ThemeProvider

src/textual/app.py

@@ -122,7 +122,7 @@ from textual.screen import (
     SystemModalScreen,
 )
 from textual.signal import Signal
-from textual.theme import BUILTIN_THEMES, Theme
+from textual.theme import BUILTIN_THEMES, Theme, ThemeProvider
 from textual.timer import Timer
 from textual.widget import AwaitMount, Widget
 from textual.widgets._toast import ToastRack
@@ -1527,7 +1527,12 @@ class App(Generic[ReturnType], DOMNode):
 
     def action_change_theme(self) -> None:
         """An [action](/guide/actions) to change the current theme."""
-        self.push_screen(CommandPalette())
+        self.app.push_screen(
+            CommandPalette(
+                [ThemeProvider],
+                placeholder="Search for themes…",
+            ),
+        )
 
     def action_screenshot(
         self, filename: str | None = None, path: str | None = None
@@ -4138,7 +4143,7 @@ class App(Generic[ReturnType], DOMNode):
     def action_command_palette(self) -> None:
         """Show the Textual command palette."""
         if self.use_command_palette and not CommandPalette.is_open(self):
-            self.push_screen(CommandPalette())
+            self.push_screen(CommandPalette(id="--command-palette"))
 
     def _suspend_signal(self) -> None:
         """Signal that the application is being suspended."""

src/textual/command.py

@@ -597,9 +597,6 @@ class CommandPalette(SystemModalScreen):
     _calling_screen: var[Screen[Any] | None] = var(None)
     """A record of the screen that was active when we were called."""
 
-    _PALETTE_ID: Final[str] = "--command-palette"
-    """The internal ID for the command palette."""
-
     @dataclass
     class OptionHighlighted(Message):
         """Posted to App when an option is highlighted in the command palette."""
@@ -618,14 +615,29 @@ class CommandPalette(SystemModalScreen):
         option_selected: bool
         """True if an option was selected, False if the palette was closed without selecting an option."""
 
-    def __init__(self, providers: ProviderSource | None = None) -> None:
+    def __init__(
+        self,
+        providers: ProviderSource | None = None,
+        *,
+        placeholder: str = "Search for commands…",
+        name: str | None = None,
+        id: str | None = None,
+        classes: str | None = None,
+    ) -> None:
         """Initialise the command palette.
 
         Args:
             providers: An optional list of providers to use. If None, the providers supplied
                 in the App or Screen will be used.
+            placeholder: The placeholder text for the command palette.
         """
-        super().__init__(id=self._PALETTE_ID)
+        super().__init__(
+            id=id,
+            classes=classes,
+            name=name,
+        )
+        self.add_class("--textual-command-palette")
+
         self._selected_command: DiscoveryHit | Hit | None = None
         """The command that was selected by the user."""
         self._busy_timer: Timer | None = None
@@ -637,18 +649,19 @@ class CommandPalette(SystemModalScreen):
         """List of Provider instances involved in searches."""
         self._hit_count: int = 0
         """Number of hits displayed."""
+        self._placeholder = placeholder
 
     @staticmethod
     def is_open(app: App[object]) -> bool:
-        """Is the command palette current open?
+        """Is a command palette current open?
 
         Args:
             app: The app to test.
 
         Returns:
-            `True` if the command palette is currently open, `False` if not.
+            `True` if a command palette is currently open, `False` if not.
         """
-        return app.screen.id == CommandPalette._PALETTE_ID
+        return app.screen.has_class("--textual-command-palette")
 
     @property
     def _provider_classes(self) -> set[type[Provider]]:
@@ -697,7 +710,7 @@ class CommandPalette(SystemModalScreen):
         with Vertical(id="--container"):
             with Horizontal(id="--input"):
                 yield SearchIcon()
-                yield CommandInput(placeholder="Search for commands…")
+                yield CommandInput(placeholder=self._placeholder)
                 if not self.run_on_select:
                     yield Button("\u25b6")
             with Vertical(id="--results"):

src/textual/theme.py

@@ -1,7 +1,10 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from functools import partial
+from typing import Callable
 
+from textual.command import DiscoveryHit, Hit, Hits, Provider
 from textual.design import ColorSystem
 
 
@@ -366,3 +369,34 @@ BUILTIN_THEMES: dict[str, Theme] = {
         panel="#2A2A2A",  # Dark Gray
     ),
 }
+
+
+class ThemeProvider(Provider):
+    """A provider for themes."""
+
+    @property
+    def commands(self) -> list[tuple[str, Callable[[], None]]]:
+        themes = self.app.available_themes
+
+        def set_app_theme(name: str) -> None:
+            self.app.theme = name
+
+        return [
+            (theme.name, partial(set_app_theme, theme.name))
+            for theme in themes.values()
+        ]
+
+    async def discover(self) -> Hits:
+        for command in self.commands:
+            yield DiscoveryHit(*command)
+
+    async def search(self, query: str) -> Hits:
+        matcher = self.matcher(query)
+
+        for name, callback in self.commands:
+            if (match := matcher.match(name)) > 0:
+                yield Hit(
+                    match,
+                    matcher.highlight(name),
+                    callback,
+                )