Startup optimizations

CHANGELOG.md

@@ -5,6 +5,13 @@ 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/).
 
+## Unreleased
+
+### Changed
+
+- Optimized startup https://github.com/Textualize/textual/pull/5869
+- New blank visual which makes background faster to render (note this will break snapshots tests this version) https://github.com/Textualize/textual/pull/5869
+
 ## [3.4.0] - 2025-06-14
 
 ### Fixed

pyproject.toml

@@ -63,7 +63,7 @@ tree-sitter-yaml = { version = ">=0.6.0", optional = true, python = ">=3.9" }
 tree-sitter-html = { version = ">=0.23.0", optional = true, python = ">=3.9" }
 tree-sitter-css = { version = ">=0.23.0", optional = true, python = ">=3.9" }
 tree-sitter-javascript = { version = ">=0.23.0", optional = true, python = ">=3.9" }
-tree-sitter-rust = { version = ">=0.23.0", optional = true, python = ">=3.9" }
+tree-sitter-rust = { version = ">=0.23.0,<=0.23.2", optional = true, python = ">=3.9" }
 tree-sitter-go = { version = ">=0.23.0", optional = true, python = ">=3.9" }
 tree-sitter-regex = { version = ">=0.24.0", optional = true, python = ">=3.9" }
 tree-sitter-xml = { version = ">=0.7.0", optional = true, python = ">=3.9" }

src/textual/app.py

@@ -791,8 +791,8 @@ def __init__(
         perform work after the app has resumed.
         """
 
-        self.set_class(self.current_theme.dark, "-dark-mode")
-        self.set_class(not self.current_theme.dark, "-light-mode")
+        self.set_class(self.current_theme.dark, "-dark-mode", update=False)
+        self.set_class(not self.current_theme.dark, "-light-mode", update=False)
 
         self.animation_level: AnimationLevel = constants.TEXTUAL_ANIMATIONS
         """Determines what type of animations the app will display.

src/textual/dom.py

@@ -1684,9 +1684,9 @@ def set_class(self, add: bool, *class_names: str, update: bool = True) -> Self:
             Self.
         """
         if add:
-            self.add_class(*class_names, update=update and self.is_attached)
+            self.add_class(*class_names, update=update)
         else:
-            self.remove_class(*class_names, update=update and self.is_attached)
+            self.remove_class(*class_names, update=update)
         return self
 
     def set_classes(self, classes: str | Iterable[str]) -> Self:
@@ -1707,6 +1707,8 @@ def _update_styles(self) -> None:
 
         Should be called whenever CSS classes / pseudo classes change.
         """
+        if not self.is_attached:
+            return
         try:
             self.app.update_styles(self)
         except NoActiveAppError:

src/textual/renderables/blank.py

@@ -1,27 +1,39 @@
 from __future__ import annotations
 
-from rich.console import Console, ConsoleOptions, RenderResult
-from rich.segment import Segment
-from rich.style import Style
+from rich.style import Style as RichStyle
 
 from textual.color import Color
+from textual.content import Style
+from textual.css.styles import RulesMap
+from textual.selection import Selection
+from textual.strip import Strip
+from textual.visual import Visual
 
 
-class Blank:
+class Blank(Visual):
     """Draw solid background color."""
 
     def __init__(self, color: Color | str = "transparent") -> None:
-        background = Color.parse(color)
-        self._style = Style.from_color(bgcolor=background.rich_color)
-
-    def __rich_console__(
-        self, console: Console, options: ConsoleOptions
-    ) -> RenderResult:
-        width = options.max_width
-        height = options.height or options.max_height
-
-        segment = Segment(" " * width, self._style)
-        line = Segment.line()
-        for _ in range(height):
-            yield segment
-            yield line
+        self._rich_style = RichStyle.from_color(bgcolor=Color.parse(color).rich_color)
+
+    def visualize(self) -> Blank:
+        return self
+
+    def get_optimal_width(self, rules: RulesMap, container_width: int) -> int:
+        return container_width
+
+    def get_height(self, rules: RulesMap, width: int) -> int:
+        return 1
+
+    def render_strips(
+        self,
+        rules: RulesMap,
+        width: int,
+        height: int | None,
+        style: Style,
+        selection: Selection | None = None,
+        selection_style: Style | None = None,
+        post_style: Style | None = None,
+    ) -> list[Strip]:
+        line_count = 1 if height is None else height
+        return [Strip.blank(width, self._rich_style)] * line_count

src/textual/screen.py

@@ -1318,14 +1318,16 @@ def _get_inline_height(self, size: Size) -> int:
 
     def _screen_resized(self, size: Size) -> None:
         """Called by App when the screen is resized."""
-        if self.stack_updates:
+        if self.stack_updates and self.is_attached:
             self._refresh_layout(size)
 
     def _on_screen_resume(self) -> None:
         """Screen has resumed."""
         if self.app.SUSPENDED_SCREEN_CLASS:
             self.remove_class(self.app.SUSPENDED_SCREEN_CLASS)
+
         self.stack_updates += 1
+
         self.app._refresh_notifications()
         size = self.app.size
 
@@ -1340,10 +1342,11 @@ def _on_screen_resume(self) -> None:
                         self.set_focus(widget)
                         break
 
-        self._compositor_refresh()
-        self.app.stylesheet.update(self)
-        self._refresh_layout(size)
-        self.refresh()
+        if self.is_attached:
+            self._compositor_refresh()
+            self.app.stylesheet.update(self)
+            self._refresh_layout(size)
+            self.refresh()
 
     def _on_screen_suspend(self) -> None:
         """Screen has suspended."""