fix(widget): fix visual not updated after style changes

src/textual/widget.py

@@ -455,8 +455,6 @@ def __init__(
         self._layout_cache: dict[str, object] = {}
         """A dict that is refreshed when the widget is resized / refreshed."""
 
-        self._visual_style: VisualStyle | None = None
-
         self._render_cache = _RenderCache(_null_size, [])
         # Regions which need to be updated (in Widget)
         self._dirty_regions: set[Region] = set()
@@ -721,14 +719,6 @@ def preflight_checks(self) -> None:
                     f"'{self.__class__.__name__}.CSS' will be ignored (use 'DEFAULT_CSS' class variable for widgets)"
                 )
 
-    def pre_render(self) -> None:
-        """Called prior to rendering.
-
-        If you implement this in a subclass, be sure to call the base class method via super.
-
-        """
-        self._visual_style = None
-
     def _cover(self, widget: Widget) -> None:
         """Set a widget used to replace the visuals of this widget (used for loading indicator).
 
@@ -4127,43 +4117,41 @@ def _scroll_update(self, virtual_size: Size) -> None:
 
     @property
     def visual_style(self) -> VisualStyle:
-        if self._visual_style is None:
-            background = Color(0, 0, 0, 0)
-            color = Color(255, 255, 255, 0)
-
-            style = Style()
-            opacity = 1.0
+        background = Color(0, 0, 0, 0)
+        color = Color(255, 255, 255, 0)
 
-            for node in reversed(self.ancestors_with_self):
-                styles = node.styles
-                has_rule = styles.has_rule
-                opacity *= styles.opacity
-                if has_rule("background"):
-                    text_background = background + styles.background.tint(
-                        styles.background_tint
-                    )
-                    background += (
-                        styles.background.tint(styles.background_tint)
-                    ).multiply_alpha(opacity)
-                else:
-                    text_background = background
-                if has_rule("color"):
-                    color = styles.color
-                style += styles.text_style
-                if has_rule("auto_color") and styles.auto_color:
-                    color = text_background.get_contrast_text(color.a)
+        style = Style()
+        opacity = 1.0
 
-            self._visual_style = VisualStyle(
-                background,
-                color,
-                bold=style.bold,
-                dim=style.dim,
-                italic=style.italic,
-                reverse=style.reverse,
-                underline=style.underline,
-                strike=style.strike,
-            )
-        return self._visual_style
+        for node in reversed(self.ancestors_with_self):
+            styles = node.styles
+            has_rule = styles.has_rule
+            opacity *= styles.opacity
+            if has_rule("background"):
+                text_background = background + styles.background.tint(
+                    styles.background_tint
+                )
+                background += (
+                    styles.background.tint(styles.background_tint)
+                ).multiply_alpha(opacity)
+            else:
+                text_background = background
+            if has_rule("color"):
+                color = styles.color
+            style += styles.text_style
+            if has_rule("auto_color") and styles.auto_color:
+                color = text_background.get_contrast_text(color.a)
+
+        return VisualStyle(
+            background,
+            color,
+            bold=style.bold,
+            dim=style.dim,
+            italic=style.italic,
+            reverse=style.reverse,
+            underline=style.underline,
+            strike=style.strike,
+        )
 
     def get_selection(self, selection: Selection) -> tuple[str, str] | None:
         """Get the text under the selection.
@@ -4633,7 +4621,6 @@ async def broker_event(self, event_name: str, event: events.Event) -> bool:
     def notify_style_update(self) -> None:
         self._rich_style_cache.clear()
         self._visual_style_cache.clear()
-        self._visual_style = None
         super().notify_style_update()
 
     async def _on_mouse_down(self, event: events.MouseDown) -> None:

tests/snapshot_tests/test_snapshots.py

@@ -4804,3 +4804,28 @@ async def run_before(pilot: Pilot) -> None:
         await pilot.press("ctrl+v")
 
     assert snap_compare(TextAreaApp(), run_before=run_before)
+
+
+def test_visual_updates_after_style_changes(snap_compare) -> None:
+    """Regression test for https://github.com/Textualize/textual/issues/6289
+
+    You should see a widget with a red background and yellow text.
+    """
+
+    class UpdateStylesApp(App):
+        CSS = """
+        Static {
+            height: 1fr;
+            content-align: center middle;
+        }
+        """
+
+        def compose(self) -> ComposeResult:
+            yield Static("yellow on red")
+
+        def key_s(self) -> None:
+            widget = self.query_one(Static)
+            widget.styles.color = "yellow"
+            widget.styles.background = "red"
+
+    assert snap_compare(UpdateStylesApp(), press=["s"])