:mod:`!curses` --- Terminal handling for character-cell displays

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

.. module:: curses

:synopsis: An interface to the curses library, providing portable

terminal handling.

**Source code:** :source:`Lib/curses`

--------------

The :mod:`!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.

.. include:: ../includes/wasm-mobile-notavail.rst

.. include:: ../includes/optional-module.rst

.. availability:: Unix.

.. note::

Whenever the documentation mentions a *character* it can be specified

as an integer, a one-character Unicode string or a one-byte byte string.

An integer is the code of a single encoded byte, optionally combined with

attributes and a color pair, as returned by :meth:`window.inch`.

Whenever the documentation mentions a *character string* it can be specified

as a Unicode string or a byte string.

.. note::

Whether curses may be used from several threads

depends on the underlying library and how it was built.

In many implementations, including the default build of ncurses,

the screen state is shared and not thread-safe;

since the blocking and refresh methods

(such as :meth:`~window.getch` and :meth:`~window.refresh`)

release the :term:`GIL`,

unsynchronized use from several threads can then crash the interpreter.

Serialize the calls.

.. seealso::

Module :mod:`curses.ascii`

Utilities for working with ASCII characters, regardless of your locale settings.

Module :mod:`curses.panel`

A panel stack extension that adds depth to curses windows.

Module :mod:`curses.textpad`

Editable text widget for curses supporting :program:`Emacs`\ -like bindings.

:ref:`curses-howto`

Tutorial material on using curses with Python, by Andrew Kuchling and Eric

Raymond.

.. _curses-functions:

Functions

---------

The module :mod:`!curses` defines the following exception:

.. exception:: 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 :const:`A_NORMAL`.

The module :mod:`!curses` defines the following functions:

.. function:: assume_default_colors(fg, bg, /)

Allow use of default values for colors on terminals supporting this feature.

Use this to support transparency in your application.

* Assign terminal default foreground/background colors to color number ``-1``.

So ``init_pair(x, COLOR_RED, -1)`` will initialize pair *x* as red

on default background and ``init_pair(x, -1, COLOR_BLUE)`` will

initialize pair *x* as default foreground on blue.

* Change the definition of the color-pair ``0`` to ``(fg, bg)``.

This is an ncurses extension.

.. versionadded:: 3.14

.. function:: 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.

.. function:: beep()

Emit a short attention sound.

.. function:: can_change_color()

Return ``True`` or ``False``, depending on whether the programmer can change the colors

displayed by the terminal.

.. function:: 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 :func:`raw` then :func:`cbreak` leaves the terminal in cbreak mode.

.. function:: 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 - 1``. Return a 3-tuple,

containing the R,G,B values for the given color, which will be between

``0`` (no component) and ``1000`` (maximum amount of component). Raise an

exception if the color is not supported.

.. function:: color_pair(pair_number)

Return the attribute value for displaying text in the specified color pair.

Only the first 256 color pairs are supported. This

attribute value can be combined with :const:`A_STANDOUT`, :const:`A_REVERSE`,

and the other :const:`!A_\*` attributes. :func:`pair_number` is the counterpart

to this function.

.. function:: 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, return the

previous cursor state; otherwise raise an exception. On many

terminals, the "visible" mode is an underline cursor and the "very visible" mode

is a block cursor.

.. function:: 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 :func:`reset_prog_mode` will

restore this mode.

.. function:: 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

:func:`reset_shell_mode` will restore this mode.

.. function:: delay_output(ms)

Insert an *ms* millisecond pause in output.

.. function:: 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 :func:`doupdate` function updates the

physical screen to match the virtual screen.

The virtual screen may be updated by a :meth:`~window.noutrefresh` call after write

operations such as :meth:`~window.addstr` have been performed on a window. The normal

:meth:`~window.refresh` call is simply :meth:`!noutrefresh` followed by :func:`!doupdate`;

if you have to update multiple windows, you can speed performance and perhaps

reduce screen flicker by issuing :meth:`!noutrefresh` calls on all windows,

followed by a single :func:`!doupdate`.

.. function:: echo()

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

it is entered.

