pdcurses/color.c

/* Public Domain Curses */

#include <curspriv.h>

RCSID("$Id: color.c,v 1.83 2008/07/13 16:08:18 wmcbrine Exp $")

/*man-start**************************************************************

  Name:                                                         color

  Synopsis:
        int start_color(void);
        int init_pair(short pair, short fg, short bg);
        int init_color(short color, short red, short green, short blue);
        bool has_colors(void);
        bool can_change_color(void);
        int color_content(short color, short *red, short *green, short *blue);
        int pair_content(short pair, short *fg, short *bg);

        int assume_default_colors(int f, int b);
        int use_default_colors(void);

        int PDC_set_line_color(short color);

  Description:
        To use these routines, start_color() must be called, usually
        immediately after initscr(). Colors are always used in pairs, 
        referred to as color-pairs. A color-pair consists of a 
        foreground color and a background color. A color-pair is 
        initialized via init_pair(). After initialization, COLOR_PAIR(n) 
        can be used like any other video attribute.

        start_color() initializes eight basic colors (black, red, green,
        yellow, blue, magenta, cyan, and white), and two global
        variables; COLORS and COLOR_PAIRS (respectively defining the
        maximum number of colors and color-pairs the terminal is capable
        of displaying).

        init_pair() changes the definition of a color-pair. It takes 
        three arguments: the number of the color-pair to be redefined, 
        and the new values of the foreground and background colors. The 
        pair number must be between 0 and COLOR_PAIRS - 1, inclusive. 
        The foreground and background must be between 0 and COLORS - 1, 
        inclusive. If the color pair was previously initialized, the 
        screen is refreshed, and all occurrences of that color-pair are 
        changed to the new definition.

        has_colors() indicates if the terminal supports, and can 
        maniplulate color. It returns TRUE or FALSE.

        can_change_color() indicates if the terminal has the capability
        to change the definition of its colors.

        pair_content() is used to determine what the colors of a given
        color-pair consist of.

        assume_default_colors() and use_default_colors() emulate the
        ncurses extensions of the same names. assume_default_colors(f,
        b) is essentially the same as init_pair(0, f, b) (which isn't
        allowed); it redefines the default colors. use_default_colors()
        allows the use of -1 as a foreground or background color with
        init_pair(), and calls assume_default_colors(-1, -1); -1
        represents the foreground or background color that the terminal
        had at startup. If the environment variable PDC_ORIGINAL_COLORS
        is set at the time start_color() is called, that's equivalent to
        calling use_default_colors().

        PDC_set_line_color() is used to set the color, globally, for
        the color of the lines drawn for the attributes: A_UNDERLINE,
        A_OVERLINE, A_LEFTLINE and A_RIGHTLINE. A value of -1 (the
        default) indicates that the current foreground color should be
        used.

        NOTE: COLOR_PAIR() and PAIR_NUMBER() are implemented as macros.

  Return Value:
        All functions return OK on success and ERR on error, except for
        has_colors() and can_change_colors(), which return TRUE or FALSE.

  Portability                                X/Open    BSD    SYS V
        start_color                             Y       -      3.2
        init_pair                               Y       -      3.2
        init_color                              Y       -      3.2
        has_colors                              Y       -      3.2
        can_change_color                        Y       -      3.2
        color_content                           Y       -      3.2
        pair_content                            Y       -      3.2
        assume_default_colors                   -       -       -
        use_default_colors                      -       -       -
        PDC_set_line_color                      -       -       -

**man-end****************************************************************/

#include <stdlib.h>
#include <string.h>

int COLORS = 0;
int COLOR_PAIRS = PDC_COLOR_PAIRS;

bool pdc_color_started = FALSE;

/* pair_set[] tracks whether a pair has been set via init_pair() */

static bool pair_set[PDC_COLOR_PAIRS];
static bool default_colors = FALSE;
static short first_col = 0;

int start_color(void)
{
    PDC_LOG(("start_color() - called\n"));

    if (SP->mono)
        return ERR;

    pdc_color_started = TRUE;

    PDC_set_blink(FALSE);   /* Also sets COLORS, to 8 or 16 */

    if (!default_colors && SP->orig_attr && getenv("PDC_ORIGINAL_COLORS"))
        default_colors = TRUE;

