6. The PixelPi Button

6.1. Using the Button

class pixelpi.PixelPiButton(callingclass=None, shortpresstime=0.5, shortpress=None, longpresstime=2.0, longpress=None)

A class to handle the button on the PixelPi board for the Raspberry Pi.

If no parameters are supplied, the Raspberry Pi will be rebooted after the button has been held for 0.5 seconds, or will be shut down if the button is held for 2 seconds or all.

Alternatively, a local Class can be created with two methods to handle a short and a long press. Create an instance of the class and supply the class, method names and press-times to this class. For example:

class MyButtons:
def __init__(self, strips=None):
    self.__strips = strips

def clear(self):
    try:
        if self.__strips is not None:
            for strip in self.__strips:
                strip.clearLEDs()
                strip.showLEDs()
    except:
        raise AttributeError('The strip list contained an error.')

def whitelights(self):
    try:
        if self.__strips is not None:
            for strip in self.__strips:
                strip.setLEDs(rgb=(255, 255, 255))
                strip.showLEDs()
    except:
        raise AttributeError('The strip list contained an error.')

Create an instance of the MyButtons class:

mybuttons = MyButtons([strip1, strip2, strip3, strip4])

Then create an instance of the PixelPiButton class, passing in the local class and methods:

button = PixelPiButton(callingclass=mybuttons, shortpresstime=0.5, shortpress="clear", longpresstime=1.0,
longpress="whitelights")

When the button is held for shortpresstime, the ‘clear’ method will be executed, unless it is held for longpresstime after which ‘whitelights’ will be called.

Parameters:

• callingclass (object) – The ‘local’ class.
• shortpresstime (float) – The short press time.
• shortpress (str) – The method in class callingclass that is called after the button has been pressed for shortpresstime seconds.
• longpresstime (float) – The long press time.
• longpress (str) – The method in class callingclass that is called after the button has been pressed for longpresstime seconds.

6.2. Example

#!/usr/bin/env python3

import colorsys
import time

from pixelpi import Strip, PixelPiButton


class MyButtons:
    def __init__(self, strips=None):
        self.__strips = strips

    def clear(self):
        try:
            print("clearing strips")
            if self.__strips is not None:
                for leds in self.__strips:
                    leds.clearLEDs()
                    leds.showLEDs()
        except:
            raise AttributeError('The strip list contained an error.')

    def whitelights(self):
        try:
            if self.__strips is not None:
                for strip in self.__strips:
                    strip.setLEDs(rgb=(255, 255, 255))
                    strip.showLEDs()
        except:
            raise AttributeError('The strip list contained an error.')


# Change the terminal type to the type you have
strip1 = Strip(1, 256, ledtype='WS2811_GRB', brightness=30)
strip2 = Strip(2, 256, ledtype='WS2811_GRB', brightness=30)
strip3 = Strip(3, 256, ledtype='WS2811_GRB', brightness=30)
strip4 = Strip(4, 256, ledtype='WS2811_GRB', brightness=30)

mybuttons = MyButtons([strip1, strip2, strip3, strip4])

button = PixelPiButton(callingclass=mybuttons, shortpress="clear", longpress="dosomethingelse")

spacing = 360.0 / 16.0
hue = 0

try:
    while True:
        hue = int(time.time() * 100) % 360
        for x in range(256):
            offset = x * spacing
            h = ((hue + offset) % 360) / 360.0
            r, g, b = [int(c * 255) for c in colorsys.hsv_to_rgb(h, 1.0, 1.0)]

            for strip in [strip1, strip2, strip3, strip4]:
                strip.setLEDs(rgb=(r, g, b), led=x)

        for strip in [strip1, strip2, strip3, strip4]:
            strip.showLEDs()

        time.sleep(0.001)

except KeyboardInterrupt:
    for strip in [strip1, strip2, strip3, strip4]:
        strip.clearLEDs()
        strip.showLEDs()
        del strip