96 lines
2.5 KiB
Python
96 lines
2.5 KiB
Python
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"""Detecting and acting upon "Pull down actions" in a RecycleView
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- When using overscroll or being at the to, a "pull down to refresh" message
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appears
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- if the user pulls down far enough, then a refresh is triggered, which adds
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new elements at the top of the list.
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"""
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from threading import Thread
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from time import sleep
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from datetime import datetime
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from kivy.app import App
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from kivy.lang import Builder
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from kivy.properties import ListProperty, BooleanProperty
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from kivy.metrics import dp
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from kivy.clock import mainthread
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KV = r'''
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FloatLayout:
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Label:
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opacity: 1 if app.refreshing or rv.scroll_y > 1 else 0
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size_hint_y: None
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pos_hint: {'top': 1}
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text: 'Refreshing…' if app.refreshing else 'Pull down to refresh'
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RecycleView:
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id: rv
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data: app.data
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viewclass: 'Row'
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do_scroll_y: True
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do_scroll_x: False
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on_scroll_y: app.check_pull_refresh(self, grid)
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RecycleGridLayout:
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id: grid
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cols: 1
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size_hint_y: None
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height: self.minimum_height
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default_size: 0, 36
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default_size_hint: 1, None
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<Row@Label>:
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_id: 0
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text: ''
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canvas:
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Line:
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rectangle: self.pos + self.size
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width: 0.6
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'''
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class Application(App):
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data = ListProperty([])
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refreshing = BooleanProperty()
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def build(self):
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self.refresh_data()
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return Builder.load_string(KV)
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def check_pull_refresh(self, view, grid):
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"""Check the amount of overscroll to decide if we want to trigger the
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refresh or not.
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"""
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max_pixel = dp(200)
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to_relative = max_pixel / (grid.height - view.height)
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if view.scroll_y <= 1.0 + to_relative or self.refreshing:
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return
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self.refresh_data()
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def refresh_data(self):
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# using a Thread to do a potentially long operation without blocking
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# the UI.
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self.refreshing = True
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Thread(target=self._refresh_data).start()
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def _refresh_data(self):
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sleep(2)
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update_time = datetime.now().strftime("%H:%M:%S")
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self.prepend_data([
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{'_id': i, 'text': '[{}] hello {}'.format(update_time, i)}
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for i in range(len(self.data) + 10, len(self.data), -1)
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])
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@mainthread
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def prepend_data(self, data):
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self.data = data + self.data
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self.refreshing = False
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if __name__ == "__main__":
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Application().run()
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