinates of the source window, the other variables
   mark a rectangle in the destination window.

window.putwin(file)

   Write all data associated with the window into the provided file
   object.  This information can be later retrieved using the
   "getwin()" function.

window.redrawln(beg, num)

   Indicate that the *num* screen lines, starting at line *beg*, are
   corrupted and should be completely redrawn on the next "refresh()"
   call.

window.redrawwin()

   Touch the entire window, causing it to be completely redrawn on the
   next "refresh()" call.

window.refresh([pminrow, pmincol, sminrow, smincol, smaxrow, smaxcol])

   Update the display immediately (sync actual screen with previous
   drawing/deleting methods).

   The 6 optional arguments can only be specified when the window is a
   pad created with "newpad()".  The additional parameters are needed
   to indicate what part of the pad and screen are involved. *pminrow*
   and *pmincol* specify the upper left-hand corner of the rectangle
   to be displayed in the pad.  *sminrow*, *smincol*, *smaxrow*, and
   *smaxcol* specify the edges of the rectangle to be displayed on the
   screen.  The lower right-hand corner of the rectangle to be
   displayed in the pad is calculated from the screen coordinates,
   since the rectangles must be the same size.  Both rectangles must
   be entirely contained within their respective structures.  Negative
   values of *pminrow*, *pmincol*, *sminrow*, or *smincol* are treated
   as if they were zero.

window.resize(nlines, ncols)

   Reallocate storage for a curses window to adjust its dimensions to
   the specified values.  If either dimension is larger than the
   current values, the window’s data is filled with blanks that have
   the current background rendition (as set by "bkgdset()") merged
   into them.

window.scroll([lines=1])

   Scroll the screen or scrolling region upward by *lines* lines.

window.scrollok(flag)

   Control what happens when the cursor of a window is moved off the
   edge of the window or scrolling region, either as a result of a
   newline action on the bottom line, or typing the last character of
   the last line.  If *flag* is false, the cursor is left on the
   bottom line.  If *flag* is true, the window is scrolled up one
   line.  Note that in order to get the physical scrolling effect on
   the terminal, it is also necessary to call "idlok()".

window.setscrreg(top, bottom)

   Set the scrolling region from line *top* to line *bottom*. All
   scrolling actions will take place in this region.

window.standend()

   Turn off the standout attribute.  On some terminals this has the
   side effect of turning off all attributes.

window.standout()

   Turn on attribute *A_STANDOUT*.

window.subpad(begin_y, begin_x)
window.subpad(nlines, ncols, begin_y, begin_x)

   Return a sub-window, whose upper-left corner is at "(begin_y,
   begin_x)", and whose width/height is *ncols*/*nlines*.

window.subwin(begin_y, begin_x)
window.subwin(nlines, ncols, begin_y, begin_x)

   Return a sub-window, whose upper-left corner is at "(begin_y,
   begin_x)", and whose width/height is *ncols*/*nlines*.

   By default, the sub-window will extend from the specified position
   to the lower right corner of the window.

window.syncdown()

   Touch each location in the window that has been touched in any of
   its ancestor windows.  This routine is called by "refresh()", so it
   should almost never be necessary to call it manually.

window.syncok(flag)

   If called with *flag* set to "True", then "syncup()" is called
   automatically whenever there is a change in the window.

window.syncup()

   Touch all locations in ancestors of the window that have been
   changed in  the window.

window.timeout(delay)

   Set blocking or non-blocking read behavior for the window.  If
   *delay* is negative, blocking read is used (which will wait
   indefinitely for input).  If *delay* is zero, then non-blocking
   read is used, and -1 will be returned by "getch()" if no input is
   waiting.  If *delay* is positive, then "getch()" will block for
   *delay* milliseconds, and return -1 if there is still no input at
   the end of that time.

window.touchline(start, count[, changed])

   Pretend *count* lines have been changed, starting with line
   *start*.  If *changed* is supplied, it specifies whether the
   affected lines are marked as having been changed (*changed*=1) or
   unchanged (*changed*=0).

window.touchwin()

   Pretend the whole window has been changed, for purposes of drawing
   optimizations.

window.untouchwin()

   Mark all lines in  the  window  as unchanged since the last call to
   "refresh()".

window.vline(ch, n)
window.vline(y, x, ch, n)

   Display a vertical line starting at "(y, x)" with length *n*
   consisting of the character *ch*.


