Faster breakpoints

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [8.2.2] - 2026-04-03
+
+### Fixed
+
+- Fixed Pointless style updates when resizing https://github.com/Textualize/textual/pull/6464
 
 ## [8.2.1] - 2026-03-29
 
@@ -3402,6 +3407,7 @@ https://textual.textualize.io/blog/2022/11/08/version-040/#version-040
 - New handler system for messages that doesn't require inheritance
 - Improved traceback handling
 
+[8.2.2]: https://github.com/Textualize/textual/compare/v8.2.1...v8.2.2
 [8.2.1]: https://github.com/Textualize/textual/compare/v8.2.0...v8.2.1
 [8.2.0]: https://github.com/Textualize/textual/compare/v8.1.1...v8.2.0
 [8.1.1]: https://github.com/Textualize/textual/compare/v8.1.0...v8.1.1

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "8.2.1"
+version = "8.2.2"
 homepage = "https://github.com/Textualize/textual"
 repository = "https://github.com/Textualize/textual"
 documentation = "https://textual.textualize.io/"

src/textual/app.py

@@ -1630,6 +1630,8 @@ def size(self) -> Size:
             width, height = self._driver._size
         else:
             width, height = self.console.size
+            if self._driver is not None:
+                self._driver._size = (width, height)
         return Size(width, height)
 
     @property

src/textual/dom.py

@@ -125,8 +125,9 @@ def __set__(self, obj: DOMNode, classes: str | Iterable[str]) -> None:
         else:
             class_names = set(classes)
         check_identifiers("class name", *class_names)
-        obj._classes = class_names
-        obj.update_node_styles()
+        if obj._classes != class_names:
+            obj._classes = class_names
+            obj.update_node_styles()
 
 
 @rich.repr.auto
@@ -1795,10 +1796,9 @@ def add_class(self, *class_names: str, update: bool = True) -> Self:
             Self.
         """
         check_identifiers("class name", *class_names)
-        old_classes = self._classes.copy()
-        self._classes.update(class_names)
-        if old_classes == self._classes:
+        if self._classes.issuperset(class_names):
             return self
+        self._classes.update(class_names)
         if update:
             self.update_node_styles()
         return self
@@ -1814,10 +1814,9 @@ def remove_class(self, *class_names: str, update: bool = True) -> Self:
             Self.
         """
         check_identifiers("class name", *class_names)
-        old_classes = self._classes.copy()
-        self._classes.difference_update(class_names)
-        if old_classes == self._classes:
+        if self._classes.isdisjoint(class_names):
             return self
+        self._classes.difference_update(class_names)
         if update:
             self.update_node_styles()
         return self

src/textual/drivers/linux_driver.py

@@ -241,6 +241,7 @@ def on_terminal_resize(signum, stack) -> None:
                 send_size_event()
 
         signal.signal(signal.SIGWINCH, on_terminal_resize)
+        send_size_event()
 
         self.write("\x1b[?1049h")  # Alt screen
 
@@ -277,7 +278,7 @@ def on_terminal_resize(signum, stack) -> None:
 
         self.flush()
         self._key_thread = Thread(target=self._run_input_thread, name="textual-input")
-        send_size_event()
+
         self._key_thread.start()
         self._request_terminal_sync_mode_support()
         self._query_in_band_window_resize()

src/textual/screen.py

@@ -1528,27 +1528,52 @@ async def _on_resize(self, event: events.Resize) -> None:
         ) or []
 
         width, height = event.size
-        if horizontal_breakpoints:
-            self._set_breakpoints(width, horizontal_breakpoints)
-        if vertical_breakpoints:
-            self._set_breakpoints(height, vertical_breakpoints)
 
-    def _set_breakpoints(
+        if horizontal_breakpoints or vertical_breakpoints:
+
+            remove_breakpoint_classes = {
+                breakpoint for _, breakpoint in horizontal_breakpoints
+            } | {breakpoint for _, breakpoint in vertical_breakpoints}
+            remove_breakpoint_classes = self._classes.intersection(
+                remove_breakpoint_classes
+            )
+
+            breakpoint_classes: set[str] = set()
+
+            if horizontal_breakpoints:
+                breakpoint_classes |= self._get_breakpoint_classes(
+                    width, horizontal_breakpoints
+                )
+            if vertical_breakpoints:
+                breakpoint_classes |= self._get_breakpoint_classes(
+                    height, vertical_breakpoints
+                )
+
+            remove_breakpoint_classes -= breakpoint_classes
+            classes = self._classes.copy()
+            if remove_breakpoint_classes:
+                self._classes.difference_update(remove_breakpoint_classes)
+            if breakpoint_classes:
+                self._classes.update(breakpoint_classes)
+            if self._classes != classes:
+                self.update_node_styles(animate=False)
+
+    def _get_breakpoint_classes(
         self, dimension: int, breakpoints: list[tuple[int, str]]
-    ) -> None:
-        """Set horizontal or vertical breakpoints.
+    ) -> set[str]:
+        """Get breakpoint classes for given dimension.
 
         Args:
-            dimension: Either the width or the height.
-            breakpoints: A list of breakpoints.
+            dimension: Size in cells.
+            breakpoints: Associated breakpoints.
 
+        Returns:
+            A set containing a breakpoint, or an empty set if none apply.
         """
-        class_names = [class_name for _breakpoint, class_name in breakpoints]
-        self.remove_class(*class_names)
         for breakpoint, class_name in sorted(breakpoints, reverse=True):
             if dimension >= breakpoint:
-                self.add_class(class_name)
-                return
+                return {class_name}
+        return set()
 
     def _update_tooltip(self, widget: Widget) -> None:
         """Update the content of the tooltip."""