/*----------------------------------------------------------------------  File    : xshades.c  Contents: X11 functions for color and grey shades allocation  Author  : Christian Borgelt  History : 07.01.2000 file created            09.01.2000 color offset saved in structure            10.01.2000 grey shades added----------------------------------------------------------------------*/#include <stdio.h>#include <stdlib.h>#include <math.h>#include <assert.h>#include "xshades.h"/*----------------------------------------------------------------------  Preprocessor Definitions----------------------------------------------------------------------*/#define RGB_MAX   65535               /* maximum RGB value *//*----------------------------------------------------------------------  Auxiliary Functions----------------------------------------------------------------------*/static double intensity (double col){                               /* --- get rgb color intensity */  assert((col >= -2) && (col <= 3));  /* check the function argument */  if (col <= 0)   return 0;           /* intensity curve: */  if (col <  0.5) return 2*col;       /*   0.5 1.5        */  if (col <= 1.5) return 1;           /*    _____       1 */  if (col <  2)   return 4 -2*col;    /*   /     \_____ 0 */  return 0;                           /*  0   1   2   3   */}  /* intensity() *//*----------------------------------------------------------------------  Main Functions----------------------------------------------------------------------*/void shd_delete (SHADES *shds){                               /* --- delete color shades */  int   i;                      /* loop variable */  PIXEL **pp;                   /* to delete the pixel vectors */  assert(shds);                 /* check the function argument */  i = (shds->colcnt > 0) ? shds->colcnt : 1;  for (pp = shds->pixels; (--i >= 0) && *pp; pp++)    XFreeColors(shds->disp, shds->colmap, *pp, shds->shdcnt, 0);  free(shds->pixels[0]);        /* delete the pixel vector */  free(shds);                   /* and the base structure */}  /* shd_delete() *//*--------------------------------------------------------------------*/SHADES* shd_create (Display *disp, Colormap colmap,                    double coloff, int colcnt, int shdbase, int shdcnt){                               /* --- create color shades */  int     i, k;                 /* loop variables, buffers */  SHADES  *shds;                /* created color shades */  double  col, dc;              /* color and color difference */  double  t;                    /* temporary buffer */  double  red, green, blue;     /* RGB intensities */  XColor  xc;                   /* buffer for X color allocation */  PIXEL   **pp, *p;             /* to traverse the pixels */  assert(disp && colmap);       /* check the function arguments */  if (shdcnt <= 0) shdcnt = 1;  /* check and adapt number of shades */  if (shdcnt > SHD_MAXCNT) shdcnt = SHD_MAXCNT;  coloff = fmod(coloff, 360);   /* compute color offset and */  if (coloff < 0) coloff += 360;/* ensure that it is positive */  k    = (colcnt > 0) ? colcnt : 1;  shds = (SHADES*)calloc(1, sizeof(SHADES) +(k-1) *sizeof(PIXEL*));  if (!shds) return NULL;       /* allocate the base structure */  shds->pixels[0] = p = (PIXEL*)malloc(k *shdcnt *sizeof(PIXEL));  if (!p) { free(shds); return NULL; }  shds->disp    = disp;         /* and initialize other fields */  shds->colmap  = colmap;  shds->coloff  = coloff;  shds->colcnt  = (colcnt <= 0) ? 0 : colcnt;  shds->shdbase = (shdbase == SHD_BLACK) ? SHD_BLACK : SHD_WHITE;  shds->shdcnt  = shdcnt;  /* --- grey shades --- */  if (colcnt <= 0) {            /* if no color shades requested */    for (p += i = shdcnt; --i >= 0; ) {      t = (shdcnt > 1)          /* compute the intensity value */        ? ((double)i/(shdcnt-1)) *(RGB_MAX+0.99) : (RGB_MAX +0.99);      k = (int)floor(t); /* compute RGB values of grey shade */      if (shdbase != SHD_BLACK) k = RGB_MAX -k;      xc.red = xc.green = xc.blue = (unsigned short)k;      if (XAllocColor(disp, colmap, &xc) == 0) {        if ((k = shdcnt -i -1) > 0) XFreeColors(disp, colmap, p, k, 0);        free(shds->pixels[0]); free(shds);        return NULL;            /* allocate the computed grey */      }                         /* and check for success */      *--p = xc.pixel;          /* store the pixel value */              }    return shds;                /* return the created grey shades */  }  /* --- color shades --- */  coloff /= 120;                /* compute color offset from angle */  dc      = 3.0/colcnt;         /* and color difference as a fraction */  for (pp = shds->pixels, k = 0; k < colcnt; k++, p += shdcnt) {    col   = k *dc +coloff;      /* traverse the colors */    col  -= t = col -floor(col);    col   = (((2*t -3)*t +2)*t +fmod(col, 3));    red   = intensity((col >= 2) ? col -2 : col +1);    green = intensity(col);     /* transform the color and */    blue  = intensity(col -1);  /* compute the RGB intensities */    for (*pp++ = p, p += i = shdcnt; --i >= 0; ) {      t = (shdcnt > 1)          /* compute the scaling factor */        ? ((double)i/(shdcnt-1)) *(RGB_MAX+0.99) : (RGB_MAX +0.99);      if (shdbase == SHD_BLACK){/* if shading from black */        xc.red   = (unsigned short)floor(red   *t);        xc.green = (unsigned short)floor(green *t);        xc.blue  = (unsigned short)floor(blue  *t); }      else {                    /* if shading from white */        xc.red   = RGB_MAX -(unsigned short)floor((1 -red)   *t);        xc.green = RGB_MAX -(unsigned short)floor((1 -green) *t);        xc.blue  = RGB_MAX -(unsigned short)floor((1 -blue)  *t);      }                         /* compute integer RGB values */      if (XAllocColor(disp, colmap, &xc) == 0) {        if ((k = shdcnt -i -1) > 0) XFreeColors(disp, colmap, p, k, 0);        shd_delete(shds); return NULL;      }                         /* allocate the computed color */      *--p = xc.pixel;          /* store the pixel value */    }  }  return shds;                  /* return the created color shades */}  /* shd_create() */