evince/libview/ev-page-accessible.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8; c-indent-level: 8 -*- */
/* this file is part of evince, a gnome document viewer
 *
 * Copyright (C) 2014 Igalia S.L.
 *
 * Evince 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.
 *
 * Evince 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.
 *
 * Author: Alejandro Piñeiro Iglesias <apinheiro@igalia.com>
 */

#include <config.h>

#include <glib/gi18n-lib.h>
#include "ev-page-accessible.h"
#include "ev-form-field-accessible.h"
#include "ev-image-accessible.h"
#include "ev-link-accessible.h"
#include "ev-view-private.h"

struct _EvPageAccessiblePrivate {
        EvViewAccessible *view_accessible;
	gint              page;
	GHashTable       *links;
	GPtrArray        *children;
	gboolean          children_initialized;
};


enum {
	PROP_0,
	PROP_VIEW_ACCESSIBLE,
	PROP_PAGE,
};

static void ev_page_accessible_component_iface_init (AtkComponentIface *iface);
static void ev_page_accessible_hypertext_iface_init (AtkHypertextIface *iface);
static void ev_page_accessible_text_iface_init (AtkTextIface *iface);

G_DEFINE_TYPE_WITH_CODE (EvPageAccessible, ev_page_accessible, ATK_TYPE_OBJECT,
			 G_ADD_PRIVATE (EvPageAccessible)
			 G_IMPLEMENT_INTERFACE (ATK_TYPE_COMPONENT, ev_page_accessible_component_iface_init)
			 G_IMPLEMENT_INTERFACE (ATK_TYPE_HYPERTEXT, ev_page_accessible_hypertext_iface_init)
			 G_IMPLEMENT_INTERFACE (ATK_TYPE_TEXT, ev_page_accessible_text_iface_init))

gint
ev_page_accessible_get_page (EvPageAccessible *page_accessible)
{
	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (page_accessible), -1);

	return page_accessible->priv->page;
}

EvViewAccessible *
ev_page_accessible_get_view_accessible (EvPageAccessible *page_accessible)
{
	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (page_accessible), NULL);

	return page_accessible->priv->view_accessible;
}

static AtkObject *
ev_page_accessible_get_parent (AtkObject *obj)
{
	EvPageAccessible *self;

	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (obj), NULL);

	self = EV_PAGE_ACCESSIBLE (obj);

	return ATK_OBJECT (self->priv->view_accessible);
}

static gint
compare_mappings (EvMapping *a, EvMapping *b)
{
	gdouble dx, dy;

	/* Very rough heuristic for simple, non-tagged PDFs. */

	dy = a->area.y1 - b->area.y1;
	dx = a->area.x1 - b->area.x1;

	return ABS (dy) > 10 ? dy : dx;
}

static void
ev_page_accessible_initialize_children (EvPageAccessible *self)
{
	EvView *view;
	EvMappingList *images;
	EvMappingList *links;
	EvMappingList *fields;
	GList *children = NULL;
	GList *list;

	if (self->priv->children_initialized)
		return;

	view = ev_page_accessible_get_view (self);
	if (!ev_page_cache_is_page_cached (view->page_cache, self->priv->page))
		return;

	self->priv->children_initialized = TRUE;

	links = ev_page_cache_get_link_mapping (view->page_cache, self->priv->page);
	images = ev_page_cache_get_image_mapping (view->page_cache, self->priv->page);
	fields = ev_page_cache_get_form_field_mapping (view->page_cache, self->priv->page);
	if (!links && !images && !fields)
		return;

	children = g_list_copy (ev_mapping_list_get_list (links));
	children = g_list_concat (children, g_list_copy (ev_mapping_list_get_list (images)));
	children = g_list_concat (children, g_list_copy (ev_mapping_list_get_list (fields)));

	children = g_list_sort (children, (GCompareFunc) compare_mappings);
	self->priv->children = g_ptr_array_new_full (g_list_length (children), (GDestroyNotify) g_object_unref);

	for (list = children; list && list->data; list = list->next) {
		EvMapping *mapping = list->data;
		AtkObject *child = NULL;

		if (links && ev_mapping_list_find (links, mapping->data)) {
			EvLinkAccessible *link = ev_link_accessible_new (self, EV_LINK (mapping->data), &mapping->area);
			AtkHyperlink *atk_link = atk_hyperlink_impl_get_hyperlink (ATK_HYPERLINK_IMPL (link));

			child = atk_hyperlink_get_object (atk_link, 0);
		} else if (images && ev_mapping_list_find (images, mapping->data))
			child = ATK_OBJECT (ev_image_accessible_new (self, EV_IMAGE (mapping->data), &mapping->area));
		else if (fields && ev_mapping_list_find (fields, mapping->data))
			child = ATK_OBJECT (ev_form_field_accessible_new (self, EV_FORM_FIELD (mapping->data), &mapping->area));

		if (child)
			g_ptr_array_add (self->priv->children, child);
	}

	g_list_free (children);
}

static void
clear_children (EvPageAccessible *self)
{
	gint i;
	AtkObject *child;

	if (!self->priv->children)
		return;

	for (i = 0; i < self->priv->children->len; i++) {
		child = g_ptr_array_index (self->priv->children, i);
		atk_object_notify_state_change (child, ATK_STATE_DEFUNCT, TRUE);
	}

	g_clear_pointer (&self->priv->children, g_ptr_array_unref);
}

static void
ev_page_accessible_finalize (GObject *object)
{
	EvPageAccessiblePrivate *priv = EV_PAGE_ACCESSIBLE (object)->priv;

        g_clear_pointer (&priv->links, g_hash_table_destroy);
	clear_children (EV_PAGE_ACCESSIBLE (object));

