[nautilus] general: Set labelled-by for view cells

[António Fernandes <antoniof src gnome org>]

commit ee38cbef43784412147547648298de1db667c39c
Author: Corey Berla <corey berla me>
Date:   Wed Aug 31 15:42:49 2022 +0000

    general: Set labelled-by for view cells
    
    In gtk4, we need to set labelled-by to help a11y programs know what
    it currently selected.
    
    Unfortunately, the focus is on a GTK internal widget, so at the moment
    this solution requires a hack: we mark the internal list item widget as
    being labeled by our cell (which is, in turn, labeled by the filename label).
    
    We are reporting this to GTK to work toward a better solution.
    
    Fixes: https://gitlab.gnome.org/GNOME/nautilus/-/issues/2460

 src/nautilus-grid-view.c               |  4 ++++
 src/nautilus-list-view.c               | 16 ++++++++++++++++
 src/resources/ui/nautilus-grid-cell.ui |  3 +++
 src/resources/ui/nautilus-name-cell.ui |  3 +++
 4 files changed, 26 insertions(+)
---
diff --git a/src/nautilus-grid-view.c b/src/nautilus-grid-view.c
index 74a80e1f5..cbeea42de 100644
--- a/src/nautilus-grid-view.c
+++ b/src/nautilus-grid-view.c
@@ -367,6 +367,10 @@ bind_cell (GtkSignalListItemFactory *factory,
         gtk_widget_set_margin_bottom (parent, 3);
         gtk_widget_set_margin_start (parent, 3);
         gtk_widget_set_margin_end (parent, 3);
+
+        gtk_accessible_update_relation (GTK_ACCESSIBLE (parent),
+                                        GTK_ACCESSIBLE_RELATION_LABELLED_BY, cell, NULL,
+                                        -1);
     }
 }
 
diff --git a/src/nautilus-list-view.c b/src/nautilus-list-view.c
index e2389eac3..4b7a5f2e1 100644
--- a/src/nautilus-list-view.c
+++ b/src/nautilus-list-view.c
@@ -945,11 +945,27 @@ bind_name_cell (GtkSignalListItemFactory *factory,
                 GtkListItem              *listitem,
                 gpointer                  user_data)
 {
+    GtkWidget *cell;
     NautilusViewItem *item;
 
+    cell = gtk_list_item_get_child (listitem);
     item = NAUTILUS_VIEW_ITEM (gtk_list_item_get_item (listitem));
 
     nautilus_view_item_set_item_ui (item, gtk_list_item_get_child (listitem));
+
+    if (nautilus_view_cell_once (NAUTILUS_VIEW_CELL (cell)))
+    {
+        GtkWidget *row_widget;
+
+        /* At the time of ::setup emission, the item ui has got no parent yet,
+         * that's why we need to complete the widget setup process here, on the
+         * first time ::bind is emitted. */
+        row_widget = gtk_widget_get_parent (gtk_widget_get_parent (cell));
+
+        gtk_accessible_update_relation (GTK_ACCESSIBLE (row_widget),
+                                        GTK_ACCESSIBLE_RELATION_LABELLED_BY, cell, NULL,
+                                        -1);
+    }
 }
 
 static void
diff --git a/src/resources/ui/nautilus-grid-cell.ui b/src/resources/ui/nautilus-grid-cell.ui
index 2ca1f2755..cfc0ced89 100644
--- a/src/resources/ui/nautilus-grid-cell.ui
+++ b/src/resources/ui/nautilus-grid-cell.ui
@@ -3,6 +3,9 @@
   <requires lib="gtk" version="4.0"/>
   <template class="NautilusGridCell" parent="NautilusViewCell">
     <property name="valign">start</property>
+    <accessibility>
+      <relation name="labelled-by">label</relation>
+    </accessibility>
     <child>
       <object class="AdwClamp">
         <property name="maximum-size">0</property>
diff --git a/src/resources/ui/nautilus-name-cell.ui b/src/resources/ui/nautilus-name-cell.ui
index f2105fb55..246aa3ab2 100644
--- a/src/resources/ui/nautilus-name-cell.ui
+++ b/src/resources/ui/nautilus-name-cell.ui
@@ -2,6 +2,9 @@
 <interface>
   <requires lib="gtk" version="4.0"/>
   <template class="NautilusNameCell" parent="NautilusViewCell">
+    <accessibility>
+      <relation name="labelled-by">label</relation>
+    </accessibility>
     <child>
       <object class="GtkBox">
         <property name="spacing">6</property>