def __init__(self, mobject, midle_color=None, **kwargs):
digest_config(self, kwargs)
self.mobject = mobject
self.rectangle_kwargs["color"] = self.color
if midle_color == None:
midle_color = self.rectangle_kwargs["color"]
rectangle = Rectangle(height=mobject.get_height() + self.margin,
width=mobject.get_width() + self.margin,
**self.rectangle_kwargs)
rectangle.move_to(mobject)
rectangle.init_state = rectangle.copy()
rectangle_width = rectangle.get_width()
def return_updater(mob, alpha):
dx = interpolate(-PI / 2, PI / 2, alpha)
mob.become(mob.init_state)
mob.set_width(rectangle_width * np.cos(dx), stretch=True)
# dx should not be zero
sign = -abs(dx) / (dx + 0.00000000001)
direction = LEFT * sign
reference_line = Line(
rectangle.init_state.get_corner(UP + direction),
rectangle.init_state.get_corner(DOWN + direction))
mob.next_to(reference_line, -direction, buff=0)
opacity = self.init_opacity + (self.max_opacity -
self.init_opacity) * np.cos(dx)
mob.set_style(fill_opacity=opacity)
mob.set_color(
interpolate_color(self.rectangle_kwargs["color"], midle_color,
np.cos(dx)))
super().__init__(rectangle, return_updater)
def add_black_keys(self):
key = Rectangle(*self.black_key_dims)
key.set_fill(self.black_key_color, 1)
key.set_stroke(width=0)
self.black_keys = VGroup()
for i in range(len(self.white_keys) - 1):
if i % self.white_keys_per_octave not in self.black_pattern:
continue
wk1 = self.white_keys[i]
wk2 = self.white_keys[i + 1]
bk = key.copy()
bk.move_to(midpoint(wk1.get_top(), wk2.get_top()), UP)
big_bk = bk.copy()
big_bk.stretch((bk.get_width() + self.key_buff) / bk.get_width(),
0)
big_bk.stretch((bk.get_height() + self.key_buff) / bk.get_height(),
1)
big_bk.move_to(bk, UP)
for wk in wk1, wk2:
wk.become(Difference(wk, big_bk).match_style(wk))
self.black_keys.add(bk)
self.add(*self.black_keys)
