Add "horizontal" and "vertical" aliases for align_items and justify_c…

…ontent (#3113)

* Add "horizontal" and "vertical" aliases for align_items and justify_content

* Work around Travertino _ALL_PROPERTIES version differences

* Improve wording

Co-authored-by: Russell Keith-Magee <[email protected]>

---------

Co-authored-by: Russell Keith-Magee <[email protected]>

changes/3111.feature.rst

@@ -0,0 +1 @@
+The ``align_items`` and ``justify_content`` properties now have the aliases ``horizontal_align_items``, ``vertical_align_items``, ``horizontal_align_content`` and ``vertical_align_content`` that explicitly describe layout behavior in the named direction.

core/src/toga/style/mixin.py

@@ -2,6 +2,9 @@ class StyleProperty:
     def __set_name__(self, mixin_cls, name):
         self.name = name
 
+    def __repr__(self):
+        return f"<StyleProperty {self.name!r}>"
+
     def __get__(self, widget, mixin_cls):
         return self if widget is None else getattr(widget.style, self.name)
 
@@ -21,8 +24,13 @@ def style_mixin(style_cls):
             """
     }
 
-    for name in dir(style_cls):
-        if not name.startswith("_") and isinstance(getattr(style_cls, name), property):
-            mixin_dict[name] = StyleProperty()
+    try:
+        _all_properties = style_cls._BASE_ALL_PROPERTIES
+    except AttributeError:
+        # Travertino 0.3 compatibility
+        _all_properties = style_cls._ALL_PROPERTIES
+
+    for name in _all_properties[style_cls]:
+        mixin_dict[name] = StyleProperty()
 
     return type(style_cls.__name__ + "Mixin", (), mixin_dict)

core/src/toga/style/pack.py

@@ -115,6 +115,11 @@ def _hidden(self) -> bool:
     ######################################################################
 
     def update(self, **properties):
+        # Set direction first, as it may change the interpretation of direction-based
+        # property aliases in _update_property_name.
+        if direction := properties.pop("direction", None):
+            self.direction = direction
+
         properties = {
             self._update_property_name(name.replace("-", "_")): value
             for name, value in properties.items()
@@ -128,7 +133,7 @@ def reapply(self, *args, **kwargs):
             warnings.filterwarnings("ignore", category=DeprecationWarning)
             super().reapply(*args, **kwargs)
 
-    DEPRECATED_PROPERTIES = {
+    _DEPRECATED_PROPERTIES = {
         # Map each deprecated property name to its replacement.
         # alignment / align_items is handled separately.
         "padding": "margin",
@@ -138,22 +143,38 @@ def reapply(self, *args, **kwargs):
         "padding_left": "margin_left",
     }
 
-    @classmethod
-    def _update_property_name(cls, name):
-        if new_name := cls.DEPRECATED_PROPERTIES.get(name):
-            cls._warn_deprecated(name, new_name, stacklevel=4)
+    _ALIASES = {
+        "horizontal_align_content": {ROW: "justify_content"},
+        "horizontal_align_items": {COLUMN: "align_items"},
+        "vertical_align_content": {COLUMN: "justify_content"},
+        "vertical_align_items": {ROW: "align_items"},
+    }
+
+    def _update_property_name(self, name):
+        if aliases := self._ALIASES.get(name):
+            try:
+                name = aliases[self.direction]
+            except KeyError:
+                raise AttributeError(
+                    f"{name!r} is not supported on a {self.direction}"
+                ) from None
+
+        if new_name := self._DEPRECATED_PROPERTIES.get(name):
+            self._warn_deprecated(name, new_name, stacklevel=4)
             name = new_name
 
         return name
 
-    @staticmethod
-    def _warn_deprecated(old_name, new_name, stacklevel=3):
+    def _warn_deprecated(self, old_name, new_name, stacklevel=3):
         msg = f"Pack.{old_name} is deprecated; use {new_name} instead"
         warnings.warn(msg, DeprecationWarning, stacklevel=stacklevel)
 
     # Dot lookup
 
     def __getattribute__(self, name):
+        if name.startswith("_"):
+            return super().__getattribute__(name)
+
         # Align_items and alignment are paired. Both can never be set at the same time;
         # if one is requested, and the other one is set, compute the requested value
         # from the one that is set.
@@ -197,7 +218,7 @@ def __getattribute__(self, name):
                 # Only CENTER remains
                 return CENTER
 
