release/src/router/libncurses/doc/html/man/curs_color.3x.html

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  39 <H1>curs_color 3x</H1>
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  43 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>                                           <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
  44
  45
  46
  47
  48 </PRE>
  49 <H2>NAME</H2><PRE>
  50        <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
  51        <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG>
  52        - <STRONG>curses</STRONG> color manipulation routines
  53
  54
  55 </PRE>
  56 <H2>SYNOPSIS</H2><PRE>
  57        <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
  58
  59        <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
  60        <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
  61        <STRONG>int</STRONG> <STRONG>init_color(short</STRONG> <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>r,</STRONG> <STRONG>short</STRONG> <STRONG>g,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
  62        <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
  63        <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
  64        <STRONG>int</STRONG>  <STRONG>color_content(short</STRONG>  <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>*r,</STRONG> <STRONG>short</STRONG> <STRONG>*g,</STRONG> <STRONG>short</STRONG>
  65        <STRONG>*b);</STRONG>
  66        <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
  67
  68
  69 </PRE>
  70 <H2>DESCRIPTION</H2><PRE>
  71    <STRONG>Overview</STRONG>
  72        <STRONG>curses</STRONG> support color attributes on terminals with that ca-
  73        pability.   To  use  these  routines  <STRONG>start_color</STRONG>  must be
  74        called, usually right after <STRONG>initscr</STRONG>.   Colors  are  always
  75        used  in pairs (referred to as color-pairs).  A color-pair
  76        consists of a foreground  color  (for  characters)  and  a
  77        background color (for the blank field on which the charac-
  78        ters are displayed).  A programmer  initializes  a  color-
  79        pair  with  the routine <STRONG>init_pair</STRONG>.  After it has been ini-
  80        tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro  defined  in  <STRONG>&lt;curses.h&gt;</STRONG>,
  81        can be used as a new video attribute.
  82
  83        If  a  terminal  is capable of redefining colors, the pro-
  84        grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
  85        nition   of   a   color.    The  routines  <STRONG>has_colors</STRONG>  and
  86        <STRONG>can_change_color</STRONG>  return  <STRONG>TRUE</STRONG>  or  <STRONG>FALSE</STRONG>,  depending   on
  87        whether  the  terminal  has color capabilities and whether
  88        the programmer can change the colors.   The  routine  <STRONG>col-</STRONG>
  89        <STRONG>or_content</STRONG>  allows  a programmer to extract the amounts of
  90        red, green, and blue components in an  initialized  color.
  91        The  routine  <STRONG>pair_content</STRONG> allows a programmer to find out
  92        how a given color-pair is currently defined.
  93
  94    <STRONG>Routine</STRONG> <STRONG>Descriptions</STRONG>
  95        The <STRONG>start_color</STRONG> routine requires no arguments.  It must be
  96        called  if  the programmer wants to use colors, and before
  97        any other color manipulation routine  is  called.   It  is
  98        good  practice  to  call this routine right after <STRONG>initscr</STRONG>.
  99        <STRONG>start_color</STRONG> initializes eight basic  colors  (black,  red,
 100        green,  yellow,  blue,  magenta, cyan, and white), and two
 101        global variables,  <STRONG>COLORS</STRONG>  and  <STRONG>COLOR_PAIRS</STRONG>  (respectively
 102        defining  the maximum number of colors and color-pairs the
 103        terminal can support).  It also restores the colors on the
 104        terminal to the values they had when the terminal was just
 105        turned on.
 106
 107        The <STRONG>init_pair</STRONG> routine changes the definition of  a  color-
 108        pair.   It takes three arguments: the number of the color-
 109        pair to be changed, the foreground color number,  and  the
 110        background color number.  For portable applications:
 111
 112        <STRONG>o</STRONG>   The  value of the first argument must be between <STRONG>1</STRONG> and
 113            <STRONG>COLOR_PAIRS-1</STRONG>, except that if default colors are  used
 114            (see  <STRONG>use_default_colors</STRONG>)  the upper limit is adjusted
 115            to allow for extra pairs which use a default color  in
 116            foreground and/or background.
