djvu-text-page.c

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/*
 * Implements search and copy functionality for Djvu files.
 * Copyright (C) 2006 Michael Hofmann <mh21@piware.de>
 *
 * 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-text-page.h"


static void
djvu_text_page_union (EvRectangle *target,
              EvRectangle *source)
{
    if (source->x1 < target->x1)
        target->x1 = source->x1;
    if (source->x2 > target->x2)
        target->x2 = source->x2;
    if (source->y1 < target->y1)
        target->y1 = source->y1;
    if (source->y2 > target->y2)
        target->y2 = source->y2;
}

static gboolean
djvu_text_page_selection_process_box (DjvuTextPage *page,
                      miniexp_t     p,
                      int           delimit)
{
    if (page->results || p == page->start) {
        EvRectangle box;

        box.x1 = miniexp_to_int (miniexp_nth (1, p));
        box.y1 = miniexp_to_int (miniexp_nth (2, p));
        box.x2 = miniexp_to_int (miniexp_nth (3, p));
        box.y2 = miniexp_to_int (miniexp_nth (4, p));

        if (!(delimit & 2) && page->results != NULL) {
            EvRectangle *union_box = (EvRectangle *)page->results->data;

                        /* If still on the same line, add box to union */
            djvu_text_page_union (union_box, &box);
        } else {
            /* A new line, a new box */
            page->results = g_list_prepend (page->results, ev_rectangle_copy (&box));
        }

        if (p == page->end)
            return FALSE;
    }
    return TRUE;
}

static gboolean
djvu_text_page_selection_process_text (DjvuTextPage *page,
                                       miniexp_t     p,
                                       int           delimit)
{
    if (page->text || p == page->start) {
        char *token_text = (char *) miniexp_to_str (miniexp_nth (5, p));
        if (page->text) {
            char *new_text =
                g_strjoin (delimit & 2 ? "\n" : 
                           delimit & 1 ? " " : NULL,
                       page->text, token_text,
                       NULL);
            g_free (page->text);
            page->text = new_text;
        } else
            page->text = g_strdup (token_text);
        if (p == page->end) 
            return FALSE;
    }
    return TRUE;
}

static gboolean
djvu_text_page_selection (DjvuSelectionType type,
              DjvuTextPage *page,
              miniexp_t     p,
              int           delimit)
{
        miniexp_t deeper;

    g_return_val_if_fail (miniexp_consp (p) && miniexp_symbolp
                  (miniexp_car (p)), FALSE);

    if (miniexp_car (p) != page->char_symbol) 
        delimit |= miniexp_car (p) == page->word_symbol ? 1 : 2;
        
    deeper = miniexp_cddr (miniexp_cdddr (p));
    while (deeper != miniexp_nil) {
        miniexp_t str = miniexp_car (deeper);
        if (miniexp_stringp (str)) {
            if (type == DJVU_SELECTION_TEXT) {
                if (!djvu_text_page_selection_process_text (page, p, delimit))
                    return FALSE;
            } else {
                if (!djvu_text_page_selection_process_box (page, p, delimit))
                    return FALSE;
            }
        } else {
            if (!djvu_text_page_selection (type, page, str, delimit))
                return FALSE;
        }
        delimit = 0;
        deeper = miniexp_cdr (deeper);
    }
    return TRUE;
}

static void
djvu_text_page_limits_process (DjvuTextPage *page,
                   miniexp_t     p, 
                   EvRectangle  *rect)
{
    EvRectangle current;
    
    current.x1 = miniexp_to_int (miniexp_nth (1, p));
    current.y1 = miniexp_to_int (miniexp_nth (2, p));
    current.x2 = miniexp_to_int (miniexp_nth (3, p));
    current.y2 = miniexp_to_int (miniexp_nth (4, p));
    if (current.x2 >= rect->x1 && current.y1 <= rect->y2 &&
        current.x1 <= rect->x2 && current.y2 >= rect->y1) {
            if (page->start == miniexp_nil)
                page->start = p;
            page->end = p;
    }
}


static void
djvu_text_page_limits (DjvuTextPage *page,
              miniexp_t     p, 
              EvRectangle  *rect)
{
        miniexp_t deeper;

    g_return_if_fail (miniexp_consp (p) && 
              miniexp_symbolp (miniexp_car (p)));

    deeper = miniexp_cddr (miniexp_cdddr (p));
    while (deeper != miniexp_nil) {
        miniexp_t str = miniexp_car (deeper);
        if (miniexp_stringp (str))
            djvu_text_page_limits_process (page, p, rect);
        else
            djvu_text_page_limits (page, str, rect);

        deeper = miniexp_cdr (deeper);
    }
}

GList *
djvu_text_page_get_selection_region (DjvuTextPage *page,
                                     EvRectangle  *rectangle)
{
    page->start = miniexp_nil;
    page->end = miniexp_nil;

    /* Get page->start and page->end filled from selection rectangle */
    djvu_text_page_limits (page, page->text_structure, rectangle);
    /* Fills page->results with the bouding boxes */
    djvu_text_page_selection (DJVU_SELECTION_BOX,
                              page, page->text_structure, 0);

    return g_list_reverse (page->results);
}

char *
djvu_text_page_copy (DjvuTextPage *page, 
             EvRectangle  *rectangle)
{
    char* text;
    
    page->start = miniexp_nil;
    page->end = miniexp_nil;
    djvu_text_page_limits (page, page->text_structure, rectangle);
    djvu_text_page_selection (DJVU_SELECTION_TEXT, page,
                              page->text_structure, 0);
    
