text: /* $OpenBSD: lib_color.c,v 1.11 2010/01/12 23:22:05 nicm Exp $ */
  
  /****************************************************************************
   * Copyright (c) 1998-2006,2007 Free Software Foundation, Inc.              *
   *                                                                          *
   * Permission is hereby granted, free of charge, to any person obtaining a  *
   * copy of this software and associated documentation files (the            *
   * "Software"), to deal in the Software without restriction, including      *
   * without limitation the rights to use, copy, modify, merge, publish,      *
   * distribute, distribute with modifications, sublicense, and/or sell       *
   * copies of the Software, and to permit persons to whom the Software is    *
   * furnished to do so, subject to the following conditions:                 *
   *                                                                          *
   * The above copyright notice and this permission notice shall be included  *
   * in all copies or substantial portions of the Software.                   *
   *                                                                          *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
   * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
   * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
   * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
   * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
   * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
   *                                                                          *
   * Except as contained in this notice, the name(s) of the above copyright   *
   * holders shall not be used in advertising or otherwise to promote the     *
   * sale, use or other dealings in this Software without prior written       *
   * authorization.                                                           *
   ****************************************************************************/
  
  /****************************************************************************
   *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
   *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
   *     and: Thomas E. Dickey                        1996-on                 *
   ****************************************************************************/
  
  /* lib_color.c
   *
   * Handles color emulation of SYS V curses
   */
  
  #include <curses.priv.h>
  
  #include <term.h>
  #include <tic.h>
  
  MODULE_ID("$Id: lib_color.c,v 1.11 2010/01/12 23:22:05 nicm Exp $")
  
  /*
   * These should be screen structure members.  They need to be globals for
   * historical reasons.  So we assign them in start_color() and also in
   * set_term()'s screen-switching logic.
   */
  #if USE_REENTRANT
  NCURSES_EXPORT(int)
  NCURSES_PUBLIC_VAR(COLOR_PAIRS) (void)
  {
      return SP ? SP->_pair_count : -1;
  }
  NCURSES_EXPORT(int)
  NCURSES_PUBLIC_VAR(COLORS) (void)
  {
      return SP ? SP->_color_count : -1;
  }
  #else
  NCURSES_EXPORT_VAR(int) COLOR_PAIRS = 0;
  NCURSES_EXPORT_VAR(int) COLORS = 0;
  #endif
  
  #define DATA(r,g,b) {r,g,b, 0,0,0, 0}
  
  #define TYPE_CALLOC(type,elts) typeCalloc(type, (unsigned)(elts))
  
  #define MAX_PALETTE	8
  
  #define OkColorHi(n)	(((n) < COLORS) && ((n) < max_colors))
  #define InPalette(n)	((n) >= 0 && (n) < MAX_PALETTE)
  
  /*
   * Given a RGB range of 0..1000, we'll normally set the individual values
   * to about 2/3 of the maximum, leaving full-range for bold/bright colors.
   */
  #define RGB_ON  680
  #define RGB_OFF 0
  /* *INDENT-OFF* */
  static const color_t cga_palette[] =
  {
      /*  R               G               B */
      DATA(RGB_OFF,	RGB_OFF,	RGB_OFF),	/* COLOR_BLACK */
      DATA(RGB_ON,	RGB_OFF,	RGB_OFF),	/* COLOR_RED */
      DATA(RGB_OFF,	RGB_ON,		RGB_OFF),	/* COLOR_GREEN */
      DATA(RGB_ON,	RGB_ON,		RGB_OFF),	/* COLOR_YELLOW */
      DATA(RGB_OFF,	RGB_OFF,	RGB_ON),	/* COLOR_BLUE */
      DATA(RGB_ON,	RGB_OFF,	RGB_ON),	/* COLOR_MAGENTA */
      DATA(RGB_OFF,	RGB_ON,		RGB_ON),	/* COLOR_CYAN */
      DATA(RGB_ON,	RGB_ON,		RGB_ON),	/* COLOR_WHITE */
  };
  
  static const color_t hls_palette[] =
  {
      /*  	H       L       S */
      DATA(	0,	0,	0),		/* COLOR_BLACK */
      DATA(	120,	50,	100),		/* COLOR_RED */
      DATA(	240,	50,	100),		/* COLOR_GREEN */
      DATA(	180,	50,	100),		/* COLOR_YELLOW */
      DATA(	330,	50,	100),		/* COLOR_BLUE */
      DATA(	60,	50,	100),		/* COLOR_MAGENTA */
      DATA(	300,	50,	100),		/* COLOR_CYAN */
      DATA(	0,	50,	100),		/* COLOR_WHITE */
  };
  /* *INDENT-ON* */
  