16.10.3. Constants
==================

The "curses" module defines the following data members:

curses.ERR

   Some curses routines  that  return  an integer, such as  "getch()",
   return "ERR" upon failure.

curses.OK

   Some curses routines  that  return  an integer, such as  "napms()",
   return "OK" upon success.

curses.version

   A string representing the current version of the module.  Also
   available as "__version__".

Some constants are available to specify character cell attributes. The
exact constants available are system dependent.

+--------------------+---------------------------------+
| Attribute          | Meaning                         |
+====================+=================================+
| "A_ALTCHARSET"     | Alternate character set mode    |
+--------------------+---------------------------------+
| "A_BLINK"          | Blink mode                      |
+--------------------+---------------------------------+
| "A_BOLD"           | Bold mode                       |
+--------------------+---------------------------------+
| "A_DIM"            | Dim mode                        |
+--------------------+---------------------------------+
| "A_INVIS"          | Invisible or blank mode         |
+--------------------+---------------------------------+
| "A_NORMAL"         | Normal attribute                |
+--------------------+---------------------------------+
| "A_PROTECT"        | Protected mode                  |
+--------------------+---------------------------------+
| "A_REVERSE"        | Reverse background and          |
|                    | foreground colors               |
+--------------------+---------------------------------+
| "A_STANDOUT"       | Standout mode                   |
+--------------------+---------------------------------+
| "A_UNDERLINE"      | Underline mode                  |
+--------------------+---------------------------------+
| "A_HORIZONTAL"     | Horizontal highlight            |
+--------------------+---------------------------------+
| "A_LEFT"           | Left highlight                  |
+--------------------+---------------------------------+
| "A_LOW"            | Low highlight                   |
+--------------------+---------------------------------+
| "A_RIGHT"          | Right highlight                 |
+--------------------+---------------------------------+
| "A_TOP"            | Top highlight                   |
+--------------------+---------------------------------+
| "A_VERTICAL"       | Vertical highlight              |
+--------------------+---------------------------------+
| "A_CHARTEXT"       | Bit-mask to extract a character |
+--------------------+---------------------------------+

Several constants are available to extract corresponding attributes
returned by some methods.

+--------------------+---------------------------------+
| Bit-mask           | Meaning                         |
+====================+=================================+
| "A_ATTRIBUTES"     | Bit-mask to extract attributes  |
+--------------------+---------------------------------+
| "A_CHARTEXT"       | Bit-mask to extract a character |
+--------------------+---------------------------------+
| "A_COLOR"          | Bit-mask to extract color-pair  |
|                    | field information               |
+--------------------+---------------------------------+

Keys are referred to by integer constants with names starting with
"KEY_". The exact keycaps available are system dependent.

