animator interface

Author: willmcgugan

src/textual/_animator.py

@@ -43,6 +43,28 @@ def __call__(self, obj: object, time: float) -> bool:
         return value == self.end_value
 
 
+class BoundAnimator:
+    def __init__(self, animator: Animator, obj: object) -> None:
+        self._animator = animator
+        self._obj = obj
+
+    def __call__(
+        self,
+        attribute: str,
+        value: float,
+        *,
+        duration: float = 1,
+        easing: EasingFunction = InOutCubitEasing,
+    ) -> None:
+        self._animator.animate(
+            self._obj,
+            attribute=attribute,
+            value=value,
+            duration=duration,
+            easing=easing,
+        )
+
+
 class Animator:
     def __init__(self, target: MessageTarget) -> None:
         self._animations: dict[tuple[object, str], Animation] = {}
@@ -54,11 +76,15 @@ async def start(self) -> None:
     async def stop(self) -> None:
         self._timer.stop()
 
+    def bind(self, obj: object) -> BoundAnimator:
+        return BoundAnimator(self, obj)
+
     def animate(
         self,
         obj: object,
         attribute: str,
         value: float,
+        *,
         duration: float = 1,
         easing: EasingFunction = InOutCubitEasing,
     ) -> None:
@@ -75,13 +101,16 @@ def animate(
             easing_function=easing,
         )
         self._animations[(obj, attribute)] = animation
+        self._timer.resume()
 
     async def __call__(self) -> None:
-        log.debug("ANIMATION FRAME")
-        animation_time = time()
-        animation_keys = list(self._animations.keys())
-        for animation_key in animation_keys:
-            animation = self._animations[animation_key]
-            obj, _attribute = animation_key
-            if animation(obj, animation_time):
-                del self._animations[animation_key]
+        if not self._animations:
+            self._timer.pause()
+        else:
+            animation_time = time()
+            animation_keys = list(self._animations.keys())
+            for animation_key in animation_keys:
+                animation = self._animations[animation_key]
+                obj, _attribute = animation_key
+                if animation(obj, animation_time):
+                    del self._animations[animation_key]

src/textual/_timer.py

@@ -40,6 +40,7 @@ def __init__(
         self._callback = callback
         self._repeat = repeat
         self._stop_event = Event()
+        self._active = Event()
 
     def __rich_repr__(self) -> RichReprResult:
         yield self._interval
@@ -54,19 +55,21 @@ def target(self) -> MessageTarget:
         return target
 
     def stop(self) -> None:
+        self._active.set()
         self._stop_event.set()
 
-    async def pause(self) -> None:
-        pass
+    def pause(self) -> None:
+        self._active.clear()
 
-    async def resume(self) -> None:
-        pass
+    def resume(self) -> None:
+        self._active.set()
 
     async def run(self) -> None:
         count = 0
         _repeat = self._repeat
         _interval = self._interval
         _wait = self._stop_event.wait
+        _wait_active = self._active.wait
         start = monotonic()
         try:
             while _repeat is None or count <= _repeat:
@@ -84,5 +87,6 @@ async def run(self) -> None:
                 except EventTargetGone:
                     break
                 count += 1
+                await _wait_active()
         except CancelledError:
             pass

src/textual/widget.py

@@ -20,6 +20,7 @@
 from rich.style import Style
 
 from . import events
+from ._animator import BoundAnimator
 from ._context import active_app
 from ._loop import loop_last
 from ._line_cache import LineCache
@@ -112,6 +113,7 @@ def __init__(self, name: str | None = None) -> None:
         self.size = Dimensions(0, 0)
         self.size_changed = False
         self._repaint_required = False
+        self._animate: BoundAnimator | None = None
 
         super().__init__()
         # self.disable_messages(events.MouseMove)
@@ -139,6 +141,13 @@ def console(self) -> Console:
         """Get the current console."""
         return active_app.get().console
 
+    @property
+    def animate(self) -> BoundAnimator:
+        if self._animate is None:
+            self._animate = self.app.animator.bind(self)
+        assert self._animate is not None
+        return self._animate
+
     def require_repaint(self) -> None:
         """Mark widget as requiring a repaint.
 

src/textual/widgets/scroll_view.py

@@ -64,11 +64,12 @@ async def on_mouse_scroll_down(self, event: events.MouseScrollUp) -> None:
         self._vertical_scrollbar.position -= 1
 
     async def on_key(self, event: events.Key) -> None:
-        if event.key == "down":
+        key = event.key
+        if key == "down":
             self.y += 1
-        elif event.key == "up":
+        elif key == "up":
             self.y -= 1
-        elif event.key == "pagedown":
-            self.app.animator.animate(self, "y", self.y + self.size.height, duration=1)
-        elif event.key == "pageup":
-            self.app.animator.animate(self, "y", self.y - self.size.height, duration=1)
+        elif key == "pagedown":
+            self.animate("y", self.y + self.size.height)
+        elif key == "pageup":
+            self.animate("y", self.y - self.size.height)