djvu-links.c

Go to the documentation of this file.

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8; c-indent-level: 8 -*- */
/*
 * Implements hyperlink functionality for Djvu files.
 * Copyright (C) 2006 Pauli Virtanen <pav@iki.fi>
 *
 * 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, 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 <string.h>
#include <glib.h>
#include <libdjvu/miniexp.h>
#include "djvu-document.h"
#include "djvu-links.h"
#include "djvu-document-private.h"
#include "ev-document-links.h"
#include "ev-mapping-list.h"

static gboolean number_from_miniexp(miniexp_t sexp, int *number)
{
    if (miniexp_numberp (sexp)) {
        *number = miniexp_to_int (sexp);
        return TRUE;
    } else {
        return FALSE;
    }
}

static gboolean string_from_miniexp(miniexp_t sexp, const char **str)
{
    if (miniexp_stringp (sexp)) {
        *str = miniexp_to_str (sexp);
        return TRUE;
    } else {
        return FALSE;
    }
}

static gboolean number_from_string_10(const gchar *str, guint64 *number)
{
    gchar *end_ptr;

    *number = g_ascii_strtoull(str, &end_ptr, 10);
    if (*end_ptr == '\0') {
        return TRUE;
    } else {
        return FALSE;
    }
}

static guint64
get_djvu_link_page (const DjvuDocument *djvu_document, const gchar *link_name, int base_page)
{
    guint64 page_num = 0;

    /* #pagenum, #+pageoffset, #-pageoffset */
    if (g_str_has_prefix (link_name, "#")) {
        if (g_str_has_suffix (link_name,".djvu")) {
            /* File identifiers */
            gpointer page = NULL;

            if (g_hash_table_lookup_extended (djvu_document->file_ids, link_name + 1, NULL, &page)) {
                return GPOINTER_TO_INT (page);
            }
        } else if (base_page > 0 && g_str_has_prefix (link_name + 1, "+")) {
            if (number_from_string_10 (link_name + 2, &page_num)) {
                return base_page + page_num;
            }
        } else if (base_page > 0 && g_str_has_prefix (link_name + 1, "-")) {
            if (number_from_string_10 (link_name + 2, &page_num)) {
                return base_page - page_num;
            }
        } else {
            if (number_from_string_10 (link_name + 1, &page_num)) {
                return page_num - 1;
            }
        }
    } else {
        /* FIXME: should we handle this case */
    }

    return page_num;
}

static EvLinkDest *
get_djvu_link_dest (const DjvuDocument *djvu_document, const gchar *link_name, int base_page)
{
    /* #+pagenum #-pagenum #file_id.djvu */
    if (g_str_has_prefix (link_name, "#")) {
        if (g_str_has_suffix (link_name, ".djvu") ||
            (base_page > 0 && g_str_has_prefix (link_name + 1, "+")) ||
            (base_page > 0 && g_str_has_prefix (link_name + 1, "-"))) {
            return ev_link_dest_new_page (get_djvu_link_page (djvu_document, link_name, base_page));
        } else {
            /* #pagenum #page_label: the djvu spec is not clear on whether #pagenum represents
             * a link to a page number or to a page label. Here we mimick djview,
             * and always treat #pagenum as a link to a page label */
            return ev_link_dest_new_page_label (link_name + 1);
        }
    }

    return NULL;
}

static EvLinkAction *
get_djvu_link_action (const DjvuDocument *djvu_document, const gchar *link_name, int base_page)
{
    EvLinkDest *ev_dest = NULL;
    EvLinkAction *ev_action = NULL;