-        return super().__getattribute__(type(self)._update_property_name(name))
+        return super().__getattribute__(self._update_property_name(name))
 
     def __setattr__(self, name, value):
         # Only one of these can be set at a time.
@@ -979,3 +1000,11 @@ def __css__(self) -> str:
 #     'font_family', 'font_style', 'font_variant', 'font_weight', 'font_size'
 #     FONT_CHOICES
 # ])
+
+try:
+    _all_properties = Pack._BASE_ALL_PROPERTIES
+except AttributeError:
+    # Travertino 0.3 compatibility
+    _all_properties = Pack._ALL_PROPERTIES
+
+_all_properties[Pack].update(Pack._ALIASES)

core/tests/style/pack/__init__.py

@@ -0,0 +1,48 @@
+from toga.style.pack import Pack
+
+
+def with_init(**kwargs):
+    return Pack(**kwargs)
+
+
+def with_update(**kwargs):
+    style = Pack()
+    style.update(**kwargs)
+    return style
+
+
+def with_setattr(**kwargs):
+    style = Pack()
+    for name, value in kwargs.items():
+        setattr(style, name, value)
+    return style
+
+
+def with_setitem(**kwargs):
+    style = Pack()
+    for name, value in kwargs.items():
+        style[name] = value
+    return style
+
+
+def with_setitem_hyphen(**kwargs):
+    style = Pack()
+    for name, value in kwargs.items():
+        style[name.replace("_", "-")] = value
+    return style
+
+
+def getitem(obj, name):
+    return obj[name]
+
+
+def getitem_hyphen(obj, name):
+    return obj[name.replace("_", "-")]
+
+
+def delitem(obj, name):
+    del obj[name]
+
+
+def delitem_hyphen(obj, name):
+    del obj[name.replace("_", "-")]

core/tests/style/pack/test_aliases.py

@@ -0,0 +1,108 @@
+import pytest
+from pytest import raises
+
+from toga.style.pack import CENTER, COLUMN, END, ROW
+
+from . import (
+    delitem,
+    delitem_hyphen,
+    getitem,
+    getitem_hyphen,
+    with_init,
+    with_setattr,
+    with_setitem,
+    with_setitem_hyphen,
+    with_update,
+)
+
+
+@pytest.mark.parametrize(
+    "css_name, row_alias, column_alias, default",
+    [
+        (
+            "align_items",
+            "vertical_align_items",
+            "horizontal_align_items",
+            None,
+        ),
+        (
+            "justify_content",
+            "horizontal_align_content",
+            "vertical_align_content",
+            "start",
+        ),
+    ],
+)
+@pytest.mark.parametrize(
+    "style_with",
+    (with_init, with_update, with_setattr, with_setitem, with_setitem_hyphen),
+)
+@pytest.mark.parametrize("get_fn", (getattr, getitem, getitem_hyphen))
+@pytest.mark.parametrize("del_fn", (delattr, delitem, delitem_hyphen))
+def test_align(css_name, row_alias, column_alias, default, style_with, get_fn, del_fn):
+    """The `vertical_align` and `horizontal_align` aliases work correctly."""
+    # Row alias
+    style = style_with(**{row_alias: CENTER})
+    assert get_fn(style, css_name) == CENTER
+
+    del_fn(style, row_alias)
+    assert get_fn(style, css_name) == default
+
+    style = style_with(**{css_name: CENTER})
+    assert get_fn(style, row_alias) == CENTER
+
+    del_fn(style, css_name)
+    assert get_fn(style, row_alias) == default
+
+    # Column alias
+    style = style_with(**{"direction": COLUMN, column_alias: CENTER})
+    assert get_fn(style, css_name) == CENTER
+
+    del_fn(style, column_alias)
+    assert get_fn(style, css_name) == default
+
+    style = style_with(**{"direction": COLUMN, css_name: CENTER})
+    assert get_fn(style, column_alias) == CENTER
+
+    del_fn(style, css_name)
+    assert get_fn(style, column_alias) == default
+
+    # Column alias is not accepted in a row, and vice versa.
+    def assert_invalid_alias(alias, direction):
+        style = style_with(direction=direction)
+        raises_kwargs = dict(
+            expected_exception=AttributeError,
+            match=f"'{alias}' is not supported on a {direction}",
+        )
+
+        with raises(**raises_kwargs):
+            get_fn(style, alias)
+        with raises(**raises_kwargs):
+            setattr(style, alias, END)
+        with raises(**raises_kwargs):
+            del_fn(style, alias)
+        with raises(**raises_kwargs):
+            style.update(**{"direction": direction, alias: END})
+        with raises(**raises_kwargs):
+            style.update(**{alias: END, "direction": direction})
+
+    assert_invalid_alias(column_alias, ROW)
+    assert_invalid_alias(row_alias, COLUMN)
+
+    # Consistent values of direction and alias can be updated together, regardless of
+    # argument order.
+    style = style_with(direction=COLUMN)
+    style.update(**{"direction": ROW, row_alias: CENTER})
+    assert get_fn(style, row_alias) == CENTER
+    assert get_fn(style, css_name) == CENTER
+    style.update(**{column_alias: END, "direction": COLUMN})
+    assert get_fn(style, column_alias) == END
+    assert get_fn(style, css_name) == END
+
+    style = style_with(direction=ROW)
+    style.update(**{"direction": COLUMN, column_alias: CENTER})
+    assert get_fn(style, column_alias) == CENTER
+    assert get_fn(style, css_name) == CENTER
+    style.update(**{row_alias: END, "direction": ROW})
+    assert get_fn(style, row_alias) == END
+    assert get_fn(style, css_name) == END