.. function:: endwin()

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

.. function:: erasechar()

Return the user's current erase character as a one-byte bytes object. 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.

.. function:: filter()

The :func:`.filter` routine, if used, must be called before :func:`initscr` is

called. The effect is that, during the initialization, :envvar:`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.

.. function:: 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 :func:`beep`.

.. function:: 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.

.. function:: getmouse()

After :meth:`~window.getch` returns :const:`KEY_MOUSE` to signal a mouse event, this

method should be called 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 5:

:const:`BUTTONn_PRESSED`, :const:`BUTTONn_RELEASED`, :const:`BUTTONn_CLICKED`,

:const:`BUTTONn_DOUBLE_CLICKED`, :const:`BUTTONn_TRIPLE_CLICKED`,

:const:`BUTTON_SHIFT`, :const:`BUTTON_CTRL`, :const:`BUTTON_ALT`.

.. versionchanged:: 3.10

The ``BUTTON5_*`` constants are now exposed if they are provided by the

underlying curses library.

.. function:: getsyx()

Return the current coordinates of the virtual screen cursor as a tuple

``(y, x)``. If :meth:`leaveok <window.leaveok>` is currently ``True``, then return ``(-1, -1)``.

.. function:: getwin(file)

Read window-related data stored in the file by an earlier :meth:`window.putwin` call.

The routine then creates and initializes a new window using that data, returning

the new window object. The *file* argument must be a file object opened for

reading in binary mode.

.. function:: has_colors()

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

.. function:: has_extended_color_support()

Return ``True`` if the module supports extended colors; otherwise, return

``False``. Extended color support allows more than 256 color pairs for

terminals that support more than 16 colors (for example, xterm-256color).

Extended color support requires ncurses version 6.1 or later.

.. versionadded:: 3.10

.. function:: 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.

.. function:: 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.

.. function:: has_key(ch)

Take a key value *ch*, and return ``True`` if the current terminal type recognizes

a key with that value.

.. function:: 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, if nothing has been typed,

:meth:`~window.getch` returns ``-1``, while :meth:`~window.getkey` and

:meth:`~window.get_wch` raise :exc:`curses.error`.

The value of *tenths* must be a number between ``1`` and ``255``.

Use :func:`nocbreak` to leave half-delay mode.

.. function:: 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 - 1``. Each of *r*, *g*, *b*, must be a value between ``0`` and

``1000``. When :func:`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 :func:`can_change_color` returns ``True``.

.. function:: 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 can only be changed by

:func:`use_default_colors` and :func:`assume_default_colors`).

The value of *fg* and *bg* arguments must be between ``0`` and

``COLORS - 1``, or, after calling :func:`!use_default_colors` or

:func:`!assume_default_colors`, ``-1``.

If the color-pair was previously initialized, the screen is

refreshed and all occurrences of that color-pair are changed to the new

definition.

.. function:: initscr()

Initialize the library. Return a :ref:`window <curses-window-objects>` object

which represents the whole screen.

See :func:`setupterm` for a caveat about calling it before this function.

.. note::

If there is an error opening the terminal, the underlying curses library may

cause the interpreter to exit.

.. function:: intrflush(flag)

If *flag* is ``True``, pressing an interrupt key (interrupt, break, or quit)

will flush all output in the terminal driver queue. If *flag* is ``False``,

no flushing is done.

.. function:: is_term_resized(nlines, ncols)

Return ``True`` if :func:`resize_term` would modify the window structure,

``False`` otherwise.

.. function:: isendwin()

Return ``True`` if :func:`endwin` has been called (that is, the curses library has

been deinitialized).

.. function:: keyname(k)

Return the name of the key numbered *k* as a bytes object. The name of a key generating printable

ASCII character is the key's character. The name of a control-key combination

is a two-byte bytes object consisting of a caret (``b'^'``) followed by the corresponding

printable ASCII character. The name of an alt-key combination (128--255) is a

bytes object consisting of the prefix ``b'M-'`` followed by the name of the corresponding

ASCII character.

Raise a :exc:`ValueError` if *k* is negative.

.. function:: killchar()

Return the user's current line kill character as a one-byte bytes object. 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.

