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# -*- coding: utf-8 -*-
#
# Python porting of qtractor fade functions
#
# This file is part of Linux Show Player
#
# Copyright 2012-2016 Francesco Ceruti <ceppofrancy@gmail.com>
#
# Linux Show Player is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Linux Show Player is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Linux Show Player. If not, see <http://www.gnu.org/licenses/>
"""
Functor arguments normalization:
t = (x - x0) / (x1 - x0) where 'x' is the time (x0 initial, x1 final)
a = y1 - y0 where 'y' is the value (y0 initial, y1 final)
b = y0
"""
from enum import Enum
from lisp.core.util import FunctionProxy
def fade_linear(t, a, b):
"""Linear fade."""
return a * t + b
def fadein_quad(t, a, b):
"""Quadratic (t^2) fade in: accelerating from zero velocity."""
return a * (t ** 2) + b
def fadeout_quad(t, a, b):
"""Quadratic (t^2) fade out: decelerating to zero velocity."""
return a * (t * (2 - t)) + b
def fade_inout_quad(t, a, b):
"""Quadratic (t^2) fade in-out: acceleration until halfway,
then deceleration.
"""
t *= 2
if t < 1.0:
return 0.5 * a * (t ** 2) + b
else:
t -= 1
return 0.5 * a * (1 - (t * (t - 2))) + b
def ntime(time, begin, duration):
"""Return normalized time."""
return (time - begin) / (duration - begin)
class FadeInType(Enum):
Linear = FunctionProxy(fade_linear)
Quadratic = FunctionProxy(fadein_quad)
Quadratic2 = FunctionProxy(fade_inout_quad)
class FadeOutType(Enum):
Linear = FunctionProxy(fade_linear)
Quadratic = FunctionProxy(fadeout_quad)
Quadratic2 = FunctionProxy(fade_inout_quad)
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