Fix #3342: consider text opacity in partial rich styles.

src/textual/css/styles.py

@@ -627,12 +627,24 @@ def partial_rich_style(self) -> Style:
         Returns:
             Rich Style object.
         """
-        style = Style(
-            color=(self.color.rich_color if self.has_rule("color") else None),
-            bgcolor=(
-                self.background.rich_color if self.has_rule("background") else None
-            ),
-        )
+        if self.has_rule("color"):
+            # If there is text opacity, we need to get the background color from the
+            # parents to compute the correct final text color.
+            if self.has_rule("text_opacity") and self.text_opacity < 1:
+                reference_background = (
+                    self.node.background_colors[1]
+                    if self.node is not None
+                    else self.background
+                )
+                color = (
+                    reference_background + self.color.multiply_alpha(self.text_opacity)
+                ).rich_color
+            else:
+                color = self.color.rich_color
+        else:
+            color = None
+        bgcolor = self.background.rich_color if self.has_rule("background") else None
+        style = Style(color=color, bgcolor=bgcolor)
         style += self.text_style
         return style
 

tests/snapshot_tests/snapshot_apps/component_classes_opacity.py

@@ -30,7 +30,7 @@ class ComponentClassesOpacity(App[None]):
     Footer > .footer--key,
     Input > .input--placeholder,
     OptionList > .option-list--option-highlighted,
-    ProgressBar Bar > .bar--indeterminate,
+    ProgressBar Bar > .bar--bar,
     RadioButton > .toggle--label,
     SelectionList > .selection-list--button-highlighted,
     Switch > .switch--slider,
@@ -50,7 +50,9 @@ def compose(self) -> ComposeResult:
         yield Footer()
         yield Input(placeholder="this should be invisible")
         yield OptionList(Option("this should be invisible"))
-        yield ProgressBar()
+        pb = ProgressBar(total=100)
+        pb.advance(50)
+        yield pb
         yield RadioButton("this should be invisible")
         yield SelectionList(("this should be invisible", 0))
         yield Switch()

tests/snapshot_tests/test_snapshots.py

@@ -708,7 +708,9 @@ def test_nested_fr(snap_compare) -> None:
     assert snap_compare(SNAPSHOT_APPS_DIR / "nested_fr.py")
 
 
-@pytest.mark.skipif(sys.version_info < (3, 8), reason="tree-sitter requires python3.8 or higher")
+@pytest.mark.skipif(
+    sys.version_info < (3, 8), reason="tree-sitter requires python3.8 or higher"
+)
 @pytest.mark.parametrize("language", BUILTIN_LANGUAGES)
 def test_text_area_language_rendering(language, snap_compare):
     # This test will fail if we're missing a snapshot test for a valid
@@ -760,9 +762,12 @@ def setup_selection(pilot):
     )
 
 
-@pytest.mark.skipif(sys.version_info < (3, 8), reason="tree-sitter requires python3.8 or higher")
-@pytest.mark.parametrize("theme_name",
-                         [theme.name for theme in TextAreaTheme.builtin_themes()])
+@pytest.mark.skipif(
+    sys.version_info < (3, 8), reason="tree-sitter requires python3.8 or higher"
+)
+@pytest.mark.parametrize(
+    "theme_name", [theme.name for theme in TextAreaTheme.builtin_themes()]
+)
 def test_text_area_themes(snap_compare, theme_name):
     """Each theme should have its own snapshot with at least some Python
     to check that the rendering is sensible. This also ensures that theme
@@ -807,3 +812,16 @@ def test_scoped_css(snap_compare) -> None:
 
 def test_unscoped_css(snap_compare) -> None:
     assert snap_compare(SNAPSHOT_APPS_DIR / "unscoped_css.py")
+
+
+def test_component_classes_opacity(snap_compare) -> None:
+    """Regression test for
+
+    - https://github.com/Textualize/textual/issues/3304
+    - https://github.com/Textualize/textual/issues/3342
+    - https://github.com/Textualize/textual/issues/3413
+    """
+    # We _need_ a height of at least 27 to show all the widgets that we're testing.
+    assert snap_compare(
+        SNAPSHOT_APPS_DIR / "component_classes_opacity.py", terminal_size=(80, 30)
+    )