'\" t .\" $OpenBSD: curs_util.3,v 1.7 2023/10/17 09:52:08 nicm Exp $ .\" .\"*************************************************************************** .\" Copyright 2018-2022,2023 Thomas E. Dickey * .\" Copyright 1998-2015,2017 Free Software Foundation, Inc. * .\" * .\" Permission is hereby granted, free of charge, to any person obtaining a * .\" copy of this software and associated documentation files (the * .\" "Software"), to deal in the Software without restriction, including * .\" without limitation the rights to use, copy, modify, merge, publish, * .\" distribute, distribute with modifications, sublicense, and/or sell * .\" copies of the Software, and to permit persons to whom the Software is * .\" furnished to do so, subject to the following conditions: * .\" * .\" The above copyright notice and this permission notice shall be included * .\" in all copies or substantial portions of the Software. * .\" * .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * .\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * .\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * .\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * .\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. * .\" * .\" Except as contained in this notice, the name(s) of the above copyright * .\" holders shall not be used in advertising or otherwise to promote the * .\" sale, use or other dealings in this Software without prior written * .\" authorization. * .\"*************************************************************************** .\" .\" $Id: curs_util.3,v 1.7 2023/10/17 09:52:08 nicm Exp $ .TH curs_util 3 2023-08-19 "ncurses 6.4" "Library calls" .ie \n(.g .ds `` \(lq .el .ds `` `` .ie \n(.g .ds '' \(rq .el .ds '' '' .de bP .ie n .IP \(bu 4 .el .IP \(bu 2 .. .na .hy 0 .SH NAME \fBdelay_output\fP, \fBfilter\fP, \fBflushinp\fP, \fBgetwin\fP, \fBkey_name\fP, \fBkeyname\fP, \fBnofilter\fP, \fBputwin\fP, \fBunctrl\fP, \fBuse_env\fP, \fBuse_tioctl\fP, \fBwunctrl\fP \- miscellaneous \fBcurses\fP utility routines .ad .hy .SH SYNOPSIS \fB#include \fP .sp \fBconst char *unctrl(chtype \fIc\fB);\fR .br \fBwchar_t *wunctrl(cchar_t *\fIc\fB);\fR .sp \fBconst char *keyname(int \fIc\fB);\fR .br \fBconst char *key_name(wchar_t \fIw\fB);\fR .sp \fBvoid filter(void);\fP .sp \fBvoid use_env(bool \fIf\fB);\fR .sp \fBint putwin(WINDOW *\fIwin\fB, FILE *\fIfilep\fB);\fR .br \fBWINDOW *getwin(FILE *\fIfilep\fB);\fR .sp \fBint delay_output(int \fIms\fB);\fR .br \fBint flushinp(void);\fP .sp /* extensions */ .br \fBvoid nofilter(void);\fP .br \fBvoid use_tioctl(bool \fIf\fB);\fR .SH DESCRIPTION .SS unctrl The \fBunctrl\fP routine returns a character string which is a printable representation of the character \fIc\fP: .bP Printable characters are displayed as themselves, e.g., a one-character string containing the key. .bP Control characters are displayed in the \fB^\fIX\fR notation. .bP Printing characters are displayed as is. .bP DEL (character 127) is displayed as \fB^?\fP. .bP Values above 128 are either meta characters (if the screen has not been initialized, or if \fBmeta\fP(3) has been called with a \fBTRUE\fP parameter), shown in the \fBM\-\fIX\fR notation, or are displayed as themselves. In the latter case, the values may not be printable; this follows the X/Open specification. .PP The corresponding \fBwunctrl\fP returns a printable representation of a complex character \fIc\fP. .PP In both \fBunctrl\fP and \fBwunctrl\fP the attributes and color associated with the character parameter are ignored. .SS keyname/key_name The \fBkeyname\fP routine returns a character string corresponding to the key \fIc\fP. Key codes are different from character codes. .bP Key codes below 256 are characters. They are displayed using \fBunctrl\fP. .bP Values above 256 may be the codes for function keys. The function key name is displayed. .bP Otherwise (if there is no corresponding name and the key is not a character) the function returns null, to denote an error. X/Open also lists an \*(``UNKNOWN KEY\*('' return value, which some implementations return rather than null. .LP The corresponding \fBkey_name\fP returns a multibyte character string corresponding to the wide-character value \fIw\fP. The two functions (\fBkeyname\fP and \fBkey_name\fP) do not return the same set of strings: .bP \fBkeyname\fP returns null where \fBkey_name\fP would display a meta character. .bP \fBkey_name\fP does not return the name of a function key. .SS filter/nofilter The \fBfilter\fP routine, if used, must be called before \fBinitscr\fP or \fBnewterm\fP are called. Calling \fBfilter\fP causes these changes in initialization: .bP \fBLINES\fP is set to 1; .bP the capabilities \fBclear\fP, \fBcud1\fP, \fBcud\fP, \fBcup\fP, \fBcuu1\fP, \fBcuu\fP, \fBvpa\fP are disabled; .bP the capability \fBed\fP is disabled if \fBbce\fP is set; .bP and the \fBhome\fP string is set to the value of \fBcr\fP. .PP The \fBnofilter\fP routine cancels the effect of a preceding \fBfilter\fP call. That allows the caller to initialize a screen on a different device, using a different value of \fB$TERM\fP. The limitation arises because the \fBfilter\fP routine modifies the in-memory copy of the terminal information. .SS use_env The \fBuse_env\fP routine, if used, should be called before \fBinitscr\fP or \fBnewterm\fP are called (because those compute the screen size). It modifies the way \fBncurses\fP treats environment variables when determining the screen size. .bP Normally \fBncurses\fP looks first at the terminal database for the screen size. .IP If \fBuse_env\fP was called with \fBFALSE\fP for parameter, it stops here unless \fBuse_tioctl\fP was also called with \fBTRUE\fP for parameter. .bP Then it asks for the screen size via operating system calls. If successful, it overrides the values from the terminal database. .bP Finally (unless \fBuse_env\fP was called with \fBFALSE\fP parameter), \fBncurses\fP examines the \fBLINES\fP or \fBCOLUMNS\fP environment variables, using a value in those to override the results from the operating system or terminal database. .IP \fBNcurses\fP also updates the screen size in response to \fBSIGWINCH\fP, unless overridden by the \fBLINES\fP or \fBCOLUMNS\fP environment variables, .SS use_tioctl The \fBuse_tioctl\fP routine, if used, should be called before \fBinitscr\fP or \fBnewterm\fP are called (because those compute the screen size). After \fBuse_tioctl\fP is called with \fBTRUE\fP as an argument, \fBncurses\fP modifies the last step in its computation of screen size as follows: .bP checks if the \fBLINES\fP and \fBCOLUMNS\fP environment variables are set to a number greater than zero. .bP for each, \fBncurses\fP updates the corresponding environment variable with the value that it has obtained via operating system call or from the terminal database. .bP \fBncurses\fP re-fetches the value of the environment variables so that it is still the environment variables which set the screen size. .PP The \fBuse_env\fP and \fBuse_tioctl\fP routines combine as summarized here: .PP .TS center tab(/); l l l _ _ _ lw7 lw7 lw40. \fBuse_env\fP/\fBuse_tioctl\fP/\fBSummary\fP TRUE/FALSE/T{ This is the default behavior. \fBncurses\fP uses operating system calls unless overridden by $LINES or $COLUMNS environment variables. T} TRUE/TRUE/T{ \fBncurses\fP updates $LINES and $COLUMNS based on operating system calls. T} FALSE/TRUE/T{ \fBncurses\fP ignores $LINES and $COLUMNS, uses operating system calls to obtain size. T} FALSE/FALSE/T{ \fBncurses\fP relies on the terminal database to determine size. T} .TE .SS putwin/getwin The \fBputwin\fP routine writes all data associated with window (or pad) \fIwin\fP into the file to which \fIfilep\fP points. This information can be later retrieved using the \fBgetwin\fP function. .PP The \fBgetwin\fP routine reads window related data stored in the file by \fBputwin\fP. The routine then creates and initializes a new window using that data. It returns a pointer to the new window. There are a few caveats: .bP the data written is a copy of the \fBWINDOW\fP structure, and its associated character cells. The format differs between the wide-character (\fBncursesw\fP) and non-wide (\fBncurses\fP) libraries. You can transfer data between the two, however. .bP the retrieved window is always created as a top-level window (or pad), rather than a subwindow. .bP the window's character cells contain the color pair \fIvalue\fP, but not the actual color \fInumbers\fP. If cells in the retrieved window use color pairs which have not been created in the application using \fBinit_pair\fP, they will not be colored when the window is refreshed. .SS delay_output The \fBdelay_output\fP routine inserts an \fIms\fP millisecond pause in output. This routine should not be used extensively because padding characters are used rather than a CPU pause. If no padding character is specified, this uses \fBnapms\fP to perform the delay. .SS flushinp The \fBflushinp\fP routine throws away any typeahead that has been typed by the user and has not yet been read by the program. .SH RETURN VALUE Except for \fBflushinp\fP, routines that return an integer return \fBERR\fP upon failure and \fBOK\fP (SVr4 specifies only "an integer value other than \fBERR\fP") upon successful completion. .PP Routines that return pointers return \fBNULL\fP on error. .PP X/Open does not define any error conditions. In this implementation .RS 3 .TP 5 \fBflushinp\fP returns an error if the terminal was not initialized. .TP 5 \fBputwin\fP returns an error if the associated \fBfwrite\fP calls return an error. .RE .SH PORTABILITY .SS filter The SVr4 documentation describes the action of \fBfilter\fP only in the vaguest terms. The description here is adapted from the XSI Curses standard (which erroneously fails to describe the disabling of \fBcuu\fP). .SS keyname The \fBkeyname\fP function may return the names of user-defined string capabilities which are defined in