  #if NCURSES_EXT_FUNCS
  /*
   * These are called from _nc_do_color(), which in turn is called from
   * vidattr - so we have to assume that SP may be null.
   */
  static int
  default_fg(void)
  {
      return (SP != 0) ? SP->_default_fg : COLOR_WHITE;
  }
  
  static int
  default_bg(void)
  {
      return SP != 0 ? SP->_default_bg : COLOR_BLACK;
  }
  #else
  #define default_fg() COLOR_WHITE
  #define default_bg() COLOR_BLACK
  #endif
  
  /*
   * SVr4 curses is known to interchange color codes (1,4) and (3,6), possibly
   * to maintain compatibility with a pre-ANSI scheme.  The same scheme is
   * also used in the FreeBSD syscons.
   */
  static int
  toggled_colors(int c)
  {
      if (c < 16) {
  	static const int table[] =
  	{0, 4, 2, 6, 1, 5, 3, 7,
  	 8, 12, 10, 14, 9, 13, 11, 15};
  	c = table[c];
      }
      return c;
  }
  
  static void
  set_background_color(int bg, int (*outc) (int))
  {
      if (set_a_background) {
  	TPUTS_TRACE("set_a_background");
  	tputs(TPARM_1(set_a_background, bg), 1, outc);
      } else {
  	TPUTS_TRACE("set_background");
  	tputs(TPARM_1(set_background, toggled_colors(bg)), 1, outc);
      }
  }
  
  static void
  set_foreground_color(int fg, int (*outc) (int))
  {
      if (set_a_foreground) {
  	TPUTS_TRACE("set_a_foreground");
  	tputs(TPARM_1(set_a_foreground, fg), 1, outc);
      } else {
  	TPUTS_TRACE("set_foreground");
  	tputs(TPARM_1(set_foreground, toggled_colors(fg)), 1, outc);
      }
  }
  
  static void
  init_color_table(void)
  {
      const color_t *tp;
      int n;
  
      tp = (hue_lightness_saturation) ? hls_palette : cga_palette;
      for (n = 0; n < COLORS; n++) {
  	if (InPalette(n)) {
  	    SP->_color_table[n] = tp[n];
  	} else {
  	    SP->_color_table[n] = tp[n % MAX_PALETTE];
  	    if (hue_lightness_saturation) {
  		SP->_color_table[n].green = 100;
  	    } else {
  		if (SP->_color_table[n].red)
  		    SP->_color_table[n].red = 1000;
  		if (SP->_color_table[n].green)
  		    SP->_color_table[n].green = 1000;
  		if (SP->_color_table[n].blue)
  		    SP->_color_table[n].blue = 1000;
  	    }
  	}
      }
  }
  
  /*
   * Reset the color pair, e.g., to whatever color pair 0 is.
   */
  static bool
  reset_color_pair(void)
  {
      bool result = FALSE;
  
      if (orig_pair != 0) {
  	TPUTS_TRACE("orig_pair");
  	putp(orig_pair);
  	result = TRUE;
      }
      return result;
  }
  
  /*
   * Reset color pairs and definitions.  Actually we do both more to accommodate
   * badly-written terminal descriptions than for the relatively rare case where
   * someone has changed the color definitions.
   */
  bool
  _nc_reset_colors(void)
  {
      int result = FALSE;
  
      T((T_CALLED("_nc_reset_colors()")));
      if (SP->_color_defs > 0)
  	SP->_color_defs = -(SP->_color_defs);
  
      if (reset_color_pair())
  	result = TRUE;
      if (orig_colors != 0) {
  	TPUTS_TRACE("orig_colors");
  	putp(orig_colors);
  	result = TRUE;
      }
      returnBool(result);
  }
  