	G_OBJECT_CLASS (ev_page_accessible_parent_class)->finalize (object);
}

static void
ev_page_accessible_set_property (GObject      *object,
				 guint         prop_id,
				 const GValue *value,
				 GParamSpec   *pspec)
{
	EvPageAccessible *accessible = EV_PAGE_ACCESSIBLE (object);

	switch (prop_id) {
	case PROP_VIEW_ACCESSIBLE:
		accessible->priv->view_accessible = EV_VIEW_ACCESSIBLE (g_value_get_object (value));
		break;
	case PROP_PAGE:
		accessible->priv->page = g_value_get_int (value);
		break;
	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	}
}

static void
ev_page_accessible_get_property (GObject    *object,
				 guint       prop_id,
				 GValue     *value,
				 GParamSpec *pspec)
{
	EvPageAccessible *accessible = EV_PAGE_ACCESSIBLE (object);

	switch (prop_id) {
	case PROP_VIEW_ACCESSIBLE:
		g_value_set_object (value, ev_page_accessible_get_view_accessible (accessible));
		break;
	case PROP_PAGE:
		g_value_set_int (value, ev_page_accessible_get_page (accessible));
		break;
	default:
		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
	}
}

/*
 * We redefine atk_class->ref_relation_set instead of just calling
 * atk_object_add_relationship on ev_page_accessible_new because at
 * that moment not all the pages could be created, being easier add
 * the relation on demand.
 */
static AtkRelationSet *
ev_page_accessible_ref_relation_set (AtkObject *accessible)
{
	gint n_pages;
	EvPageAccessible *self;
	AtkRelationSet *relation_set;
	AtkObject *accessible_array[1];
	AtkRelation *relation;

	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (accessible), NULL);
	self = EV_PAGE_ACCESSIBLE (accessible);

	relation_set = ATK_OBJECT_CLASS (ev_page_accessible_parent_class)->ref_relation_set (accessible);
	if (relation_set == NULL)
		return NULL;

	n_pages = ev_view_accessible_get_n_pages (self->priv->view_accessible);
	if (n_pages == 0)
		return relation_set;

	if ((self->priv->page + 1) < n_pages && !atk_relation_set_contains (relation_set, ATK_RELATION_FLOWS_TO)) {
		AtkObject *next_page;

		next_page = atk_object_ref_accessible_child (ATK_OBJECT (self->priv->view_accessible),
							     self->priv->page + 1);
		accessible_array [0] = next_page;
		relation = atk_relation_new (accessible_array, 1, ATK_RELATION_FLOWS_TO);
		atk_relation_set_add (relation_set, relation);

		g_object_unref (relation);
		g_object_unref (next_page);
	}

	if (self->priv->page > 0 && !atk_relation_set_contains (relation_set, ATK_RELATION_FLOWS_FROM)) {
		AtkObject *prev_page;

		prev_page = atk_object_ref_accessible_child (ATK_OBJECT (self->priv->view_accessible),
							     self->priv->page - 1);
		accessible_array [0] = prev_page;
		relation = atk_relation_new (accessible_array, 1, ATK_RELATION_FLOWS_FROM);
		atk_relation_set_add (relation_set, relation);

		g_object_unref (relation);
		g_object_unref (prev_page);
	}

	return relation_set;
}

/* page accessible's state set is a copy ev-view accessible's state
 * set but removing ATK_STATE_SHOWING if the page is not on screen and
 * ATK_STATE_FOCUSED if it is not the relevant page. */
static AtkStateSet *
ev_page_accessible_ref_state_set (AtkObject *accessible)
{
	AtkStateSet *state_set;
	AtkStateSet *copy_set;
	AtkStateSet *view_accessible_state_set;
	EvPageAccessible *self;
	EvView *view;
	gint relevant_page;

	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (accessible), NULL);
	self = EV_PAGE_ACCESSIBLE (accessible);
	view = ev_page_accessible_get_view (self);

	state_set = ATK_OBJECT_CLASS (ev_page_accessible_parent_class)->ref_state_set (accessible);
	atk_state_set_clear_states (state_set);

	view_accessible_state_set = atk_object_ref_state_set (ATK_OBJECT (self->priv->view_accessible));
	copy_set = atk_state_set_or_sets (state_set, view_accessible_state_set);

	if (self->priv->page >= view->start_page && self->priv->page <= view->end_page)
		atk_state_set_add_state (copy_set, ATK_STATE_SHOWING);
	else
		atk_state_set_remove_state (copy_set, ATK_STATE_SHOWING);

	relevant_page = ev_view_accessible_get_relevant_page (self->priv->view_accessible);
	if (atk_state_set_contains_state (view_accessible_state_set, ATK_STATE_FOCUSED) &&
	    self->priv->page == relevant_page)
		atk_state_set_add_state (copy_set, ATK_STATE_FOCUSED);
	else
		atk_state_set_remove_state (copy_set, ATK_STATE_FOCUSED);

	relevant_page = ev_view_accessible_get_relevant_page (self->priv->view_accessible);
	if (atk_state_set_contains_state (view_accessible_state_set, ATK_STATE_FOCUSED) &&
	    self->priv->page == relevant_page)
		atk_state_set_add_state (copy_set, ATK_STATE_FOCUSED);
	else
		atk_state_set_remove_state (copy_set, ATK_STATE_FOCUSED);

	g_object_unref (state_set);
	g_object_unref (view_accessible_state_set);

	return copy_set;
}

static gint
ev_page_accessible_get_n_children (AtkObject *accessible)
{
       EvPageAccessible *self;

       self = EV_PAGE_ACCESSIBLE (accessible);

       return self->priv->children == NULL ? 0 : self->priv->children->len;
}

static AtkObject *
ev_page_accessible_ref_child (AtkObject *accessible,
			      gint       i)
{
       EvPageAccessible *self;

       self = EV_PAGE_ACCESSIBLE (accessible);

       g_return_val_if_fail (i >= 0 || i < self->priv->children->len, NULL);

