fontsrch.c

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/* fontsearch.c -- implements the font lookup mechanism in MDVI */
/*
 * 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.
 */

/*
 * How this works:
 *   Fonts are divided into MAX_CLASS priority classes. The first
 * MAX_CLASS-1 ones correspond to `real' fonts (pk, gf, vf, type1, truetype,
 * etc). The last one corresponds to `metric' fonts that are used as a last
 * resort (tfm, afm, ofm, ...). When a font is looked up, it is tried in a
 * `high' priority class (0 being the highest priority). The priority is
 * lowered until it reaches MAX_CLASS-1. Then the whole thing is repeated
 * for the fallback font. When the search reaches MAX_CLASS-1, we lookup the
 * original font, and then the fallback font. The search can be done
 * incrementally, with several calls to mdvi_lookup_font(). If this function
 * is called again to continue a search, the function assumes the previous
 * font it returned was not valid, and it goes on to the next step.
 *
 * Reason for this:
 *   Some font types are quite expensive to load (e.g. Type1),  so loading
 * them is deferred until the last possible moment. This means that a font that
 * was supposed to exist may have to be discarded. Until now, MDVI had no ability to
 * "resume" a search, so in this case it would have produced an error, regardless
 * of whether the offending font existed in other formats.
 *   Also, given the large number of font types supported by MDVI, some mechanism
 * was necessary to bring some order into the chaos.
 *
 * This mechanism fixes these two problems. For the first one, a search can
 * be "resumed" and all the font formats tried for the missing font, and
 * again for the fallback font (see above). As for the second, the
 * hierarchical division in classes gives a lot of flexibility in how the
 * fonts are configured.
 */

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

#define HAVE_PROTOTYPES 1
#include <kpathsea/tex-file.h>
#include <kpathsea/tex-glyph.h>

struct _DviFontClass {
    DviFontClass *next;
    DviFontClass *prev;
    DviFontInfo  info;
    int links;
    int id;
};

char *_mdvi_fallback_font = MDVI_FALLBACK_FONT;

/* this leaves classes 0 and 1 for `real' fonts */
#define MAX_CLASS   3
static ListHead font_classes[MAX_CLASS];
static int initialized = 0;

static void init_font_classes(void)
{
    int i;
    
    for(i = 0; i < MAX_CLASS; i++)
        listh_init(&font_classes[i]);
    initialized = 1;
}

int mdvi_get_font_classes(void)
{
    return (MAX_CLASS - 2);
}

char    **mdvi_list_font_class(int klass)
{
    char    **list;
    int i, n;
    DviFontClass *fc;
    
    if(klass == -1)
        klass = MAX_CLASS-1;
    if(klass < 0 || klass >= MAX_CLASS)
        return NULL;
    n = font_classes[klass].count;
    list = xnalloc(char *, n + 1);
    fc = (DviFontClass *)font_classes[klass].head;
    for(i = 0; i < n; fc = fc->next, i++) {
        list[i] = mdvi_strdup(fc->info.name);
    }
    list[i] = NULL;
    return list;
}

int mdvi_register_font_type(DviFontInfo *info, int klass)
{
    DviFontClass *fc;

    if(klass == -1)
        klass = MAX_CLASS-1;
    if(klass < 0 || klass >= MAX_CLASS)
        return -1;
    if(!initialized)
        init_font_classes();
    fc = xalloc(struct _DviFontClass);
    fc->links = 0;
    fc->id = klass;
    fc->info.name = mdvi_strdup(info->name);
    fc->info.scalable = info->scalable;
    fc->info.load = info->load;
    fc->info.getglyph = info->getglyph;
    fc->info.shrink0 = info->shrink0;
    fc->info.shrink1 = info->shrink1;
    fc->info.freedata = info->freedata;
    fc->info.reset = info->reset;
    fc->info.lookup = info->lookup;
    fc->info.kpse_type = info->kpse_type;
    listh_append(&font_classes[klass], LIST(fc));
    return 0;
}

int mdvi_unregister_font_type(const char *name, int klass)
{
    DviFontClass *fc;
    int k;

    if(klass == -1)
        klass = MAX_CLASS - 1;
    
    if(klass >= 0 && klass < MAX_CLASS) {
        k = klass;
        LIST_FOREACH(fc, DviFontClass, &font_classes[k]) {
            if(STREQ(fc->info.name, name))
                break;
        }
    } else if(klass < 0) {
        for(k = 0; k < MAX_CLASS; k++) {
            LIST_FOREACH(fc, DviFontClass, &font_classes[k]) {
                if(STREQ(fc->info.name, name))
                    break;
            }
            if(fc) break;
        }
    } else
        return -1;
    
    if(fc == NULL || fc->links)
        return -1;
    /* remove it */
    listh_remove(&font_classes[k], LIST(fc));
    
    /* and destroy it */
    mdvi_free(fc->info.name);
    mdvi_free(fc);
    return 0;
}

static char *lookup_font(DviFontClass *ptr, const char *name, Ushort *h, Ushort *v)
{
    char    *filename;

    /*
     * If the font type registered a function to do the lookup, use that. 
     * Otherwise we use kpathsea.
     */ 
    if(ptr->info.lookup)
        filename = ptr->info.lookup(name, h, v);
    else if(ptr->info.kpse_type <= kpse_any_glyph_format) {
        kpse_glyph_file_type type;

        filename = kpse_find_glyph(name, Max(*h, *v),
            ptr->info.kpse_type, &type);
        /* if kpathsea returned a fallback font, reject it */
        if(filename && type.source == kpse_glyph_source_fallback) {
            mdvi_free(filename);
            filename = NULL;
        } else if(filename)
            *h = *v = type.dpi;
    } else
        filename = kpse_find_file(name, ptr->info.kpse_type, 1);
    return filename;
}