+---------------------+----------------------------------------------+
| Key constant        | Key                                          |
+=====================+==============================================+
| "KEY_MIN"           | Minimum key value                            |
+---------------------+----------------------------------------------+
| "KEY_BREAK"         | Break key (unreliable)                       |
+---------------------+----------------------------------------------+
| "KEY_DOWN"          | Down-arrow                                   |
+---------------------+----------------------------------------------+
| "KEY_UP"            | Up-arrow                                     |
+---------------------+----------------------------------------------+
| "KEY_LEFT"          | Left-arrow                                   |
+---------------------+----------------------------------------------+
| "KEY_RIGHT"         | Right-arrow                                  |
+---------------------+----------------------------------------------+
| "KEY_HOME"          | Home key (upward+left arrow)                 |
+---------------------+----------------------------------------------+
| "KEY_BACKSPACE"     | Backspace (unreliable)                       |
+---------------------+----------------------------------------------+
| "KEY_F0"            | Function keys.  Up to 64 function keys are   |
|                     | supported.                                   |
+---------------------+----------------------------------------------+
| "KEY_Fn"            | Value of function key *n*                    |
+---------------------+----------------------------------------------+
| "KEY_DL"            | Delete line                                  |
+---------------------+----------------------------------------------+
| "KEY_IL"            | Insert line                                  |
+---------------------+----------------------------------------------+
| "KEY_DC"            | Delete character                             |
+---------------------+----------------------------------------------+
| "KEY_IC"            | Insert char or enter insert mode             |
+---------------------+----------------------------------------------+
| "KEY_EIC"           | Exit insert char mode                        |
+---------------------+----------------------------------------------+
| "KEY_CLEAR"         | Clear screen                                 |
+---------------------+----------------------------------------------+
| "KEY_EOS"           | Clear to end of screen                       |
+---------------------+----------------------------------------------+
| "KEY_EOL"           | Clear to end of line                         |
+---------------------+----------------------------------------------+
| "KEY_SF"            | Scroll 1 line forward                        |
+---------------------+----------------------------------------------+
| "KEY_SR"            | Scroll 1 line backward (reverse)             |
+---------------------+----------------------------------------------+
| "KEY_NPAGE"         | Next page                                    |
+---------------------+----------------------------------------------+
| "KEY_PPAGE"         | Previous page                                |
+---------------------+----------------------------------------------+
| "KEY_STAB"          | Set tab                                      |
+---------------------+----------------------------------------------+
| "KEY_CTAB"          | Clear tab                                    |
+---------------------+----------------------------------------------+
| "KEY_CATAB"         | Clear all tabs                               |
+---------------------+----------------------------------------------+
| "KEY_ENTER"         | Enter or send (unreliable)                   |
+---------------------+----------------------------------------------+
| "KEY_SRESET"        | Soft (partial) reset (unreliable)            |
+---------------------+----------------------------------------------+
| "KEY_RESET"         | Reset or hard reset (unreliable)             |
+---------------------+----------------------------------------------+
| "KEY_PRINT"         | Print                                        |
+---------------------+----------------------------------------------+
| "KEY_LL"            | Home down or bottom (lower left)             |
+---------------------+----------------------------------------------+
| "KEY_A1"            | Upper left of keypad                         |
+---------------------+----------------------------------------------+
| "KEY_A3"            | Upper right of keypad                        |
+---------------------+----------------------------------------------+
| "KEY_B2"            | Center of keypad                             |
+---------------------+----------------------------------------------+
| "KEY_C1"            | Lower left of keypad                         |
+---------------------+----------------------------------------------+
| "KEY_C3"            | Lower right of keypad                        |
+---------------------+----------------------------------------------+
| "KEY_BTAB"          | Back tab                                     |
+---------------------+----------------------------------------------+
| "KEY_BEG"           | Beg (beginning)                              |
+---------------------+----------------------------------------------+
| "KEY_CANCEL"        | Cancel                                       |
+---------------------+----------------------------------------------+
| "KEY_CLOSE"         | Close                                        |
+---------------------+----------------------------------------------+
| "KEY_COMMAND"       | Cmd (command)                                |
+---------------------+----------------------------------------------+
| "KEY_COPY"          | Copy                                         |
+---------------------+----------------------------------------------+
| "KEY_CREATE"        | Create                                       |
+---------------------+----------------------------------------------+
| "KEY_END"           | End                                          |
+---------------------+----------------------------------------------+
| "KEY_EXIT"          | Exit                                         |
+---------------------+----------------------------------------------+
| "KEY_FIND"          | Find                                         |
+---------------------+----------------------------------------------+
| "KEY_HELP"          | Help                                         |
+---------------------+----------------------------------------------+