  NCURSES_EXPORT(int)
  start_color(void)
  {
      int result = ERR;
  
      T((T_CALLED("start_color()")));
  
      if (SP == 0) {
  	result = ERR;
      } else if (SP->_coloron) {
  	result = OK;
      } else {
  
  	if (reset_color_pair() != TRUE) {
  	    set_foreground_color(default_fg(), _nc_outch);
  	    set_background_color(default_bg(), _nc_outch);
  	}
  
  	if (max_pairs > 0 && max_colors > 0) {
  	    SP->_pair_count = max_pairs;
  	    SP->_color_count = max_colors;
  #if !USE_REENTRANT
  	    COLOR_PAIRS = max_pairs;
  	    COLORS = max_colors;
  #endif
  
  	    if ((SP->_color_pairs = TYPE_CALLOC(colorpair_t,
  						max_pairs)) != 0) {
  		if ((SP->_color_table = TYPE_CALLOC(color_t,
  						    max_colors)) != 0) {
  		    SP->_color_pairs[0] = PAIR_OF(default_fg(), default_bg());
  		    init_color_table();
  
  		    T(("started color: COLORS = %d, COLOR_PAIRS = %d",
  		       COLORS, COLOR_PAIRS));
  
  		    SP->_coloron = 1;
  		    result = OK;
  		} else if (SP->_color_pairs != 0) {
  		    FreeAndNull(SP->_color_pairs);
  		}
  	    }
  	} else {
  	    result = OK;
  	}
      }
      returnCode(result);
  }
  
  /* This function was originally written by Daniel Weaver <danw@znyx.com> */
  static void
  rgb2hls(short r, short g, short b, short *h, short *l, short *s)
  /* convert RGB to HLS system */
  {
      short min, max, t;
  
      if ((min = g < r ? g : r) > b)
  	min = b;
      if ((max = g > r ? g : r) < b)
  	max = b;
  
      /* calculate lightness */
      *l = (min + max) / 20;
  
      if (min == max) {		/* black, white and all shades of gray */
  	*h = 0;
  	*s = 0;
  	return;
      }
  
      /* calculate saturation */
      if (*l < 50)
  	*s = ((max - min) * 100) / (max + min);
      else
  	*s = ((max - min) * 100) / (2000 - max - min);
  
      /* calculate hue */
      if (r == max)
  	t = 120 + ((g - b) * 60) / (max - min);
      else if (g == max)
  	t = 240 + ((b - r) * 60) / (max - min);
      else
  	t = 360 + ((r - g) * 60) / (max - min);
  
      *h = t % 360;
  }
  
  /*
   * Extension (1997/1/18) - Allow negative f/b values to set default color
   * values.
   */
  NCURSES_EXPORT(int)
  init_pair(short pair, short f, short b)
  {
      colorpair_t result;
  
      T((T_CALLED("init_pair(%d,%d,%d)"), pair, f, b));
  
      if ((pair < 0) || (pair >= COLOR_PAIRS) || SP == 0 || !SP->_coloron)
  	returnCode(ERR);
  #if NCURSES_EXT_FUNCS
      if (SP->_default_color) {
  	if (f < 0)
  	    f = COLOR_DEFAULT;
  	if (b < 0)
  	    b = COLOR_DEFAULT;
  	if (!OkColorHi(f) && !isDefaultColor(f))
  	    returnCode(ERR);
  	if (!OkColorHi(b) && !isDefaultColor(b))
  	    returnCode(ERR);
      } else
  #endif
      {
  	if ((f < 0) || !OkColorHi(f)
  	    || (b < 0) || !OkColorHi(b)
  	    || (pair < 1))
  	    returnCode(ERR);
      }
  