    /* File component identifiers are handled by get_djvu_link_dest */

    ev_dest = get_djvu_link_dest (djvu_document, link_name, base_page);
    if (ev_dest) {
        ev_action = ev_link_action_new_dest (ev_dest);
        g_object_unref (ev_dest);
    } else if (strstr(link_name, "://") != NULL) {
        /* It's probably an URI */
        ev_action = ev_link_action_new_external_uri (link_name);
    }

    return ev_action;
}

static gchar *
str_to_utf8 (const gchar *text)
{
    static const gchar *encodings_to_try[2];
    static gint n_encodings_to_try = 0;
    gchar *utf8_text = NULL;
    gint i;

    if (n_encodings_to_try == 0) {
        const gchar *charset;
        gboolean charset_is_utf8;

        charset_is_utf8 = g_get_charset (&charset);
        if (!charset_is_utf8) {
            encodings_to_try[n_encodings_to_try++] = charset;
        }

        if (g_ascii_strcasecmp (charset, "ISO-8859-1") != 0) {
            encodings_to_try[n_encodings_to_try++] = "ISO-8859-1";
        }
    }

    for (i = 0; i < n_encodings_to_try; i++) {
        utf8_text = g_convert (text, -1, "UTF-8",
                       encodings_to_try[i],
                       NULL, NULL, NULL);
        if (utf8_text)
            break;
    }

    return utf8_text;
}

static void
build_tree (const DjvuDocument *djvu_document,
        GtkTreeModel       *model,
        GtkTreeIter        *parent,
        miniexp_t           iter)
{
    const char *title, *link_dest;
    char *title_markup;

    EvLinkAction *ev_action = NULL;
    EvLink *ev_link = NULL;
    GtkTreeIter tree_iter;

    if (miniexp_car (iter) == miniexp_symbol ("bookmarks")) {
        /* The (bookmarks) cons */
        iter = miniexp_cdr (iter);
    } else if ( miniexp_length (iter) >= 2 ) {
        gchar *utf8_title = NULL;
        
        /* An entry */
        if (!string_from_miniexp (miniexp_car (iter), &title)) goto unknown_entry;
        if (!string_from_miniexp (miniexp_cadr (iter), &link_dest)) goto unknown_entry;

        
        if (!g_utf8_validate (title, -1, NULL)) {
            utf8_title = str_to_utf8 (title);
            title_markup = g_markup_escape_text (utf8_title, -1);
        } else {
            title_markup = g_markup_escape_text (title, -1);
        }

        ev_action = get_djvu_link_action (djvu_document, link_dest, -1);

        if (ev_action) {
            ev_link = ev_link_new (utf8_title ? utf8_title : title, ev_action);
            gtk_tree_store_append (GTK_TREE_STORE (model), &tree_iter, parent);
            gtk_tree_store_set (GTK_TREE_STORE (model), &tree_iter,
                        EV_DOCUMENT_LINKS_COLUMN_MARKUP, title_markup,
                        EV_DOCUMENT_LINKS_COLUMN_LINK, ev_link,
                        EV_DOCUMENT_LINKS_COLUMN_EXPAND, FALSE,
                        -1);
            g_object_unref (ev_action);
            g_object_unref (ev_link);
        } else {
            gtk_tree_store_append (GTK_TREE_STORE (model), &tree_iter, parent);
            gtk_tree_store_set (GTK_TREE_STORE (model), &tree_iter,
                        EV_DOCUMENT_LINKS_COLUMN_MARKUP, title_markup,
                        EV_DOCUMENT_LINKS_COLUMN_EXPAND, FALSE,
                        -1);
        }

        g_free (title_markup);
        g_free (utf8_title);
        iter = miniexp_cddr (iter);
        parent = &tree_iter;
    } else {
        goto unknown_entry;
    }

    for (; iter != miniexp_nil; iter = miniexp_cdr (iter)) {
        build_tree (djvu_document, model, parent, miniexp_car (iter));
    }
    return;

 unknown_entry:
    g_warning ("DjvuLibre error: Unknown entry in bookmarks");
    return;
}

static gboolean
get_djvu_hyperlink_area (ddjvu_pageinfo_t *page_info,
             miniexp_t         sexp,
             EvMapping        *ev_link_mapping)
{
    miniexp_t iter;

    iter = sexp;
    
    if ((miniexp_car (iter) == miniexp_symbol ("rect") || miniexp_car (iter) == miniexp_symbol ("oval"))
        && miniexp_length (iter) == 5) {
        /* FIXME: get bounding box for (oval) since Evince doesn't support shaped links */
        int minx, miny, width, height;

