import pygame
import math

class Knob:
    
    def __init__(self, screen, color, radius, position):
        self.screen = screen
        self.color = color
        self.radius = radius
        self.position = position
        self.value = 0

    def set_value(self, value):
        self.value = value

    def set_color(self, color):
        self.color = color

    def get_position(self):
        return self.position

    def get_pointer_position(self):
        angle = (self.value * 0.8 * 2 + 0.7) * math.pi
        x = (self.radius - 5) * math.cos(angle) + self.position[0]
        y = (self.radius - 5) * math.sin(angle) + self.position[1]
        return(x, y)

    def display(self):
        pygame.draw.circle(self.screen, self.color, self.position, self.radius)
        pygame.draw.line(self.screen, "black", self.position, self.get_pointer_position(), 4)