15.8. 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 DOS, OS/2, 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.
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:
code = locale.getpreferredencoding()
Then use code as the encoding for str.encode() calls.
- 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.
- Module curses.wrapper
- Convenience function to ensure proper terminal setup and resetting on
application entry and exit.
- Curses Programming with Python
- Tutorial material on using curses with Python, by Andrew Kuchling and Eric
The Demo/curses/ directory in the Python source distribution contains
some example programs using the curses bindings provided by this module.
The module curses defines the following exception:
- Exception raised when a curses library function returns an error.
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
The module curses defines the following functions:
- Returns 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.
- Emit a short attention sound.
- Returns true or false, depending on whether the programmer can change the colors
displayed by the terminal.
- 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.
- Returns 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).
- Returns 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.
- Sets 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.
- Saves 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.
- Saves 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.
- Inserts an ms millisecond pause in output.
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().
- Enter echo mode. In echo mode, each character input is echoed to the screen as
it is entered.
- De-initialize the library, and return terminal to normal status.
- Returns 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.
- 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.
- 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().
- 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.
- 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,
BUTTON_SHIFT, BUTTON_CTRL, BUTTON_ALT.
- Returns the current coordinates of the virtual screen cursor in y and x. If
leaveok is currently true, then -1,-1 is returned.
- Reads 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.
- Returns true if the terminal can display colors; otherwise, it returns false.
- Returns 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.
- Returns 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
- Takes a key value ch, and returns true if the current terminal type recognizes
a key with that value.
- 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)
- Changes 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)
- Changes 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
Initialize the library. Returns a WindowObject which represents the
If there is an error opening the terminal, the underlying curses library may
cause the interpreter to exit.
- Returns true if endwin() has been called (that is, the curses library has
- 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
- Returns 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.
- Returns 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().
- If yes is 1, allow 8-bit characters to be input. If yes is 0, allow only
- Sets the maximum time in milliseconds that can elapse between press and release
events in order for them to be recognized as a click, and returns the previous
interval value. The default value is 200 msec, or one fifth of a second.
- Sets the mouse events to be reported, and returns 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.
- Sleep for ms milliseconds.
Creates and returns 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], 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.
- 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
- Leave cbreak mode. Return to normal “cooked” mode with line buffering.
- Leave echo mode. Echoing of input characters is turned off.
- 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.
- 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.
- Leave raw mode. Return to normal “cooked” mode with line buffering.
- Returns 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.
- Returns the number of the color-pair set by the attribute value attr.
color_pair() is the counterpart to this function.
- Equivalent to tputs(str, 1, putchar); emits the value of a specified
terminfo capability for the current terminal. Note that the output of putp
always goes to standard output.
- 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.
- 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.
- Restores the terminal to “program” mode, as previously saved by
- Restores the terminal to “shell” mode, as previously saved by
- Sets the virtual screen cursor to y, x. If y and x are both -1, then
leaveok is set.
- Initializes 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.
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
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.
- Returns 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.
- Returns the value of the environment variable TERM, truncated to 14 characters.
- Returns 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
- Returns 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
- Returns 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.
- Instantiates 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 '\033[6;4H', the exact
result depending on terminal type.
Specifies 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.
- Returns 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.
Push ch so the next getch() will return it.
Only one ch can be pushed before getch() is called.
curses.ungetmouse(id, x, y, z, bstate)
- Push a KEY_MOUSE event onto the input queue, associating the given
state data with it.
- 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).
- 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.
15.8.2. Window Objects
Window objects, as returned by initscr() and newwin() above, have
the following methods:
window.addch([y, x], ch[, attr])
A character means a C character (an ASCII code), rather then 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([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([y, x], str[, attr])
- Paint the string str at (y, x) with attributes attr, overwriting
anything previously on the display.
- Remove attribute attr from the “background” set applied to all writes to the
- Add attribute attr from the “background” set applied to all writes to the
- Set the “background” set of attributes to attr. This set is initially 0 (no
Sets the background property of the window to the character ch, with
attributes attr. The change is then applied to every character position in
- The attribute of every character in the window is changed to the new
- Wherever the former background character appears, it is changed to the new
- Sets 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
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:
- 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([y, x][, num], attr)
- Sets 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
- Like erase(), but also causes the whole window to be repainted upon next
call to refresh().
- If yes is 1, the next call to refresh() will clear the window
- Erase from cursor to the end of the window: all lines below the cursor are
deleted, and then the equivalent of clrtoeol() is performed.
- Erase from cursor to the end of the line.
- Updates the current cursor position of all the ancestors of the window to
reflect the current cursor position of the window.
- Delete any character at (y, x).
- Delete the line under the cursor. All following lines are moved up by 1 line.
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. Returns a window
object for the derived window.
- Add character ch with attribute attr, and immediately call refresh()
on the window.
- Tests 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
- Clear the window.
- Return a tuple (y, x) of co-ordinates of upper-left corner.
- 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.
- Get a character, returning a string instead of an integer, as getch()
does. Function keys, keypad keys and so on return a multibyte string containing
the key name. In no-delay mode, an exception is raised if there is no input.
- Return a tuple (y, x) of the height and width of the window.
- Returns the beginning coordinates of this window relative to its parent window
into two integer variables y and x. Returns -1,-1 if this window has no
- Read a string from the user, with primitive line editing capacity.
