gtk4 a11y: Implement new GtkAccessibleTextInterface::get_extents

Implement the new `get_extents` method for
`GtkAccessibleTextInterface` newly introduced
in GTK 4 in GTK commits

      commit 7955efef6c31d23c8553dc3464e72273886a4417
      Author: Matthias Clasen <mclasen@redhat.com>
      Date:   Sun Mar 10 14:28:07 2024 -0400

          atspi: Use gtk_accessible_text_get_extents

          Implement the GetCharacterExtents and GetRangeExtents methods of
          the atspi Text interface using the new GtkAccessibleText api.

      commit 3134003376fc37c6d5e7e6eb7c6f36307039a92c
      Author: Matthias Clasen <mclasen@redhat.com>
      Date:   Sun Mar 10 14:27:42 2024 -0400

          a11y: Add gtk_accessible_text_get_extents

          This will be used to implement GetRangeExtents in atspi.

The `XAccessibleText` UNO interface currently
only has a way to retrieve the extents of a
single character, so just return `false`
if the extents for a larger text range is
requested.
(LO's gtk3/ATK implemenation currently also doesn't
implement AtkText.get_range_extents` [1])

To actually work, this also needs changes on
GTK side to support non-GtkWidget GtkAccessible
implementations. Pending MR: [2]

[1] https://docs.gtk.org/atk/vfunc.Text.get_range_extents.html
[2] https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/7104

Change-Id: I7d171b6696037a696f0d767d3134c7a7184f93a3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165793
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/vcl/unx/gtk4/gtkaccessibletext.cxx b/vcl/unx/gtk4/gtkaccessibletext.cxx
index 0dc9b8cd04a9..40040fb52f1c 100644
--- a/vcl/unx/gtk4/gtkaccessibletext.cxx
+++ b/vcl/unx/gtk4/gtkaccessibletext.cxx
@@ -221,6 +221,38 @@ static void lo_accessible_text_get_default_attributes(GtkAccessibleText* self,
     convertUnoTextAttributesToGtk(aAttribs, attribute_names, attribute_values);
 }
 
+#if GTK_CHECK_VERSION(4, 15, 0)
+static gboolean lo_accessible_text_get_extents(GtkAccessibleText* self, unsigned int start,
+                                               unsigned int end, graphene_rect_t* extents)
+{
+    css::uno::Reference<css::accessibility::XAccessibleText> xText = getXText(self);
+    if (!xText.is())
+        return false;
+
+    if (end != start + 1)
+    {
+        SAL_WARN("vcl.gtk", "lo_accessible_text_get_extents called for a text range of more than a "
+                            "single character. This is not implemented yet.");
+        return false;
+    }
+
+    if (start > o3tl::make_unsigned(xText->getCharacterCount()))
+    {
+        SAL_WARN("vcl.gtk",
+                 "lo_accessible_text_get_extents called with invalid start index: " << start);
+        return false;
+    }
+
+    com::sun::star::awt::Rectangle aBounds = xText->getCharacterBounds(start);
+    extents->origin.x = aBounds.X;
+    extents->origin.y = aBounds.Y;
+    extents->size.width = aBounds.Width;
+    extents->size.height = aBounds.Height;
+
+    return true;
+}
+#endif
+
 void lo_accessible_text_init(gpointer iface_, gpointer)
 {
     auto const iface = static_cast<GtkAccessibleTextInterface*>(iface_);
@@ -230,6 +262,9 @@ void lo_accessible_text_init(gpointer iface_, gpointer)
     iface->get_selection = lo_accessible_text_get_selection;
     iface->get_attributes = lo_accessible_text_get_attributes;
     iface->get_default_attributes = lo_accessible_text_get_default_attributes;
+#if GTK_CHECK_VERSION(4, 15, 0)
+    iface->get_extents = lo_accessible_text_get_extents;
+#endif
 }
 
 #endif