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import asyncio
import sys
from abc import ABC, abstractmethod
from dataclasses import dataclass
from functools import partial
from typing import Any, Callable, TypeVar, TYPE_CHECKING
from . import _clock
from ._callback import invoke
from ._easing import DEFAULT_EASING, EASING
from ._types import CallbackType
from .timer import Timer
if sys.version_info >= (3, 8):
from typing import Protocol, runtime_checkable
else: # pragma: no cover
from typing_extensions import Protocol, runtime_checkable
if TYPE_CHECKING:
from textual.app import App
EasingFunction = Callable[[float], float]
T = TypeVar("T")
@runtime_checkable
class Animatable(Protocol):
def blend(self: T, destination: T, factor: float) -> T: # pragma: no cover
...
class Animation(ABC):
on_complete: CallbackType | None = None
"""Callback to run after animation completes"""
@abstractmethod
def __call__(self, time: float) -> bool: # pragma: no cover
"""Call the animation, return a boolean indicating whether animation is in-progress or complete.
Args:
time (float): The current timestamp
Returns:
bool: True if the animation has finished, otherwise False.
"""
raise NotImplementedError("")
def __eq__(self, other: object) -> bool:
return False
@dataclass
class SimpleAnimation(Animation):
obj: object
attribute: str
start_time: float
duration: float
start_value: float | Animatable
end_value: float | Animatable
final_value: object
easing: EasingFunction
on_complete: CallbackType | None = None
def __call__(self, time: float) -> bool:
if self.duration == 0:
setattr(self.obj, self.attribute, self.final_value)
return True
factor = min(1.0, (time - self.start_time) / self.duration)
eased_factor = self.easing(factor)
if factor == 1.0:
value = self.final_value
elif isinstance(self.start_value, Animatable):
assert isinstance(
self.end_value, Animatable
), "end_value must be animatable"
value = self.start_value.blend(self.end_value, eased_factor)
else:
assert isinstance(
self.start_value, (int, float)
), f"`start_value` must be float, not {self.start_value!r}"
assert isinstance(
self.end_value, (int, float)
), f"`end_value` must be float, not {self.end_value!r}"
if self.end_value > self.start_value:
eased_factor = self.easing(factor)
value = (
self.start_value
+ (self.end_value - self.start_value) * eased_factor
)
else:
eased_factor = 1 - self.easing(factor)
value = (
self.end_value + (self.start_value - self.end_value) * eased_factor
)
setattr(self.obj, self.attribute, value)
return factor >= 1
def __eq__(self, other: object) -> bool:
if isinstance(other, SimpleAnimation):
return (
self.final_value == other.final_value
and self.duration == other.duration
)
return False
class BoundAnimator:
def __init__(self, animator: Animator, obj: object) -> None:
self._animator = animator
self._obj = obj
def __call__(
self,
attribute: str,
value: float | Animatable,
*,
final_value: object = ...,
duration: float | None = None,
speed: float | None = None,
delay: float = 0.0,
easing: EasingFunction | str = DEFAULT_EASING,
on_complete: CallbackType | None = None,
) -> None:
"""Animate an attribute.
Args:
attribute (str): Name of the attribute to animate.
value (float | Animatable): The value to animate to.
final_value (object, optional): The final value of the animation. Defaults to `value` if not set.
duration (float | None, optional): The duration of the animate. Defaults to None.
speed (float | None, optional): The speed of the animation. Defaults to None.
delay (float, optional): A delay (in seconds) before the animation starts. Defaults to 0.0.
easing (EasingFunction | str, optional): An easing method. Defaults to "in_out_cubic".
on_complete (CallbackType | None, optional): A callable to invoke when the animation is finished. Defaults to None.
"""
easing_function = EASING[easing] if isinstance(easing, str) else easing
return self._animator.animate(
self._obj,
attribute=attribute,
value=value,
final_value=final_value,
duration=duration,
speed=speed,
delay=delay,
easing=easing_function,
on_complete=on_complete,
)
class Animator:
"""An object to manage updates to a given attribute over a period of time."""
def __init__(self, app: App, frames_per_second: int = 60) -> None:
self._animations: dict[tuple[object, str], Animation] = {}
self.app = app
self._timer = Timer(
app,
1 / frames_per_second,
app,
name="Animator",
callback=self,
pause=True,
)
self._idle_event = asyncio.Event()
async def start(self) -> None:
"""Start the animator task."""
self._idle_event.set()
self._timer.start()
async def stop(self) -> None:
"""Stop the animator task."""
try:
await self._timer.stop()
except asyncio.CancelledError:
pass
def bind(self, obj: object) -> BoundAnimator:
"""Bind the animator to a given objects."""
return BoundAnimator(self, obj)
def animate(
self,
obj: object,
attribute: str,
value: Any,
*,
final_value: object = ...,
duration: float | None = None,
speed: float | None = None,
easing: EasingFunction | str = DEFAULT_EASING,
delay: float = 0.0,
on_complete: CallbackType | None = None,
) -> None:
"""Animate an attribute to a new value.
