Register callbacks at message pump level, invoke them after refresh (#607)

* Register callbacks at message pump level, invoke them after refresh

* Fix a typo

* Code review feedback actions

* call_later callbacks invoked after refresh or on idle

* Fix space key in text input

* Make Widget.on_idle synchronous

* Fix call_later

* Rename PostScreenUpdate to InvokeCallbacks, and only fire if callbacks exist

* Update type hints for InvokeLater callbacks

* Update type signature of call_later callbacks, extract typevar

Makefile

@@ -1,5 +1,7 @@
 test:
 	pytest --cov-report term-missing --cov=textual tests/ -vv
+unit-test:
+	pytest --cov-report term-missing --cov=textual tests/ -vv -m "not integration_test"
 typecheck:
 	mypy src/textual
 format:

sandbox/darren/file_search.py

@@ -4,7 +4,6 @@ from pathlib import Path
 from typing import Iterable
 
 from rich.console import RenderableType
-from rich.style import Style
 from rich.table import Table
 from rich.text import Text
 

src/textual/css/Makefile

@@ -1,3 +0,0 @@
-parser.py:
-	python -m lark.tools.standalone css.g > parser.py
-	black parser.py

src/textual/events.py

@@ -45,6 +45,10 @@ class Callback(Event, bubble=False, verbosity=3):
         yield "callback", self.callback
 
 
+class InvokeCallbacks(Event, bubble=False):
+    """Sent after the Screen is updated"""
+
+
 class ShutdownRequest(Event):
     pass
 
@@ -209,7 +213,7 @@ class Key(InputEvent):
         Returns:
             bool: True if the key is printable. False otherwise.
         """
-        return self.key not in KEY_VALUES
+        return self.key == Keys.Space or self.key not in KEY_VALUES
 
 
 @rich.repr.auto

src/textual/message_pump.py

@@ -193,14 +193,20 @@ class MessagePump:
         return timer
 
     def call_later(self, callback: Callable, *args, **kwargs) -> None:
-        """Run a callback after processing all messages and refreshing the screen.
+        """Schedule a callback to run after all messages are processed and the screen
+        has been refreshed.
 
         Args:
             callback (Callable): A callable.
         """
-        self.post_message_no_wait(
-            events.Callback(self, partial(callback, *args, **kwargs))
-        )
+        # We send the InvokeLater message to ourselves first, to ensure we've cleared
+        # out anything already pending in our own queue.
+        message = messages.InvokeLater(self, partial(callback, *args, **kwargs))
+        self.post_message_no_wait(message)
+
+    def handle_invoke_later(self, message: messages.InvokeLater) -> None:
+        # Forward InvokeLater message to the Screen
+        self.app.screen.post_message_no_wait(message)
 
     def close_messages_no_wait(self) -> None:
         """Request the message queue to exit."""
@@ -392,9 +398,6 @@ class MessagePump:
             return False
         return self.post_message_no_wait(message)
 
-    async def on_callback(self, event: events.Callback) -> None:
-        await invoke(event.callback)
-
     def emit_no_wait(self, message: Message) -> bool:
         if self._parent:
             return self._parent.post_message_from_child_no_wait(message)

src/textual/messages.py

@@ -1,5 +1,5 @@
 from __future__ import annotations
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Callable, Awaitable, Union
 
 import rich.repr
 
@@ -11,6 +11,9 @@ if TYPE_CHECKING:
     from .widget import Widget
 
 
+CallbackType = Union[Callable[[], Awaitable[None]], Callable[[], None]]
+
+
 @rich.repr.auto
 class Update(Message, verbosity=3):
     def __init__(self, sender: MessagePump, widget: Widget):
@@ -37,6 +40,16 @@ class Layout(Message, verbosity=3):
         return isinstance(message, Layout)
 
 
+@rich.repr.auto
+class InvokeLater(Message, verbosity=3):
+    def __init__(self, sender: MessagePump, callback: CallbackType) -> None:
+        self.callback = callback
+        super().__init__(sender)
+
+    def __rich_repr__(self) -> rich.repr.Result:
+        yield "callback", self.callback
+
+
 @rich.repr.auto
 class CursorMove(Message):
     def __init__(self, sender: MessagePump, line: int) -> None:

src/textual/screen.py

@@ -8,16 +8,18 @@ from rich.style import Style
 
 
 from . import events, messages, errors
+from ._callback import invoke
 
 from .geometry import Offset, Region, Size
 from ._compositor import Compositor, MapGeometry
+from .messages import CallbackType
 from .reactive import Reactive
 from .renderables.blank import Blank
 from ._timer import Timer
 from .widget import Widget
 
 if sys.version_info >= (3, 8):
-    from typing import Final
+    from typing import Final, Callable, Awaitable
 else:
     from typing_extensions import Final
 
