path: root/src/fl_color.cxx

//
// "$Id$"
//
// Color functions for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2009 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

/**
  \file fl_color.cxx
  \brief Color handling
*/

// Implementation of fl_color(i), fl_color(r,g,b).

#ifdef WIN32
#  include "fl_color_win32.cxx"
#elif defined(__APPLE__)
#  include "fl_color_mac.cxx"
#else

// Also code to look at the X visual and figure out the best way to turn
// a color into a pixel value.

// SGI compiler seems to have problems with unsigned char arguments
// being used to index arrays.  So I always copy them to an integer
// before use.

#  include "Fl_XColor.H"
#  include <FL/Fl.H>
#  include <FL/x.H>
#  include <FL/fl_draw.H>

////////////////////////////////////////////////////////////////
// figure_out_visual() calculates masks & shifts for generating
// pixels in true-color visuals:

uchar fl_redmask;	/**< color mask used in current color map handling */
uchar fl_greenmask;	/**< color mask used in current color map handling */
uchar fl_bluemask;	/**< color mask used in current color map handling */

int fl_redshift;	/**< color shift used in current color map handling */
int fl_greenshift;	/**< color shift used in current color map handling */
int fl_blueshift;	/**< color shift used in current color map handling */
int fl_extrashift;	/**< color shift used in current color map handling */

static uchar beenhere;

static void figure_out_visual() {
  beenhere = 1;
  if (!fl_visual->red_mask || !fl_visual->green_mask || !fl_visual->blue_mask){
#  if USE_COLORMAP
    fl_redmask = 0;
    return;
#  else
    Fl::fatal("Requires true color visual");
#  endif
  }

  // get the bit masks into a more useful form:
  int i,j,m;

  for (i = 0, m = 1; m; i++, m<<=1) if (fl_visual->red_mask & m) break;
  for (j = i; m; j++, m<<=1) if (!(fl_visual->red_mask & m)) break;
  fl_redshift = j-8;
  fl_redmask = (j-i >= 8) ? 0xFF : 0xFF-(255>>(j-i));

  for (i = 0, m = 1; m; i++, m<<=1) if (fl_visual->green_mask & m) break;
  for (j = i; m; j++, m<<=1) if (!(fl_visual->green_mask & m)) break;
  fl_greenshift = j-8;
  fl_greenmask = (j-i >= 8) ? 0xFF : 0xFF-(255>>(j-i));

  for (i = 0, m = 1; m; i++, m<<=1) if (fl_visual->blue_mask & m) break;
  for (j = i; m; j++, m<<=1) if (!(fl_visual->blue_mask & m)) break;
  fl_blueshift = j-8;
  fl_bluemask = (j-i >= 8) ? 0xFF : 0xFF-(255>>(j-i));

  i = fl_redshift;
  if (fl_greenshift < i) i = fl_greenshift;
  if (fl_blueshift < i) i = fl_blueshift;
  if (i < 0) {
    fl_extrashift = -i;
    fl_redshift -= i; fl_greenshift -= i; fl_blueshift -= i;
  } else
    fl_extrashift = 0;

}

static unsigned fl_cmap[256] = {
#include "fl_cmap.h" // this is a file produced by "cmap.cxx":
};

#  if HAVE_OVERLAY
/** HAVE_OVERLAY determines whether fl_xmap is one or two planes */
Fl_XColor fl_xmap[2][256];
/** HAVE_OVERLAY determines whether fl_overlay is variable or defined as 0 */
uchar fl_overlay;
Colormap fl_overlay_colormap;
XVisualInfo* fl_overlay_visual;
ulong fl_transparent_pixel;
#  else
/** HAVE_OVERLAY determines whether fl_xmap is one or two planes */
Fl_XColor fl_xmap[1][256];
/** HAVE_OVERLAY determines whether fl_overlay is variable or defined as 0 */
#    define fl_overlay 0
#  endif

/** \addtogroup  fl_attributes
    @{ */
////////////////////////////////////////////////////////////////
// Get an rgb color.  This is easy for a truecolor visual.  For
// colormapped it picks the closest color out of the cube in the
// fltk colormap.  However if this color cube entry has been
// requested before, you will get the earlier requested color, and
// even this may be approximated if the X colormap was full.

