gistfile1.py

class TouchRippleBehavior(object):
    ripple_rad = NumericProperty(10)
    ripple_pos = ListProperty([0, 0])
    ripple_color = ListProperty((0., 0., 0., 1.))
    ripple_duration_in = NumericProperty(.4)
    ripple_duration_out = NumericProperty(.4)
    fade_to_alpha = NumericProperty(.12)
    ripple_scale = NumericProperty(4.0)
    ripple_func_in = StringProperty('in_cubic')
    ripple_func_out = StringProperty('out_quad')
    add_before = BooleanProperty(False)
    add_main = BooleanProperty(True)

    def on_touch_down(self, touch):
        if self in touch.ud:
            self.anim_complete(self, self)
            self.ripple_pos = ripple_pos = (touch.x, touch.y)
            Animation.cancel_all(self, 'ripple_rad', 'ripple_color')
            rc = self.ripple_color
            ripple_rad = self.ripple_rad
            self.ripple_color = [rc[0], rc[1], rc[2], .16]
            anim = Animation(
                ripple_rad=max(self.width, self.height) * self.ripple_scale,
                t=self.ripple_func_in,
                ripple_color=[rc[0], rc[1], rc[2], self.fade_to_alpha],
                duration=self.ripple_duration_in)
            anim.start(self)
            with self.canvas.after:
                StencilPush()
            if self.canvas.has_before and self.add_before:
                for c in self.canvas.before.children[:]:
                    if isinstance(c, VertexInstruction):
                        self.canvas.after.add(c)
            if self.add_main:
                for c in self.canvas.children[:]:
                    if self.canvas.has_after:
                        if c is self.canvas.after:
                            continue
                    if isinstance(c, VertexInstruction):
                        self.canvas.after.add(c)
            with self.canvas.after:
                StencilUse(op='equal')
                self.col_instruction = Color(rgba=self.ripple_color)
                self.ellipse = Ellipse(size=(ripple_rad, ripple_rad),
                                       pos=(ripple_pos[0] - ripple_rad/2.,
                                            ripple_pos[1] - ripple_rad/2.))
                StencilUnUse()
                StencilPop()
            self.bind(ripple_color=self.set_color, ripple_pos=self.set_ellipse,
                      ripple_rad=self.set_ellipse)
        return super(TouchRippleBehavior, self).on_touch_down(touch)

    def set_ellipse(self, instance, value):
        ellipse = self.ellipse
        ripple_pos = self.ripple_pos
        ripple_rad = self.ripple_rad
        ellipse.size = (ripple_rad, ripple_rad)
        ellipse.pos = (ripple_pos[0] - ripple_rad/2.,
                       ripple_pos[1] - ripple_rad/2.)

    def set_color(self, instance, value):
        self.col_instruction.rgba = value

    def on_touch_up(self, touch):
        if self in touch.ud:
            rc = self.ripple_color
            anim = Animation(ripple_color=[rc[0], rc[1], rc[2], 0.],
                             t=self.ripple_func_out, duration=self.ripple_duration_out)
            anim.bind(on_complete=self.anim_complete)
            anim.start(self)
        return super(TouchRippleBehavior, self).on_touch_up(touch)

    def anim_complete(self, anim, instance):
        self.ripple_rad = 10
        self.canvas.after.clear()