| "KEY_MARK"          | Mark                                         |
+---------------------+----------------------------------------------+
| "KEY_MESSAGE"       | Message                                      |
+---------------------+----------------------------------------------+
| "KEY_MOVE"          | Move                                         |
+---------------------+----------------------------------------------+
| "KEY_NEXT"          | Next                                         |
+---------------------+----------------------------------------------+
| "KEY_OPEN"          | Open                                         |
+---------------------+----------------------------------------------+
| "KEY_OPTIONS"       | Options                                      |
+---------------------+----------------------------------------------+
| "KEY_PREVIOUS"      | Prev (previous)                              |
+---------------------+----------------------------------------------+
| "KEY_REDO"          | Redo                                         |
+---------------------+----------------------------------------------+
| "KEY_REFERENCE"     | Ref (reference)                              |
+---------------------+----------------------------------------------+
| "KEY_REFRESH"       | Refresh                                      |
+---------------------+----------------------------------------------+
| "KEY_REPLACE"       | Replace                                      |
+---------------------+----------------------------------------------+
| "KEY_RESTART"       | Restart                                      |
+---------------------+----------------------------------------------+
| "KEY_RESUME"        | Resume                                       |
+---------------------+----------------------------------------------+
| "KEY_SAVE"          | Save                                         |
+---------------------+----------------------------------------------+
| "KEY_SBEG"          | Shifted Beg (beginning)                      |
+---------------------+----------------------------------------------+
| "KEY_SCANCEL"       | Shifted Cancel                               |
+---------------------+----------------------------------------------+
| "KEY_SCOMMAND"      | Shifted Command                              |
+---------------------+----------------------------------------------+
| "KEY_SCOPY"         | Shifted Copy                                 |
+---------------------+----------------------------------------------+
| "KEY_SCREATE"       | Shifted Create                               |
+---------------------+----------------------------------------------+
| "KEY_SDC"           | Shifted Delete char                          |
+---------------------+----------------------------------------------+
| "KEY_SDL"           | Shifted Delete line                          |
+---------------------+----------------------------------------------+
| "KEY_SELECT"        | Select                                       |
+---------------------+----------------------------------------------+
| "KEY_SEND"          | Shifted End                                  |
+---------------------+----------------------------------------------+
| "KEY_SEOL"          | Shifted Clear line                           |
+---------------------+----------------------------------------------+
| "KEY_SEXIT"         | Shifted Exit                                 |
+---------------------+----------------------------------------------+
| "KEY_SFIND"         | Shifted Find                                 |
+---------------------+----------------------------------------------+
| "KEY_SHELP"         | Shifted Help                                 |
+---------------------+----------------------------------------------+
| "KEY_SHOME"         | Shifted Home                                 |
+---------------------+----------------------------------------------+
| "KEY_SIC"           | Shifted Input                                |
+---------------------+----------------------------------------------+
| "KEY_SLEFT"         | Shifted Left arrow                           |
+---------------------+----------------------------------------------+
| "KEY_SMESSAGE"      | Shifted Message                              |
+---------------------+----------------------------------------------+
| "KEY_SMOVE"         | Shifted Move                                 |
+---------------------+----------------------------------------------+
| "KEY_SNEXT"         | Shifted Next                                 |
+---------------------+----------------------------------------------+
| "KEY_SOPTIONS"      | Shifted Options                              |
+---------------------+----------------------------------------------+
| "KEY_SPREVIOUS"     | Shifted Prev                                 |
+---------------------+----------------------------------------------+
| "KEY_SPRINT"        | Shifted Print                                |
+---------------------+----------------------------------------------+
| "KEY_SREDO"         | Shifted Redo                                 |
+---------------------+----------------------------------------------+
| "KEY_SREPLACE"      | Shifted Replace                              |
+---------------------+----------------------------------------------+
| "KEY_SRIGHT"        | Shifted Right arrow                          |
+---------------------+----------------------------------------------+
| "KEY_SRSUME"        | Shifted Resume                               |
+---------------------+----------------------------------------------+
| "KEY_SSAVE"         | Shifted Save                                 |
+---------------------+----------------------------------------------+
| "KEY_SSUSPEND"      | Shifted Suspend                              |
+---------------------+----------------------------------------------+
| "KEY_SUNDO"         | Shifted Undo                                 |
+---------------------+----------------------------------------------+
| "KEY_SUSPEND"       | Suspend                                      |
+---------------------+----------------------------------------------+
| "KEY_UNDO"          | Undo                                         |
+---------------------+----------------------------------------------+
| "KEY_MOUSE"         | Mouse event has occurred                     |
+---------------------+----------------------------------------------+
| "KEY_RESIZE"        | Terminal resize event                        |
+---------------------+----------------------------------------------+
| "KEY_MAX"           | Maximum key value                            |
+---------------------+----------------------------------------------+