.. function:: longname()

Return a bytes object 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 :func:`initscr`.

.. function:: meta(flag)

If *flag* is ``True``, allow 8-bit characters to be input. If

*flag* is ``False``, allow only 7-bit chars.

.. function:: 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 166 milliseconds, or one sixth of a second.

Use a negative *interval* to obtain the interval value without changing it.

.. function:: 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 mouse event mask. If this function is never called, no mouse

events are ever reported.

.. function:: napms(ms)

Sleep for *ms* milliseconds.

.. function:: newpad(nlines, ncols)

Create and return a pointer to a new pad data structure with the given number

of lines and columns. Return a pad 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 :meth:`~window.refresh` and :meth:`~window.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.

.. function:: newwin(nlines, ncols)

newwin(nlines, ncols, begin_y, begin_x)

Return a new :ref:`window <curses-window-objects>`, 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.

.. function:: nl(flag=True)

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.

If *flag* is ``False``, the effect is the same as calling :func:`nonl`.

.. function:: nocbreak()

Leave cbreak mode. Return to normal "cooked" mode with line buffering.

.. function:: noecho()

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

.. function:: 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.

.. function:: noqiflush()

When the :func:`!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 :func:`!noqiflush` in a signal handler if you want output to

continue as though the interrupt had not occurred, after the handler exits.

.. function:: noraw()

Leave raw mode. Return to normal "cooked" mode with line buffering.

.. function:: 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 ``0`` and ``COLOR_PAIRS - 1``.

.. function:: pair_number(attr)

Return the number of the color-pair set by the attribute value *attr*.

:func:`color_pair` is the counterpart to this function.

.. function:: putp(str)

Equivalent to ``tputs(str, 1, putchar)``; emit the value of a specified

terminfo capability, a bytes object, for the current terminal.

Note that the output of :func:`putp` always goes to standard output.

:func:`setupterm` (or :func:`initscr`) must be called first.

.. function:: qiflush([flag])

If *flag* is ``False``, the effect is the same as calling :func:`noqiflush`. If

*flag* is ``True``, or no argument is provided, the queues will be flushed when

these control characters are read.

.. function:: 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.

.. function:: reset_prog_mode()

Restore the terminal to "program" mode, as previously saved by

:func:`def_prog_mode`.

.. function:: reset_shell_mode()

Restore the terminal to "shell" mode, as previously saved by

:func:`def_shell_mode`.

.. function:: resetty()

Restore the state of the terminal modes to what it was at the last call to

:func:`savetty`.

.. function:: resize_term(nlines, ncols)

Backend function used by :func:`resizeterm`, performing most of the work;

when resizing the windows, :func:`resize_term` blank-fills the areas that are

extended. The calling application should fill in these areas with

appropriate data. The :func:`!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.

.. function:: 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).

.. function:: savetty()

Save the current state of the terminal modes in a buffer, usable by

:func:`resetty`.

.. function:: get_escdelay()

Retrieves the value set by :func:`set_escdelay`.

.. versionadded:: 3.9

.. function:: set_escdelay(ms)

Sets the number of milliseconds to wait after reading an escape character,

to distinguish between an individual escape character entered on the

keyboard from escape sequences sent by cursor and function keys.

.. versionadded:: 3.9

.. function:: get_tabsize()

Retrieves the value set by :func:`set_tabsize`.

.. versionadded:: 3.9

.. function:: set_tabsize(size)

Sets the number of columns used by the curses library when converting a tab

character to spaces as it adds the tab to a window.

.. versionadded:: 3.9

.. function:: setsyx(y, x)

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

:meth:`leaveok <window.leaveok>` is set ``True``.

.. function:: setupterm(term=None, fd=-1)

Initialize the terminal. *term* is a string giving

the terminal name, or ``None``; if omitted or ``None``, the value of the

:envvar:`TERM` environment variable will be used. *fd* is the

file descriptor to which any initialization sequences will be sent; if not

supplied or ``-1``, the file descriptor for ``sys.stdout`` will be used.

Raise a :exc:`curses.error` if the terminal could not be found or its

terminfo database entry could not be read. If the terminal has already

been initialized, this function has no effect.

