Merge pull request #2950 from HalfWhitt/fix-visibility

Fix visibility for descendants of hidden widgets

changes/2950.bugfix.rst

@@ -0,0 +1 @@
+Fixed a bug that allowed descendents of hidden widgets to be visible.

core/src/toga/style/pack.py

@@ -110,6 +110,15 @@ def apply(self, prop: str, value: object) -> None:
             elif prop == "background_color":
                 self._applicator.set_background_color(value)
             elif prop == "visibility":
+                if value == VISIBLE:
+                    # If visibility is being set to VISIBLE, look up the chain to see if
+                    # an ancestor is hidden.
+                    widget = self._applicator.widget
+                    while widget := widget.parent:
+                        if widget.style._hidden:
+                            value = HIDDEN
+                            break
+
                 self._applicator.set_hidden(value == HIDDEN)
             elif prop in (
                 "font_family",

core/tests/style/pack/test_apply.py

@@ -8,10 +8,11 @@
     LEFT,
     RIGHT,
     RTL,
+    VISIBLE,
     Pack,
 )
 
-from .utils import ExampleNode
+from .utils import ExampleNode, ExampleParentNode
 
 
 def test_set_default_right_textalign_when_rtl():
@@ -72,3 +73,48 @@ def test_set_visibility_hidden():
     root = ExampleNode("app", style=Pack(visibility=HIDDEN))
     root.style.reapply()
     root._impl.set_hidden.assert_called_once_with(True)
+
+
+def test_set_visibility_inherited():
+    """Nodes should be hidden when an ancestor is hidden."""
+    grandparent = ExampleParentNode("grandparent", style=Pack())
+    parent = ExampleParentNode("parent", style=Pack())
+    child = ExampleNode("child", style=Pack())
+    grandparent.add(parent)
+    parent.add(child)
+
+    def assert_hidden_called(grandparent_value, parent_value, child_value):
+        for node, value in [
+            (grandparent, grandparent_value),
+            (parent, parent_value),
+            (child, child_value),
+        ]:
+            if value is None:
+                node._impl.set_hidden.assert_not_called()
+            else:
+                node._impl.set_hidden.assert_called_once_with(value)
+
+            node._impl.set_hidden.reset_mock()
+
+    # Hiding grandparent should hide all.
+    grandparent.style.visibility = HIDDEN
+    assert_hidden_called(True, True, True)
+
+    # Just setting child or parent to VISIBLE won't trigger an apply, because that's
+    # their default value. So first, set them to hidden.
+    parent.style.visibility = HIDDEN
+    assert_hidden_called(None, True, True)
+
+    child.style.visibility = HIDDEN
+    assert_hidden_called(None, None, True)
+
+    # Then set them to visible. They should still not actually be shown.
+    parent.style.visibility = VISIBLE
+    assert_hidden_called(None, True, True)
+
+    child.style.visibility = VISIBLE
+    assert_hidden_called(None, None, True)
+
+    # Show grandparent again; the other two should reappear.
+    grandparent.style.visibility = VISIBLE
+    assert_hidden_called(False, False, False)

core/tests/style/pack/utils.py

@@ -63,6 +63,13 @@ def refresh(self):
         pass
 
 
+class ExampleParentNode(ExampleNode):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self._children = []
+
+
 class ExampleViewport:
     def __init__(self, width, height):
         self.height = height

testbed/tests/widgets/test_base.py

@@ -69,7 +69,10 @@ async def test_visibility(widget, probe):
     assert child_probe.is_hidden
     assert grandchild_probe.is_hidden
 
-    # Mark the child style as visible.
+    # Mark the child style as visible. Mark it as hidden first, so that a change is
+    # registered and the property is applied. However, regardless, the widget
+    # won't be visible because it has an ancestor that is hidden.
+    child.style.visibility = HIDDEN
     child.style.visibility = VISIBLE
     await probe.redraw("Child style of widget should be visible")