        iter = miniexp_cdr (iter);
        if (!number_from_miniexp (miniexp_car (iter), &minx)) goto unknown_link;
        iter = miniexp_cdr (iter);
        if (!number_from_miniexp (miniexp_car (iter), &miny)) goto unknown_link;
        iter = miniexp_cdr (iter);
        if (!number_from_miniexp (miniexp_car (iter), &width)) goto unknown_link;
        iter = miniexp_cdr (iter);
        if (!number_from_miniexp (miniexp_car (iter), &height)) goto unknown_link;

        ev_link_mapping->area.x1 = minx;
        ev_link_mapping->area.x2 = (minx + width);
        ev_link_mapping->area.y1 = (page_info->height - (miny + height));
        ev_link_mapping->area.y2 = (page_info->height - miny);
    } else if (miniexp_car (iter) == miniexp_symbol ("poly")
           && miniexp_length (iter) >= 5 && miniexp_length (iter) % 2 == 1) {
        
        /* FIXME: get bounding box since Evince doesn't support shaped links */
        int minx = G_MAXINT, miny = G_MAXINT;
        int maxx = G_MININT, maxy = G_MININT;

        iter = miniexp_cdr(iter);
        while (iter != miniexp_nil) {
            int x, y;

            if (!number_from_miniexp (miniexp_car(iter), &x)) goto unknown_link;
            iter = miniexp_cdr (iter);
            if (!number_from_miniexp (miniexp_car(iter), &y)) goto unknown_link;
            iter = miniexp_cdr (iter);

            minx = MIN (minx, x);
            miny = MIN (miny, y);
            maxx = MAX (maxx, x);
            maxy = MAX (maxy, y);
        }

        ev_link_mapping->area.x1 = minx;
        ev_link_mapping->area.x2 = maxx;
        ev_link_mapping->area.y1 = (page_info->height - maxy);
        ev_link_mapping->area.y2 = (page_info->height - miny);
    } else {
        /* unknown */
        goto unknown_link;
    }

    return TRUE;
    
 unknown_link:
    g_warning("DjvuLibre error: Unknown hyperlink area %s", miniexp_to_name(miniexp_car(sexp)));
    return FALSE;
}

static EvMapping *
get_djvu_hyperlink_mapping (DjvuDocument     *djvu_document,
                int               page,
                ddjvu_pageinfo_t *page_info,
                miniexp_t         sexp)
{
    EvMapping *ev_link_mapping = NULL;
    EvLinkAction *ev_action = NULL;
    miniexp_t iter;
    const char *url, *url_target, *comment;

    ev_link_mapping = g_new (EvMapping, 1);

    iter = sexp;

    if (miniexp_car (iter) != miniexp_symbol ("maparea")) goto unknown_mapping;

    iter = miniexp_cdr(iter);

    if (miniexp_caar(iter) == miniexp_symbol("url")) {
        if (!string_from_miniexp (miniexp_cadr (miniexp_car (iter)), &url)) goto unknown_mapping;
        if (!string_from_miniexp (miniexp_caddr (miniexp_car (iter)), &url_target)) goto unknown_mapping;
    } else {
        if (!string_from_miniexp (miniexp_car(iter), &url)) goto unknown_mapping;
        url_target = NULL;
    }

    iter = miniexp_cdr (iter);
    if (!string_from_miniexp (miniexp_car(iter), &comment)) goto unknown_mapping;

    iter = miniexp_cdr (iter);
    if (!get_djvu_hyperlink_area (page_info, miniexp_car(iter), ev_link_mapping)) goto unknown_mapping;

    iter = miniexp_cdr (iter);
    /* FIXME: DjVu hyperlink attributes are ignored */

    ev_action = get_djvu_link_action (djvu_document, url, page);
    if (!ev_action) goto unknown_mapping;

    ev_link_mapping->data = ev_link_new (comment, ev_action);
    g_object_unref (ev_action);

    return ev_link_mapping;

 unknown_mapping:
    if (ev_link_mapping) g_free(ev_link_mapping);
    g_warning("DjvuLibre error: Unknown hyperlink %s", miniexp_to_name(miniexp_car(sexp)));
    return NULL;
}


