[evince] Implement ATK's scrollSubstringTo() and scrollSubstringToPoint().

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 61ad97f7962ae9bf4cbd4a31f3d940e3d3fb7cd5
Author: Martin Pieuchot <mpi grenadille net>
Date:   Wed Sep 25 10:42:32 2019 -0300

    Implement ATK's scrollSubstringTo() and scrollSubstringToPoint().
    
    This implementation considers only the positions of the first and
    last characters of the substring.
    
    Close #1203

 libview/ev-page-accessible.c | 143 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
---
diff --git a/libview/ev-page-accessible.c b/libview/ev-page-accessible.c
index 455a0bf4..ea8d4862 100644
--- a/libview/ev-page-accessible.c
+++ b/libview/ev-page-accessible.c
@@ -1042,6 +1042,145 @@ ev_page_accessible_add_selection (AtkText *text,
 
 }
 
+#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 pos, 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_changed (view->hadjustment);
+               gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);
+               gtk_adjustment_changed (view->vadjustment);
+               break;
+       case ATK_SCROLL_BOTTOM_RIGHT:
+               gtk_adjustment_clamp_page (view->hadjustment, end_point.x - hpage_size, end_point.x);
+               gtk_adjustment_changed (view->hadjustment);
+               gtk_adjustment_clamp_page (view->vadjustment, end_point.y - vpage_size, end_point.y);
+               gtk_adjustment_changed (view->vadjustment);
+               break;
+       case ATK_SCROLL_TOP_EDGE:
+               gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);
+               gtk_adjustment_changed (view->vadjustment);
+               break;
+       case ATK_SCROLL_BOTTOM_EDGE:
+               gtk_adjustment_clamp_page (view->vadjustment, end_point.y - vpage_size, end_point.y);
+               gtk_adjustment_changed (view->vadjustment);
+               break;
+       case ATK_SCROLL_LEFT_EDGE:
+               gtk_adjustment_clamp_page (view->hadjustment, start_point.x, start_point.x + hpage_size);
+               gtk_adjustment_changed (view->hadjustment);
+               break;
+       case ATK_SCROLL_RIGHT_EDGE:
+               gtk_adjustment_clamp_page (view->hadjustment, end_point.x - hpage_size, end_point.x);
+               gtk_adjustment_changed (view->hadjustment);
+               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_changed (view->hadjustment);
+       gtk_adjustment_clamp_page (view->vadjustment, start_point.y, start_point.y + vpage_size);
+       gtk_adjustment_changed (view->vadjustment);
+
+       return TRUE;
+}
+#endif
+
 static void
 ev_page_accessible_init (EvPageAccessible *page)
 {
@@ -1067,6 +1206,10 @@ ev_page_accessible_text_iface_init (AtkTextIface *iface)
        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 *