color command example (#3314)

* color command example

* Scroll to end

examples/color_command.py

@@ -0,0 +1,67 @@
+from dataclasses import dataclass
+from functools import partial
+
+from textual import on
+from textual._color_constants import COLOR_NAME_TO_RGB
+from textual.app import App, ComposeResult
+from textual.command import Hit, Hits, Provider
+from textual.message import Message
+from textual.widgets import Header, Static
+
+
+@dataclass
+class SwitchColor(Message, bubble=False):
+    """Message to tell the app to switch color."""
+
+    color: str
+
+
+class ColorCommands(Provider):
+    """A command provider to select colors."""
+
+    async def search(self, query: str) -> Hits:
+        """Called for each key."""
+        matcher = self.matcher(query)
+        for color in COLOR_NAME_TO_RGB.keys():
+            score = matcher.match(color)
+            if score > 0:
+                yield Hit(
+                    score,
+                    matcher.highlight(color),
+                    partial(self.app.post_message, SwitchColor(color)),
+                )
+
+
+class ColorBlock(Static):
+    """Simple block of color."""
+
+    DEFAULT_CSS = """
+    ColorBlock{
+        padding: 3 6;
+        margin: 1 2;
+        color: auto;
+    }
+    """
+
+
+class ColorApp(App):
+    """Experiment with the command palette."""
+
+    COMMANDS = App.COMMANDS | {ColorCommands}
+    TITLE = "Press ctrl + \\ and type a color"
+
+    def compose(self) -> ComposeResult:
+        yield Header()
+
+    @on(SwitchColor)
+    def switch_color(self, event: SwitchColor) -> None:
+        """Adds a color block on demand."""
+        color_block = ColorBlock(event.color)
+        color_block.styles.background = event.color
+        self.mount(color_block)
+        self.screen.scroll_end()
+
+
+if __name__ == "__main__":
+    app = ColorApp()
+    app.run()

src/textual/_types.py

@@ -29,6 +29,8 @@ def post_message(self, message: "Message") -> bool:
 SegmentLines = List[List["Segment"]]
 CallbackType = Union[Callable[[], Awaitable[None]], Callable[[], None]]
 """Type used for arbitrary callables used in callbacks."""
+IgnoreReturnCallbackType = Union[Callable[[], Awaitable[Any]], Callable[[], Any]]
+"""A callback which ignores the return type."""
 WatchCallbackType = Union[
     Callable[[], Awaitable[None]],
     Callable[[Any], Awaitable[None]],

src/textual/command.py

@@ -31,7 +31,7 @@
 from .reactive import var
 from .screen import ModalScreen, Screen
 from .timer import Timer
-from .types import CallbackType
+from .types import CallbackType, IgnoreReturnCallbackType
 from .widget import Widget
 from .widgets import Button, Input, LoadingIndicator, OptionList, Static
 from .widgets.option_list import Option
@@ -62,7 +62,7 @@ class Hit:
     match_display: RenderableType
     """A string or Rich renderable representation of the hit."""
 
-    command: CallbackType
+    command: IgnoreReturnCallbackType
     """The function to call when the command is chosen."""
 
     text: str | None = None
@@ -354,8 +354,13 @@ class CommandPalette(ModalScreen[CallbackType], inherit_css=False):
         color: $text-muted;
     }
 
+    App.-dark-mode CommandPalette > .command-palette--highlight {
+        text-style: bold;
+        color: $warning;
+    }
     CommandPalette > .command-palette--highlight {
-        text-style: bold reverse;
+        text-style: bold;
+        color: $warning-darken-2;
     }
 
     CommandPalette > Vertical {

src/textual/types.py

@@ -5,7 +5,12 @@
 from ._animator import Animatable, EasingFunction
 from ._context import NoActiveAppError
 from ._path import CSSPathError, CSSPathType
-from ._types import CallbackType, MessageTarget, WatchCallbackType
+from ._types import (
+    CallbackType,
+    IgnoreReturnCallbackType,
+    MessageTarget,
+    WatchCallbackType,
+)
 from .actions import ActionParseResult
 from .css.styles import RenderStyles
 from .widgets._data_table import CursorType
@@ -19,6 +24,7 @@
     "CSSPathType",
     "CursorType",
     "EasingFunction",
+    "IgnoreReturnCallbackType",
     "InputValidationOn",
     "MessageTarget",
     "NoActiveAppError",