/**
  Returns the X pixel number used to draw the given rgb color.
  This is the X pixel that fl_color() would use.
  \param[in] r,g,b color components
  \return X pixel number
*/
ulong fl_xpixel(uchar r,uchar g,uchar b) {
  if (!beenhere) figure_out_visual();
#  if USE_COLORMAP
  if (!fl_redmask) {
    // find closest entry in the colormap:
    Fl_Color i =
      fl_color_cube(r*FL_NUM_RED/256,g*FL_NUM_GREEN/256,b*FL_NUM_BLUE/256);
    Fl_XColor &xmap = fl_xmap[fl_overlay][i];
    if (xmap.mapped) return xmap.pixel;
    // if not black or white, change the entry to be an exact match:
    if (i != FL_COLOR_CUBE && i != 0xFF)
      fl_cmap[i] = (r<<24)|(g<<16)|(b<<8);
    return fl_xpixel(i); // allocate an X color
  }
#  endif
  return
    (((r&fl_redmask) << fl_redshift)+
     ((g&fl_greenmask)<<fl_greenshift)+
     ((b&fl_bluemask)<< fl_blueshift)
     ) >> fl_extrashift;
}

/**
  Set the color for all subsequent drawing operations.
  The closest possible match to the RGB color is used.
  The RGB color is used directly on TrueColor displays.
  For colormap visuals the nearest index in the gray
  ramp or color cube is used.
  If no valid graphical context (fl_gc) is available,
  the foreground is not set for the current window.
  \param[in] r,g,b color components
*/
void fl_color(uchar r,uchar g,uchar b) {
  fl_color_ = fl_rgb_color(r, g, b);
  if(!fl_gc) return; // don't get a default gc if current window is not yet created/valid
  XSetForeground(fl_display, fl_gc, fl_xpixel(r,g,b));
}

////////////////////////////////////////////////////////////////
// Get a color out of the the fltk colormap.  Again for truecolor
// visuals this is easy.  For colormap this actually tries to allocate
// an X color, and does a least-squares match to find the closest
// color if X cannot allocate that color.

// calculate what color is actually on the screen for a mask:
static inline uchar realcolor(uchar color, uchar mask) {
#  if 0
  // accurate version if the display has linear gamma, but fl_draw_image
  // works better with the simpler version on most screens...
  uchar m = mask;
  uchar result = color&m;
  for (;;) {
    while (m&mask) {m>>=1; color>>=1;}
    if (!m) break;
    mask = m;
    result |= color&m;
  }
  return result;
#  else
  return (color&mask) | (~mask)&(mask>>1);
#  endif
}

/**
  Returns the X pixel number used to draw the given FLTK color index.
  This is the X pixel that fl_color() would use.
  \param[in] i color index
  \return X pixel number
*/
ulong fl_xpixel(Fl_Color i) {
  if (i & 0xffffff00) {
    return fl_xpixel((i >> 24) & 255, (i >> 16) & 255, (i >> 8) & 255);
  }

  Fl_XColor &xmap = fl_xmap[fl_overlay][i];
  if (xmap.mapped) return xmap.pixel;

  if (!beenhere) figure_out_visual();

  uchar r,g,b;
  {unsigned c = fl_cmap[i]; r=uchar(c>>24); g=uchar(c>>16); b=uchar(c>>8);}

#  if USE_COLORMAP
  Colormap colormap = fl_colormap;
#    if HAVE_OVERLAY
  if (fl_overlay) colormap = fl_overlay_colormap; else
#    endif
  if (fl_redmask) {
#  endif
    // return color for a truecolor visual:
    xmap.mapped = 2; // 2 prevents XFreeColor from being called
    xmap.r = realcolor(r, fl_redmask);
    xmap.g = realcolor(g, fl_greenmask);
    xmap.b = realcolor(b, fl_bluemask);
    return xmap.pixel = 
      (((r&fl_redmask) << fl_redshift)+
       ((g&fl_greenmask)<<fl_greenshift)+
       ((b&fl_bluemask)<< fl_blueshift)
       ) >> fl_extrashift;
#  if USE_COLORMAP
  }
#    if HAVE_OVERLAY
  static XColor* ac[2];
  XColor*& allcolors = ac[fl_overlay];
  static int nc[2];
  int& numcolors = nc[fl_overlay];
#    else
  static XColor *allcolors;
  static int numcolors;
#    endif

