fltk/src/fl_color.cxx

// fl_color.C

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

#ifdef WIN32
#include "fl_color_win32.C"
#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, fl_greenmask, fl_bluemask;
int fl_redshift, fl_greenshift, fl_blueshift, fl_extrashift;
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;

}

////////////////////////////////////////////////////////////////
// Get an rgb color.  This is easy for a truecolor visual.  For
// colormapped it picks the closest color out of the fltk colormap
// but be warned that this results in *two* approximations: one
// to the fltk colormap, and another to whatever colors X allocates.

ulong fl_xpixel(uchar r,uchar g,uchar b) {
  if (!beenhere) figure_out_visual();
#if USE_COLORMAP
  if (!fl_redmask) {
    Fl_Color i;
    if (r == g && r == b) { // get it out of gray ramp
      i = fl_gray_ramp(r*FL_NUM_GRAY/256);
    } else {		// get it out of color cube:
      i = fl_color_cube(r*FL_NUM_RED/256,g*FL_NUM_GREEN/256,b*FL_NUM_BLUE/256);
    }
    return fl_xpixel(i);
  }
#endif
  return
    (((r&fl_redmask) << fl_redshift)+
     ((g&fl_greenmask)<<fl_greenshift)+
     ((b&fl_bluemask)<< fl_blueshift)
     ) >> fl_extrashift;
}

void fl_color(uchar r,uchar g,uchar b) {
  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.

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

#if HAVE_OVERLAY
Fl_XColor fl_xmap[2][256];
uchar fl_overlay;
Colormap fl_overlay_colormap;
XVisualInfo* fl_overlay_visual;
ulong fl_transparent_pixel;
#else
Fl_XColor fl_xmap[1][256];
#endif

// calculate what color is actually on the screen for a mask:
static inline uchar realcolor(uchar color, uchar mask) {
#if 1
  // 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
}

ulong fl_xpixel(Fl_Color i) {

#if HAVE_OVERLAY
  Fl_XColor &xmap = fl_xmap[fl_overlay][i];
#else
  Fl_XColor &xmap = fl_xmap[0][i];
#endif
  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;
#if HAVE_OVERLAY
  if (fl_overlay) {colormap = fl_overlay_colormap; goto J1;}
#endif
  if (!fl_redmask) {
    colormap = fl_colormap;
#if HAVE_OVERLAY
  J1:
    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
      // assumme 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
  // 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 = fl_xpixel(r,g,b);
}

Fl_Color fl_color_;

void fl_color(Fl_Color i) {
  fl_color_ = i;
  XSetForeground(fl_display, fl_gc, fl_xpixel(i));
}

////////////////////////////////////////////////////////////////
// Ways to modify the fltk colormap:

Fl_Color contrast(Fl_Color fg, Fl_Color bg) {
  // bright/dark is decided based on high bit of green:
  if (fl_cmap[bg] & 0x800000) {
    if (fl_cmap[fg] & 0x800000) return FL_GRAY_RAMP; // black from gray ramp
  } else {
    if (!(fl_cmap[fg] & 0x800000))
      return (Fl_Color)(FL_COLOR_CUBE-1); // white from gray ramp
  }
  return fg; // this color is ok
}

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;
  }
}

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;
  }
}

unsigned Fl::get_color(Fl_Color i) {
  return fl_cmap[i];
}

void Fl::set_color(Fl_Color i, uchar red, uchar green, uchar blue) {
  Fl::set_color(i,
	((unsigned)red<<24)+((unsigned)green<<16)+((unsigned)blue<<8));
}

void Fl::get_color(Fl_Color i, uchar &red, uchar &green, uchar &blue) {
  unsigned c = fl_cmap[i];
  red   = uchar(c>>24);
  green = uchar(c>>16);
  blue  = uchar(c>>8);
}

#endif
// end of fl_color.C