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/****************************************************************************/
/* */
/* Program: i_colourmap.c */
/* Author: Simon A.J. Winder */
/* Date: Wed Feb 26 11:49:16 1992 */
/* Function: Colourmap Routines */
/* Copyright (C) 1994 Simon A.J. Winder */
/* */
/****************************************************************************/
#include "lib.h"
/*#define debug(m) DEBUG("<colourmap> " m)*/
#define debug(m)
#define colour_hash(p) ((((p)->r+(p)->g+(p)->b)&0x7fff)%IM_CMAP_HASHSIZE)
/****************************************************************************/
it_cmap *i_create_colourmap(int maxindex)
{
it_cmap *cmap;
it_cmap_entry *ptr;
int i;
if(maxindex<1)
return(NULL);
if((cmap=(it_cmap *) calloc(1,sizeof(it_cmap)))==NULL)
return(NULL);
cmap->maxindex=maxindex;
cmap->cmap_list=(it_cmap_entry *) calloc(maxindex,sizeof(it_cmap_entry));
if(cmap->cmap_list==NULL)
{
free((char *) cmap);
return(NULL);
}
/* build hash list - all colours start as rgb={0,0,0} due to calloc */
ptr=cmap->cmap_list;
cmap->hash_col[colour_hash(&(ptr->colour))]=ptr;
for(i=1;i<maxindex;i++)
ptr=(ptr->next_col= &(cmap->cmap_list[i]));
return(cmap);
}
void i_destroy_colourmap(it_cmap *cmap)
{
if(cmap!=NULL)
{
if(cmap->cmap_list!=NULL) free((char *) (cmap->cmap_list));
free((char *) cmap);
}
}
void i_set_colourmap_entry(it_cmap *cmap,int index,it_rgb *colour)
{
it_cmap_entry *entry,*ptr;
int old_colour,new_colour;
if(index<0 || index>=cmap->maxindex) return;
entry= &(cmap->cmap_list[index]);
/* find previous colour in this index position and unlink */
old_colour=colour_hash(&(entry->colour));
if(cmap->hash_col[old_colour]==entry)
cmap->hash_col[old_colour]=entry->next_col;
else
for(ptr=cmap->hash_col[old_colour];ptr->next_col!=NULL;ptr=ptr->next_col)
if(ptr->next_col==entry)
{
ptr->next_col=entry->next_col;
break;
}
/* write new colour values and link into hash list */
(entry->colour).r=colour->r;
(entry->colour).g=colour->g;
(entry->colour).b=colour->b;
new_colour=colour_hash(colour);
entry->next_col=cmap->hash_col[new_colour];
cmap->hash_col[new_colour]=entry;
}
int i_lookup_colourmap_colour(it_cmap *cmap,it_rgb *colour)
{
it_cmap_entry *ptr;
/* skip down the hash chain until the rgb values match */
for(ptr=cmap->hash_col[colour_hash(colour)];ptr!=NULL;ptr=ptr->next_col)
if(im_rgb_equal(colour,&(ptr->colour))) break;
if(ptr==NULL) return(-1);
/* return the index (pointer subtraction - don't need a sizeof) */
return(ptr-cmap->cmap_list);
}
it_rgb *i_lookup_colourmap_index(it_cmap *cmap,int index)
{
if(index<0 || index>=cmap->maxindex) return(NULL);
return(&((cmap->cmap_list[index]).colour));
}
/* Version 1.0 (Oct 1994) */
/* Version 1.1 (Nov 1994) */
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