fltk/src/fl_color.cxx

//
// "$Id$"
//
// Color functions for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2010 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

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

void Fl_Graphics_Driver::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));
  }
}

void Fl_Graphics_Driver::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));
}

/** \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;
}

////////////////////////////////////////////////////////////////
// Get a color out of 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
}

/**
  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.
    
    This 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.
*/
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));
}
/**
    Returns the RGB value(s) for the given FLTK color index. 
    
    This form returns the red, green, and blue values
    separately in referenced variables.

    See also 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 "$Id$".
//