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