CircuitPython script to display icons on TFT display

code.py

import time
import random
import board
import displayio
import fourwire
import adafruit_ili9341
import pwmio

# Create display
displayio.release_displays()
spi = board.SPI()
tft_cs = board.D9
tft_dc = board.D10
display_bus = fourwire.FourWire(spi, command=tft_dc, chip_select=tft_cs, reset=board.D7)
display = adafruit_ili9341.ILI9341(display_bus, width=320, height=240)
display.auto_refresh = False
display.rotation = 270

# Change backlight brightness
brightness = 0.1
duty_cycle = int(brightness * 65535)
frequency = 500
backlight_pwm = pwmio.PWMOut(board.D5, duty_cycle=duty_cycle, frequency=frequency)

# Create main display groups
main_group = displayio.Group()
display.root_group = main_group

# Icon file names
icon_fnames = [
    'img/snowman.bmp',
    'img/santa.bmp',
    'img/glove.bmp',
    'img/ornament.bmp',
    'img/present.bmp',
    'img/tree.bmp',
    'img/candle.bmp',
    'img/stocking.bmp',
    'img/lollipop.bmp',
    'img/hat.bmp',
    'img/cup.bmp',
    'img/candycane.bmp',
    'img/snowflake.bmp',
    'img/gingerbread.bmp'
]

# Define bouncing icon class
class BouncingIcon:
    def __init__(self, fname, x, y, speed_x, speed_y):

        image = displayio.OnDiskBitmap(fname)
        image.pixel_shader.make_transparent(0)

        self.icon = displayio.TileGrid(
            image,
            pixel_shader=image.pixel_shader,
            x=x,
            y=y
        )
        main_group.append(self.icon)
        self.speed_x = speed_x
        self.speed_y = speed_y

# Init icons array
icon_size = 40
icons = []

# Create BouncingIcon instance for each filename
for icon_fname in icon_fnames:
    icons.append(BouncingIcon(
        icon_fname,
        random.randint(0, display.width - icon_size),
        random.randint(0, display.height - icon_size),
        random.choice([-1, 1]),
        random.choice([-1, 1])
    ))

# Miain loop
while True:
    time.sleep(0.01)
    print('test')

    for icon in icons:
        # Update icon position
        icon.icon.x += icon.speed_x
        icon.icon.y += icon.speed_y

        # Bounce off the right and left edges
        if icon.icon.x + icon_size >= display.width or icon.icon.x <= 0:
            icon.speed_x = -icon.speed_x

        # Bounce off the bottom and top edges
        if icon.icon.y + icon_size >= display.height or icon.icon.y <= 0:
            icon.speed_y = -icon.speed_y

    display.refresh()