fdo#35105: notify role change through a new UNO a11y event

A new UNO accessibility event called ROLE_CHANGED has been created.
It should be triggered when an accessible object changes its role and
every accessibility toolkit should use its own methods to make that
change effective.

Code to support the event in ATK has been added.

Change-Id: I132e303bdb148967231334458c3cfa369c36ec8f
Reviewed-on: https://gerrit.libreoffice.org/7853Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>

offapi/com/sun/star/accessibility/AccessibleEventId.idl

@@ -380,6 +380,13 @@ constants AccessibleEventId
     const short PAGE_CHANGED =38;
     const short SECTION_CHANGED =39;
     const short COLUMN_CHANGED =40;
+
+    /** Constant used to indicate that the role of an accessible object has
+        changed.
+
+        @since LibreOffice 4.3
+    */
+    const short ROLE_CHANGED =41;
 };
 
 }; }; }; };

sw/source/core/access/accpara.cxx

@@ -437,7 +437,16 @@ void SwAccessibleParagraph::_InvalidateContent( sal_Bool bVisibleDataFired )
             bIsHeading = bNewIsHeading;
     }
 
-    if( bNewIsHeading != bOldIsHeading || rText != sOldText )
+    if( bNewIsHeading != bOldIsHeading )
+    {
+        // The role has changed
+        AccessibleEventObject aEvent;
+        aEvent.EventId = AccessibleEventId::ROLE_CHANGED;
+
+        FireAccessibleEvent( aEvent );
+    }
+
+    if( rText != sOldText )
     {
         OUString sNewDesc( GetDescription() );
         OUString sOldDesc;

vcl/unx/gtk/a11y/atklistener.cxx

@@ -549,6 +549,14 @@ void AtkListener::notifyEvent( const accessibility::AccessibleEventObject& aEven
             g_signal_emit_by_name( G_OBJECT( atk_obj ), "property_change::accessible-hypertext-offset");
             break;
 
+        case accessibility::AccessibleEventId::ROLE_CHANGED:
+        {
+            uno::Reference< accessibility::XAccessibleContext > xContext;
+            xContext = getAccessibleContextFromSource( aEvent.Source );
+            atk_object_wrapper_set_role( mpWrapper, xContext->getAccessibleRole() );
+            break;
+        }
+
     default:
             g_warning( "Unknown event notification %d", aEvent.EventId );
             break;

vcl/unx/gtk/a11y/atkwrapper.cxx

@@ -876,6 +876,14 @@ void atk_object_wrapper_remove_child(AtkObjectWrapper* wrapper, AtkObject *child
 
 /*****************************************************************************/
 
+void atk_object_wrapper_set_role(AtkObjectWrapper* wrapper, sal_Int16 role)
+{
+    AtkObject *atk_obj = ATK_OBJECT( wrapper );
+    atk_object_set_role( atk_obj, mapToAtkRole( role ) );
+}
+
+/*****************************************************************************/
+
 #define RELEASE(i) if( i ) { i->release(); i = NULL; }
 
 void atk_object_wrapper_dispose(AtkObjectWrapper* wrapper)

vcl/unx/gtk/a11y/atkwrapper.hxx

@@ -84,6 +84,7 @@ AtkObject *            atk_object_wrapper_new(
 
 void                   atk_object_wrapper_add_child(AtkObjectWrapper* wrapper, AtkObject *child, gint index);
 void                   atk_object_wrapper_remove_child(AtkObjectWrapper* wrapper, AtkObject *child, gint index);
+void                   atk_object_wrapper_set_role(AtkObjectWrapper* wrapper, sal_Int16 role);
 
 void                   atk_object_wrapper_dispose(AtkObjectWrapper* wrapper);