color.c

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/*
 * Copyright (C) 2000, Matias Atria
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <config.h>
#include "mdvi.h"
#include "color.h"

void    mdvi_set_color(DviContext *dvi, Ulong fg, Ulong bg)
{
    if(dvi->curr_fg != fg || dvi->curr_bg != bg) {
        DEBUG((DBG_DEVICE, "setting color to (%lu,%lu)\n", fg, bg));
        if(dvi->device.set_color)
            dvi->device.set_color(dvi->device.device_data, fg, bg);
        dvi->curr_fg = fg;
        dvi->curr_bg = bg;
    }
}

void    mdvi_push_color(DviContext *dvi, Ulong fg, Ulong bg)
{
    if(dvi->color_top == dvi->color_size) {
        dvi->color_size += 32;
        dvi->color_stack = mdvi_realloc(dvi->color_stack,
            dvi->color_size * sizeof(DviColorPair));
    }
    dvi->color_stack[dvi->color_top].fg = dvi->curr_fg;
    dvi->color_stack[dvi->color_top].bg = dvi->curr_bg;
    dvi->color_top++;
    mdvi_set_color(dvi, fg, bg);
}

void    mdvi_pop_color(DviContext *dvi)
{
    Ulong   fg, bg;
    
    if(dvi->color_top == 0)
        return;
    dvi->color_top--;
    fg = dvi->color_stack[dvi->color_top].fg;
    bg = dvi->color_stack[dvi->color_top].bg;
    mdvi_set_color(dvi, fg, bg);
}

void    mdvi_reset_color(DviContext *dvi)
{
    dvi->color_top = 0;
    mdvi_set_color(dvi, dvi->params.fg, dvi->params.bg);
}

/* cache for color tables, to avoid creating them for every glyph */
typedef struct {
    Ulong   fg;
    Ulong   bg;
    Uint    nlevels;
    Ulong   *pixels;
    int density;
    double  gamma;
    Uint    hits;
} ColorCache;

#define CCSIZE      256
static ColorCache   color_cache[CCSIZE];
static int      cc_entries;

#define GAMMA_DIFF  0.005


/* create a color table */
Ulong   *get_color_table(DviDevice *dev, 
             int nlevels, Ulong fg, Ulong bg, double gamma, int density)
{
    ColorCache  *cc, *tofree;
    int     lohits;
    Ulong       *pixels;
    int     status;

    lohits = color_cache[0].hits;
    tofree = &color_cache[0];
    /* look in the cache and see if we have one that matches this request */
    for(cc = &color_cache[0]; cc < &color_cache[cc_entries]; cc++) {
        if(cc->hits < lohits) {
            lohits = cc->hits;
            tofree = cc;
        }
        if(cc->fg == fg && cc->bg == bg && cc->density == density &&
           cc->nlevels == nlevels && fabs(cc->gamma - gamma) <= GAMMA_DIFF)
            break;
    }

    if(cc < &color_cache[cc_entries]) {
        cc->hits++;
        return cc->pixels;
    }

    DEBUG((DBG_DEVICE, "Adding color table to cache (fg=%lu, bg=%lu, n=%d)\n",
        fg, bg, nlevels));
        
    /* no entry was found in the cache, create a new one */
    if(cc_entries < CCSIZE) {
        cc = &color_cache[cc_entries++];
        cc->pixels = NULL;
    } else {
        cc = tofree;
        mdvi_free(cc->pixels);
    }
    pixels = xnalloc(Ulong, nlevels);
    status = dev->alloc_colors(dev->device_data, 
        pixels, nlevels, fg, bg, gamma, density);
    if(status < 0) {
        mdvi_free(pixels);
        return NULL;
    }
    cc->fg = fg;
    cc->bg = bg;
    cc->gamma = gamma;
    cc->density = density;
    cc->nlevels = nlevels;
    cc->pixels = pixels;
    cc->hits = 1;
    return pixels;  
}