factory: Create a TreeRow

The TreeRow is used to display rows from a Gtk.TreeListModel. I adjust
the TreeRow "item" and "child" properties so they still access the
underlying item or child widget instead of the Gtk.TreeRow or
Gtk.TreeExpander.

I also give the TreeRow widget "n-children" and "have-children" properties
which are used to dynamically show or hide the expander arrow when there
aren't any children.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

emmental/factory.py

@@ -2,6 +2,7 @@
 """A customized Gtk.SignalListItemFactory for easier use."""
 import typing
 from gi.repository import GObject
+from gi.repository import Gio
 from gi.repository import Gtk
 
 
@@ -86,6 +87,54 @@ class InscriptionRow(ListRow):
         self.bind_and_set_property(self.item_property, "text")
 
 
+class TreeRow(ListRow):
+    """A ListRow for displaying child widgets in a Tree."""
+
+    n_children = GObject.Property(type=int)
+    have_children = GObject.Property(type=bool, default=False)
+    indented = GObject.Property(type=bool, default=True)
+
+    def __init__(self, listitem: Gtk.ListItem, **kwargs) -> None:
+        """Create a new TreeRow."""
+        super().__init__(listitem, **kwargs)
+        listitem.set_child(Gtk.TreeExpander(hide_expander=True,
+                                            indent_for_icon=self.indented))
+        self.bind_property("n-children", self, "have-children")
+        self.bind_property("have-children", listitem.get_child(),
+                           "hide-expander",
+                           GObject.BindingFlags.INVERT_BOOLEAN)
+        self.bind_property("indented", listitem.get_child(), "indent-for-icon")
+
+    def bind(self) -> None:
+        """Bind a TreeRow to the TreeExpander."""
+        self.listitem.get_child().set_list_row(self.listitem.get_item())
+        super().bind()
+
+    def bind_n_children(self, children: Gio.ListModel | None) -> None:
+        """Bind to the n-items property of the child listmodel."""
+        if children is not None:
+            self.bind_and_set(children, "n-items", self, "n-children")
+
+    def unbind(self) -> None:
+        """Unbind a TreeRow from the TreeExpander."""
+        self.listitem.get_child().set_list_row(None)
+        super().unbind()
+
+    @GObject.Property(type=Gtk.Widget)
+    def child(self) -> Gtk.Widget | None:
+        """Get the child widget displayed by this Row."""
+        return self.listitem.get_child().get_child()
+
+    @child.setter
+    def child(self, newval=Gtk.Widget) -> None:
+        self.listitem.get_child().set_child(newval)
+
+    @GObject.Property(type=GObject.TYPE_PYOBJECT)
+    def item(self) -> GObject.TYPE_PYOBJECT:
+        """Get the list item for this Row."""
+        return self.listitem.get_item().get_item()
+
+
 class Factory(Gtk.SignalListItemFactory):
     """A customized Factory for making list row widgets."""
 

tests/test_factory.py

@@ -3,6 +3,7 @@
 import unittest
 import unittest.mock
 import emmental.factory
+from gi.repository import Gio
 from gi.repository import Gtk
 from gi.repository import GObject
 
@@ -102,6 +103,74 @@ class TestInscriptionRow(unittest.TestCase):
         self.assertTrue(row.child.has_css_class("numeric"))
 
 
+class TestTreeRow(unittest.TestCase):
+    """Test our pre-configured TreeRow."""
+
+    def setUp(self):
+        """Set up common variables."""
+        self.item = Gtk.Label(label="Test")
+        self.child = Gtk.Label()
+
+        self.treerow = Gtk.TreeListRow()
+        self.treerow.get_item = unittest.mock.Mock(return_value=self.item)
+
+        self.listitem = Gtk.ListItem()
+        self.listitem.get_item = unittest.mock.Mock(return_value=self.treerow)
+        self.row = emmental.factory.TreeRow(self.listitem)
+
+    def test_tree_row(self):
+        """Test that the TreeRow works as expected."""
+        self.assertIsInstance(self.row, emmental.factory.ListRow)
+        self.assertIsInstance(self.listitem.get_child(), Gtk.TreeExpander)
+        self.assertEqual(self.row.item, self.item)
+
+        self.row.child = self.child
+        self.assertEqual(self.listitem.get_child().get_child(), self.child)
+        self.assertEqual(self.row.child, self.child)
+
+        self.row.bind()
+        self.assertEqual(self.listitem.get_child().get_list_row(),
+                         self.treerow)
+        self.row.unbind()
+        self.assertIsNone(self.listitem.get_child().get_list_row())
+
+    def test_indented(self):
+        """Test the indended property."""
+        self.assertTrue(self.row.indented)
+        self.assertTrue(self.listitem.get_child().get_indent_for_icon())
+
+        self.row.indented = False
+        self.assertFalse(self.listitem.get_child().get_indent_for_icon())
+
+        row2 = emmental.factory.TreeRow(self.listitem, indented=False)
+        self.assertFalse(row2.indented)
+        self.assertFalse(self.listitem.get_child().get_indent_for_icon())
+
+    def test_bind_n_children(self):
+        """Test binding to the n_children property."""
+        expander = self.listitem.get_child()
+        liststore = Gio.ListStore()
+
+        self.assertEqual(self.row.n_children, 0)
+        self.assertFalse(self.row.have_children)
+        self.assertTrue(expander.get_hide_expander())
+
+        self.row.n_children = 1
+        self.assertTrue(self.row.have_children)
+        self.assertFalse(expander.get_hide_expander())
+
+        self.row.bind_n_children(None)
+        self.assertEqual(len(self.row.bindings), 0)
+
+        self.row.bind_n_children(liststore)
+        self.assertEqual(self.row.n_children, 0)
+        self.assertTrue(expander.get_hide_expander())
+
+        liststore.append(Gtk.Label())
+        self.assertEqual(self.row.n_children, 1)
+        self.assertFalse(expander.get_hide_expander())
+
+
 class TestFactory(unittest.TestCase):
     """Test a Factory."""