On VT100s and their software emulations, such as X terminal emulators,
there are normally at least four function keys ("KEY_F1", "KEY_F2",
"KEY_F3", "KEY_F4") available, and the arrow keys mapped to "KEY_UP",
"KEY_DOWN", "KEY_LEFT" and "KEY_RIGHT" in the obvious way.  If your
machine has a PC keyboard, it is safe to expect arrow keys and twelve
function keys (older PC keyboards may have only ten function keys);
also, the following keypad mappings are standard:

+--------------------+-------------+
| Keycap             | Constant    |
+====================+=============+
| "Insert"           | KEY_IC      |
+--------------------+-------------+
| "Delete"           | KEY_DC      |
+--------------------+-------------+
| "Home"             | KEY_HOME    |
+--------------------+-------------+
| "End"              | KEY_END     |
+--------------------+-------------+
| "Page Up"          | KEY_PPAGE   |
+--------------------+-------------+
| "Page Down"        | KEY_NPAGE   |
+--------------------+-------------+

The following table lists characters from the alternate character set.
These are inherited from the VT100 terminal, and will generally be
available on software emulations such as X terminals.  When there is
no graphic available, curses falls back on a crude printable ASCII
approximation.

Note: These are available only after "initscr()" has  been called.

+--------------------+--------------------------------------------+
| ACS code           | Meaning                                    |
+====================+============================================+
| "ACS_BBSS"         | alternate name for upper right corner      |
+--------------------+--------------------------------------------+
| "ACS_BLOCK"        | solid square block                         |
+--------------------+--------------------------------------------+
| "ACS_BOARD"        | board of squares                           |
+--------------------+--------------------------------------------+
| "ACS_BSBS"         | alternate name for horizontal line         |
+--------------------+--------------------------------------------+
| "ACS_BSSB"         | alternate name for upper left corner       |
+--------------------+--------------------------------------------+
| "ACS_BSSS"         | alternate name for top tee                 |
+--------------------+--------------------------------------------+
| "ACS_BTEE"         | bottom tee                                 |
+--------------------+--------------------------------------------+
| "ACS_BULLET"       | bullet                                     |
+--------------------+--------------------------------------------+
| "ACS_CKBOARD"      | checker board (stipple)                    |
+--------------------+--------------------------------------------+
| "ACS_DARROW"       | arrow pointing down                        |
+--------------------+--------------------------------------------+
| "ACS_DEGREE"       | degree symbol                              |
+--------------------+--------------------------------------------+
| "ACS_DIAMOND"      | diamond                                    |
+--------------------+--------------------------------------------+
| "ACS_GEQUAL"       | greater-than-or-equal-to                   |
+--------------------+--------------------------------------------+
| "ACS_HLINE"        | horizontal line                            |
+--------------------+--------------------------------------------+
| "ACS_LANTERN"      | lantern symbol                             |
+--------------------+--------------------------------------------+
| "ACS_LARROW"       | left arrow                                 |
+--------------------+--------------------------------------------+
| "ACS_LEQUAL"       | less-than-or-equal-to                      |
+--------------------+--------------------------------------------+
| "ACS_LLCORNER"     | lower left-hand corner                     |
+--------------------+--------------------------------------------+
| "ACS_LRCORNER"     | lower right-hand corner                    |
+--------------------+--------------------------------------------+
| "ACS_LTEE"         | left tee                                   |
+--------------------+--------------------------------------------+
| "ACS_NEQUAL"       | not-equal sign                             |
+--------------------+--------------------------------------------+
| "ACS_PI"           | letter pi                                  |
+--------------------+--------------------------------------------+
| "ACS_PLMINUS"      | plus-or-minus sign                         |
+--------------------+--------------------------------------------+
| "ACS_PLUS"         | big plus sign                              |
+--------------------+--------------------------------------------+