core/tests/style/pack/test_deprecated_properties.py

@@ -15,49 +15,17 @@
     Pack,
 )
 
-
-def with_init(name, value):
-    return Pack(**{name: value})
-
-
-def with_update(name, value):
-    style = Pack()
-    style.update(**{name: value})
-    return style
-
-
-def with_setattr(name, value):
-    style = Pack()
-    setattr(style, name, value)
-    return style
-
-
-def with_setitem(name, value):
-    style = Pack()
-    style[name] = value
-    return style
-
-
-def with_setitem_hyphen(name, value):
-    style = Pack()
-    style[name.replace("_", "-")] = value
-    return style
-
-
-def getitem(obj, name):
-    return obj[name]
-
-
-def getitem_hyphen(obj, name):
-    return obj[name.replace("_", "-")]
-
-
-def delitem(obj, name):
-    del obj[name]
-
-
-def delitem_hyphen(obj, name):
-    del obj[name.replace("_", "-")]
+from . import (
+    delitem,
+    delitem_hyphen,
+    getitem,
+    getitem_hyphen,
+    with_init,
+    with_setattr,
+    with_setitem,
+    with_setitem_hyphen,
+    with_update,
+)
 
 
 @pytest.mark.parametrize(
@@ -80,7 +48,7 @@ def test_padding_margin(old_name, new_name, value, default, style_with, get_fn,
     """Padding (with deprecation warning) and margin map to each other."""
     # Set the old name, then check the new name
     with pytest.warns(DeprecationWarning):
-        style = style_with(old_name, value)
+        style = style_with(**{old_name: value})
     assert get_fn(style, new_name) == value
 
     # Delete the old name, check new name
@@ -89,7 +57,7 @@ def test_padding_margin(old_name, new_name, value, default, style_with, get_fn,
     assert get_fn(style, new_name) == default
 
     # Set the new name, then check the old name
-    style = style_with(new_name, value)
+    style = style_with(**{new_name: value})
     with pytest.warns(DeprecationWarning):
         assert get_fn(style, old_name) == value
 
@@ -128,7 +96,7 @@ def test_alignment_align_items(
     """Alignment (with deprecation warning) and align_items map to each other."""
     # Set alignment, check align_items
     with pytest.warns(DeprecationWarning):
-        style = style_with("alignment", alignment)
+        style = style_with(alignment=alignment)
         style.update(direction=direction, text_direction=text_direction)
 
     assert get_fn(style, "align_items") == align_items
@@ -139,7 +107,7 @@ def test_alignment_align_items(
     assert get_fn(style, "align_items") is None
 
     # Set align_items, check alignment
-    style = style_with("align_items", align_items)
+    style = style_with(align_items=align_items)
     style.update(direction=direction, text_direction=text_direction)
 
     with pytest.warns(DeprecationWarning):