       return g_object_ref (g_ptr_array_index (self->priv->children, i));
}

static void
ev_page_accessible_class_init (EvPageAccessibleClass *klass)
{
	GObjectClass   *g_object_class = G_OBJECT_CLASS (klass);
	AtkObjectClass *atk_class = ATK_OBJECT_CLASS (klass);

	atk_class->get_parent  = ev_page_accessible_get_parent;
	atk_class->ref_relation_set = ev_page_accessible_ref_relation_set;
	atk_class->ref_state_set = ev_page_accessible_ref_state_set;
	atk_class->get_n_children = ev_page_accessible_get_n_children;
	atk_class->ref_child = ev_page_accessible_ref_child;

	g_object_class->get_property = ev_page_accessible_get_property;
	g_object_class->set_property = ev_page_accessible_set_property;
        g_object_class->finalize = ev_page_accessible_finalize;

	g_object_class_install_property (g_object_class,
					 PROP_VIEW_ACCESSIBLE,
					 g_param_spec_object ("view-accessible",
							      "View Accessible",
							      "The view accessible associated to this page",
							      EV_TYPE_VIEW_ACCESSIBLE,
							      G_PARAM_READWRITE |
							      G_PARAM_CONSTRUCT_ONLY |
                                                              G_PARAM_STATIC_STRINGS));
	g_object_class_install_property (g_object_class,
					 PROP_PAGE,
					 g_param_spec_int ("page",
							   "Page",
							   "Page index this page represents",
							   -1, G_MAXINT, -1,
							   G_PARAM_READWRITE |
							   G_PARAM_CONSTRUCT_ONLY |
                                                           G_PARAM_STATIC_STRINGS));

}

EvView *
ev_page_accessible_get_view (EvPageAccessible *page_accessible)
{
	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (page_accessible), NULL);

	return EV_VIEW (gtk_accessible_get_widget (GTK_ACCESSIBLE (page_accessible->priv->view_accessible)));
}

/* ATs expect to be able to identify sentence boundaries based on content. Valid,
 * content-based boundaries may be present at the end of a newline, for instance
 * at the end of a heading within a document. Thus being able to distinguish hard
 * returns from soft returns is necessary. However, the text we get from Poppler
 * for non-tagged PDFs has "\n" inserted at the end of each line resulting in a
 * broken accessibility implementation w.r.t. sentences.
 */
static gboolean
treat_as_soft_return (EvView       *view,
		      gint          page,
		      PangoLogAttr *log_attrs,
		      gint          offset)
{
	EvRectangle *areas = NULL;
	guint n_areas = 0;
	gdouble line_spacing, this_line_height, next_word_width;
	EvRectangle *this_line_start;
	EvRectangle *this_line_end;
	EvRectangle *next_line_start;
	EvRectangle *next_line_end;
	EvRectangle *next_word_end;
	gint prev_offset, next_offset;


	if (!log_attrs[offset].is_white)
		return FALSE;

	ev_page_cache_get_text_layout (view->page_cache, page, &areas, &n_areas);
	if (n_areas <= offset + 1)
		return FALSE;

	prev_offset = offset - 1;
	next_offset = offset + 1;

	/* In wrapped text, the character at the start of the next line starts a word.
	 * Examples where this condition might fail include bullets and images. But it
	 * also includes things like "(", so also check the next character.
	 */
	if (!log_attrs[next_offset].is_word_start &&
	    (next_offset + 1 >= n_areas || !log_attrs[next_offset + 1].is_word_start))
		return FALSE;

	/* In wrapped text, the chars on either side of the newline have very similar heights.
	 * Examples where this condition might fail include a newline at the end of a heading,
	 * and a newline at the end of a paragraph that is followed by a heading.
	 */
	this_line_end = areas + prev_offset;
	next_line_start = areas + next_offset;;

	this_line_height = this_line_end->y2 - this_line_end->y1;
	if (ABS (this_line_height - (next_line_start->y2 - next_line_start->y1)) > 0.25)
		return FALSE;

	/* If there is significant white space between this line and the next, odds are this
	 * is not a soft return in wrapped text. Lines within a typical paragraph are at most
	 * double-spaced. If the spacing is more than that, assume a hard return is present.
	 */
	line_spacing = next_line_start->y1 - this_line_end->y2;
	if (line_spacing - this_line_height > 1)
		return FALSE;

	/* Lines within a typical paragraph have *reasonably* similar x1 coordinates. But
	 * we cannot count on them being nearly identical. Examples where indentation can
	 * be present in wrapped text include indenting the first line of the paragraph,
	 * and hanging indents (e.g. in the works cited within an academic paper). So we'll
	 * be somewhat tolerant here.
	 */
	for ( ; prev_offset > 0 && !log_attrs[prev_offset].is_mandatory_break; prev_offset--);
	this_line_start = areas + prev_offset;
	if (ABS (this_line_start->x1 - next_line_start->x1) > 20)
		return FALSE;

	/* Ditto for x2, but this line might be short due to a wide word on the next line. */
	for ( ; next_offset < n_areas && !log_attrs[next_offset].is_word_end; next_offset++);
	next_word_end = areas + next_offset;
	next_word_width = next_word_end->x2 - next_line_start->x1;

	for ( ; next_offset < n_areas && !log_attrs[next_offset + 1].is_mandatory_break; next_offset++);
	next_line_end = areas + next_offset;
	if (next_line_end->x2 - (this_line_end->x2 + next_word_width) > 20)
		return FALSE;

	return TRUE;
}

static gchar *
ev_page_accessible_get_substring (AtkText *text,
				  gint     start_offset,
				  gint     end_offset)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	gchar *substring, *normalized;
	const gchar* page_text;

	if (!view->page_cache)
		return NULL;

	page_text = ev_page_cache_get_text (view->page_cache, self->priv->page);
	if (end_offset < 0 || end_offset > g_utf8_strlen (page_text, -1))
		end_offset = strlen (page_text);
	start_offset = CLAMP (start_offset, 0, end_offset);