the terminfo entry via the \fB\-x\fP option of \fBtic\fP. This implementation automatically assigns at run-time keycodes to user-defined strings which begin with \*(``k\*(''. The keycodes start at KEY_MAX, but are not guaranteed to be the same value for different runs because user-defined codes are merged from all terminal descriptions which have been loaded. The \fBuse_extended_names\fP(3) function controls whether this data is loaded when the terminal description is read by the library. .SS nofilter/use_tioctl The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to \fBncurses\fP. They were not supported on Version 7, BSD or System V implementations. It is recommended that any code depending on \fBncurses\fP extensions be conditioned using NCURSES_VERSION. .SS putwin/getwin file-format The \fBputwin\fP and \fBgetwin\fP functions have several issues with portability: .bP The files written and read by these functions use an implementation-specific format. Although the format is an obvious target for standardization, it has been overlooked. .IP Interestingly enough, according to the copyright dates in Solaris source, the functions (along with \fBscr_init\fP, etc.) originated with the University of California, Berkeley (in 1982) and were later (in 1988) incorporated into SVr4. Oddly, there are no such functions in the 4.3BSD curses sources. .bP Most implementations simply dump the binary \fBWINDOW\fP structure to the file. These include SVr4 curses, NetBSD and PDCurses, as well as older \fBncurses\fP versions. This implementation (as well as the X/Open variant of Solaris curses, dated 1995) uses textual dumps. .IP The implementations which use binary dumps use block-I/O (the \fBfwrite\fP and \fBfread\fP functions). Those that use textual dumps use buffered-I/O. A few applications may happen to write extra data in the file using these functions. Doing that can run into problems mixing block- and buffered-I/O. This implementation reduces the problem on writes by flushing the output. However, reading from a file written using mixed schemes may not be successful. .SS unctrl/wunctrl The XSI Curses standard, Issue 4 describes these functions. It states that \fBunctrl\fP and \fBwunctrl\fP will return a null pointer if unsuccessful, but does not define any error conditions. This implementation checks for three cases: .bP the parameter is a 7-bit US\-ASCII code. This is the case that X/Open Curses documented. .bP the parameter is in the range 128\-159, i.e., a C1 control code. If \fBuse_legacy_coding\fP(3) has been called with a \fB2\fP parameter, \fBunctrl\fP returns the parameter, i.e., a one-character string with the parameter as the first character. Otherwise, it returns \*(``~@\*('', \*(``~A\*('', etc., analogous to \*(``^@\*('', \*(``^A\*('', C0 controls. .IP X/Open Curses does not document whether \fBunctrl\fP can be called before initializing curses. This implementation permits that, and returns the \*(``~@\*('', etc., values in that case. .bP parameter values outside the 0 to 255 range. \fBunctrl\fP returns a null pointer. .PP The strings returned by \fBunctrl\fP in this implementation are determined at compile time, showing C1 controls from the upper-128 codes with a \*(``~\*('' prefix rather than \*(``^\*(''. Other implementations have different conventions. For example, they may show both sets of control characters with \*(``^\*('', and strip the parameter to 7 bits. Or they may ignore C1 controls and treat all of the upper-128 codes as printable. This implementation uses 8 bits but does not modify the string to reflect locale. The \fBuse_legacy_coding\fP(3) function allows the caller to change the output of \fBunctrl\fP. .PP Likewise, the \fBmeta\fP(3) function allows the caller to change the output of \fBkeyname\fP, i.e., it determines whether to use the \*(``M\-\*('' prefix for \*(``meta\*('' keys (codes in the range 128 to 255). Both \fBuse_legacy_coding\fP(3) and \fBmeta\fP(3) succeed only after curses is initialized. X/Open Curses does not document the treatment of codes 128 to 159. When treating them as \*(``meta\*('' keys (or if \fBkeyname\fP is called before initializing curses), this implementation returns strings \*(``M\-^@\*('', \*(``M\-^A\*('', etc. .PP X/Open Curses documents \fBunctrl\fP as declared in \fB\fP, which \fBncurses\fP does. However, \fBncurses\fP' \fB\fP includes \fB\fP, matching the behavior of SVr4 curses. Other implementations may not do that. .SS use_env/use_tioctl If \fBncurses\fP is configured to provide the sp-functions extension, the state of \fBuse_env\fP and \fBuse_tioctl\fP may be updated before creating each \fIscreen\fP rather than once only (\fBcurs_sp_funcs\fP(3)). This feature of \fBuse_env\fP is not provided by other implementations of curses. .SH SEE ALSO \fBcurses\fP(3), \fBcurs_initscr\fP(3), \fBcurs_inopts\fP(3), \fBcurs_kernel\fP(3), \fBcurs_scr_dump\fP(3), \fBcurs_sp_funcs\fP(3), \fBcurs_variables\fP(3), \fBlegacy_coding\fP(3).