| "ACS_RARROW"       | right arrow                                |
+--------------------+--------------------------------------------+
| "ACS_RTEE"         | right tee                                  |
+--------------------+--------------------------------------------+
| "ACS_S1"           | scan line 1                                |
+--------------------+--------------------------------------------+
| "ACS_S3"           | scan line 3                                |
+--------------------+--------------------------------------------+
| "ACS_S7"           | scan line 7                                |
+--------------------+--------------------------------------------+
| "ACS_S9"           | scan line 9                                |
+--------------------+--------------------------------------------+
| "ACS_SBBS"         | alternate name for lower right corner      |
+--------------------+--------------------------------------------+
| "ACS_SBSB"         | alternate name for vertical line           |
+--------------------+--------------------------------------------+
| "ACS_SBSS"         | alternate name for right tee               |
+--------------------+--------------------------------------------+
| "ACS_SSBB"         | alternate name for lower left corner       |
+--------------------+--------------------------------------------+
| "ACS_SSBS"         | alternate name for bottom tee              |
+--------------------+--------------------------------------------+
| "ACS_SSSB"         | alternate name for left tee                |
+--------------------+--------------------------------------------+
| "ACS_SSSS"         | alternate name for crossover or big plus   |
+--------------------+--------------------------------------------+
| "ACS_STERLING"     | pound sterling                             |
+--------------------+--------------------------------------------+
| "ACS_TTEE"         | top tee                                    |
+--------------------+--------------------------------------------+
| "ACS_UARROW"       | up arrow                                   |
+--------------------+--------------------------------------------+
| "ACS_ULCORNER"     | upper left corner                          |
+--------------------+--------------------------------------------+
| "ACS_URCORNER"     | upper right corner                         |
+--------------------+--------------------------------------------+
| "ACS_VLINE"        | vertical line                              |
+--------------------+--------------------------------------------+

The following table lists the predefined colors:

+---------------------+------------------------------+
| Constant            | Color                        |
+=====================+==============================+
| "COLOR_BLACK"       | Black                        |
+---------------------+------------------------------+
| "COLOR_BLUE"        | Blue                         |
+---------------------+------------------------------+
| "COLOR_CYAN"        | Cyan (light greenish blue)   |
+---------------------+------------------------------+
| "COLOR_GREEN"       | Green                        |
+---------------------+------------------------------+
| "COLOR_MAGENTA"     | Magenta (purplish red)       |
+---------------------+------------------------------+
| "COLOR_RED"         | Red                          |
+---------------------+------------------------------+
| "COLOR_WHITE"       | White                        |
+---------------------+------------------------------+
| "COLOR_YELLOW"      | Yellow                       |
+---------------------+------------------------------+


16.11. "curses.textpad" — Text input widget for curses programs
***************************************************************

The "curses.textpad" module provides a "Textbox" class that handles
elementary text editing in a curses window, supporting a set of
keybindings resembling those of Emacs (thus, also of Netscape
Navigator, BBedit 6.x, FrameMaker, and many other programs).  The
module also provides a rectangle-drawing function useful for framing
text boxes or for other purposes.

The module "curses.textpad" defines the following function:

curses.textpad.rectangle(win, uly, ulx, lry, lrx)

   Draw a rectangle.  The first argument must be a window object; the
   remaining arguments are coordinates relative to that window.  The
   second and third arguments are the y and x coordinates of the upper
   left hand corner of the rectangle to be drawn; the fourth and fifth
   arguments are the y and x coordinates of the lower right hand
   corner. The rectangle will be drawn using VT100/IBM PC forms
   characters on terminals that make this possible (including xterm
   and most other software terminal emulators).  Otherwise it will be
   drawn with ASCII  dashes, vertical bars, and plus signs.


