1default_colors(3X) default_colors(3X)
2
6 use_default_colors, assume_default_colors - use terminal's default col‐
7 ors
8
10 #include <curses.h>
11 int use_default_colors(void);
13 int assume_default_colors(int fg, int bg);
14
16 The use_default_colors and assume_default_colors functions are exten‐
17 sions to the curses library. They are used with terminals that support
18 ISO 6429 color, or equivalent. These terminals allow the application
19 to reset color to an unspecified default value (e.g., with SGR 39 or
20 SGR 49).
21 Applications that paint a colored background over the whole screen do
23 not take advantage of SGR 39 and SGR 49. Some applications are de‐
24 signed to work with the default background, using colors only for text.
25 For example, there are several implementations of the ls program which
26 use colors to denote different file types or permissions. These “color
27 ls” programs do not necessarily modify the background color, typically
28 using only the setaf terminfo capability to set the foreground color.
29 Full-screen applications that use default colors can achieve similar
30 visual effects.
31 The first function, use_default_colors tells the curses library to as‐
33 sign terminal default foreground/background colors to color number -1.
34 So init_pair(x,COLOR_RED,-1) will initialize pair x as red on default
35 background and init_pair(x,-1,COLOR_BLUE) will initialize pair x as de‐
36 fault foreground on blue.
37 The other, assume_default_colors is a refinement which tells which col‐
39 ors to paint for color pair 0. This function recognizes a special
40 color number -1, which denotes the default terminal color.
41 The following are equivalent:
43 use_default_colors();
44 assume_default_colors(-1,-1);
45 These are ncurses extensions. For other curses implementations, color
47 number -1 does not mean anything, just as for ncurses before a success‐
48 ful call of use_default_colors or assume_default_colors.
49 Other curses implementations do not allow an application to modify
51 color pair 0. They assume that the background is COLOR_BLACK, but do
52 not ensure that the color pair 0 is painted to match the assumption.
53 If your application does not use either use_default_colors or as‐
54 sume_default_colors ncurses will paint a white foreground (text) with
55 black background for color pair 0.
56
58 These functions return the integer ERR upon failure and OK on success.
59 They will fail if either the terminal does not support the orig_pair or
60 orig_colors capability. If the initialize_pair capability is not
61 found, this causes an error as well.
62
64 Associated with this extension, the init_pair function accepts negative
65 arguments to specify default foreground or background colors.
66 The use_default_colors function was added to support ded. This is a
68 full-screen application which uses curses to manage only part of the
69 screen. The bottom portion of the screen, which is of adjustable size,
70 is left uncolored to display the results from shell commands. The top
71 portion of the screen colors filenames using a scheme like the “color
72 ls” programs. Attempting to manage the background color of the screen
73 for this application would give unsatisfactory results for a variety of
74 reasons. This extension was devised after noting that color xterm (and
75 similar programs) provides a background color which does not necessar‐
76 ily correspond to any of the ANSI colors. While a special terminfo en‐
77 try could be constructed using nine colors, there was no mechanism pro‐
78 vided within curses to account for the related orig_pair and
79 back_color_erase capabilities.
80 The assume_default_colors function was added to solve a different prob‐
82 lem: support for applications which would use environment variables and
83 other configuration to bypass curses' notion of the terminal's default
84 colors, setting specific values.
85
87 These routines are specific to ncurses. They were not supported on
88 Version 7, BSD or System V implementations. It is recommended that any
89 code depending on them be conditioned using NCURSES_VERSION.
90
92 ded(1), curs_color(3X).
93
95 Thomas Dickey (from an analysis of the requirements for color xterm for
96 XFree86 3.1.2C, February 1996).
97 default_colors(3X)