Sensible default key displays + allow users to override key displays at the App level

CHANGELOG.md

@@ -26,6 +26,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Added Pilot.wait_for_animation
 - Added `Widget.move_child` https://github.com/Textualize/textual/issues/1121
 - Support lazy-instantiated Screens (callables in App.SCREENS) https://github.com/Textualize/textual/pull/1185
+- Display of keys in footer has more sensible defaults https://github.com/Textualize/textual/pull/1213
+- Add App.get_key_display, allowing custom key_display App-wide https://github.com/Textualize/textual/pull/1213
 
 ### Changed
 

src/textual/app.py

@@ -56,12 +56,12 @@
 from .features import FeatureFlag, parse_features
 from .file_monitor import FileMonitor
 from .geometry import Offset, Region, Size
-from .keys import REPLACED_KEYS
+from .keys import REPLACED_KEYS, _get_key_display
 from .messages import CallbackType
 from .reactive import Reactive
 from .renderables.blank import Blank
 from .screen import Screen
-from .widget import AwaitMount, Widget, MountError
+from .widget import AwaitMount, Widget
 
 if TYPE_CHECKING:
     from .devtools.client import DevtoolsClient
@@ -102,7 +102,6 @@
 ComposeResult = Iterable[Widget]
 RenderResult = RenderableType
 
-
 AutopilotCallbackType: TypeAlias = "Callable[[Pilot], Coroutine[Any, Any, None]]"
 
 
@@ -668,6 +667,22 @@ def bind(
             keys, action, description, show=show, key_display=key_display
         )
 
+    def get_key_display(self, key: str) -> str:
+        """For a given key, return how it should be displayed in an app
+        (e.g. in the Footer widget).
+        By key, we refer to the string used in the "key" argument for
+        a Binding instance. By overriding this method, you can ensure that
+        keys are displayed consistently throughout your app, without
+        needing to add a key_display to every binding.
+
+        Args:
+            key (str): The binding key string.
+
+        Returns:
+            str: The display string for the input key.
+        """
+        return _get_key_display(key)
+
     async def _press_keys(self, keys: Iterable[str]) -> None:
         """A task to send key events."""
         app = self
@@ -705,7 +720,7 @@ async def _press_keys(self, keys: Iterable[str]) -> None:
                 #  This conditional sleep can be removed after that issue is closed.
                 if key == "tab":
                     await asyncio.sleep(0.05)
-                await asyncio.sleep(0.02)
+                await asyncio.sleep(0.025)
         await app._animator.wait_for_idle()
 
     @asynccontextmanager

src/textual/keys.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import unicodedata
 from enum import Enum
 
 
@@ -219,7 +220,34 @@ class Keys(str, Enum):
     "ctrl+j": ["newline"],
 }
 
+KEY_DISPLAY_ALIASES = {
+    "up": "↑",
+    "down": "↓",
+    "left": "←",
+    "right": "→",
+    "backspace": "⌫",
+    "escape": "ESC",
+    "enter": "⏎",
+}
+
 
 def _get_key_aliases(key: str) -> list[str]:
     """Return all aliases for the given key, including the key itself"""
     return [key] + KEY_ALIASES.get(key, [])
+
+
+def _get_key_display(key: str) -> str:
+    """Given a key (i.e. the `key` string argument to Binding __init__),
+    return the value that should be displayed in the app when referring
+    to this key (e.g. in the Footer widget)."""
+    display_alias = KEY_DISPLAY_ALIASES.get(key)
+    if display_alias:
+        return display_alias
+
+    original_key = REPLACED_KEYS.get(key, key)
+    try:
+        unicode_character = unicodedata.lookup(original_key.upper().replace("_", " "))
+    except KeyError:
+        return original_key.upper()
+
+    return unicode_character

src/textual/widgets/_footer.py

@@ -7,6 +7,7 @@
 from rich.text import Text
 
 from .. import events
+from ..keys import _get_key_display
 from ..reactive import Reactive, watch
 from ..widget import Widget
 
@@ -99,11 +100,12 @@ def make_key_text(self) -> Text:
 
         for action, bindings in action_to_bindings.items():
             binding = bindings[0]
-            key_display = (
-                binding.key.upper()
-                if binding.key_display is None
-                else binding.key_display
-            )
+            if binding.key_display is None:
+                key_display = self.app.get_key_display(binding.key)
+                if key_display is None:
+                    key_display = binding.key.upper()
+            else:
+                key_display = binding.key_display
             hovered = self.highlight_key == binding.key
             key_text = Text.assemble(
                 (f" {key_display} ", highlight_key_style if hovered else key_style),

tests/snapshot_tests/__snapshots__/test_snapshots.ambr

@@ -6166,6 +6166,163 @@
 
   '''
 # ---
+# name: test_key_display
+  '''
+  <svg class="rich-terminal" viewBox="0 0 994 635.5999999999999" xmlns="http://www.w3.org/2000/svg">
+      <!-- Generated with Rich https://www.textualize.io -->
+      <style>
+
+      @font-face {
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+          src: local("FiraCode-Regular"),
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+                  url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff/FiraCode-Regular.woff") format("woff");
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+                  url("https://cdnjs.cloudflare.com/ajax/libs/firacode/6.2.0/woff/FiraCode-Bold.woff") format("woff");
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+          font-weight: 700;
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+
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+  '''
+# ---
 # name: test_layers
   '''
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tests/snapshot_tests/snapshot_apps/key_display.py

@@ -0,0 +1,36 @@
+from textual.app import App, ComposeResult
+from textual.binding import Binding
+from textual.widgets import Footer
+
+
+class KeyDisplayApp(App):
+    """Tests how keys are displayed in the Footer, and ensures
+    that overriding the key_displays works as expected.
+    Exercises both the built-in Textual key display replacements,
+    and user supplied replacements.
+    Will break when we update the Footer - but we should add a similar
+    test (or updated snapshot) for the updated Footer."""
+    BINDINGS = [
+        Binding("question_mark", "question", "Question"),
+        Binding("ctrl+q", "quit", "Quit app"),
+        Binding("escape", "escape", "Escape"),
+        Binding("a", "a", "Letter A"),
+    ]
+
+    def compose(self) -> ComposeResult:
+        yield Footer()
+
+    def get_key_display(self, key: str) -> str:
+        key_display_replacements = {
+            "escape": "Escape!",
+            "ctrl+q": "^q",
+        }
+        display = key_display_replacements.get(key)
+        if display:
+            return display
+        return super().get_key_display(key)
+
+
+app = KeyDisplayApp()
+if __name__ == '__main__':
+    app.run()

tests/snapshot_tests/test_snapshots.py

@@ -118,3 +118,9 @@ def test_css_property(file_name, snap_compare):
 def test_multiple_css(snap_compare):
     # Interaction between multiple CSS files and app-level/classvar CSS
     assert snap_compare("snapshot_apps/multiple_css/multiple_css.py")
+
+
+# --- Other ---
+
+def test_key_display(snap_compare):
+    assert snap_compare(SNAPSHOT_APPS_DIR / "key_display.py")