gboolean
djvu_links_has_document_links (EvDocumentLinks *document_links)
{
    DjvuDocument *djvu_document = DJVU_DOCUMENT (document_links);
    miniexp_t outline;

    while ((outline = ddjvu_document_get_outline (djvu_document->d_document)) == miniexp_dummy)
        djvu_handle_events (djvu_document, TRUE, NULL);

    if (outline) {
        ddjvu_miniexp_release (djvu_document->d_document, outline);
        return TRUE;
    }
    
    return FALSE;
}

EvMappingList *
djvu_links_get_links (EvDocumentLinks *document_links,
                      gint             page,
                      double           scale_factor)
{
    DjvuDocument *djvu_document = DJVU_DOCUMENT (document_links);
    GList *retval = NULL;
    miniexp_t page_annotations = miniexp_nil;
    miniexp_t *hyperlinks = NULL, *iter = NULL;
    EvMapping *ev_link_mapping;
        ddjvu_pageinfo_t page_info;

    while ((page_annotations = ddjvu_document_get_pageanno (djvu_document->d_document, page)) == miniexp_dummy)
        djvu_handle_events (djvu_document, TRUE, NULL);

    while (ddjvu_document_get_pageinfo (djvu_document->d_document, page, &page_info) < DDJVU_JOB_OK)
        djvu_handle_events(djvu_document, TRUE, NULL);

    if (page_annotations) {
        hyperlinks = ddjvu_anno_get_hyperlinks (page_annotations);
        if (hyperlinks) {
            for (iter = hyperlinks; *iter; ++iter) {
                ev_link_mapping = get_djvu_hyperlink_mapping (djvu_document, page, &page_info, *iter);
                if (ev_link_mapping) {
                    ev_link_mapping->area.x1 *= scale_factor;
                    ev_link_mapping->area.x2 *= scale_factor;
                    ev_link_mapping->area.y1 *= scale_factor;
                    ev_link_mapping->area.y2 *= scale_factor;
                    retval = g_list_prepend (retval, ev_link_mapping);
                }
            }
            free (hyperlinks);
        }
        ddjvu_miniexp_release (djvu_document->d_document, page_annotations);
    }
    
    return ev_mapping_list_new (page, retval, (GDestroyNotify)g_object_unref);
}

EvLinkDest *
djvu_links_find_link_dest (EvDocumentLinks  *document_links,
                           const gchar      *link_name)
{
    DjvuDocument *djvu_document = DJVU_DOCUMENT (document_links);
    EvLinkDest *ev_dest = NULL;
    
    ev_dest = get_djvu_link_dest (djvu_document, link_name, -1);

    if (!ev_dest) {
        g_warning ("DjvuLibre error: unknown link destination %s", link_name);
    }
    
    return ev_dest;
}

gint
djvu_links_find_link_page (EvDocumentLinks  *document_links,
               const gchar      *link_name)
{
    DjvuDocument *djvu_document = DJVU_DOCUMENT (document_links);
    gint page;

    page = get_djvu_link_page (djvu_document, link_name, -1);

    if (page == -1) {
        g_warning ("DjvuLibre error: unknown link destination %s", link_name);
    }

    return page;
}

GtkTreeModel *
djvu_links_get_links_model (EvDocumentLinks *document_links)
{
    DjvuDocument *djvu_document = DJVU_DOCUMENT (document_links);
    GtkTreeModel *model = NULL;
    miniexp_t outline = miniexp_nil;

    while ((outline = ddjvu_document_get_outline (djvu_document->d_document)) == miniexp_dummy)
        djvu_handle_events (djvu_document, TRUE, NULL);

    if (outline) {
        model = (GtkTreeModel *) gtk_tree_store_new (EV_DOCUMENT_LINKS_COLUMN_NUM_COLUMNS,
                                 G_TYPE_STRING,
                                 G_TYPE_OBJECT,
                                 G_TYPE_BOOLEAN,
                                 G_TYPE_STRING);
        build_tree (djvu_document, model, NULL, outline);

        ddjvu_miniexp_release (djvu_document->d_document, outline);
    }
    
    return model;
}