76 lines
2.2 KiB
Python
76 lines
2.2 KiB
Python
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__all__ = ('interpolate', 'fade_transition', )
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import typing as T
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from contextlib import asynccontextmanager
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from kivy.animation import AnimationTransition
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from ._anim_with_xxx import anim_with_ratio
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linear = AnimationTransition.linear
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async def interpolate(start, end, *, duration=1.0, step=0, transition=linear) -> T.AsyncIterator:
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'''
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Interpolates between the values ``start`` and ``end`` in an async-manner.
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Inspired by wasabi2d's interpolate_.
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.. code-block::
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async for v in interpolate(0, 100, duration=1.0, step=.3):
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print(int(v))
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============ ======
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elapsed time output
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============ ======
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0 sec 0
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0.3 sec 30
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0.6 sec 60
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0.9 sec 90
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**1.2 sec** 100
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============ ======
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.. _interpolate: https://wasabi2d.readthedocs.io/en/stable/coros.html#clock.coro.interpolate
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'''
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if isinstance(transition, str):
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transition = getattr(AnimationTransition, transition)
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slope = end - start
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yield transition(0.) * slope + start
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async for p in anim_with_ratio(step=step, duration=duration):
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if p >= 1.0:
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break
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yield transition(p) * slope + start
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yield transition(1.) * slope + start
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@asynccontextmanager
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async def fade_transition(*widgets, duration=1.0, step=0) -> T.AsyncContextManager:
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'''
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Returns an async context manager that:
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* fades-out the given widgets on ``__aenter__``.
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* fades-in the given widgets on ``__aexit__``.
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.. code-block::
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async with fade_transition(widget1, widget2):
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...
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The ``widgets`` don't have to be actual Kivy widgets.
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Anything that has an attribute named ``opacity`` would work.
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'''
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half_duration = duration / 2.
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org_opas = tuple(w.opacity for w in widgets)
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try:
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async for p in anim_with_ratio(duration=half_duration, step=step):
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p = 1.0 - p
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for w, o in zip(widgets, org_opas):
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w.opacity = p * o
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yield
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async for p in anim_with_ratio(duration=half_duration, step=step):
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for w, o in zip(widgets, org_opas):
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w.opacity = p * o
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finally:
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for w, o in zip(widgets, org_opas):
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w.opacity = o
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