      /*
       * When a pair's content is changed, replace its colors (if pair was
       * initialized before a screen update is performed replacing original
       * pair colors with the new ones).
       */
      result = PAIR_OF(f, b);
      if (SP->_color_pairs[pair] != 0
  	&& SP->_color_pairs[pair] != result) {
  	int y, x;
  
  	for (y = 0; y <= curscr->_maxy; y++) {
  	    struct ldat *ptr = &(curscr->_line[y]);
  	    bool changed = FALSE;
  	    for (x = 0; x <= curscr->_maxx; x++) {
  		if (GetPair(ptr->text[x]) == pair) {
  		    /* Set the old cell to zero to ensure it will be
  		       updated on the next doupdate() */
  		    SetChar(ptr->text[x], 0, 0);
  		    CHANGED_CELL(ptr, x);
  		    changed = TRUE;
  		}
  	    }
  	    if (changed)
  		_nc_make_oldhash(y);
  	}
      }
      SP->_color_pairs[pair] = result;
      if (GET_SCREEN_PAIR(SP) == pair)
  	SET_SCREEN_PAIR(SP, (chtype) (~0));	/* force attribute update */
  
      if (initialize_pair && InPalette(f) && InPalette(b)) {
  	const color_t *tp = hue_lightness_saturation ? hls_palette : cga_palette;
  
  	TR(TRACE_ATTRS,
  	   ("initializing pair: pair = %d, fg=(%d,%d,%d), bg=(%d,%d,%d)",
  	    pair,
  	    tp[f].red, tp[f].green, tp[f].blue,
  	    tp[b].red, tp[b].green, tp[b].blue));
  
  	TPUTS_TRACE("initialize_pair");
  	putp(TPARM_7(initialize_pair,
  		     pair,
  		     tp[f].red, tp[f].green, tp[f].blue,
  		     tp[b].red, tp[b].green, tp[b].blue));
      }
  
      returnCode(OK);
  }
  
  #define okRGB(n) ((n) >= 0 && (n) <= 1000)
  
  NCURSES_EXPORT(int)
  init_color(short color, short r, short g, short b)
  {
      int result = ERR;
  
      T((T_CALLED("init_color(%d,%d,%d,%d)"), color, r, g, b));
  
      if (initialize_color != NULL
  	&& SP != 0
  	&& SP->_coloron
  	&& (color >= 0 && OkColorHi(color))
  	&& (okRGB(r) && okRGB(g) && okRGB(b))) {
  
  	SP->_color_table[color].init = 1;
  	SP->_color_table[color].r = r;
  	SP->_color_table[color].g = g;
  	SP->_color_table[color].b = b;
  
  	if (hue_lightness_saturation) {
  	    rgb2hls(r, g, b,
  		    &SP->_color_table[color].red,
  		    &SP->_color_table[color].green,
  		    &SP->_color_table[color].blue);
  	} else {
  	    SP->_color_table[color].red = r;
  	    SP->_color_table[color].green = g;
  	    SP->_color_table[color].blue = b;
  	}
  
  	TPUTS_TRACE("initialize_color");
  	putp(TPARM_4(initialize_color, color, r, g, b));
  	SP->_color_defs = max(color + 1, SP->_color_defs);
  	result = OK;
      }
      returnCode(result);
  }
  
  NCURSES_EXPORT(bool)
  can_change_color(void)
  {
      T((T_CALLED("can_change_color()")));
      returnCode((can_change != 0) ? TRUE : FALSE);
  }
  
  NCURSES_EXPORT(bool)
  has_colors(void)
  {
      T((T_CALLED("has_colors()")));
      returnCode((VALID_NUMERIC(max_colors) && VALID_NUMERIC(max_pairs)
  		&& (((set_foreground != NULL)
  		     && (set_background != NULL))
  		    || ((set_a_foreground != NULL)
  			&& (set_a_background != NULL))
  		    || set_color_pair)) ? TRUE : FALSE);
  }
  
  NCURSES_EXPORT(int)
  color_content(short color, short *r, short *g, short *b)
  {
      int result;
  
      T((T_CALLED("color_content(%d,%p,%p,%p)"), color, r, g, b));
      if (color < 0 || !OkColorHi(color) || SP == 0 || !SP->_coloron) {
  	result = ERR;
      } else {
  	NCURSES_COLOR_T c_r = SP->_color_table[color].red;
  	NCURSES_COLOR_T c_g = SP->_color_table[color].green;
  	NCURSES_COLOR_T c_b = SP->_color_table[color].blue;
  
  	if (r)
  	    *r = c_r;
  	if (g)
  	    *g = c_g;
  	if (b)
  	    *b = c_b;
  
