X-Git-Url: https://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=man%2Fcurs_bkgrnd.3x;h=2b49db04c230d0e2d75404e2b8ff8cd8a3f06c4b;hp=2f7ee44873b22af31960250f452a992510404b00;hb=HEAD;hpb=084e3b44fc1c904d5ab941da55f47a237cb15766 diff --git a/man/curs_bkgrnd.3x b/man/curs_bkgrnd.3x index 2f7ee448..2551924c 100644 --- a/man/curs_bkgrnd.3x +++ b/man/curs_bkgrnd.3x @@ -1,5 +1,5 @@ .\"*************************************************************************** -.\" Copyright 2018-2022,2023 Thomas E. Dickey * +.\" Copyright 2018-2023,2024 Thomas E. Dickey * .\" Copyright 2002-2015,2017 Free Software Foundation, Inc. * .\" * .\" Permission is hereby granted, free of charge, to any person obtaining a * @@ -27,8 +27,19 @@ .\" authorization. * .\"*************************************************************************** .\" -.\" $Id: curs_bkgrnd.3x,v 1.32 2023/11/25 14:01:49 tom Exp $ -.TH curs_bkgrnd 3X 2023-11-25 "ncurses 6.4" "Library calls" +.\" $Id: curs_bkgrnd.3x,v 1.42 2024/04/20 18:54:36 tom Exp $ +.TH curs_bkgrnd 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls" +.ie \n(.g \{\ +.ds `` \(lq +.ds '' \(rq +.\} +.el \{\ +.ie t .ds `` `` +.el .ds `` "" +.ie t .ds '' '' +.el .ds '' "" +.\} +. .de bP .ie n .IP \(bu 4 .el .IP \(bu 2 @@ -55,63 +66,151 @@ manipulate background of a \fIcurses\fP window of wide characters \fBint wgetbkgrnd(WINDOW *\fIwin\fP, cchar_t *\fIwch\fP); .fi .SH DESCRIPTION -.SS bkgrndset -The \fBbkgrndset\fP and \fBwbkgrndset\fP routines manipulate the -background of the named window. -The window background is a \fBcchar_t\fP consisting of -any combination of attributes (i.e., rendition) and a complex character. +The +.I background +of a +.I curses +window +(in the library's \*(``wide\*('' configuration) +is a +.I \%cchar_t +combining a set of attributes +(see \fB\%curs_attr\fP(3X)) +with a complex character called the +.I "blank character." +.PP +The blank character is a spacing character that populates a window's +character cells when their contents are erased without replacement. +The background's attributes are combined with all non-blank characters +written to the window, +as with the \fB\%wadd_wch\fP(3X) and \fB\%wins_wch\fP(3X) families of +functions. +.PP +The blank character and attributes of the background combine with +characters written to the window as described below. +The background becomes a property of the character and moves with it +through any scrolling and insert/delete line/character operations. +.PP +To the extent possible on a given terminal, +the attribute part of the background is displayed as the graphic +rendition of the character put on the screen. +.SS "bkgrnd, wbkgrnd" +\fB\%bkgrnd\fP and \fB\%wbkgrnd\fP set the background property of +\fB\%stdscr\fP or the specified window and then apply this setting to +every character cell in that window. .bP -The attribute part of the background is combined (OR'ed) with all non-blank -characters that are written into the window with \fBwaddch\fP. +The rendition of every character in the window changes to the new +background rendition. .bP -Both -the character and attribute parts of the background are combined with -the blank characters. +Wherever the former background character appears, +it changes to the new background character. .PP -The background becomes a property of the -character and moves with the character through any scrolling and -insert/delete line/character operations. -.PP -To the extent possible on a -particular terminal, the attribute part of the background is displayed -as the graphic rendition of the character put on the screen. -.SS bkgrnd -The \fBbkgrnd\fP and \fBwbkgrnd\fP functions -set the background property of the current or specified window -and then apply this setting to every character position in that window: +.I \%ncurses +updates the rendition of each character cell by comparing the character, +non-color attributes, +and colors. +The library