	substring = g_utf8_substring (page_text, start_offset, end_offset);
	normalized = g_utf8_normalize (substring, -1, G_NORMALIZE_NFKC);
	g_free (substring);

	return normalized;
}

static gchar *
ev_page_accessible_get_text (AtkText *text,
			     gint     start_pos,
			     gint     end_pos)
{
	return ev_page_accessible_get_substring (text, start_pos, end_pos);
}

static gunichar
ev_page_accessible_get_character_at_offset (AtkText *text,
					    gint     offset)
{
	gchar *string;
	gunichar unichar;

	string = ev_page_accessible_get_substring (text, offset, offset + 1);
	unichar = g_utf8_get_char (string);
	g_free(string);

	return unichar;
}

static void
ev_page_accessible_get_range_for_boundary (AtkText          *text,
					   AtkTextBoundary   boundary_type,
					   gint              offset,
					   gint             *start_offset,
					   gint             *end_offset)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	gint start = 0;
	gint end = 0;
	PangoLogAttr *log_attrs = NULL;
	gulong n_attrs;

	if (!view->page_cache)
		return;

	ev_page_cache_get_text_log_attrs (view->page_cache, self->priv->page, &log_attrs, &n_attrs);
	if (!log_attrs)
		return;

	if (offset < 0 || offset >= n_attrs)
		return;

	switch (boundary_type) {
	case ATK_TEXT_BOUNDARY_CHAR:
		start = offset;
		end = offset + 1;
		break;
	case ATK_TEXT_BOUNDARY_WORD_START:
		for (start = offset; start > 0 && !log_attrs[start].is_word_start; start--);
		for (end = offset + 1; end < n_attrs && !log_attrs[end].is_word_start; end++);
		break;
	case ATK_TEXT_BOUNDARY_SENTENCE_START:
		for (start = offset; start > 0; start--) {
			if (log_attrs[start].is_mandatory_break && treat_as_soft_return (view, self->priv->page, log_attrs, start - 1))
				continue;
			if (log_attrs[start].is_sentence_start)
				break;
		}
		for (end = offset + 1; end < n_attrs; end++) {
			if (log_attrs[end].is_mandatory_break && treat_as_soft_return (view, self->priv->page, log_attrs, end - 1))
				continue;
			if (log_attrs[end].is_sentence_start)
				break;
		}
		break;
	case ATK_TEXT_BOUNDARY_LINE_START:
		for (start = offset; start > 0 && !log_attrs[start].is_mandatory_break; start--);
		for (end = offset + 1; end < n_attrs && !log_attrs[end].is_mandatory_break; end++);
		break;
	default:
		/* The "END" boundary types are deprecated */
		break;
	}

	*start_offset = start;
	*end_offset = end;
}

static gchar *
ev_page_accessible_get_text_at_offset (AtkText        *text,
                                       gint            offset,
                                       AtkTextBoundary boundary_type,
                                       gint           *start_offset,
                                       gint           *end_offset)
{
	gchar *retval;

	ev_page_accessible_get_range_for_boundary (text, boundary_type, offset, start_offset, end_offset);
	retval = ev_page_accessible_get_substring (text, *start_offset, *end_offset);

	/* If newlines appear inside the text of a sentence (i.e. between the start and
	 * end offsets returned by ev_page_accessible_get_substring), it interferes with
	 * the prosody of text-to-speech based-solutions such as a screen reader because
	 * speech synthesizers tend to pause after the newline char as if it were the end
	 * of the sentence.
	 */
        if (boundary_type == ATK_TEXT_BOUNDARY_SENTENCE_START)
		g_strdelimit (retval, "\n", ' ');

	return retval;
}

static gint
ev_page_accessible_get_caret_offset (AtkText *text)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);

	if (self->priv->page == view->cursor_page && view->caret_enabled)
		return view->cursor_offset;

	return -1;
}

static gboolean
ev_page_accessible_set_caret_offset (AtkText *text, gint offset)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);

	ev_view_set_caret_cursor_position (view,
					   self->priv->page,
					   offset);

	return TRUE;
}

static gint
ev_page_accessible_get_character_count (AtkText *text)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	gint retval;

	retval = g_utf8_strlen (ev_page_cache_get_text (view->page_cache, self->priv->page), -1);

	return retval;
}

static gboolean
get_selection_bounds (EvView          *view,
		      EvViewSelection *selection,
		      gint            *start_offset,
		      gint            *end_offset)
{
	cairo_rectangle_int_t rect;
	gint start, end;

	if (!selection->covered_region || cairo_region_is_empty (selection->covered_region))
		return FALSE;

	cairo_region_get_rectangle (selection->covered_region, 0, &rect);
	start = _ev_view_get_caret_cursor_offset_at_doc_point (view,
							       selection->page,
							       rect.x / view->scale,
							       (rect.y + (rect.height / 2)) / view->scale);
	if (start == -1)
		return FALSE;

	cairo_region_get_rectangle (selection->covered_region,
				    cairo_region_num_rectangles (selection->covered_region) - 1,
				    &rect);
	end = _ev_view_get_caret_cursor_offset_at_doc_point (view,
							     selection->page,
							     (rect.x + rect.width) / view->scale,
							     (rect.y + (rect.height / 2)) / view->scale);
	if (end == -1)
		return FALSE;

	*start_offset = start;
	*end_offset = end;

	return TRUE;
}

static gint
ev_page_accessible_get_n_selections (AtkText *text)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	gint n_selections = 0;
	GList *l;

	if (!EV_IS_SELECTION (view->document) || !view->selection_info.selections)
		return 0;

	for (l = view->selection_info.selections; l != NULL; l = l->next) {
		EvViewSelection *selection = (EvViewSelection *)l->data;

		if (selection->page != self->priv->page)
			continue;

		n_selections = 1;
		break;
	}

	return n_selections;
}

static gchar *
ev_page_accessible_get_selection (AtkText *text,
				  gint     selection_num,
				  gint    *start_pos,
				  gint    *end_pos)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	gchar *selected_text = NULL;
	gchar *normalized_text = NULL;
	GList *l;