    PDC_init_atrtab();

    memset(pair_set, 0, PDC_COLOR_PAIRS);

    return OK;
}

static void _normalize(short *fg, short *bg)
{
    if (*fg == -1)
        *fg = SP->orig_attr ? SP->orig_fore : COLOR_WHITE;

    if (*bg == -1)
        *bg = SP->orig_attr ? SP->orig_back : COLOR_BLACK;
}

int init_pair(short pair, short fg, short bg)
{
    PDC_LOG(("init_pair() - called: pair %d fg %d bg %d\n", pair, fg, bg));

    if (!pdc_color_started || pair < 1 || pair >= COLOR_PAIRS ||
        fg < first_col || fg >= COLORS || bg < first_col || bg >= COLORS)
        return ERR;

    _normalize(&fg, &bg);

    /* To allow the PDC_PRESERVE_SCREEN option to work, we only reset 
       curscr if this call to init_pair() alters a color pair created by 
       the user. */

    if (pair_set[pair])
    {
        short oldfg, oldbg;

        PDC_pair_content(pair, &oldfg, &oldbg);

        if (oldfg != fg || oldbg != bg)
            curscr->_clear = TRUE;
    }

    PDC_init_pair(pair, fg, bg);

    pair_set[pair] = TRUE;

    return OK;
}

bool has_colors(void)
{
    PDC_LOG(("has_colors() - called\n"));

    return !(SP->mono);
}

int init_color(short color, short red, short green, short blue)
{
    PDC_LOG(("init_color() - called\n"));

    if (color < 0 || color >= COLORS || !PDC_can_change_color() ||
        red < 0 || red > 1000 || green < 0 || green > 1000 ||
        blue < 0 || blue > 1000)
        return ERR;

    return PDC_init_color(color, red, green, blue);
}

int color_content(short color, short *red, short *green, short *blue)
{
    PDC_LOG(("color_content() - called\n"));

    if (color < 0 || color >= COLORS || !red || !green || !blue)
        return ERR;

    if (PDC_can_change_color())
        return PDC_color_content(color, red, green, blue);
    else
    {
        /* Simulated values for platforms that don't support palette 
           changing */

        short maxval = (color & 8) ? 1000 : 680;

        *red = (color & COLOR_RED) ? maxval : 0;
        *green = (color & COLOR_GREEN) ? maxval : 0;
        *blue = (color & COLOR_BLUE) ? maxval : 0;

        return OK;
    }
}

bool can_change_color(void)
{
    PDC_LOG(("can_change_color() - called\n"));

    return PDC_can_change_color();
}

int pair_content(short pair, short *fg, short *bg)
{
    PDC_LOG(("pair_content() - called\n"));

    if (pair < 0 || pair >= COLOR_PAIRS || !fg || !bg)
        return ERR;

    return PDC_pair_content(pair, fg, bg);
}

int assume_default_colors(int f, int b)
{
    PDC_LOG(("assume_default_colors() - called: f %d b %d\n", f, b));

    if (f < -1 || f >= COLORS || b < -1 || b >= COLORS)
        return ERR;

    if (pdc_color_started)
    {
        short fg, bg, oldfg, oldbg;

        fg = f;
        bg = b;

        _normalize(&fg, &bg);

        PDC_pair_content(0, &oldfg, &oldbg);

        if (oldfg != fg || oldbg != bg)
            curscr->_clear = TRUE;

        PDC_init_pair(0, fg, bg);
    }

    return OK;
}

int use_default_colors(void)
{
    PDC_LOG(("use_default_colors() - called\n"));

    default_colors = TRUE;
    first_col = -1;

    return assume_default_colors(-1, -1);
}

int PDC_set_line_color(short color)
{
    PDC_LOG(("PDC_set_line_color() - called: %d\n", color));

    if (color < -1 || color >= COLORS)
        return ERR;

    SP->line_color = color;

    return OK;
}

void PDC_init_atrtab(void)
{
    int i;
    short fg, bg;

    if (pdc_color_started && !default_colors)
    {
        fg = COLOR_WHITE;
        bg = COLOR_BLACK;
    }
    else
        fg = bg = -1;

    _normalize(&fg, &bg);

    for (i = 0; i < PDC_COLOR_PAIRS; i++)
        PDC_init_pair(i, fg, bg);
}