 117
 118        <STRONG>o</STRONG>   The  value  of  the second and third arguments must be
 119            between 0 and <STRONG>COLORS</STRONG>.  Color pair 0 is assumed  to  be
 120            white  on black, but is actually whatever the terminal
 121            implements before color is initialized.  It cannot  be
 122            modified by the application.
 123
 124        If  the  color-pair was previously initialized, the screen
 125        is refreshed and all occurrences of  that  color-pair  are
 126        changed to the new definition.
 127
 128        As  an  extension,  ncurses allows you to set color pair 0
 129        via the <STRONG>assume_default_colors</STRONG> routine, or to  specify  the
 130        use  of  default colors (color number <STRONG>-1</STRONG>) if you first in-
 131        voke the <STRONG>use_default_colors</STRONG> routine.
 132
 133        The <STRONG>init_color</STRONG> routine changes the definition of a  color.
 134        It  takes  four  arguments:  the number of the color to be
 135        changed followed by three RGB values (for the  amounts  of
 136        red,  green, and blue components).  The value of the first
 137        argument must be between <STRONG>0</STRONG> and <STRONG>COLORS</STRONG>.  (See  the  section
 138        <STRONG>Colors</STRONG>  for  the  default  color index.)  Each of the last
 139        three arguments must be a value between 0 and 1000.   When
 140        <STRONG>init_color</STRONG>  is  used, all occurrences of that color on the
 141        screen immediately change to the new definition.
 142
 143        The <STRONG>has_colors</STRONG> routine requires no arguments.  It  returns
 144        <STRONG>TRUE</STRONG>  if the terminal can manipulate colors; otherwise, it
 145        returns <STRONG>FALSE</STRONG>.  This routine facilitates writing terminal-
 146        independent  programs.   For example, a programmer can use
 147        it to decide whether to use color or some other video  at-
 148        tribute.
 149
 150        The  <STRONG>can_change_color</STRONG>  routine  requires no arguments.  It
 151        returns <STRONG>TRUE</STRONG> if  the  terminal  supports  colors  and  can
 152        change  their  definitions; other, it returns <STRONG>FALSE</STRONG>.  This
 153        routine facilitates writing terminal-independent programs.
 154
 155        The <STRONG>color_content</STRONG> routine gives programmers a way to  find
 156        the intensity of the red, green, and blue (RGB) components
 157        in a color.  It requires four arguments: the color number,
 158        and  three addresses of <STRONG>short</STRONG>s for storing the information
 159        about the amounts of red, green, and  blue  components  in
 160        the  given color.  The value of the first argument must be
 161        between 0 and <STRONG>COLORS</STRONG>.  The values that are stored  at  the
 162        addresses  pointed  to by the last three arguments are be-
 163        tween 0 (no component) and 1000 (maximum amount of  compo-
 164        nent).
 165
 166        The  <STRONG>pair_content</STRONG>  routine  allows programmers to find out
 167        what colors a given color-pair consists of.   It  requires
 168        three  arguments: the color-pair number, and two addresses
 169        of <STRONG>short</STRONG>s for storing the foreground  and  the  background
 170        color  numbers.   The  value of the first argument must be
 171        between 1 and <STRONG>COLOR_PAIRS-1</STRONG>.  The values that  are  stored
 172        at  the addresses pointed to by the second and third argu-
 173        ments are between 0 and <STRONG>COLORS</STRONG>.
 174
 175    <STRONG>Colors</STRONG>
 176        In <STRONG>&lt;curses.h&gt;</STRONG> the following macros are defined.  These are
 177        the  default colors.  <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
 178        is the default background color for all terminals.
 179
 180              <STRONG>COLOR_BLACK</STRONG>
 181              <STRONG>COLOR_RED</STRONG>
 182              <STRONG>COLOR_GREEN</STRONG>
 183              <STRONG>COLOR_YELLOW</STRONG>
 184              <STRONG>COLOR_BLUE</STRONG>
 185              <STRONG>COLOR_MAGENTA</STRONG>
 186              <STRONG>COLOR_CYAN</STRONG>
 187              <STRONG>COLOR_WHITE</STRONG>
 188
 189
 190 </PRE>
 191 <H2>RETURN VALUE</H2><PRE>
 192        The routines <STRONG>can_change_color()</STRONG>  and  <STRONG>has_colors()</STRONG>  return
 193        <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
 194
 195        All other routines return the integer <STRONG>ERR</STRONG> upon failure and
 196        an <STRONG>OK</STRONG> (SVr4 specifies only "an integer  value  other  than
 197        <STRONG>ERR</STRONG>") upon successful completion.
