110 lines
3.6 KiB
Python
110 lines
3.6 KiB
Python
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'''How to use Animation with RecycleView items?
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In case you really want to use the Animation class with RecycleView, you'll
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likely encounter an issue, as widgets are moved around, they are used to
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represent different items, so an animation on a specific item is going to
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affect others, and this will lead to really confusing results.
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This example works around that by creating a "proxy" widget for the animation,
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and, by putting it in the data, allowing the displayed widget to mimic the
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animation. As the item always refers to its proxy, whichever widget is used to
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display the item will keep in sync with the animation.
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'''
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from copy import copy
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from kivy.app import App
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from kivy.clock import triggered
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from kivy.lang import Builder
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from kivy.uix.widget import Widget
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from kivy.animation import Animation
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from kivy.uix.button import Button
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from kivy.properties import (
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ObjectProperty, ListProperty
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)
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KV = '''
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<Item>:
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index: None
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animation_proxy: None
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on_release: app.animate_item(self.index)
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RecycleView:
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data: app.data
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viewclass: 'Item'
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RecycleBoxLayout:
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orientation: 'vertical'
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size_hint: 1, None
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height: self.minimum_height
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default_size_hint: 1, None
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default_size: 0, dp(40)
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'''
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class Item(Button):
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animation_proxy = ObjectProperty(allownone=True)
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_animation_proxy = None
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def update_opacity(self, proxy, opacity):
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# sync one animated property to the value in the proxy
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self.opacity = opacity
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def on_animation_proxy(self, *args):
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"""When we create an animation proxy for an item, we need to bind to
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the animated property to update our own.
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"""
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if self._animation_proxy:
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self._animation_proxy.unbind(opacity=self.update_opacity)
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self._animation_proxy = self.animation_proxy
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if self.animation_proxy:
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# when we are assigned an animation_proxy, sync our properties to
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# the animated version.
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self.opacity = self.animation_proxy.opacity
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self.animation_proxy.bind(opacity=self.update_opacity)
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else:
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# if we lose our animation proxy, we need to reset the animated
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# property to their default values.
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self.opacity = 1
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class Application(App):
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data = ListProperty()
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def build(self):
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self.data = [
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{'index': i, 'text': 'hello {}'.format(i), 'animation_proxy': None}
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for i in range(1000)
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]
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return Builder.load_string(KV)
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# the triggered decorator allows delaying the animation until after the
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# blue effect on the button is removed, to avoid a flash as widgets gets
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# reordered when that happens
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@triggered(timeout=0.05)
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def animate_item(self, index):
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# the animation we actually want to do on the item, note that any
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# property animated here needs to be synchronized from the proxy to the
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# animated widget (in on_animation_proxy and using methods for each
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# animation)
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proxy = Widget(opacity=1)
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item = copy(self.data[index])
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animation = (
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Animation(opacity=0, d=.1, t='out_quad')
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+ Animation(opacity=1, d=5, t='out_quad')
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)
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animation.bind(on_complete=lambda *x: self.reset_animation(item))
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item['animation_proxy'] = proxy
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self.data[index] = item
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animation.start(proxy)
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def reset_animation(self, item):
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# animation is complete, widget should be garbage collected
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item['animation_proxy'] = None
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if __name__ == "__main__":
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Application().run()
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