.. note::

Calling :func:`initscr` after :func:`setupterm`

leaks the terminal that :func:`setupterm` allocated:

the curses library keeps only a single current terminal

and does not free the previously allocated one.

.. function:: 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 :func:`initscr`.

:func:`start_color` initializes eight basic colors (black, red, green, yellow,

blue, magenta, cyan, and white), and two global variables in the :mod:`!curses`

module, :const:`COLORS` and :const:`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.

.. function:: 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.

.. function:: termname()

Return the name of the terminal in use, as a bytes object.

This is the name passed to :func:`setupterm`,

or the value of the :envvar:`TERM` environment variable if none was given.

Some curses libraries truncate it to 14 characters.

.. function:: tigetflag(capname)

Return the value of the Boolean capability corresponding to the terminfo

capability name *capname* as an integer. Return the value ``-1`` if *capname* is not a

Boolean capability, or ``0`` if it is canceled or absent from the terminal

description.

:func:`setupterm` (or :func:`initscr`) must be called first.

.. function:: tigetnum(capname)

Return the value of the numeric capability corresponding to the terminfo

capability name *capname* as an integer. Return the value ``-2`` if *capname* is not a

numeric capability, or ``-1`` if it is canceled or absent from the terminal

description.

:func:`setupterm` (or :func:`initscr`) must be called first.

.. function:: tigetstr(capname)

Return the value of the string capability corresponding to the terminfo

capability name *capname* as a bytes object. Return ``None`` if *capname*

is not a terminfo "string capability", or is canceled or absent from the

terminal description.

:func:`setupterm` (or :func:`initscr`) must be called first.

.. function:: tparm(str[, ...])

Instantiate the bytes object *str* with the supplied parameters, where *str* should

be a parameterized byte string obtained from the terminfo database. For example,

``tparm(tigetstr("cup"), 5, 3)`` could result in ``b'\033[6;4H'``, the exact

result depending on terminal type. Up to nine integer parameters may be supplied.

:func:`setupterm` (or :func:`initscr`) must be called first.

.. function:: 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.

.. function:: unctrl(ch)

Return a bytes object which is a printable representation of the character *ch*;

any attributes and color pair are ignored.

Control characters are represented as a caret followed by the character, for

example as ``b'^C'``. Printing characters are left as they are.

.. function:: ungetch(ch)

Push *ch* so the next :meth:`~window.getch` will return it.

*ch* may be an integer (a key code or the code of an encoded byte), a byte,

or a string of length 1 which encodes to a single byte.

.. note::

Only one *ch* can be pushed before :meth:`!getch` is called.

.. function:: update_lines_cols()

Update the :const:`LINES` and :const:`COLS` module variables.

Useful for detecting manual screen resize.

.. versionadded:: 3.5

.. function:: unget_wch(ch)

Push *ch* so the next :meth:`~window.get_wch` will return it.

*ch* may be an integer (a character code, not a key code) or a string of

length 1.

.. note::

Only one *ch* can be pushed before :meth:`!get_wch` is called.

.. versionadded:: 3.3

.. function:: ungetmouse(id, x, y, z, bstate)

Push a :const:`KEY_MOUSE` event onto the input queue, associating the given

state data with it.

.. function:: use_env(flag)

If used, this function should be called before :func:`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 :envvar:`LINES`

and :envvar:`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

:envvar:`LINES` and :envvar:`COLUMNS` are not set).

.. function:: use_default_colors()

Equivalent to ``assume_default_colors(-1, -1)``.

.. function:: wrapper(func, /, *args, **kwargs)

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 :func:`!wrapper`. Before calling *func*, :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.

.. _curses-window-objects:

Window objects

--------------

.. class:: window

Window objects, as returned by :func:`initscr` and :func:`newwin` above, have

the following methods and attributes:

.. method:: window.addch(ch[, attr])

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

Paint character *ch* at ``(y, x)`` with attributes *attr*, overwriting any

character previously painted at that location. By default, the character

position and attributes are the current settings for the window object.

.. note::

Writing outside the window, subwindow, or pad raises a :exc:`curses.error`.