- Return a tuple (y, x) of current cursor position relative to the window’s
window.hline([y, x], ch, n)
- Display a horizontal line starting at (y, x) with length n consisting of
the character ch.
- 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.
- If called with yes equal to 1, curses will try and use hardware line
editing facilities. Otherwise, line insertion/deletion are disabled.
- 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.
- 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([y, x], ch[, attr])
- Paint character ch at (y, x) with attributes attr, moving the line from
position x right by one character.
- Inserts 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
- Insert a blank line under the cursor. All following lines are moved down by 1
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([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([y, x][, n])
- Returns 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 return a string
at most n characters long (exclusive of the trailing NUL).
- Returns true if the specified line was modified since the last call to
refresh(); otherwise returns false. Raises a curses.error
exception if line is not valid for the given window.
- Returns true if the specified window was modified since the last call to
refresh(); otherwise returns false.
- 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.
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.
- Move cursor to (new_y, new_x).
- Moves 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.
- Move the window so its upper-left corner is at (new_y, new_x).
- If yes is 1, getch() will be non-blocking.
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.
- 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
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
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
- Writes all data associated with the window into the provided file object. This
information can be later retrieved using the getwin() function.
- Indicates that the num screen lines, starting at line beg, are corrupted and
should be completely redrawn on the next refresh() call.
- Touches the entire window, causing it to be completely redrawn on the next
window.refresh([pminrow, pmincol, sminrow, smincol, smaxrow, smaxcol])
Update the display immediately (sync actual screen with previous
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.
- Scroll the screen or scrolling region upward by lines lines.
- Controls 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().
- Set the scrolling region from line top to line bottom. All scrolling actions
will take place in this region.
- Turn off the standout attribute. On some terminals this has the side effect of
turning off all attributes.
- Turn on attribute A_STANDOUT.
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([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.
- Touches 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.
- If called with flag set to true, then syncup() is called automatically
whenever there is a change in the window.
- Touches all locations in ancestors of the window that have been changed in the
- Sets 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).
- Pretend the whole window has been changed, for purposes of drawing
- Marks all lines in the window as unchanged since the last call to
window.vline([y, x], ch, n)
- Display a vertical line starting at (y, x) with length n consisting of the
The curses module defines the following data members:
- Some curses routines that return an integer, such as getch(), return
ERR upon failure.
- Some curses routines that return an integer, such as napms(), return
OK upon success.
- A string representing the current version of the module. Also available as
Several constants are available to specify character cell attributes:
||Alternate character set mode.
||Reverse background and
Keys are referred to by integer constants with names starting with KEY_.
The exact keycaps available are system dependent.
||Minimum key value
||Break key (unreliable)
||Home key (upward+left arrow)
||Function keys. Up to 64 function keys are
||Value of function key n
||Insert char or enter insert mode
||Exit insert char mode
||Clear to end of screen
||Clear to end of line
||Scroll 1 line forward
||Scroll 1 line backward (reverse)
||Clear all tabs
||Enter or send (unreliable)
||Soft (partial) reset (unreliable)
||Reset or hard reset (unreliable)
||Home down or bottom (lower left)
||Upper left of keypad
||Upper right of keypad
||Center of keypad
||Lower left of keypad
||Lower right of keypad
||Shifted Beg (beginning)
||Shifted Delete char
||Shifted Delete line
||Shifted Clear line
||Shifted Left arrow
||Shifted Right arrow
||Mouse event has occurred
||Terminal resize event
||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:
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.
These are available only after initscr() has been called.
||alternate name for upper right corner
||solid square block
||board of squares
||alternate name for horizontal line
||alternate name for upper left corner
||alternate name for top tee
||checker board (stipple)
||arrow pointing down
||lower left-hand corner
||lower right-hand corner
||big plus sign
||scan line 1
||scan line 3
||scan line 7
||scan line 9
||alternate name for lower right corner
||alternate name for vertical line
||alternate name for right tee
||alternate name for lower left corner
||alternate name for bottom tee
||alternate name for left tee
||alternate name for crossover or big plus
||upper left corner
||upper right corner
The following table lists the predefined colors:
||Cyan (light greenish blue)
||Magenta (purplish red)
15.9. 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.
15.9.1. Textbox objects
You can instantiate a Textbox object as follows:
Return a textbox widget object. The win argument should be a curses
WindowObject 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:
- 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
Process a single command keystroke. Here are the supported special
||Go to left edge of window.
||Cursor left, wrapping to previous line if
||Delete character under cursor.
||Go to right edge (stripspaces off) or end
of line (stripspaces on).
||Cursor right, wrapping to next line when
||Terminate, returning the window contents.
||Delete character backward.
||Terminate if the window is 1 line,
otherwise insert newline.
||If line is blank, delete it, otherwise
clear to end of line.
||Cursor down; move down one line.
||Insert a blank line at cursor location.
||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:
All other keystrokes are treated as a command to insert the given
character and move right (with line wrapping).
- This method returns the window contents as a string; whether blanks in the
window are included is affected by the stripspaces member.
- This data member 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.
15.10. curses.wrapper — Terminal handler for curses programs
This module supplies one function, wrapper(), which runs another function
which should be the rest of your curses-using application. If the application
raises an exception, wrapper() will restore the terminal to a sane state
before re-raising the exception and generating a traceback.
- Wrapper function that initializes curses and calls another function, func,
restoring normal keyboard/screen behavior on error. 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 the hook function, 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.