Fix color picker example for animation

[nnja]

The current color picker example is problematic when displaying animations on the pixel strip.

As soon as the app connects to the device, the animation noticeably slows down.

Checking if the UARTService is in waiting before attempting to read from the stream fixes this issue.

Also renamed uart_service to uart_server for consistency.

Examples below.

1. Running the code below will display the animation normally until the app connects. Once the app is connected to the device, the animation slows down.

# CircuitPython NeoPixel Color Picker Example
# Animation slows down when device is connected to from app

import board
import neopixel
from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.nordic import UARTService
from adafruit_bluefruit_connect.packet import Packet
from adafruit_bluefruit_connect.color_packet import ColorPacket

from adafruit_led_animation.animation.blink import Blink
from adafruit_led_animation.color import RED

ble = BLERadio()
uart_service = UARTService()
advertisement = ProvideServicesAdvertisement(uart_service)

pixels = neopixel.NeoPixel(board.D12, 5, brightness=0.1)
blink = Blink(pixels, speed=0.5, color=RED)

while True:
    # Advertise when not connected.
    ble.start_advertising(advertisement)
    while not ble.connected:
        blink.animate()
    ble.stop_advertising()

    while ble.connected:
        blink.animate()
        packet = Packet.from_stream(uart_service)
        if isinstance(packet, ColorPacket):
            print(packet.color)
            blink = Blink(pixels, speed=0.5, color=packet.color)

2. This behavior is fixed when checking for uart_service.in_waiting like in the updated example.

# CircuitPython NeoPixel Color Picker Example
# Animation doesn't slow down when bluetooth connected

import board
import neopixel
from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.nordic import UARTService
from adafruit_bluefruit_connect.packet import Packet
from adafruit_bluefruit_connect.color_packet import ColorPacket

from adafruit_led_animation.animation.blink import Blink
from adafruit_led_animation.color import RED

ble = BLERadio()
uart_service = UARTService()
advertisement = ProvideServicesAdvertisement(uart_service)

pixels = neopixel.NeoPixel(board.D12, 5, brightness=0.1)
blink = Blink(pixels, speed=0.5, color=RED)

while True:
    # Advertise when not connected.
    ble.start_advertising(advertisement)
    while not ble.connected:
        blink.animate()
    ble.stop_advertising()

    while ble.connected:
        blink.animate()
        if uart_service.in_waiting:
            packet = Packet.from_stream(uart_service)
            if isinstance(packet, ColorPacket):
                print(packet.color)
                blink = Blink(pixels, speed=0.5, color=packet.color)

[dhalbert]

Good fix; thank you!