  // I don't try to allocate colors with XAllocColor once it fails
  // with any color.  It is possible that it will work, since a color
  // may have been freed, but some servers are extremely slow and this
  // avoids one round trip:
  if (!numcolors) { // don't try after a failure
    XColor xcol;
    xcol.red = r<<8; xcol.green = g<<8; xcol.blue = b<<8;
    if (XAllocColor(fl_display, colormap, &xcol)) {
      xmap.mapped = 1;
      xmap.r = xcol.red>>8;
      xmap.g = xcol.green>>8;
      xmap.b = xcol.blue>>8;
      return xmap.pixel = xcol.pixel;
    }

    // I only read the colormap once.  Again this is due to the slowness
    // of round-trips to the X server, even though other programs may alter
    // the colormap after this and make decisions here wrong.
#    if HAVE_OVERLAY
    if (fl_overlay) numcolors = fl_overlay_visual->colormap_size; else
#    endif
      numcolors = fl_visual->colormap_size;
    if (!allcolors) allcolors = new XColor[numcolors];
    for (int p = numcolors; p--;) allcolors[p].pixel = p;
    XQueryColors(fl_display, colormap, allcolors, numcolors);
  }

  // find least-squares match:
  int mindist = 0x7FFFFFFF;
  unsigned int bestmatch = 0;
  for (unsigned int n = numcolors; n--;) {
#    if HAVE_OVERLAY
    if (fl_overlay && n == fl_transparent_pixel) continue;
#    endif
    XColor &a = allcolors[n];
    int d, t;
    t = int(r)-int(a.red>>8); d = t*t;
    t = int(g)-int(a.green>>8); d += t*t;
    t = int(b)-int(a.blue>>8); d += t*t;
    if (d <= mindist) {bestmatch = n; mindist = d;}
  }
  XColor &p = allcolors[bestmatch];

  // It appears to "work" to not call this XAllocColor, which will
  // avoid another round-trip to the server.  But then X does not
  // know that this program "owns" this value, and can (and will)
  // change it when the program that did allocate it exits:
  if (XAllocColor(fl_display, colormap, &p)) {
    xmap.mapped = 1;
    xmap.pixel = p.pixel;
  } else {
    // However, if that XAllocColor fails, I have to give up and
    // assume the pixel is ok for the duration of the program.  This
    // is due to bugs (?) in the Solaris X and some X terminals
    // where XAllocColor *always* fails when the colormap is full,
    // even if we ask for a color already in it...
    xmap.mapped = 2; // 2 prevents XFreeColor from being called
    xmap.pixel = bestmatch;
  }
  xmap.r = p.red>>8;
  xmap.g = p.green>>8;
  xmap.b = p.blue>>8;
  return xmap.pixel;
#  endif
}

/** Current color for drawing operations */
Fl_Color fl_color_;

/**
  Sets the color for all subsequent drawing operations.
  For colormapped displays, a color cell will be allocated out of
  \p fl_colormap the first time you use a color. If the colormap fills up
  then a least-squares algorithm is used to find the closest color.
  If no valid graphical context (fl_gc) is available,
  the foreground is not set for the current window.
  \param[in] i color 
*/
void fl_color(Fl_Color i) {
  if (i & 0xffffff00) {
    unsigned rgb = (unsigned)i;
    fl_color((uchar)(rgb >> 24), (uchar)(rgb >> 16), (uchar)(rgb >> 8));
  } else {
    fl_color_ = i;
    if(!fl_gc) return; // don't get a default gc if current window is not yet created/valid
    XSetForeground(fl_display, fl_gc, fl_xpixel(i));
  }
}

/**
  Free color \p i if used, and clear mapping table entry.
  \param[in] i color index
  \param[in] overlay 0 for normal, 1 for overlay color
*/
void Fl::free_color(Fl_Color i, int overlay) {
#  if HAVE_OVERLAY
#  else
  if (overlay) return;
#  endif
  if (fl_xmap[overlay][i].mapped) {
#  if USE_COLORMAP
#    if HAVE_OVERLAY
    Colormap colormap = overlay ? fl_overlay_colormap : fl_colormap;
#    else
    Colormap colormap = fl_colormap;
#    endif
    if (fl_xmap[overlay][i].mapped == 1)
      XFreeColors(fl_display, colormap, &(fl_xmap[overlay][i].pixel), 1, 0);
#  endif
    fl_xmap[overlay][i].mapped = 0;
  }
}

/**
  Set color mapping table entry \p i to color \p c
  \param[in] i color index
  \param[in] c color
*/
void Fl::set_color(Fl_Color i, unsigned c) {
  if (fl_cmap[i] != c) {
    free_color(i,0);
#  if HAVE_OVERLAY
    free_color(i,1);
#  endif
    fl_cmap[i] = c;
  }
}

#endif // end of X-specific code
/**
    Returns the RGB value(s) for the given FLTK color index. The
    first form returns the RGB values packed in a 32-bit unsigned
    integer with the red value in the upper 8 bits, the green value
    in the next 8 bits, and the blue value in bits 8-15.  The lower
    8 bits will always be 0.
    