	*start_pos = -1;
	*end_pos = -1;

	if (selection_num != 0)
		return NULL;

	if (!EV_IS_SELECTION (view->document) || !view->selection_info.selections)
		return NULL;

	for (l = view->selection_info.selections; l != NULL; l = l->next) {
		EvViewSelection *selection = (EvViewSelection *)l->data;
		gint start = 0, end = 0;

		if (selection->page != self->priv->page)
			continue;

		if (get_selection_bounds (view, selection, &start, &end) && start != end) {
			EvPage *page;

			page = ev_document_get_page (view->document, selection->page);

			ev_document_doc_mutex_lock ();
			selected_text = ev_selection_get_selected_text (EV_SELECTION (view->document),
									page,
									selection->style,
									&(selection->rect));

			ev_document_doc_mutex_unlock ();

			g_object_unref (page);

			*start_pos = start;
			*end_pos = end;
		}

		break;
	}

	if (selected_text) {
		normalized_text = g_utf8_normalize (selected_text, -1, G_NORMALIZE_NFKC);
		g_free (selected_text);
	}

	return normalized_text;
}

static AtkAttributeSet *
add_attribute (AtkAttributeSet  *attr_set,
               AtkTextAttribute  attr_type,
               gchar            *attr_value)
{
  AtkAttribute *attr = g_new (AtkAttribute, 1);

  attr->name = g_strdup (atk_text_attribute_get_name (attr_type));
  attr->value = attr_value;

  return g_slist_prepend (attr_set, attr);
}

static AtkAttributeSet *
get_run_attributes (PangoAttrList   *attrs,
		    const gchar     *text,
		    gint             offset,
		    gint            *start_offset,
		    gint            *end_offset)
{
	AtkAttributeSet   *atk_attr_set = NULL;
	PangoAttrString   *pango_string;
	PangoAttrInt      *pango_int;
	PangoAttrColor    *pango_color;
	PangoAttrIterator *iter;
	gint               i, start, end;
	gboolean           has_attrs = FALSE;
	glong              text_length;
	gchar             *attr_value;

	text_length = g_utf8_strlen (text, -1);
	if (offset < 0 || offset >= text_length)
		return NULL;

	/* Check if there are attributes for the offset,
	 * and set the attributes range if positive */
	iter = pango_attr_list_get_iterator (attrs);
	i = g_utf8_offset_to_pointer (text, offset) - text;

	do {
		pango_attr_iterator_range (iter, &start, &end);
		if (i >= start && i < end) {
			*start_offset = g_utf8_pointer_to_offset (text, text + start);
			if (end == G_MAXINT) /* Last iterator */
				end = text_length;
			*end_offset = g_utf8_pointer_to_offset (text, text + end);
			 has_attrs = TRUE;
		}
	} while (!has_attrs && pango_attr_iterator_next (iter));

	if (!has_attrs) {
		pango_attr_iterator_destroy (iter);
		return NULL;
	}

	/* Create the AtkAttributeSet from the Pango attributes */
	pango_string = (PangoAttrString *) pango_attr_iterator_get (iter, PANGO_ATTR_FAMILY);
	if (pango_string) {
		attr_value = g_strdup (pango_string->value);
		atk_attr_set = add_attribute (atk_attr_set, ATK_TEXT_ATTR_FAMILY_NAME, attr_value);
	}

	pango_int = (PangoAttrInt *) pango_attr_iterator_get (iter, PANGO_ATTR_SIZE);
	if (pango_int) {
		attr_value = g_strdup_printf ("%i", pango_int->value / PANGO_SCALE);
		atk_attr_set = add_attribute (atk_attr_set, ATK_TEXT_ATTR_SIZE, attr_value);
	}

	pango_int = (PangoAttrInt *) pango_attr_iterator_get (iter, PANGO_ATTR_UNDERLINE);
	if (pango_int) {
		atk_attr_set = add_attribute (atk_attr_set,
					      ATK_TEXT_ATTR_UNDERLINE,
					      g_strdup (atk_text_attribute_get_value (ATK_TEXT_ATTR_UNDERLINE,
										      pango_int->value)));
	}

	pango_color = (PangoAttrColor *) pango_attr_iterator_get (iter, PANGO_ATTR_FOREGROUND);
	if (pango_color) {
		attr_value = g_strdup_printf ("%u,%u,%u",
					      pango_color->color.red,
					      pango_color->color.green,
					      pango_color->color.blue);
		atk_attr_set = add_attribute (atk_attr_set, ATK_TEXT_ATTR_FG_COLOR, attr_value);
	}

	pango_attr_iterator_destroy (iter);

	return atk_attr_set;
}

static AtkAttributeSet*
ev_page_accessible_get_run_attributes (AtkText *text,
				       gint     offset,
				       gint    *start_offset,
				       gint    *end_offset)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	PangoAttrList *attrs;
	const gchar   *page_text;

	if (offset < 0)
		return NULL;

	if (!view->page_cache)
		return NULL;

	page_text = ev_page_cache_get_text (view->page_cache, self->priv->page);
	if (!page_text)
		return NULL;

	attrs = ev_page_cache_get_text_attrs (view->page_cache, self->priv->page);
	if (!attrs)
		return NULL;

	return get_run_attributes (attrs, page_text, offset, start_offset, end_offset);
}

static AtkAttributeSet*
ev_page_accessible_get_default_attributes (AtkText *text)
{
	/* No default attributes */
	return NULL;
}

static void
ev_page_accessible_get_character_extents (AtkText      *text,
					  gint         offset,
					  gint         *x,
					  gint         *y,
					  gint         *width,
					  gint         *height,
					  AtkCoordType coords)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	GtkWidget *toplevel;
	EvRectangle *areas = NULL;
	EvRectangle *doc_rect;
	guint n_areas = 0;
	gint x_widget, y_widget;
	GdkRectangle view_rect;

