# Copyright (c) 2015, Thomas Chiroux - Link Care Services
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"""Transitions classes.
The Transitions are used in animations to calculates new object positions
based on some parameters like transition time, transition type, etc...
Idea and implementation is taken from mootools Fx project:
https://github.com/mootools/mootools-core/blob/master/Source/Fx/Fx.Transitions.js
see: http://www.chipwreck.de/blog/2010/02/17/mootools-transitions-explained/
"""
import math
[docs]class BaseTransition():
"""Base class for all transitions.
This class will be subclassed by every transition type.
"""
@classmethod
[docs] def ease_in(cls, progress=0):
"""Method to calculate transition for easeIn display.
Ease in is the default behaviour: Here the function is applied
normally.
"""
return cls.pos(progress)
@classmethod
[docs] def ease_out(cls, progress=0):
"""Method to calculate transition for easeOut display.
Ease out inverts the behaviour - so the effect works backwards.
"""
return 1 - cls.pos(1 - progress)
@classmethod
[docs] def ease_in_out(cls, progress=0):
"""Method to calculate transition for easeInOut display.
Ease in and out is more complex:
In the first half of the time the transition is applied normally,
in the second half it is applied reverse.
"""
if progress <= 0.5:
return cls.pos(2 * progress) / 2
else:
return 2 - cls.pos(2 * (1 - progress)) / 2
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
0 is the 'beginning' of the transition, i.e. 0% of the transition
1 is the 'end' of the transition, i.e. 100% of the transition.
This method is defined in subclasses based on the transition type.
"""
raise NotImplementedError
[docs]class LinearTransition(BaseTransition):
"""Simple linear transition.
A linear transition has no additional ease-parameter,
since it simply divides the range equally along the timeline.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return progress
[docs]class QuadTransition(BaseTransition):
"""Quad (x^2) transition.
Polynomial (x^n) Transition.
For these transition the value will first increase slowly and near
the end of the effect it will grow rapidly - like the well-known parabola.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 2)
[docs]class CubicTransition(BaseTransition):
"""Cubic (x^3) transition.
Polynomial (x^n) Transition.
For these transition the value will first increase slowly and near
the end of the effect it will grow rapidly - like the well-known parabola.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 3)
[docs]class QuartTransition(BaseTransition):
"""x^4 transition.
Polynomial (x^n) Transition.
For these transition the value will first increase slowly and near
the end of the effect it will grow rapidly - like the well-known parabola.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 4)
[docs]class QuintTransition(BaseTransition):
"""x^5 transition.
Polynomial (x^n) Transition.
For these transition the value will first increase slowly and near
the end of the effect it will grow rapidly - like the well-known parabola.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 5)
[docs]class PowTransition(BaseTransition):
"""x^6 transition.
Polynomial (x^n) Transition.
For these transition the value will first increase slowly and near
the end of the effect it will grow rapidly - like the well-known parabola.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 6)
[docs]class ExpoTransition(BaseTransition):
"""Exponancial transition.
So the function grows even more rapidly towards the end -
compared to the x^n-transitions.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(2, 8 * (progress - 1))
[docs]class CircTransition(BaseTransition):
"""Circular transition.
The circular transition function describes a perfect circle
(in this case a quadrant)
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return 1 - math.sin(math.acos(progress - 1))
[docs]class SineTransition(BaseTransition):
"""Sinus transition.
The sinusiodal transition delivers a graph which behaves like a part
of a sine-curve, the result in this case is a smooth, nearly linear
transition (see the graph below).
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return 1 - math.cos(progress * math.pi / 2)
[docs]class BackTransition(BaseTransition):
"""Back transition.
Back moves the value first in the opposite direction
and then moves it in direction of the target value.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(progress, 2) * (2.618 * progress - 1.618)
[docs]class BounceTransition(BaseTransition):
"""Bounce transition.
Bounce is the most complex function - it can’t be described as a
simple formula.
It first approaches the target value linear and then it oscillates between
descreasing intervals, creating a bouncing effect.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
value = 0
p_a = 0
p_b = 1
while True:
if progress >= (7 - 4 * p_a) / 11:
value = p_b * p_b - math.pow(
(11 - 6 * p_a - 11 * progress) / 4, 2)
break
p_a += p_b
p_b /= 2
return value
[docs]class ElasticTransition(BaseTransition):
"""Elastic transition.
Elastic oscillates in increasing intervals between the opposite direction
and the desired one. It’s best used with ease:out or ease:in:out,
otherwise it may happen that effect doesn’t reach its target value.
"""
@classmethod
[docs] def pos(cls, progress=0):
"""calculate pos based on progress value, progress is between 0 and 1.
:param float progress: the wanted progression of the transition.
"""
return math.pow(2, 10 * (progress - 1)) * math.cos(
20 * progress * math.pi * 1 / 3)