    The second form returns the red, green, and blue values
    separately in referenced variables.
*/
unsigned Fl::get_color(Fl_Color i) {
  if (i & 0xffffff00) return (i);
  else return fl_cmap[i];
}
/**
    Sets an entry in the fl_color index table.  You can set it to
    any 8-bit RGB color.  The color is not allocated until fl_color(i)
    is used.
*/
void Fl::set_color(Fl_Color i, uchar red, uchar green, uchar blue) {
  Fl::set_color((Fl_Color)(i & 255),
	((unsigned)red<<24)+((unsigned)green<<16)+((unsigned)blue<<8));
}
/** See unsigned get_color(Fl_Color c) */
void Fl::get_color(Fl_Color i, uchar &red, uchar &green, uchar &blue) {
  unsigned c;

  if (i & 0xffffff00) c = (unsigned)i;
  else c = fl_cmap[i];

  red   = uchar(c>>24);
  green = uchar(c>>16);
  blue  = uchar(c>>8);
}

/**
  Returns the weighted average color between the two given colors.
  The red, green and blue values are averages using the following formula:
  \code
  color = color1 * weight  + color2 * (1 - weight)
  \endcode
  Thus, a \p weight value of 1.0 will return the first color, while a
  value of 0.0 will return the second color.
  \param[in] color1, color2 boundary colors
  \param[in] weight weighting factor
*/
Fl_Color fl_color_average(Fl_Color color1, Fl_Color color2, float weight) {
  unsigned rgb1;
  unsigned rgb2;
  uchar r, g, b;

  if (color1 & 0xffffff00) rgb1 = color1;
  else rgb1 = fl_cmap[color1 & 255];

  if (color2 & 0xffffff00) rgb2 = color2;
  else rgb2 = fl_cmap[color2 & 255];

  r = (uchar)(((uchar)(rgb1>>24))*weight + ((uchar)(rgb2>>24))*(1-weight));
  g = (uchar)(((uchar)(rgb1>>16))*weight + ((uchar)(rgb2>>16))*(1-weight));
  b = (uchar)(((uchar)(rgb1>>8))*weight + ((uchar)(rgb2>>8))*(1-weight));

  return fl_rgb_color(r, g, b);
}

/**
  Returns the inactive, dimmed version of the given color
*/
Fl_Color fl_inactive(Fl_Color c) {
  return fl_color_average(c, FL_GRAY, .33f);
}

/**
  Returns a color that contrasts with the background color.
  This will be the foreground color if it contrasts sufficiently with the
  background color. Otherwise, returns \p FL_WHITE or \p FL_BLACK depending
  on which color provides the best contrast.
  \param[in] fg,bg foreground and background colors
  \return contrasting color
*/
Fl_Color fl_contrast(Fl_Color fg, Fl_Color bg) {
  unsigned c1, c2;	// RGB colors
  int l1, l2;		// Luminosities


  // Get the RGB values for each color...
  if (fg & 0xffffff00) c1 = (unsigned)fg;
  else c1 = fl_cmap[fg];

  if (bg & 0xffffff00) c2 = (unsigned)bg;
  else c2 = fl_cmap[bg];

  // Compute the luminosity...
  l1 = ((c1 >> 24) * 30 + ((c1 >> 16) & 255) * 59 + ((c1 >> 8) & 255) * 11) / 100;
  l2 = ((c2 >> 24) * 30 + ((c2 >> 16) & 255) * 59 + ((c2 >> 8) & 255) * 11) / 100;

  // Compare and return the contrasting color...
  if ((l1 - l2) > 99) return fg;
  else if ((l2 - l1) > 99) return fg;
  else if (l2 > 127) return FL_BLACK;
  else return FL_WHITE;
}
/**
   @}
*/
//
// End of "$Id$".
//