@@ -31,7 +33,7 @@ class Screen(Widget):
 
     CSS = """
     Screen {
-            
+
         layout: vertical;
         overflow-y: auto;
     }
@@ -44,6 +46,7 @@ class Screen(Widget):
         self._compositor = Compositor()
         self._dirty_widgets: set[Widget] = set()
         self._update_timer: Timer | None = None
+        self._callbacks: list[CallbackType] = []
 
     @property
     def is_transparent(self) -> bool:
@@ -110,7 +113,7 @@ class Screen(Widget):
         """
         return self._compositor.find_widget(widget)
 
-    def on_idle(self, event: events.Idle) -> None:
+    async def on_idle(self, event: events.Idle) -> None:
         # Check for any widgets marked as 'dirty' (needs a repaint)
         event.prevent_default()
         if self._layout_required:
@@ -125,6 +128,9 @@ class Screen(Widget):
         if self._dirty_widgets:
             self.update_timer.resume()
 
+        # The Screen is idle - a good opportunity to invoke the scheduled callbacks
+        await self._invoke_and_clear_callbacks()
+
     def _on_update(self) -> None:
         """Called by the _update_timer."""
         # Render widgets together
@@ -132,7 +138,27 @@ class Screen(Widget):
             self._compositor.update_widgets(self._dirty_widgets)
             self.app._display(self._compositor.render())
             self._dirty_widgets.clear()
+
         self.update_timer.pause()
+        if self._callbacks:
+            self.post_message_no_wait(events.InvokeCallbacks(self))
+
+    async def on_invoke_callbacks(self, event: events.InvokeCallbacks) -> None:
+        """Handle PostScreenUpdate events, which are sent after the screen is updated"""
+        await self._invoke_and_clear_callbacks()
+
+    async def _invoke_and_clear_callbacks(self) -> None:
+        """If there are scheduled callbacks to run, call them and clear
+        the callback queue."""
+        if self._callbacks:
+            callbacks = self._callbacks[:]
+            self._callbacks.clear()
+            for callback in callbacks:
+                await invoke(callback)
+
+    def handle_invoke_later(self, message: messages.InvokeLater) -> None:
+        # Enqueue the callback function to be called later
+        self._callbacks.append(message.callback)
 
     def _refresh_layout(self, size: Size | None = None, full: bool = False) -> None:
         """Refresh the layout (can change size and positions of widgets)."""

src/textual/widgets/text_input.py

@@ -40,6 +40,8 @@ class TextWidgetBase(Widget):
         key = event.key
         if key == "escape":
             return
+        elif key == "space":
+            key = " "
 
         changed = False
         if event.is_printable:

tests/test_integration_layout.py

@@ -12,6 +12,8 @@ from textual.geometry import Size
 from textual.widget import Widget
 from textual.widgets import Placeholder
 
+pytestmark = pytest.mark.integration_test
+
 # Let's allow ourselves some abbreviated names for those tests,
 # in order to make the test cases a bit easier to read :-)
 SCREEN_W = 100  # width of our Screens
@@ -26,7 +28,6 @@ SCROLL_V_SIZE = 2
 
 
 @pytest.mark.asyncio
-@pytest.mark.integration_test  # this is a slow test, we may want to skip them in some contexts
 @pytest.mark.parametrize(
     (
         "placeholders_count",
@@ -164,7 +165,6 @@ async def test_composition_of_vertical_container_with_children(
 
 
 @pytest.mark.asyncio
-@pytest.mark.integration_test
 @pytest.mark.parametrize(
     "edge_type,expected_box_inner_size,expected_box_size,expected_top_left_edge_color,expects_visible_char_at_top_left_edge",
     (

tests/test_integration_scrolling.py

@@ -9,12 +9,13 @@ from textual.geometry import Size
 from textual.widget import Widget
 from textual.widgets import Placeholder
 
+pytestmark = pytest.mark.integration_test
+
 SCREEN_SIZE = Size(100, 30)
 
 
 @pytest.mark.skip("Needs a rethink")
 @pytest.mark.asyncio
-@pytest.mark.integration_test  # this is a slow test, we may want to skip them in some contexts
 @pytest.mark.parametrize(
     (
         "screen_size",