  	TR(TRACE_ATTRS, ("...color_content(%d,%d,%d,%d)",
  			 color, c_r, c_g, c_b));
  	result = OK;
      }
      returnCode(result);
  }
  
  NCURSES_EXPORT(int)
  pair_content(short pair, short *f, short *b)
  {
      int result;
  
      T((T_CALLED("pair_content(%d,%p,%p)"), pair, f, b));
  
      if ((pair < 0) || (pair >= COLOR_PAIRS) || SP == 0 || !SP->_coloron) {
  	result = ERR;
      } else {
  	NCURSES_COLOR_T fg = ((SP->_color_pairs[pair] >> C_SHIFT) & C_MASK);
  	NCURSES_COLOR_T bg = (SP->_color_pairs[pair] & C_MASK);
  
  #if NCURSES_EXT_FUNCS
  	if (fg == COLOR_DEFAULT)
  	    fg = -1;
  	if (bg == COLOR_DEFAULT)
  	    bg = -1;
  #endif
  
  	if (f)
  	    *f = fg;
  	if (b)
  	    *b = bg;
  
  	TR(TRACE_ATTRS, ("...pair_content(%d,%d,%d)", pair, fg, bg));
  	result = OK;
      }
      returnCode(result);
  }
  
  NCURSES_EXPORT(void)
  _nc_do_color(short old_pair, short pair, bool reverse, int (*outc) (int))
  {
      NCURSES_COLOR_T fg = COLOR_DEFAULT;
      NCURSES_COLOR_T bg = COLOR_DEFAULT;
      NCURSES_COLOR_T old_fg, old_bg;
  
      if (pair < 0 || pair >= COLOR_PAIRS) {
  	return;
      } else if (pair != 0) {
  	if (set_color_pair) {
  	    TPUTS_TRACE("set_color_pair");
  	    tputs(TPARM_1(set_color_pair, pair), 1, outc);
  	    return;
  	} else if (SP != 0) {
  	    pair_content((short) pair, &fg, &bg);
  	}
      }
  
      if (old_pair >= 0
  	&& SP != 0
  	&& pair_content(old_pair, &old_fg, &old_bg) != ERR) {
  	if ((isDefaultColor(fg) && !isDefaultColor(old_fg))
  	    || (isDefaultColor(bg) && !isDefaultColor(old_bg))) {
  #if NCURSES_EXT_FUNCS
  	    /*
  	     * A minor optimization - but extension.  If "AX" is specified in
  	     * the terminal description, treat it as screen's indicator of ECMA
  	     * SGR 39 and SGR 49, and assume the two sequences are independent.
  	     */
  	    if (SP->_has_sgr_39_49
  		&& isDefaultColor(old_bg)
  		&& !isDefaultColor(old_fg)) {
  		tputs("\033[39m", 1, outc);
  	    } else if (SP->_has_sgr_39_49
  		       && isDefaultColor(old_fg)
  		       && !isDefaultColor(old_bg)) {
  		tputs("\033[49m", 1, outc);
  	    } else
  #endif
  		reset_color_pair();
  	}
      } else {
  	reset_color_pair();
  	if (old_pair < 0)
  	    return;
      }
  
  #if NCURSES_EXT_FUNCS
      if (isDefaultColor(fg))
  	fg = default_fg();
      if (isDefaultColor(bg))
  	bg = default_bg();
  #endif
  
      if (reverse) {
  	NCURSES_COLOR_T xx = fg;
  	fg = bg;
  	bg = xx;
      }
  
      TR(TRACE_ATTRS, ("setting colors: pair = %d, fg = %d, bg = %d", pair,
  		     fg, bg));
  
      if (!isDefaultColor(fg)) {
  	set_foreground_color(fg, outc);
      }
      if (!isDefaultColor(bg)) {
  	set_background_color(bg, outc);
      }
  }
  