Ajout du GUI

kivy/effects/scroll.py

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+'''
+Scroll effect
+=============
+
+.. versionadded:: 1.7.0
+
+Based on the :class:`~kivy.effects.kinetic` effect, the :class:`ScrollEffect`
+will limit the movement to bounds determined by its :attr:`~ScrollEffect.min`
+and :attr:`~ScrollEffect.max` properties. If the movement exceeds these
+bounds, it will calculate the amount of :attr:`~ScrollEffect.overscroll` and
+try to return to the value of one of the bounds.
+
+This is very useful for implementing a scrolling list. We actually use this
+class as a base effect for our :class:`~kivy.uix.scrollview.ScrollView` widget.
+
+'''
+
+
+__all__ = ('ScrollEffect', )
+
+
+from time import time
+from kivy.effects.kinetic import KineticEffect
+from kivy.uix.widget import Widget
+from kivy.properties import NumericProperty, ObjectProperty
+
+
+class ScrollEffect(KineticEffect):
+    '''ScrollEffect class. See the module documentation for more information.
+    '''
+
+    drag_threshold = NumericProperty('20sp')
+    '''Minimum distance to travel before the movement is considered as a drag.
+
+    :attr:`drag_threshold` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 20sp.
+    '''
+
+    min = NumericProperty(0)
+    '''Minimum boundary to use for scrolling.
+
+    :attr:`min` is a :class:`~kivy.properties.NumericProperty` and defaults to
+    0.
+    '''
+
+    max = NumericProperty(0)
+    '''Maximum boundary to use for scrolling.
+
+    :attr:`max` is a :class:`~kivy.properties.NumericProperty` and defaults to
+    0.
+    '''
+
+    scroll = NumericProperty(0)
+    '''Computed value for scrolling. This value is different from
+    :py:attr:`kivy.effects.kinetic.KineticEffect.value`
+    in that it will return to one of the min/max bounds.
+
+    :attr:`scroll` is a :class:`~kivy.properties.NumericProperty` and defaults
+    to 0.
+    '''
+
+    overscroll = NumericProperty(0)
+    '''Computed value when the user over-scrolls i.e. goes out of the bounds.
+
+    :attr:`overscroll` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    target_widget = ObjectProperty(None, allownone=True, baseclass=Widget)
+    '''Widget to attach to this effect. Even if this class doesn't make changes
+    to the `target_widget` by default, subclasses can use it to change the
+    graphics or apply custom transformations.
+
+    :attr:`target_widget` is a :class:`~kivy.properties.ObjectProperty` and
+    defaults to None.
+    '''
+
+    displacement = NumericProperty(0)
+    '''Cumulative distance of the movement during the interaction. This is used
+    to determine if the movement is a drag (more than :attr:`drag_threshold`)
+    or not.
+
+    :attr:`displacement` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    def reset(self, pos):
+        '''(internal) Reset the value and the velocity to the `pos`.
+        Mostly used when the bounds are checked.
+        '''
+        self.value = pos
+        self.velocity = 0
+        if self.history:
+            val = self.history[-1][1]
+            self.history = [(time(), val)]
+
+    def on_value(self, *args):
+        scroll_min = self.min
+        scroll_max = self.max
+        if scroll_min > scroll_max:
+            scroll_min, scroll_max = scroll_max, scroll_min
+        if self.value < scroll_min:
+            self.overscroll = self.value - scroll_min
+            self.reset(scroll_min)
+        elif self.value > scroll_max:
+            self.overscroll = self.value - scroll_max
+            self.reset(scroll_max)
+        else:
+            self.scroll = self.value
+
+    def start(self, val, t=None):
+        self.is_manual = True
+        self.displacement = 0
+        return super(ScrollEffect, self).start(val, t)
+
+    def update(self, val, t=None):
+        self.displacement += abs(val - self.history[-1][1])
+        return super(ScrollEffect, self).update(val, t)
+
+    def stop(self, val, t=None):
+        self.is_manual = False
+        self.displacement += abs(val - self.history[-1][1])
+        if self.displacement <= self.drag_threshold:
+            self.velocity = 0
+            return
+        return super(ScrollEffect, self).stop(val, t)