line cache

pyproject.toml

@@ -1,7 +1,7 @@
 [tool.poetry]
 name = "textual"
 version = "0.1.0"
-description = "Rich TUI"
+description = "Text User Interface using Rich"
 authors = ["Will McGugan <willmcgugan@gmail.com>"]
 license = "MIT"
 

rich-tui.code-workspace

@@ -2,6 +2,9 @@
 	"folders": [
 		{
 			"path": "."
+		},
+		{
+			"path": "../rich"
 		}
 	],
 	"settings": {

src/textual/_line_cache.py

@@ -0,0 +1,39 @@
+from typing import Iterable, List
+
+from rich.console import Console, ConsoleOptions, RenderableType, RenderResult
+from rich.control import Control
+from rich.segment import Segment
+
+
+class LineCache:
+    def __init__(self, lines: List[List[Segment]]) -> None:
+        self.lines = lines
+        self.dirty = [True] * len(self.lines)
+
+    @classmethod
+    def from_renderable(
+        cls,
+        console: Console,
+        renderable: RenderableType,
+        width: int,
+        height: int,
+    ) -> "LineCache":
+        options = console.options.update_dimensions(width, height)
+        lines = console.render_lines(renderable, options, new_lines=False)
+        return cls(lines)
+
+    def __rich_console__(
+        self, console: Console, options: ConsoleOptions
+    ) -> RenderResult:
+        new_line = Segment.line()
+        for line in self.lines:
+            yield from line
+            yield new_line
+
+    def render(self, x: int, y: int) -> Iterable[Segment]:
+        move_to = Control.move_to
+        for offset_y, (line, dirty) in enumerate(zip(self.lines, self.dirty), y):
+            if dirty:
+                yield move_to(x, offset_y).segment
+                yield from line
+        self.dirty[:] = [False] * len(self.lines)

src/textual/app.py

@@ -90,6 +90,9 @@ class App(MessagePump):
                 Screen(Control.home(), self.view, Control.home(), application_mode=True)
             )
 
+    async def on_idle(self, event: events.Idle) -> None:
+        await self.view.post_message(event)
+
     async def action(self, action: str) -> None:
         if "." in action:
             destination, action_name, *tokens = action.split(".")

src/textual/events.py

@@ -220,7 +220,6 @@ class Enter(Event, type=EventType.ENTER):
         yield "y", self.y
 
 
-@rich_repr
 class Leave(Event, type=EventType.LEAVE):
     pass
 

src/textual/message_pump.py

@@ -121,9 +121,11 @@ class MessagePump:
             except Exception:
                 log.exception("error getting message")
                 break
-            await self.dispatch_message(message, priority)
-            if self._message_queue.empty():
-                await self.dispatch_message(events.Idle(self))
+            try:
+                await self.dispatch_message(message, priority)
+            finally:
+                if self._message_queue.empty():
+                    await self.dispatch_message(events.Idle(self))
 
     async def dispatch_message(
         self, message: Message, priority: int = 0

src/textual/view.py

@@ -81,6 +81,7 @@ class LayoutView(View):
         self.focused: Optional[MessagePump] = None
         self._widgets: Set[Widget] = set()
         super().__init__()
+        self.enable_messages(events.Idle)
 
     def __rich_repr__(self) -> RichReprResult:
         yield "name", self.name
@@ -136,9 +137,6 @@ class LayoutView(View):
                 )
         self.app.refresh()
 
-    async def on_idle(self, event: events.Idle) -> None:
-        pass
-
     async def on_move(self, event: events.Move) -> None:
         try:
             widget, region = self.get_widget_at(event.x, event.y)

src/textual/widget.py

@@ -2,6 +2,7 @@ from logging import getLogger
 from typing import (
     ClassVar,
     Generic,
+    Iterable,
     List,
     NamedTuple,
     Optional,
@@ -20,6 +21,7 @@ from rich.segment import Segment
 
 from . import events
 from ._context import active_app
+from ._line_cache import LineCache
 from .message import Message
 from .message_pump import MessagePump
 
@@ -44,6 +46,7 @@ class Reactive(Generic[T]):
 
     def __set__(self, obj: "Widget", value: T) -> None:
         if getattr(obj, self.internal_name) != value:
+            log.debug("%s -> %s", self.internal_name, value)
             setattr(obj, self.internal_name, value)
             obj.require_refresh()
 
@@ -66,8 +69,7 @@ class Widget(MessagePump):
         self.size = WidgetDimensions(0, 0)
         self.size_changed = False
         self._refresh_required = False
-        self._dirty_lines: List[bool] = []
-        self._line_cache: List[List[Segment]] = []
+        self._line_cache: Optional[LineCache] = None
         super().__init__()
         if not self.mouse_events:
             self.disable_messages(
@@ -94,6 +96,9 @@ class Widget(MessagePump):
     has_focus: Reactive[bool] = Reactive(False)
     mouse_over: Reactive[bool] = Reactive(False)
 
+    def __rich_repr__(self) -> RichReprResult:
+        yield "name", self.name
+
     @property
     def app(self) -> "App":
         """Get the current app."""
@@ -104,25 +109,26 @@ class Widget(MessagePump):
         """Get the current console."""
         return active_app.get().console
 
+    @property
+    def line_cache(self) -> LineCache:
+
+        if self._line_cache is None:
+            width, height = self.size
+            renderable = self.render()
+            self._line_cache = LineCache.from_renderable(
+                self.console, renderable, width, height
+            )
+        assert self._line_cache is not None
+        return self._line_cache
+
+    def __rich__(self) -> LineCache:
+        return self.line_cache
+
     def require_refresh(self) -> None:
-        self._dirty_lines[:] = [True] * len(self._line_cache)
-        self.app.refresh()
+        self._line_cache = None
 
-    async def refresh(self) -> None:
-        self.app.refresh()
-
-    def __rich_repr__(self) -> RichReprResult:
-        yield "name", self.name
-
-    def render_line_cache(self) -> None:
-        console = self.console
-        options = console.options.update_dimensions(self.size.width, self.size.height)
-        renderable = self.render()
-        self._line_cache[:] = console.render_lines(renderable, options, new_lines=False)
-        self._dirty_lines = [True] * len(self._line_cache)
-
-    def _clean_line_cache(self) -> None:
-        self._dirty_lines = [False] * len(self._line_cache)
+    def render_update(self, x: int, y: int) -> Iterable[Segment]:
+        yield from self.line_cache.render(x, y)
 
     def render(self) -> RenderableType:
         return Panel(
@@ -132,17 +138,6 @@ class Widget(MessagePump):
             box=box.HEAVY if self.has_focus else box.ROUNDED,
         )
 
-    def __rich_console__(
-        self, console: Console, options: ConsoleOptions
-    ) -> RenderResult:
-        self.render_line_cache()
-        new_line = Segment.line()
-        for line in self._line_cache:
-            yield from line
-            yield new_line
-        self._clean_line_cache()
-        self._refresh_required = True
-
     async def post_message(
         self, message: Message, priority: Optional[int] = None
     ) -> bool:
@@ -167,3 +162,6 @@ class Widget(MessagePump):
 
     async def on_blur(self, event: events.Focus) -> None:
         self.has_focus = False
+
+    async def on_idle(self, event: events.Idle) -> None:
+        self.app.refresh()