/*
 * Class MAX_CLASS-1 is special: it consists of `metric' fonts that should
 * be tried as a last resort
 */
char    *mdvi_lookup_font(DviFontSearch *search)
{
    int kid;
    int k;
    DviFontClass *ptr;
    DviFontClass *last;
    char    *filename = NULL;
    const char *name;
    Ushort  hdpi, vdpi;

    if(search->id < 0)
        return NULL;
    
    if(search->curr == NULL) {
        /* this is the initial search */
        name = search->wanted_name;
        hdpi = search->hdpi;
        vdpi = search->vdpi;
        kid = 0;
        last = NULL;
    } else {
        name = search->actual_name;
        hdpi = search->actual_hdpi;
        vdpi = search->actual_vdpi;
        kid = search->id;
        last = search->curr;
    }

    ptr = NULL;
again:
    /* try all classes except MAX_CLASS-1 */
    for(k = kid; !filename && k < MAX_CLASS-1; k++) {
        if(last == NULL)
            ptr = (DviFontClass *)font_classes[k].head;
        else
            ptr = last->next;
        while(ptr) {
            DEBUG((DBG_FONTS, "%d: trying `%s' at (%d,%d)dpi as `%s'\n",
                k, name, hdpi, vdpi, ptr->info.name));
            /* lookup the font in this class */
            filename = lookup_font(ptr, name, &hdpi, &vdpi);
            if(filename)
                break;
            ptr = ptr->next;
        }
        last = NULL;
    }
    if(filename != NULL) {
        search->id = k-1;
        search->curr = ptr;
        search->actual_name = name;
        search->actual_hdpi = hdpi;
        search->actual_vdpi = vdpi;
        search->info = &ptr->info;
        ptr->links++;
        return filename;
    }

    if(kid < MAX_CLASS - 1 && !STREQ(name, _mdvi_fallback_font)) {
        mdvi_warning("font `%s' at %dx%d not found, trying `%s' instead\n",
                 name, hdpi, vdpi, _mdvi_fallback_font);
        name = _mdvi_fallback_font;
        kid = 0;
        goto again;
    }

    /* we tried the fallback font, and all the `real' classes. Let's
     * try the `metric' class now */
    name = search->wanted_name;
    hdpi = search->hdpi;
    vdpi = search->vdpi;
    if(kid == MAX_CLASS-1) {
        /* we were looking into this class from the beginning */
        if(last == NULL) {
            /* no more fonts to try */
            return NULL;
        }
        ptr = last->next;
    } else {
        mdvi_warning("font `%s' not found, trying metric files instead\n",
                 name);
        ptr = (DviFontClass *)font_classes[MAX_CLASS-1].head;
    }

metrics:
    while(ptr) {
        DEBUG((DBG_FONTS, "metric: trying `%s' at (%d,%d)dpi as `%s'\n",
            name, hdpi, vdpi, ptr->info.name));
        filename = lookup_font(ptr, name, &hdpi, &vdpi);
        if(filename)
            break;
        ptr = ptr->next;
    }
    if(filename != NULL) {
        if(STREQ(name, _mdvi_fallback_font))
            search->id = MAX_CLASS;
        else
            search->id = MAX_CLASS - 1;
        search->curr = ptr;
        search->actual_name = name;
        search->actual_hdpi = hdpi;
        search->actual_vdpi = vdpi;
        search->info = &ptr->info;
        ptr->links++;
        return filename;
    }
    if(!STREQ(name, _mdvi_fallback_font)) {
        mdvi_warning("metric file for `%s' not found, trying `%s' instead\n",
                 name, _mdvi_fallback_font);
        name = _mdvi_fallback_font;
        ptr = (DviFontClass *)font_classes[MAX_CLASS-1].head;
        goto metrics;
    }

    search->id = -1;
    search->actual_name = NULL;
    
    /* tough luck, nothing found */
    return NULL;
}

/* called by `font_reference' to do the initial lookup */
DviFont *mdvi_add_font(const char *name, Int32 sum,
    int hdpi, int vdpi, Int32 scale)
{
    DviFont *font;
    
    font = xalloc(DviFont);
    font->fontname = mdvi_strdup(name);
    SEARCH_INIT(font->search, font->fontname, hdpi, vdpi);
    font->filename = mdvi_lookup_font(&font->search);
    if(font->filename == NULL) {
        /* this answer is final */
        mdvi_free(font->fontname);
        mdvi_free(font);
        return NULL;
    }
    font->hdpi = font->search.actual_hdpi;
    font->vdpi = font->search.actual_vdpi;
    font->scale = scale;
    font->design = 0;
    font->checksum = sum;
    font->type = 0;
    font->links = 0;
    font->loc = 0;
    font->hic = 0;
    font->in = NULL;
    font->chars = NULL;
    font->subfonts = NULL;

    return font;
}

int mdvi_font_retry(DviParams *params, DviFont *font)
{
    /* try the search again */
    char    *filename;

    ASSERT(font->search.curr != NULL);  
    /* we won't be using this class anymore */
    font->search.curr->links--;

    filename = mdvi_lookup_font(&font->search);
    if(filename == NULL)
        return -1;
    mdvi_free(font->filename);
    font->filename = filename;
    /* copy the new information */
    font->hdpi = font->search.actual_hdpi;
    font->vdpi = font->search.actual_vdpi;

    return 0;
}