applies to following procedure to each cell in the window, +whether or not it is blank. +.bP +.I \%ncurses +first compares the cell's character to the previously specified blank +character; +if they match, +.I \%ncurses +writes the new blank character to the cell. +.bP +.I \%ncurses +then checks if the cell uses color, +that is, +its color pair value is nonzero. +If not, +it simply replaces the attributes and color pair in the cell with those +from the new background character. .bP -The rendition of every character on the screen is changed to -the new background rendition. +If the cell uses color, +and its background color matches that of the current window background, +.I \%ncurses +removes attributes that may have come from the current background and +adds those from the new background. +It finishes by setting the cell's background to use the new window +background color. .bP -Wherever the former background character -appears, it is changed to the new background character. -.SS getbkgrnd -The \fBgetbkgrnd\fP function returns the given window's current background -character/attribute pair via the +If the cell uses color, +and its background color does not match that of the current window +background, +.I \%ncurses +updates only the non-color attributes, +first removing those that may have come from the current background, +and then adding attributes from the new background. +.PP +.I \%ncurses +treats a background character value of zero (0) as a blank character. +.PP +If the terminal does not support color, +or if color has not been initialized with \fB\%start_color\fP(3X), +.I \%ncurses +ignores the new background character's color attribute. +.SS "bkgrndset, wbkgrndset" +\fB\%bkgrndset\fP and \fB\%wbkgrndset\fP manipulate the background of +the applicable window, +without updating the character cells as \fB\%bkgrnd\fP and +\fB\%wbkgrnd\fP do; +only future writes reflect the updated background. +.SS "getbkgrnd, wgetbkgrnd" +The \fB\%getbkgrnd\fP and \fB\%wgetbkgrnd\fP functions obtain the +background character and attribute pair of \fB\%stdscr\fP or the +specified window and store it via the .I wch pointer. -If the given window pointer is null, -the character is not updated (but no error is returned). .SH RETURN VALUE -The \fBbkgrndset\fP and \fBwbkgrndset\fP routines do not return a value. +\fBbkgrndset\fP and \fBwbkgrndset\fP do not return a value. .PP -Upon successful completion, the other functions return \fBOK\fP. -Otherwise, they return \fBERR\fP: +The other functions return +.B ERR +upon failure and +.B OK +upon success. +In +.IR \%ncurses , +failure occurs if .bP -A null window pointer is treated as an error. +a +.I \%WINDOW +pointer +.I win +is null, or .bP -A null character pointer is treated as an error. +a +.I \%cchar_t +pointer +.I wch +is null. .SH NOTES \fB\%bkgrnd\fP, \fB\%bkgrndset\fP, and \fB\%getbkgrnd\fP -may be available as macros. +may be implemented as macros. .PP -X/Open Curses does not provide details on how the rendition is changed. -This implementation follows the approach used in SVr4 curses, -which is explained in the manual page for \fBwbkgd\fP. +Unlike their counterparts in the non-\*(``wide\*('' configuration of +.IR \%ncurses , +\fB\%getbkgrnd\fP and \fB\%wgetbkgrnd\fP supply the background character +and attribute in a modifiable +.I \%cchar_t +parameter, +not as the return value. .SH PORTABILITY -These functions are described in the XSI Curses standard, Issue 4. +X/Open Curses, +Issue 4 describes these functions. +It specifies no error conditions for them. +.PP +X/Open Curses does not provide details of how the rendition is updated. +This implementation follows the approach used in SVr4 +.IR curses . .SH SEE ALSO +\fB\%curs_bkgd\fP(3X) describes the corresponding functions in the +non-\*(``wide\*('' configuration of +.IR \%ncurses . +.PP \fB\%curses\fP(3X), -\fB\%curs_bkgd\fP(3X) +\fB\%curs_add_wch\fP(3X), +\fB\%curs_attr\fP(3X)