    /* Do not free the string */      
    text = page->text;
    page->text = NULL;
    
    return text;
}

static miniexp_t
djvu_text_page_position (DjvuTextPage *page, 
             int           position)
{
    GArray *links = page->links;
    int low = 0;
    int hi = links->len - 1;
    int mid = 0;

    g_return_val_if_fail (hi >= 0, miniexp_nil);

    /* Shamelessly copied from GNU classpath */
    while (low <= hi) {
                DjvuTextLink *link;

        mid = (low + hi) >> 1;
        link = &g_array_index (links, DjvuTextLink, mid);
        if (link->position == position)
            break;
        else if (link->position > position)
            hi = --mid;
        else
            low = mid + 1;
    }

    return g_array_index (page->links, DjvuTextLink, mid).pair;
}

static gboolean
djvu_text_page_sexpr_process (DjvuTextPage *page, 
                              miniexp_t     p,
                              miniexp_t     start, 
                              miniexp_t     end)
{
    if (page->bounding_box || p == start) {
        EvRectangle *new_rectangle = ev_rectangle_new ();
        new_rectangle->x1 = miniexp_to_int (miniexp_nth (1, p));
        new_rectangle->y1 = miniexp_to_int (miniexp_nth (2, p));
        new_rectangle->x2 = miniexp_to_int (miniexp_nth (3, p));
        new_rectangle->y2 = miniexp_to_int (miniexp_nth (4, p));
        if (page->bounding_box) {
            djvu_text_page_union (page->bounding_box,
                          new_rectangle);
            g_free (new_rectangle);
        } else
            page->bounding_box = new_rectangle;
        if (p == end)
            return FALSE;
    }
    return TRUE;
}

static gboolean
djvu_text_page_sexpr (DjvuTextPage *page, 
              miniexp_t p,
              miniexp_t start, 
              miniexp_t end)
{
        miniexp_t deeper;

    g_return_val_if_fail (miniexp_consp (p) && miniexp_symbolp
                  (miniexp_car (p)), FALSE);

    deeper = miniexp_cddr (miniexp_cdddr (p));
    while (deeper != miniexp_nil) {
        miniexp_t str = miniexp_car (deeper);
        if (miniexp_stringp (str)) {
            if (!djvu_text_page_sexpr_process
                (page, p, start, end))
                return FALSE;
        } else {
            if (!djvu_text_page_sexpr
                (page, str, start, end))
                return FALSE;
        }
        deeper = miniexp_cdr (deeper);
    }
    return TRUE;
}

static EvRectangle *
djvu_text_page_box (DjvuTextPage *page,
            miniexp_t     start, 
            miniexp_t     end)
{
    page->bounding_box = NULL;
    djvu_text_page_sexpr (page, page->text_structure, start, end);
    return page->bounding_box;
}

static void
djvu_text_page_append_text (DjvuTextPage *page,
                miniexp_t     p, 
                gboolean      case_sensitive, 
                gboolean      delimit)
{
    char *token_text;
    miniexp_t deeper;
    
    g_return_if_fail (miniexp_consp (p) && 
              miniexp_symbolp (miniexp_car (p)));

    delimit |= page->char_symbol != miniexp_car (p);
    
    deeper = miniexp_cddr (miniexp_cdddr (p));
    while (deeper != miniexp_nil) {
        miniexp_t data = miniexp_car (deeper);
        if (miniexp_stringp (data)) {
            DjvuTextLink link;
            link.position = page->text == NULL ? 0 :
                strlen (page->text);
            link.pair = p;
            g_array_append_val (page->links, link);

            token_text = (char *) miniexp_to_str (data);
            if (!case_sensitive)
                token_text = g_utf8_casefold (token_text, -1);
            if (page->text == NULL)
                page->text = g_strdup (token_text);
            else {
                char *new_text =
                    g_strjoin (delimit ? " " : NULL,
                           page->text, token_text,
                           NULL);
                g_free (page->text);
                page->text = new_text;
            }
            if (!case_sensitive)
                g_free (token_text);
        } else
            djvu_text_page_append_text (page, data, 
                            case_sensitive, delimit);
        delimit = FALSE;
        deeper = miniexp_cdr (deeper);
    }
}

void 
djvu_text_page_search (DjvuTextPage *page, 
               const char   *text)
{
    char *haystack = page->text;
    int search_len;
    EvRectangle *result;
    if (page->links->len == 0)
        return;

    search_len = strlen (text);
    while ((haystack = strstr (haystack, text)) != NULL) {
        int start_p = haystack - page->text;
        miniexp_t start = djvu_text_page_position (page, start_p);
        int end_p = start_p + search_len - 1;
        miniexp_t end = djvu_text_page_position (page, end_p);
        result = djvu_text_page_box (page, start, end);
        g_assert (result);
        page->results = g_list_prepend (page->results, result);
        haystack = haystack + search_len;
    }
    page->results = g_list_reverse (page->results);
}


void
djvu_text_page_index_text (DjvuTextPage *page,
                       gboolean      case_sensitive)
{
    djvu_text_page_append_text (page, page->text_structure, 
                    case_sensitive, FALSE); 
}

DjvuTextPage *
djvu_text_page_new (miniexp_t text)
{
    DjvuTextPage *page;

    page = g_new0 (DjvuTextPage, 1);
    page->links = g_array_new (FALSE, FALSE, sizeof (DjvuTextLink));
    page->char_symbol = miniexp_symbol ("char");
    page->word_symbol = miniexp_symbol ("word");
    page->text_structure = text;
    return page;
}

void 
djvu_text_page_free (DjvuTextPage *page)
{
    g_free (page->text);
    g_array_free (page->links, TRUE);
    g_free (page);
}