16.11.1. Textbox objects
========================

You can instantiate a "Textbox" object as follows:

class curses.textpad.Textbox(win)

   Return a textbox widget object.  The *win* argument should be a
   curses window object in which the textbox is to be contained. The
   edit cursor of the textbox is initially located at the upper left
   hand corner of the containing window, with coordinates "(0, 0)".
   The instance’s "stripspaces" flag is initially on.

   "Textbox" objects have the following methods:

   edit([validator])

      This is the entry point you will normally use.  It accepts
      editing keystrokes until one of the termination keystrokes is
      entered.  If *validator* is supplied, it must be a function.  It
      will be called for each keystroke entered with the keystroke as
      a parameter; command dispatch is done on the result. This method
      returns the window contents as a string; whether blanks in the
      window are included is affected by the "stripspaces" attribute.

   do_command(ch)

      Process a single command keystroke.  Here are the supported
      special keystrokes:

      +--------------------+---------------------------------------------+
      | Keystroke          | Action                                      |
      +====================+=============================================+
      | "Control-A"        | Go to left edge of window.                  |
      +--------------------+---------------------------------------------+
      | "Control-B"        | Cursor left, wrapping to previous line if   |
      |                    | appropriate.                                |
      +--------------------+---------------------------------------------+
      | "Control-D"        | Delete character under cursor.              |
      +--------------------+---------------------------------------------+
      | "Control-E"        | Go to right edge (stripspaces off) or end   |
      |                    | of line (stripspaces on).                   |
      +--------------------+---------------------------------------------+
      | "Control-F"        | Cursor right, wrapping to next line when    |
      |                    | appropriate.                                |
      +--------------------+---------------------------------------------+
      | "Control-G"        | Terminate, returning the window contents.   |
      +--------------------+---------------------------------------------+
      | "Control-H"        | Delete character backward.                  |
      +--------------------+---------------------------------------------+
      | "Control-J"        | Terminate if the window is 1 line,          |
      |                    | otherwise insert newline.                   |
      +--------------------+---------------------------------------------+
      | "Control-K"        | If line is blank, delete it, otherwise      |
      |                    | clear to end of line.                       |
      +--------------------+---------------------------------------------+
      | "Control-L"        | Refresh screen.                             |
      +--------------------+---------------------------------------------+
      | "Control-N"        | Cursor down; move down one line.            |
      +--------------------+---------------------------------------------+
      | "Control-O"        | Insert a blank line at cursor location.     |
      +--------------------+---------------------------------------------+
      | "Control-P"        | Cursor up; move up one line.                |
      +--------------------+---------------------------------------------+

      Move operations do nothing if the cursor is at an edge where the
      movement is not possible.  The following synonyms are supported
      where possible:

      +--------------------------+--------------------+
      | Constant                 | Keystroke          |
      +==========================+====================+
      | "KEY_LEFT"               | "Control-B"        |
      +--------------------------+--------------------+
      | "KEY_RIGHT"              | "Control-F"        |
      +--------------------------+--------------------+
      | "KEY_UP"                 | "Control-P"        |
      +--------------------------+--------------------+
      | "KEY_DOWN"               | "Control-N"        |
      +--------------------------+--------------------+
      | "KEY_BACKSPACE"          | "Control-h"        |
      +--------------------------+--------------------+

      All other keystrokes are treated as a command to insert the
      given character and move right (with line wrapping).

   gather()

      Return the window contents as a string; whether blanks in the
      window are included is affected by the "stripspaces" member.

   stripspaces

      This attribute is a flag which controls the interpretation of
      blanks in the window.  When it is on, trailing blanks on each
      line are ignored; any cursor motion that would land the cursor
      on a trailing blank goes to the end of that line instead, and
      trailing blanks are stripped when the window contents are
      gathered.
