[PySide6] How to have one button toggle ON/OFF functions of LEDs defined in Python file?

I.Mironov · 2 Mar 2024, 21:59

Once again, I'm coming to the community for help, as I'm having a hard time finding an answer. Looking over Connections QML Type wasn't much help, as I found the "examples" given weren't really good examples; not for novices, anyway. (The Qt documentation does come across as more catered towards those with an already solid background in understanding different programming languages rather than those of us still getting our feet wet.) Because of that, it confuses me on where to start looking (Slots, Signals, onClicked handlers, Connections, etc.). Searching online also doesn't give any results that relate exactly to what I'm looking for.

I'm trying to figure out how to have one button turn my LEDs both on and off. (My button is actually an Image with button properties.) I know how to set the button to execute one of the functions, but not how to have it execute both. I'd also like the button's two images to reflect the function that's being executed; power_on.svg when LEDs are on, power_on.svg when LEDs are off, but I'll worry about that once I figure this out, first.

.

↓ main.qml ↓

import QtQuick
import QtQuick.Controls

ApplicationWindow {
	width: 800
	height: 800
	visible: true

	Image {
		id: allLights
		source: 'images/power_' + allLights.buttonState + '.svg'
		anchors.centerIn: parent

		property string buttonState: "off"

		states: [
			State { name: 'off' },
			State { name: 'on' }
		]

		MouseArea {
			anchors.fill: parent
			onClicked: {
				allLights.buttonState = (allLights.buttonState === 'on') ? 'off' : 'on';
				controlPanel.buttonClicked();
			}
		}
	}
}

.

↓ main,py ↓

import sys
from pathlib import Path
from led import grid, all_lights_on, all_lights_off
from PySide6.QtCore import QObject, Slot, Signal
from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine

class ControlPanel(QObject):
	buttonClicked = Signal()

	def __init__(self):
		super().__init__()

	@Slot()
	def buttonClicked(self):
		all_lights_on(grid)

if __name__ == '__main__':
	app = QGuiApplication(sys.argv)
	engine = QQmlApplicationEngine()
	controlPanel = ControlPanel()
	engine.rootContext().setContextProperty("controlPanel", controlPanel)
	qml_file = Path(__file__).parent / 'main.qml'
	engine.load(qml_file)
	if not engine.rootObjects():
		sys.exit(-1)

	sys.exit(app.exec())

.

↓ led,py ↓

from rpi_ws281x import PixelStrip, Color


### Global LED grid (PixelStrip) configuration ###
LED_COUNT = 256
LED_PIN = 18
LED_FREQ_HZ = 800000
LED_DMA = 10
LED_BRIGHTNESS = 25
LED_CHANNEL = 0
LED_INVERT = False


""" Initialize the LEDs """
grid = PixelStrip(LED_COUNT, LED_PIN, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS, LED_CHANNEL)
grid.begin()


""" Function to retrieve the LED index based on row and column """
def get_led_index(row, col):

	# Converting 2D coordinates into a 1D LED index #
	lookup_table = [
		[0, 15, 16, 31, 32, 47, 48, 63, 64, 79, 80, 95,  96, 111, 112, 127, 128, 143, 144, 159, 160, 175, 176, 191, 192, 207, 208, 223, 224, 239, 240, 255],
		[1, 14, 17, 30, 33, 46, 49, 62, 65, 78, 81, 94,  97, 110, 113, 126, 129, 142, 145, 158, 161, 174, 177, 190, 193, 206, 209, 222, 225, 238, 241, 254],
		[2, 13, 18, 29, 34, 45, 50, 61, 66, 77, 82, 93,  98, 109, 114, 125, 130, 141, 146, 157, 162, 173, 178, 189, 194, 205, 210, 221, 226, 237, 242, 253],
		[3, 12, 19, 28, 35, 44, 51, 60, 67, 76, 83, 92,  99, 108, 115, 124, 131, 140, 147, 156, 163, 172, 179, 188, 195, 204, 211, 220, 227, 236, 243, 252],
		[4, 11, 20, 27, 36, 43, 52, 59, 68, 75, 84, 91, 100, 107, 116, 123, 132, 139, 148, 155, 164, 171, 180, 187, 196, 203, 212, 219, 228, 235, 244, 251],
		[5, 10, 21, 26, 37, 42, 53, 58, 69, 74, 85, 90, 101, 106, 117, 122, 133, 138, 149, 154, 165, 170, 181, 186, 197, 202, 213, 218, 229, 234, 245, 250],
		[6,  9, 22, 25, 38, 41, 54, 57, 70, 73, 86, 89, 102, 105, 118, 121, 134, 137, 150, 153, 166, 169, 182, 185, 198, 201, 214, 217, 230, 233, 246, 249],
		[7,  8, 23, 24, 39, 40, 55, 56, 71, 72, 87, 88, 103, 104, 119, 120, 135, 136, 151, 152, 167, 168, 183, 184, 199, 200, 215, 216, 231, 232, 247, 248]
	]
	return lookup_table[row][col]


""" Function to set the parameters of a specific region on the LED grid and the color for it """
def set_pixel_color(top_pixel, bottom_pixel, color):
	for row in range(top_pixel[0], bottom_pixel[0] + 1):
		for col in range(top_pixel[1], bottom_pixel[1] + 1):
			index = get_led_index(row, col)
			grid.setPixelColor(index, color)

""" Function to turn off all LEDs """
def clear_grid():
	for row in range(8):
		for col in range(32):
			index = get_led_index(row, col)
			grid.setPixelColor(index, Color(0, 0, 0))

""" Function to set the brightness of the LEDs """
def set_brightness(value):
	grid.setBrightness(value)

# ===================================================== #
### All lights ###
def all_lights_on(grid):
	set_brightness(10)
	pixel_color = Color(255, 0, 0)
	set_pixel_color((0, 0), (7, 31), pixel_color)
	grid.show()

def all_lights_off(grid):
	clear_grid()
	grid.show()

I.Mironov · 2 Mar 2024, 21:58

I've found a solution, albeit with a small bit of help from ChatGPT as a last resort. I used an if/else statement (in the form of a ternary operator) for my main.qml and added an additional @Slot() decorator for the LED off function in my main,py.
.
.
↓ main.qml ↓

import QtQuick
import QtQuick.Controls

ApplicationWindow {
	width: 1920
	height: 1080
	visible: true

	// Bool property to hold the button state
	property bool buttonState: false

	// Function to toggle the LEDs
	function toggleLEDs() {
		buttonState ? controlPanel.buttonOff() : controlPanel.buttonOn();
		buttonState = !buttonState;
	}

	Image {
		id: allLights
		source: "images/power_" + (buttonState ? "on" : "off") + ".png"
		anchors.centerIn: parent
		MouseArea {
			anchors.fill: parent
			onClicked: {
				toggleLEDs();
			}
		}
	}
}

.
.
↓ main,py ↓

import sys
from pathlib import Path
from led import grid, all_lights_on, all_lights_off

from PySide6.QtCore import QObject, Slot
from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine


class ControlPanel(QObject):
	def __init__(self):
		super().__init__()

	@Slot()
	def buttonOn(self):
		all_lights_on(grid)

	@Slot()
	def buttonOff(self):
		all_lights_off(grid)


if __name__ == '__main__':
	app = QGuiApplication(sys.argv)
	engine = QQmlApplicationEngine()

	controlPanel = ControlPanel()
	engine.rootContext().setContextProperty("controlPanel", controlPanel)

	qml_file = Path(__file__).parent / 'main.qml'
	engine.load(qml_file)

	if not engine.rootObjects():
		sys.exit(-1)

	sys.exit(app.exec())