 198
 199        X/Open  defines  no error conditions.  This implementation
 200        will return <STRONG>ERR</STRONG> on attempts to use  color  values  outside
 201        the range 0 to COLORS-1 (except for the default colors ex-
 202        tension), or use color pairs outside the range 0  to  COL-
 203        OR_PAIRS-1.   Color  values  used in <STRONG>init_color</STRONG> must be in
 204        the range 0 to 1000.  An error is returned from all  func-
 205        tions  if the terminal has not been initialized.  An error
 206        is returned from secondary functions such as <STRONG>init_pair</STRONG>  if
 207        <STRONG>start_color</STRONG> was not called.
 208
 209           <STRONG>init_color</STRONG>
 210                returns  an error if the terminal does not support
 211                this feature, e.g., if the <EM>initialize</EM><STRONG>_</STRONG><EM>color</EM>  capa-
 212                bility is absent from the terminal description.
 213
 214           <STRONG>start_color</STRONG>
 215                returns  an error if the color table cannot be al-
 216                located.
 217
 218
 219 </PRE>
 220 <H2>NOTES</H2><PRE>
 221        In the <EM>ncurses</EM> implementation, there is a  separate  color
 222        activation flag, color palette, color pairs table, and as-
 223        sociated COLORS and COLOR_PAIRS counts  for  each  screen;
 224        the  <STRONG>start_color</STRONG> function only affects the current screen.
 225        The SVr4/XSI interface is not really designed with this in
 226        mind,  and  historical  implementations  may  use a single
 227        shared color palette.
 228
 229        Note that setting an implicit background color via a color
 230        pair  affects  only character cells that a character write
 231        operation explicitly touches.  To  change  the  background
 232        color  used  when parts of a window are blanked by erasing
 233        or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
 234
 235        Several caveats apply on 386 and 486  machines  with  VGA-
 236        compatible graphics:
 237
 238        <STRONG>o</STRONG>   COLOR_YELLOW  is  actually  brown.  To get yellow, use
 239            COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
 240
 241        <STRONG>o</STRONG>   The A_BLINK attribute should in theory cause the back-
 242            ground  to  go  bright.  This often fails to work, and
 243            even some cards for which it mostly works (such as the
 244            Paradise  and compatibles) do the wrong thing when you
 245            try to set a bright "yellow"  background  (you  get  a
 246            blinking yellow foreground instead).
 247
 248        <STRONG>o</STRONG>   Color RGB values are not settable.
 249
 250
 251 </PRE>
 252 <H2>PORTABILITY</H2><PRE>
 253        This  implementation  satisfies XSI Curses's minimum maxi-
 254        mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
 255
 256        The <STRONG>init_pair</STRONG> routine accepts  negative  values  of  fore-
 257        ground   and  background  color  to  support  the  <STRONG>use_de-</STRONG>
 258        <STRONG>fault_colors</STRONG> extension, but only if that routine has  been
 259        first invoked.
 260
 261        The  assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
 262        color for all terminals can  be  modified  using  the  <STRONG>as-</STRONG>
 263        <STRONG>sume_default_colors</STRONG> extension.
 264
 265        This  implementation  checks  the  pointers, e.g., for the
 266        values returned by  <STRONG>color_content</STRONG>  and  <STRONG>pair_content</STRONG>,  and
 267        will treat those as optional parameters when null.
 268
 269
 270 </PRE>
 271 <H2>SEE ALSO</H2><PRE>
 272        <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>,  <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>,  <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>,  <STRONG>curs_vari-</STRONG>
 273        <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
 274
 275
 276
 277                                                          <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
 278 </PRE>
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