from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.graphics import Color, Rectangle
from kivy.clock import Clock
from kivy.utils import get_random_color

from random import randint

kv = """
FloatLayout:
    Label:
        text: 'Falling Boxes'
    FallingBoxes:
        id: fb
"""


class FallingBoxes(Widget):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.boxes = []
        Clock.schedule_interval(self.update_boxes, 1 / 60)

    def create_box(self):
        with self.canvas:
            Color(rgba=get_random_color())
            box = Rectangle(size=(20, 20), pos=(randint(0, 600), 800))
        self.boxes.append(box)

    def update_boxes(self, dt):
        for box in self.boxes:
            box.pos = box.pos[0] + randint(1, 10), box.pos[1] - randint(1,20)
            if box.pos[1] < -10:
                box.pos = (randint(0, 600), 800)


class FallingBoxesApp(App):
    def build(self):
        return Builder.load_string(kv)

    def on_start(self):
        for i in range(1000):
            self.root.ids.fb.create_box()


FallingBoxesApp().run()