RotaryKnob element for FreeSimpleGUI

Start by comparing the proposed elements/rotaryknob.py with elements/slider.py and the existing FreeSimpleGUI element integration. Confirm how element IDs and mouse events are handled, then define completion as an integrated RotaryKnob element with the requested clamped 0–255 range and usable layout controls.

Hello everybody, I'm Fabio from Italy. I want to honestly premise I'm not so experienced with the Python matter but I feel that FreeSimpleGUI is a great thing.
For a project of mine I need to implement a rotary knob. Many, actually.
With the prompt help of chat GPT I worked out an acceptable solution - a simple knob that starts at 3 o'clock with value 0 and produces 100 steps.
My ideal was to reach the behavior of a true potentiometer knob to produce a 8 bit control for digital potentiometers, so starting at 7 o'clock with value 0 and running clockwise up to 5 o'clock with value 255, in clamped fashion between these two points of course as a true finite potentiometer.
Strangely, something occurs with the trigonometrics and I didn't get a chance to go beyond the former working mode, so I ask your help.

Further, I tried to provide a rotaryknob.py class file in the "elements" folder, similarly to slider.py, in order to easily incorporate and manage it within the layout section of the program.

Following is the produced rotaryknob.py code. At the moment it needs to be integrated, probably in dependecies, outside the element file and thus somewhere else in the FreeSimpleGUI module, because it produces a bad ID and requires to be finalized.
Of course it would be great to incorporate at least the same controls already present on sg.slider and then, I wish, much more customization, but my knowledge ask for your help. I hope also that a simple knob can be useful to many, both approaching or also mastering both Python and FreeSG. Thank you all in advance for your precious contribution!

Fabio

import FreeSimpleGUI as sg
import math

class RotaryKnob(sg.Graph): # Inheriting from sg.Graph
def init(self, key, size=(150, 150), initial_value=0, **kwargs):
super().init(
canvas_size=size,
graph_bottom_left=(0, 0),
graph_top_right=size,
key=key,
enable_events=True,
background_color='black',
**kwargs
)

    self.center = (size[0] // 2, size[1] // 2)
    self.knob_radius = min(size) // 2.5
    self.angle = math.pi / 2  # Initial position at hour 6 (90 degrees)
    self.value = initial_value
    self.is_dragging = False

    self.draw_knob()  # Draw the initial knob

def draw_knob(self):
    self.delete_figure(self.key)  # Clear previous drawings
    # Draw knob base without key argument
    self.draw_circle(self.center, self.knob_radius, fill_color='grey')  
    knob_line = self.angle_to_point(self.angle)
    self.draw_line(self.center, knob_line, width=10, color='red')  # Draw the knob indicator

def angle_to_point(self, angle):
    x = self.center[0] + self.knob_radius * math.cos(angle)
    y = self.center[1] + self.knob_radius * math.sin(angle)
    return (x, y)

def point_to_angle(self, point):
    dx = point[0] - self.center[0]
    dy = point[1] - self.center[1]
    return math.atan2(dy, dx)

def handle_drag(self, mouse_position):
    if self.is_dragging:
        self.angle = self.point_to_angle(mouse_position)  # Use point only
        self.angle = self.angle % (2 * math.pi)  # Normalize angle

        # Clamp the angle for allowed positions
        if self.angle < math.pi:  # Only allow movement CW up to hour 5
            self.angle = max(self.angle, math.pi)  # No more than hour 6

        self.value = int((self.angle / (2 * math.pi)) * 100)  # Mapping the angle to a value between 0 and 100
        self.draw_knob()  # Redraw knob

def set_dragging(self, dragging):
    self.is_dragging = dragging  # Update dragging state

Function to listen for mouse events to handle dragging

def listen_for_events(knob):
while True:
event, values = sg.read_all_windows()
if event == knob.key:
knob.handle_drag(values[knob.key])
if event in (sg.WIN_CLOSED, 'Exit'):
break
sg.Window.close()