HP-UX Reference (11i v2 04/09) - 3 Library Functions A-M (vol 6)

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can_change_color(3X) can_change_color(3X)

(ENHANCED CURSES)

User-Deﬁned Colour Pairs

Calling init_pair() deﬁnes or redeﬁnes colour-pair number pair to have foreground colour f and

background colour b. Calling

init_pair() changes any characters that were displayed in the colour

pair’s old deﬁnition to the new deﬁnition and refreshes the screen.

After deﬁning the colour pair, the macro

COLOR_PAIR(n) returns the value of colour pair n. This value

is the colour attribute as it would be extracted from a

chtype. Conversely, the macro

PAIR_NUMBER(value) returns the colour pair number associated with the colour attribute value.

The

pair_content()

function retrieves the component colours of a colour-pair number pair.Itstores

the foreground and background colour numbers in the variables pointed to by f and b, respectively.

With

init_pair() and pair_content()

, the value of pair must be in a range from 0 to and includ-

ing

COLOR_PAIRS − 1. (There may be an implementation-speciﬁc lower limit on the valid value of pair,

but any such limit is at least 63.) Valid values for f and b are the range from 0 to and including

COLORS − 1.

RETURN VALUE

The

has_colors() function returns TRUE if the terminal can manipulate colors; otherwise, it returns

FALSE.

The

can_change_color()

function returns TRUE if the terminal supports colors and can change

their deﬁnitions; otherwise, it returns FALSE.

Upon successful completion, the other functions return OK; otherwise, they return ERR.

ERRORS

No errors are deﬁned.

APPLICATION USAGE

To use these functions,

start_color()

must be called, usually right after initscr().

The

can_change_color()

and has_colors() functions facilitate writing terminal-independent

programs. For example, a programmer can use them to decide whether to use colour or some other video

attribute.

On color terminals, a typical value of

COLORS is 8 and the macros such as COLOR_BLACK

return a value

within the range from 0 to and including 7. However, applications cannot rely on this to be true.