Args:
obj (object): The object containing the attribute.
attribute (str): The name of the attribute.
value (Any): The destination value of the attribute.
final_value (Any, optional): The final value, or ellipsis if it is the same as ``value``. Defaults to Ellipsis/
duration (float | None, optional): The duration of the animation, or ``None`` to use speed. Defaults to ``None``.
speed (float | None, optional): The speed of the animation. Defaults to None.
easing (EasingFunction | str, optional): An easing function. Defaults to DEFAULT_EASING.
delay (float, optional): Number of seconds to delay the start of the animation by. Defaults to 0.
on_complete (CallbackType | None, optional): Callback to run after the animation completes.
"""
animate_callback = partial(
self._animate,
obj,
attribute,
value,
final_value=final_value,
duration=duration,
speed=speed,
easing=easing,
on_complete=on_complete,
)
if delay:
self.app.set_timer(delay, animate_callback)
else:
animate_callback()
def _animate(
self,
obj: object,
attribute: str,
value: Any,
*,
final_value: object = ...,
duration: float | None = None,
speed: float | None = None,
easing: EasingFunction | str = DEFAULT_EASING,
on_complete: CallbackType | None = None,
):
"""Animate an attribute to a new value.
Args:
obj (object): The object containing the attribute.
attribute (str): The name of the attribute.
value (Any): The destination value of the attribute.
final_value (Any, optional): The final value, or ellipsis if it is the same as ``value``. Defaults to ....
duration (float | None, optional): The duration of the animation, or ``None`` to use speed. Defaults to ``None``.
speed (float | None, optional): The speed of the animation. Defaults to None.
easing (EasingFunction | str, optional): An easing function. Defaults to DEFAULT_EASING.
on_complete (CallbackType | None, optional): Callback to run after the animation completes.
"""
if not hasattr(obj, attribute):
raise AttributeError(
f"Can't animate attribute {attribute!r} on {obj!r}; attribute does not exist"
)
assert (duration is not None and speed is None) or (
duration is None and speed is not None
), "An Animation should have a duration OR a speed"
if final_value is ...:
final_value = value
start_time = self._get_time()
animation_key = (id(obj), attribute)
easing_function = EASING[easing] if isinstance(easing, str) else easing
animation: Animation | None = None
if hasattr(obj, "__textual_animation__"):
animation = getattr(obj, "__textual_animation__")(
attribute,
value,
start_time,
duration=duration,
speed=speed,
easing=easing_function,
on_complete=on_complete,
)
if animation is None:
start_value = getattr(obj, attribute)
if start_value == value:
self._animations.pop(animation_key, None)
return
if duration is not None:
animation_duration = duration
else:
if hasattr(value, "get_distance_to"):
animation_duration = value.get_distance_to(start_value) / (
speed or 50
)
else:
animation_duration = abs(value - start_value) / (speed or 50)
animation = SimpleAnimation(
obj,
attribute=attribute,
start_time=start_time,
duration=animation_duration,
start_value=start_value,
end_value=value,
final_value=final_value,
easing=easing_function,
on_complete=on_complete,
)
assert animation is not None, "animation expected to be non-None"
current_animation = self._animations.get(animation_key)
if current_animation is not None and current_animation == animation:
return
self._animations[animation_key] = animation
self._timer.resume()
self._idle_event.clear()
async def __call__(self) -> None:
if not self._animations:
self._timer.pause()
self._idle_event.set()
else:
animation_time = self._get_time()
animation_keys = list(self._animations.keys())
for animation_key in animation_keys:
animation = self._animations[animation_key]
animation_complete = animation(animation_time)
if animation_complete:
completion_callback = animation.on_complete
if completion_callback is not None:
await invoke(completion_callback)
del self._animations[animation_key]
def _get_time(self) -> float:
"""Get the current wall clock time, via the internal Timer."""
# N.B. We could remove this method and always call `self._timer.get_time()` internally,
# but it's handy to have in mocking situations
return _clock.get_time_no_wait()
async def wait_for_idle(self) -> None:
"""Wait for any animations to complete."""
await self._idle_event.wait()
|