	if (!view->page_cache)
		return;

	ev_page_cache_get_text_layout (view->page_cache, self->priv->page, &areas, &n_areas);
	if (!areas || offset >= n_areas)
		return;

	doc_rect = areas + offset;
	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, doc_rect, &view_rect);
	view_rect.x -= view->scroll_x;
	view_rect.y -= view->scroll_y;

	toplevel = gtk_widget_get_toplevel (GTK_WIDGET (view));
	gtk_widget_translate_coordinates (GTK_WIDGET (view), toplevel, 0, 0, &x_widget, &y_widget);
	view_rect.x += x_widget;
	view_rect.y += y_widget;

	if (coords == ATK_XY_SCREEN) {
		gint x_window, y_window;

		gdk_window_get_origin (gtk_widget_get_window (toplevel), &x_window, &y_window);
		view_rect.x += x_window;
		view_rect.y += y_window;
	}

	*x = view_rect.x;
	*y = view_rect.y;
	*width = view_rect.width;
	*height = view_rect.height;
}

static gint
ev_page_accessible_get_offset_at_point (AtkText      *text,
					gint         x,
					gint         y,
					AtkCoordType coords)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	GtkWidget *toplevel;
	EvRectangle *areas = NULL;
	EvRectangle *rect = NULL;
	guint n_areas = 0;
	guint i;
	gint x_widget, y_widget;
	gint offset=-1;
	GdkPoint view_point;
	gdouble doc_x, doc_y;
	GtkBorder border;
	GdkRectangle page_area;

	if (!view->page_cache)
		return -1;

	ev_page_cache_get_text_layout (view->page_cache, self->priv->page, &areas, &n_areas);
	if (!areas)
		return -1;

	view_point.x = x;
	view_point.y = y;
	toplevel = gtk_widget_get_toplevel (GTK_WIDGET (view));
	gtk_widget_translate_coordinates (GTK_WIDGET (view), toplevel, 0, 0, &x_widget, &y_widget);
	view_point.x -= x_widget;
	view_point.y -= y_widget;

	if (coords == ATK_XY_SCREEN) {
		gint x_window, y_window;

		gdk_window_get_origin (gtk_widget_get_window (toplevel), &x_window, &y_window);
		view_point.x -= x_window;
		view_point.y -= y_window;
	}

	ev_view_get_page_extents (view, self->priv->page, &page_area, &border);
	_ev_view_transform_view_point_to_doc_point (view, &view_point, &page_area, &border, &doc_x, &doc_y);

	for (i = 0; i < n_areas; i++) {
		rect = areas + i;
		if (doc_x >= rect->x1 && doc_x <= rect->x2 &&
		    doc_y >= rect->y1 && doc_y <= rect->y2)
			offset = i;
	}

	return offset;
}

/* ATK allows for multiple, non-contiguous selections within a single AtkText
 * object. Unless and until Evince supports this, selection numbers are ignored.
 */
static gboolean
ev_page_accessible_remove_selection (AtkText *text,
				     gint     selection_num)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);

	if (ev_view_get_has_selection (view)) {
		_ev_view_clear_selection (view);
		return TRUE;
	}

	return FALSE;
}

static gboolean
ev_page_accessible_set_selection (AtkText *text,
				  gint	   selection_num,
				  gint     start_pos,
				  gint     end_pos)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	EvRectangle *areas = NULL;
	guint n_areas = 0;
	GdkRectangle start_rect, end_rect;
	GdkPoint start_point, end_point;

	ev_page_cache_get_text_layout (view->page_cache, self->priv->page, &areas, &n_areas);
	if (start_pos < 0 || end_pos >= n_areas)
		return FALSE;

	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, areas + start_pos, &start_rect);
	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, areas + end_pos - 1, &end_rect);
	start_point.x = start_rect.x;
	start_point.y = start_rect.y;
	end_point.x = end_rect.x + end_rect.width;
	end_point.y = end_rect.y + end_rect.height;
	_ev_view_set_selection (view, &start_point, &end_point);

	return TRUE;
}

static gboolean
ev_page_accessible_add_selection (AtkText *text,
				  gint     start_pos,
				  gint     end_pos)
{
	return ev_page_accessible_set_selection (text, 0, start_pos, end_pos);

}

#if ATK_CHECK_VERSION (2, 32, 0)
static gboolean
ev_page_accessible_scroll_substring_to (AtkText       *text,
					gint           start_pos,
					gint           end_pos,
					AtkScrollType  type)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	GdkRectangle start_rect, end_rect;
	GdkPoint start_point, end_point;
	gdouble hpage_size, vpage_size;
	EvRectangle *areas = NULL;
	guint n_areas = 0;

	if (end_pos < start_pos)
		return FALSE;

	ev_page_cache_get_text_layout (view->page_cache, self->priv->page, &areas, &n_areas);
	if (start_pos < 0 || end_pos >= n_areas)
		return FALSE;

