Linked List Visualizer

import pygame

pygame.init()
SCREEN = WIDTH, HEIGHT = 640, 380

info = pygame.display.Info()
width = info.current_w
height = info.current_h

if width >= height:
    win = pygame.display.set_mode(SCREEN, pygame.NOFRAME)
else:
    win = pygame.display.set_mode(SCREEN, pygame.NOFRAME | pygame.SCALED | pygame.FULLSCREEN)

clock = pygame.time.Clock()
FPS = 60

# COLORS **********************************************************************

WHITE = (255, 255, 255)
BLUE = (30, 144,255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLACK = (0, 0, 20)

font = pygame.font.SysFont('Arial', 15)
font1 = pygame.font.SysFont("Arial", 20, True)
cross = font1.render("X", True, RED)
visualizer = font1.render("Linked List Visualizer", True, BLUE)

textArray = [
    '1. Insert at Front',
    '2. Insert at Rear',
    '3. Delete from Front',
    '4. Delete from Rear',
    '5. Get Linked List Size'
]


class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkedList:
    def __init__(self):
        self.start = None
        self.initial = 40
        self.length = 0

    def insertFront(self, data):
        node = Node(data)
        if self.start is None:
            self.start = node
        else:
            node.next = self.start
            self.start = node
        self.length += 1

    def insertEnd(self, data):
        node = Node(data)
        ptr = self.start
        while (ptr.next is not None):
            ptr = ptr.next
        ptr.next = node
        self.length += 1

    def removeFront(self):
        if self.size():
            ptr = self.start
            self.start = self.start.next
            self.length -= 1
            return ptr.data
        return None

    def removeRear(self):
        if self.size():
            data = None
            if self.start.next is None:
                data = self.start.data
                self.start = None
            else:
                ptr = self.start
                while(ptr.next.next is not None):
                    ptr = ptr.next
                temp = ptr.next
                ptr.next = None
                data = temp.data
            self.length -= 1
            return data
        return None

    def size(self):
        return self.length

radius = 15
def displayList(head):
    size = ll.size()
    initial = WIDTH // 2 - ((size * 50) // 2)
    i = 0
    if head is None:
        rect = pygame.draw.circle(win, WHITE, (initial + (50 * i), 110), radius)
        pygame.draw.circle(win, RED, (initial + (50 * i), 110), radius, 1)
        pygame.draw.line(win, WHITE, (rect.right, rect.centery), (rect.right+30, rect.centery), 2)
    else:
        while (head is not None):
            rect = pygame.draw.circle(win, WHITE, (initial + (50 * i), 110), radius)
            pygame.draw.circle(win, RED, (initial + (50 * i), 110), radius, 1)
            text = font.render(f'{head.data}', True, RED)
            win.blit(text, (rect.centerx-7, rect.centery-10))
            pygame.draw.line(win, WHITE, (rect.right, rect.centery), (rect.right+30, rect.centery), 2)
            head = head.next
            i += 1
    win.blit(cross, (rect.right+30, rect.centery-12))

ll = LinkedList()

mode = None
data = ''
msg = ''
takeInput = False

running = True
while running:
    win.fill(BLACK)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE or event.key == pygame.K_q:
                running = False

            if takeInput:
                if pygame.key.name(event.key).isdigit():
                    data += pygame.key.name(event.key)

            if event.key == pygame.K_1 and not mode:
                mode = 1
                takeInput = True
                msg = ''

            if event.key == pygame.K_2 and not mode:
                mode = 2
                takeInput = True
                msg = ''

            if event.key == pygame.K_3 and not mode:
                d = ll.removeFront()
                if d:
                    msg = f'Front Element deleted : {d}'

            if event.key == pygame.K_4 and not mode:
                d = ll.removeRear()
                if d:
                    msg = f'Rear Element deleted : {d}'

            if event.key == pygame.K_5 and not mode:
                msg = f'Linked List Size : {ll.size()}'

            if event.key == pygame.K_SPACE or event.key == pygame.K_RETURN:
                if mode == 1 and data:
                    ll.insertFront(int(data))
                if mode == 2 and data:
                    ll.insertEnd(int(data))
                mode = None
                takeInput = False
                data = ''

    win.blit(visualizer, (WIDTH//2-visualizer.get_width()//2, 30))
    displayList(ll.start)
    pygame.draw.line(win, WHITE, (0, 180), (WIDTH, 180), 3)
    for index, text in enumerate(textArray):
        color = WHITE
        if mode and index == mode - 1:
            color = GREEN
        textImage = font.render(text, True, color)
        win.blit(textImage, (40, (200 + (30*index))))

    if takeInput:
        datatext = font.render(f'Enter data : {data}', True, WHITE)
        win.blit(datatext, (WIDTH//2, HEIGHT//2+50))

    if msg:
        datatext = font.render(f'{msg}', True, WHITE)
        win.blit(datatext, (WIDTH//2, HEIGHT//2+50))

    pygame.draw.rect(win, WHITE, (0, 0, WIDTH, HEIGHT), 3)

    clock.tick(FPS)
    pygame.display.update()

pygame.quit()