These functions are an extension to the curses library. They permit an
- application to dynamically allocate a color pair using the
- foreground/background colors rather than assign a fixed color pair
+ application to dynamically allocate a color pair using the
+ foreground/background colors rather than assign a fixed color pair
number, and return an unused pair to the pool.
- The number of colors may be related to the number of possible color
+ The number of colors may be related to the number of possible color
pairs for a given terminal, or it may not:
- o While almost all terminals allow setting the color attributes
- independently, it is unlikely that your terminal allows you to
- modify the attributes of a given character cell without rewriting
+ o While almost all terminals allow setting the color attributes
+ independently, it is unlikely that your terminal allows you to
+ modify the attributes of a given character cell without rewriting
it. That is, the foreground and background colors are applied as a
pair.
- o Color pairs are the curses library's way of managing a color
- palette on a terminal. If the library does not keep track of the
+ o Color pairs are the curses library's way of managing a color
+ palette on a terminal. If the library does not keep track of the
combinations of colors which are displayed, it will be inefficient.
- o For simple terminal emulators with only a few dozen color
- combinations, it is convenient to use the maximum number of
+ o For simple terminal emulators with only a few dozen color
+ combinations, it is convenient to use the maximum number of
combinations as the limit on color pairs:
COLORS*COLORS
- o Terminals which support defaultcolors distinct from "ANSI colors"
+ o Terminals which support defaultcolors distinct from "ANSI colors"
add to the possible combinations, producing this total:
(COLORS+1)*(COLORS+1)
@@ -92,43 +93,43 @@
o An application might use up to a few dozen color pairs to implement
a predefined color scheme.
- Beyond that lies in the realm of programs using the foreground and
- background colors for "ASCII art" (or some other non-textual
+ Beyond that lies in the realm of programs using the foreground and
+ background colors for "ASCII art" (or some other non-textual
application).
Also beyond those few dozen pairs, the required size for a table to
- represent the combinations grows rapidly with an increasing number
+ represent the combinations grows rapidly with an increasing number
of colors.
- These functions allow a developer to let the screen library manage
+ These functions allow a developer to let the screen library manage
color pairs.
- The alloc_pair function accepts parameters for foreground and
- background color, and checks if that color combination is already
+ The alloc_pair function accepts parameters for foreground and
+ background color, and checks if that color combination is already
associated with a color pair.
- o If the combination already exists, alloc_pair returns the existing
+ o If the combination already exists, alloc_pair returns the existing
pair.
o If the combination does not exist, alloc_pair allocates a new color
pair and returns that.
- o If the table fills up, alloc_pair discards the least-recently
+ o If the table fills up, alloc_pair discards the least-recently
allocated entry using free_pair and allocates a new color pair.
- All of the color pairs are allocated from a table of possible color
- pairs. The size of the table is determined by the terminfo pairs
- capability. The table is shared with init_pair; in fact alloc_pair
- calls init_pair after updating the ncurses library's fast index to the
+ All of the color pairs are allocated from a table of possible color
+ pairs. The size of the table is determined by the terminfo pairs
+ capability. The table is shared with init_pair; in fact alloc_pair
+ calls init_pair after updating the ncurses library's fast index to the
colors versus color pairs.
The find_pair function accepts parameters for foreground and background
- color, and checks if that color combination is already associated with
- a color pair, returning the pair number if it has been allocated.
+ color, and checks if that color combination is already associated with
+ a color pair, returning the pair number if it has been allocated.
Otherwise it returns -1.
@@ -137,20 +138,20 @@
- The alloc_pair function returns a color pair number in the range 1
- through COLOR_PAIRS-1, unless it encounters an error updating its fast
- index to the color pair values, preventing it from allocating a color
+ The alloc_pair function returns a color pair number in the range 1
+ through COLOR_PAIRS-1, unless it encounters an error updating its fast
+ index to the color pair values, preventing it from allocating a color
pair. In that case, it returns -1.
- The find_pair function returns a color pair number if the given color
+ The find_pair function returns a color pair number if the given color
combination has been associated with a color pair, or -1 if not.
- Likewise, free_pair returns OK unless it encounters an error updating
+ Likewise, free_pair returns OK unless it encounters an error updating
the fast index or if no such color pair is in use.
- These routines are specific to ncurses. They were not supported on
+ These routines are specific to ncurses. They were not supported on
Version 7, BSD or System V implementations. It is recommended that any
code depending on them be conditioned using NCURSES_VERSION.
@@ -164,7 +165,7 @@
-ncurses 6.4 2023-09-09 new_pair(3x)
+ncurses 6.4 2023-09-16 new_pair(3x)