	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, areas + start_pos, &start_rect);
	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, areas + end_pos - 1, &end_rect);
	start_point.x = start_rect.x;
	start_point.y = start_rect.y;
	end_point.x = end_rect.x + end_rect.width;
	end_point.y = end_rect.y + end_rect.height;

	hpage_size = gtk_adjustment_get_page_size (view->hadjustment);
	vpage_size = gtk_adjustment_get_page_size (view->vadjustment);

	switch (type) {
	case ATK_SCROLL_TOP_LEFT:
		gtk_adjustment_clamp_page (view->hadjustment, start_point.x, start_point.x + hpage_size);
		gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);
		break;
	case ATK_SCROLL_BOTTOM_RIGHT:
		gtk_adjustment_clamp_page (view->hadjustment, end_point.x - hpage_size, end_point.x);
		gtk_adjustment_clamp_page (view->vadjustment, end_point.y - vpage_size, end_point.y);
		break;
	case ATK_SCROLL_TOP_EDGE:
		gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);
		break;
	case ATK_SCROLL_BOTTOM_EDGE:
		gtk_adjustment_clamp_page (view->vadjustment, end_point.y - vpage_size, end_point.y);
		break;
	case ATK_SCROLL_LEFT_EDGE:
		gtk_adjustment_clamp_page (view->hadjustment, start_point.x, start_point.x + hpage_size);
		break;
	case ATK_SCROLL_RIGHT_EDGE:
		gtk_adjustment_clamp_page (view->hadjustment, end_point.x - hpage_size, end_point.x);
		break;
	case ATK_SCROLL_ANYWHERE:
		_ev_view_ensure_rectangle_is_visible (view, &end_rect);
		_ev_view_ensure_rectangle_is_visible (view, &start_rect);
		break;
	default:
		return FALSE;
	}

	return TRUE;
}

static gboolean
ev_page_accessible_scroll_substring_to_point (AtkText      *text,
					      gint          start_pos,
					      gint          end_pos,
                                              AtkCoordType  coords,
                                              gint          x,
                                              gint          y)
{
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (text);
	EvView *view = ev_page_accessible_get_view (self);
	GdkRectangle start_rect;
	GdkPoint view_point, start_point;
	gdouble hpage_size, vpage_size;
	EvRectangle *areas = NULL;
	guint n_areas = 0;
	GtkWidget *toplevel;
	gint x_widget, y_widget;
	GtkBorder border;
	GdkRectangle page_area;
	gdouble doc_x, doc_y;

	if (end_pos < start_pos)
		return FALSE;

	ev_page_cache_get_text_layout (view->page_cache, self->priv->page, &areas, &n_areas);
	if (start_pos < 0 || end_pos >= n_areas)
		return FALSE;

	/* Assume that the API wants to place the top left of the substring at (x, y). */
	_ev_view_transform_doc_rect_to_view_rect (view, self->priv->page, areas + start_pos, &start_rect);
	start_point.x = start_rect.x;
	start_point.y = start_rect.y;

	hpage_size = gtk_adjustment_get_page_size (view->hadjustment);
	vpage_size = gtk_adjustment_get_page_size (view->vadjustment);

	view_point.x = x;
	view_point.y = y;
	toplevel = gtk_widget_get_toplevel (GTK_WIDGET (view));
	gtk_widget_translate_coordinates (GTK_WIDGET (view), toplevel, 0, 0, &x_widget, &y_widget);
	view_point.x -= x_widget;
	view_point.y -= y_widget;

	if (coords == ATK_XY_SCREEN) {
		gint x_window, y_window;

		gdk_window_get_origin (gtk_widget_get_window (toplevel), &x_window, &y_window);
		view_point.x -= x_window;
		view_point.y -= y_window;
	}

	ev_view_get_page_extents (view, self->priv->page, &page_area, &border);
	_ev_view_transform_view_point_to_doc_point (view, &view_point, &page_area, &border, &doc_x, &doc_y);

	/* Calculate scrolling difference */
	start_point.x -= doc_x;
	start_point.y -= doc_y;

	gtk_adjustment_clamp_page (view->hadjustment, start_point.x, start_point.x + hpage_size);
	gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);

	return TRUE;
}
#endif

static void
ev_page_accessible_init (EvPageAccessible *page)
{
	atk_object_set_role (ATK_OBJECT (page), ATK_ROLE_PAGE);

        page->priv = ev_page_accessible_get_instance_private (page);
}

static void
ev_page_accessible_text_iface_init (AtkTextIface *iface)
{
	iface->get_text = ev_page_accessible_get_text;
	iface->get_text_at_offset = ev_page_accessible_get_text_at_offset;
	iface->get_character_at_offset = ev_page_accessible_get_character_at_offset;
	iface->get_caret_offset = ev_page_accessible_get_caret_offset;
	iface->set_caret_offset = ev_page_accessible_set_caret_offset;
	iface->get_character_count = ev_page_accessible_get_character_count;
	iface->get_n_selections = ev_page_accessible_get_n_selections;
	iface->get_selection = ev_page_accessible_get_selection;
	iface->remove_selection = ev_page_accessible_remove_selection;
	iface->add_selection = ev_page_accessible_add_selection;
	iface->get_run_attributes = ev_page_accessible_get_run_attributes;
	iface->get_default_attributes = ev_page_accessible_get_default_attributes;
	iface->get_character_extents = ev_page_accessible_get_character_extents;
	iface->get_offset_at_point = ev_page_accessible_get_offset_at_point;
#if ATK_CHECK_VERSION (2, 32, 0)
	iface->scroll_substring_to = ev_page_accessible_scroll_substring_to;
	iface->scroll_substring_to_point = ev_page_accessible_scroll_substring_to_point;
#endif
}

static GHashTable *
ev_page_accessible_get_links (EvPageAccessible *accessible)
{
	EvPageAccessiblePrivate* priv = accessible->priv;

	if (priv->links)
		return priv->links;

	priv->links = g_hash_table_new_full (g_direct_hash,
					     g_direct_equal,
					     NULL,
					     (GDestroyNotify)g_object_unref);
	return priv->links;
}

static AtkHyperlink *
ev_page_accessible_get_link (AtkHypertext *hypertext,
			     gint          link_index)
{
	GHashTable       *links;
	EvMappingList    *link_mapping;
	gint              n_links;
	EvMapping        *mapping;
	EvLinkAccessible *atk_link;
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (hypertext);
	EvView *view = ev_page_accessible_get_view (self);

	if (link_index < 0)
		return NULL;

	if (!EV_IS_DOCUMENT_LINKS (view->document))
		return NULL;

	links = ev_page_accessible_get_links (EV_PAGE_ACCESSIBLE (hypertext));

