sugar-toolkit-gtk3/src/sugar3/graphics/animator.py

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# Copyright (C) 2007, Red Hat, Inc.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
"""
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The animator module provides a simple framwork to create animations.
Example:
Animate the size of a window::
from gi.repository import Gtk
from sugar3.graphics.animator import Animator, Animation
# Construct a window to animate
w = Gtk.Window()
w.connect('destroy', Gtk.main_quit)
# Start the animation when the window is shown
w.connect('realize', lambda self: animator.start())
w.show()
# Construct a 5 second animator
animator = Animator(5, widget=w)
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# Create an animation subclass to animate the widget
class SizeAnimation(Animation):
def __init__(self):
# Tell the animation to give us values between 20 and
# 420 during the animation
Animation.__init__(self, 20, 420)
def next_frame(self, frame):
size = int(frame)
w.resize(size, size)
# Add the animation the the animator
animation = SizeAnimation()
animator.add(animation)
# The animation needs to run inside a GObject main loop
Gtk.main()
STABLE.
"""
import time
from gi.repository import GObject
from gi.repository import GLib
EASE_OUT_EXPO = 0
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EASE_IN_EXPO = 1
class Animator(GObject.GObject):
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'''
The animator class manages the the timing for calling the
animations. The animations can be added using the `add` function
and then started with the `start` function. If multiple animations
are added, then they will be played back at the same time and rate
as each other.
The `completed` signal is emitted upon the completion of the
animation and also when the `stop` function is called.
Args:
duration (float): the duration of the animation in seconds
fps (int, optional): the number of animation callbacks to make
per second (frames per second)
easing (int): the desired easing mode, either `EASE_OUT_EXPO`
or `EASE_IN_EXPO`
widget (:class:`Gtk.Widget`): one of the widgets that the animation
is acting on. If supplied and if the user's Gtk+ version
supports it, the animation will run on the frame clock of the
widget, resulting in a smoother animation and the fps value
will be disregarded.
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.. note::
When creating an animation, take into account the limited cpu power
on some devices, such as the XO. Setting the fps too high on can
use signifigant cpu usage on the XO.
'''
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__gsignals__ = {
'completed': (GObject.SignalFlags.RUN_FIRST, None, ([])),
}
def __init__(self, duration, fps=20, easing=EASE_OUT_EXPO, widget=None):
GObject.GObject.__init__(self)
self._animations = []
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self._duration = duration
self._interval = 1.0 / fps
self._easing = easing
self._widget = widget
self._timeout_sid = 0
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self._start_time = None
def add(self, animation):
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'''
Add an animation to this animator
Args:
animation (:class:`sugar3.graphics.animator.Animation`):
the animation instance to add
'''
self._animations.append(animation)
def remove_all(self):
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'''
Remove all animations and stop this animator
'''
self.stop()
self._animations = []
def start(self):
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'''
Start the animation running. This will stop and restart the
animation if the animation is currently running
'''
if self._timeout_sid:
self.stop()
self._start_time = time.time()
if hasattr(self._widget, 'add_tick_callback'):
self._timeout_sid = self._widget.add_tick_callback(
self._next_frame_cb, None)
# Make sure the 1st frame is animated so we get ticks
self._next_frame_cb()
else:
self._timeout_sid = GLib.timeout_add(
int(self._interval * 1000), self._next_frame_cb)
def stop(self):
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'''
Stop the animation and emit the `completed` signal
'''
if self._timeout_sid and \
not hasattr(self._widget, 'add_tick_callback'):
GObject.source_remove(self._timeout_sid)
self._timeout_sid = 0
self.emit('completed')
if self._timeout_sid and hasattr(self._widget, 'add_tick_callback'):
self._widget.remove_tick_callback(self._timeout_sid)
self._timeout_sid = 0
self.emit('completed')
def _next_frame_cb(self, *args):
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current_time = min(self._duration, time.time() - self._start_time)
current_time = max(current_time, 0.0)
for animation in self._animations:
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animation.do_frame(current_time, self._duration, self._easing)
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if current_time == self._duration:
self.stop()
return False
else:
return True
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class Animation(object):
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'''
The animation class is a base class for creating an animation.
It should be subclassed. Subclasses should specify a `next_frame`
function to set the required properties based on the animation
progress. The range of the `frame` value passed to the `next_frame`
function is defined by the `start` and `end` values.
Args:
start (float): the first `frame` value for the `next_frame` method
end (float): the last `frame` value for the `next_frame` method
.. code-block:: python
# Create an animation subclass
class MyAnimation(Animation):
def __init__(self, thing):
# Tell the animation to give us values between 0.0 and
# 1.0 during the animation
Animation.__init__(self, 0.0, 1.0)
self._thing = thing
def next_frame(self, frame):
# Use the `frame` value to set properties
self._thing.set_green_value(frame)
'''
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def __init__(self, start, end):
self.start = start
self.end = end
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def do_frame(self, t, duration, easing):
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'''
This method is called by the animtor class every frame. This
method calculated the `frame` value to then call `next_frame`.
Args:
t (float): the current time elapsed of the animation in seconds
duration (float): the length of the animation in seconds
easing (int): the easing mode passed to the animator
'''
start = self.start
change = self.end - self.start
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if t == duration:
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# last frame
frame = self.end
else:
if easing == EASE_OUT_EXPO:
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frame = change * (-pow(2, -10 * t / duration) + 1) + start
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elif easing == EASE_IN_EXPO:
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frame = change * pow(2, 10 * (t / duration - 1)) + start
self.next_frame(frame)
def next_frame(self, frame):
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'''
This method is called every frame and should be overriden by
subclasses.
Args:
frame (float): a value between `start` and `end` representing
the current progress in the animation
'''
pass