Attempting to write to the lower-right corner of a window, subwindow,

or pad will cause an exception to be raised after the character is printed.

.. method:: window.addnstr(str, n[, attr])

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

Paint at most *n* characters of the character string *str* at

``(y, x)`` with attributes

*attr*, overwriting anything previously on the display.

.. method:: window.addstr(str[, attr])

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

Paint the character string *str* at ``(y, x)`` with attributes

*attr*, overwriting anything previously on the display.

.. note::

* Writing outside the window, subwindow, or pad raises :exc:`curses.error`.

Attempting to write to the lower-right corner of a window, subwindow,

or pad will cause an exception to be raised after the string is printed.

* A bug in ncurses, the backend for this Python module, could cause

segfaults when resizing windows. This was fixed in ncurses-6.1-20190511.

If you are stuck with an earlier ncurses, you can avoid triggering it by

not calling :meth:`!addstr` with a *str* that has embedded newlines;

instead, call :meth:`!addstr` separately for each line.

.. method:: window.attroff(attr)

Remove attribute *attr* from the "background" set applied to all writes to the

current window.

.. method:: window.attron(attr)

Add attribute *attr* to the "background" set applied to all writes to the

current window.

.. method:: window.attrset(attr)

Set the "background" set of attributes to *attr*. This set is initially

``0`` (no attributes).

.. method:: 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.

.. method:: 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.

.. method:: 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.

.. 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 | :const:`ACS_VLINE` |

+-----------+---------------------+-----------------------+

| *rs* | Right side | :const:`ACS_VLINE` |

+-----------+---------------------+-----------------------+

| *ts* | Top | :const:`ACS_HLINE` |

+-----------+---------------------+-----------------------+

| *bs* | Bottom | :const:`ACS_HLINE` |

+-----------+---------------------+-----------------------+

| *tl* | Upper-left corner | :const:`ACS_ULCORNER` |

+-----------+---------------------+-----------------------+

| *tr* | Upper-right corner | :const:`ACS_URCORNER` |

+-----------+---------------------+-----------------------+

| *bl* | Bottom-left corner | :const:`ACS_LLCORNER` |

+-----------+---------------------+-----------------------+

| *br* | Bottom-right corner | :const:`ACS_LRCORNER` |

+-----------+---------------------+-----------------------+

.. method:: window.box([vertch, horch])

Similar to :meth:`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.

.. method:: 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 *num* is not given or is ``-1``,

the attribute will be set on all the characters to the end of the line. This

function moves cursor to position ``(y, x)`` if supplied. The changed line

will be touched using the :meth:`touchline` method so that the contents will

be redisplayed by the next window refresh.

.. method:: window.clear()

Like :meth:`erase`, but also cause the whole window to be repainted upon next

call to :meth:`refresh`.

.. method:: window.clearok(flag)

If *flag* is ``True``, the next call to :meth:`refresh` will clear the window

completely.

.. method:: window.clrtobot()

Erase from cursor to the end of the window: all lines below the cursor are

deleted, and then the equivalent of :meth:`clrtoeol` is performed.

.. method:: window.clrtoeol()

Erase from cursor to the end of the line.

.. method:: window.cursyncup()

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

reflect the current cursor position of the window.

.. method:: window.delch([y, x])

Delete the character under the cursor, or at ``(y, x)`` if specified. All

characters to the right on the same line are shifted one position left.

.. method:: window.deleteln()

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

.. method:: window.derwin(begin_y, begin_x)

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

An abbreviation for "derive window", :meth:`derwin` is the same as calling

:meth:`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.

.. method:: window.echochar(ch[, attr])

Add character *ch* with attribute *attr*, and immediately call :meth:`refresh`

on the window.

.. method:: 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.

.. versionchanged:: 3.10

Previously it returned ``1`` or ``0`` instead of ``True`` or ``False``.

.. attribute:: window.encoding

Encoding used to encode the string arguments of the methods and to decode

their results on a build without wide-character support.

The encoding attribute is inherited from the parent window when a subwindow

is created, for example with :meth:`window.subwin`.

By default, current locale encoding is used (see :func:`locale.getencoding`).

.. versionadded:: 3.3

.. method:: window.erase()