	atk_link = g_hash_table_lookup (links, GINT_TO_POINTER (link_index));
	if (atk_link)
		return atk_hyperlink_impl_get_hyperlink (ATK_HYPERLINK_IMPL (atk_link));

	link_mapping = ev_page_cache_get_link_mapping (view->page_cache, self->priv->page);
	if (!link_mapping)
		return NULL;

	n_links = ev_mapping_list_length (link_mapping);
	if (link_index > n_links - 1)
		return NULL;

	mapping = ev_mapping_list_nth (link_mapping, n_links - link_index - 1);
	atk_link = ev_link_accessible_new (EV_PAGE_ACCESSIBLE (hypertext),
					   EV_LINK (mapping->data),
					   &mapping->area);
	g_hash_table_insert (links, GINT_TO_POINTER (link_index), atk_link);

	return atk_hyperlink_impl_get_hyperlink (ATK_HYPERLINK_IMPL (atk_link));
}

static gint
ev_page_accessible_get_n_links (AtkHypertext *hypertext)
{
	EvMappingList *link_mapping;
	EvPageAccessible *self = EV_PAGE_ACCESSIBLE (hypertext);
	EvView *view = ev_page_accessible_get_view (self);

	if (!EV_IS_DOCUMENT_LINKS (view->document))
		return 0;

	link_mapping = ev_page_cache_get_link_mapping (view->page_cache,
						       self->priv->page);

	return link_mapping ? ev_mapping_list_length (link_mapping) : 0;
}

static gint
ev_page_accessible_get_link_index (AtkHypertext *hypertext,
				   gint          offset)
{
	guint i;
	gint n_links = ev_page_accessible_get_n_links (hypertext);

	for (i = 0; i < n_links; i++) {
		AtkHyperlink *hyperlink;
		gint          start_index, end_index;

		hyperlink = ev_page_accessible_get_link (hypertext, i);
		start_index = atk_hyperlink_get_start_index (hyperlink);
		end_index = atk_hyperlink_get_end_index (hyperlink);

		if (start_index <= offset && end_index >= offset)
			return i;
	}

	return -1;
}

static void
ev_page_accessible_hypertext_iface_init (AtkHypertextIface *iface)
{
	iface->get_link = ev_page_accessible_get_link;
	iface->get_n_links = ev_page_accessible_get_n_links;
	iface->get_link_index = ev_page_accessible_get_link_index;
}

static void
ev_page_accessible_get_extents (AtkComponent *atk_component,
				gint         *x,
				gint         *y,
				gint         *width,
				gint         *height,
				AtkCoordType coord_type)
{
	EvPageAccessible *self;
	EvView *view;
	GdkRectangle page_area;
	GtkBorder border;
	EvRectangle doc_rect, atk_rect;

	self = EV_PAGE_ACCESSIBLE (atk_component);
	view = ev_page_accessible_get_view (self);
	ev_view_get_page_extents (view, self->priv->page, &page_area, &border);

	doc_rect.x1 = page_area.x;
	doc_rect.y1 = page_area.y;
	doc_rect.x2 = page_area.x + page_area.width;
	doc_rect.y2 = page_area.y + page_area.height;
	_transform_doc_rect_to_atk_rect (self->priv->view_accessible, self->priv->page, &doc_rect, &atk_rect, coord_type);

	*x = atk_rect.x1;
	*y = atk_rect.y1;
	*width = atk_rect.x2 - atk_rect.x1;
	*height = atk_rect.y2 - atk_rect.y1;
}

static void
ev_page_accessible_component_iface_init (AtkComponentIface *iface)
{
        iface->get_extents = ev_page_accessible_get_extents;
}

static void
page_cached_cb (EvPageCache *cache,
		gint page,
		EvPageAccessible *self)
{
	if (page == self->priv->page)
		ev_page_accessible_initialize_children (self);
}

EvPageAccessible *
ev_page_accessible_new (EvViewAccessible *view_accessible,
                        gint              page)
{
        EvPageAccessible *atk_page;
	EvView *view;

	g_return_val_if_fail (EV_IS_VIEW_ACCESSIBLE (view_accessible), NULL);
	g_return_val_if_fail (page >= 0, NULL);

        atk_page = g_object_new (EV_TYPE_PAGE_ACCESSIBLE,
				 "view-accessible", view_accessible,
				 "page", page,
				 NULL);

	view = ev_page_accessible_get_view (EV_PAGE_ACCESSIBLE (atk_page));
	if (ev_page_cache_is_page_cached (view->page_cache, page))
		ev_page_accessible_initialize_children (EV_PAGE_ACCESSIBLE (atk_page));
	else
		g_signal_connect (view->page_cache, "page-cached",
				  G_CALLBACK (page_cached_cb),
				  atk_page);

        return EV_PAGE_ACCESSIBLE (atk_page);
}

AtkObject *
ev_page_accessible_get_accessible_for_mapping (EvPageAccessible *page_accessible,
					       EvMapping        *mapping)
{
	gint i;

	ev_page_accessible_initialize_children (page_accessible);
	if (!mapping || !page_accessible->priv->children)
		return NULL;

	for (i = 0; i < page_accessible->priv->children->len; i++) {
		AtkObject *child;

		child = g_ptr_array_index (page_accessible->priv->children, i);
		if (EV_IS_FORM_FIELD_ACCESSIBLE (child) &&
		    ev_form_field_accessible_get_field (EV_FORM_FIELD_ACCESSIBLE (child)) == mapping->data)
			return child;
	}

	return NULL;
}

void
ev_page_accessible_update_element_state (EvPageAccessible *page_accessible,
					 EvMapping        *mapping)
{
	AtkObject *child;

	child = ev_page_accessible_get_accessible_for_mapping (page_accessible, mapping);
	if (!child)
		return;

	if (EV_IS_FORM_FIELD_ACCESSIBLE (child))
		ev_form_field_accessible_update_state (EV_FORM_FIELD_ACCESSIBLE (child));
}