[PyGame] Zooming on mouse position calculation

[GJG]

HI :) ! I have been trying to create a simple zoom on point navigation with pygame, and after endless googling sessions, this is as close as I could get. The problem is that when I change the mouse position in a deeper zoom level, it shifts the image a bit to the side. I am probably missing some other value conversion, and unfortunately I do not have enough brain power to understand where or how, so any help would be greatly appreciated.

import pygame
from pygame.locals import*

pygame.init()
clock = pygame.time.Clock()

screen_size = 1920, 1080
aspect_ratio = 16,9
screen = pygame.display.set_mode((screen_size[0], screen_size[1]))
pygame.display.set_caption('Zooooom')

image_path = 'C:/world map HD.jpg'
original_image = pygame.image.load(image_path).convert()

zoom = 0 
zoom_limit = screen_size[0] / aspect_ratio[0] - 1
pos = [0,0]

running = True

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False
        elif event.type == pygame.MOUSEBUTTONDOWN:

            if event.button == 4:
                if zoom < zoom_limit:

                    this_crop_distance = zoom * aspect_ratio[0], zoom * aspect_ratio[1]
                    next_crop_distance = (zoom + 1) * aspect_ratio[0], (zoom + 1) * aspect_ratio[1]

                    this_zoom_resolution = screen_size[0] - this_crop_distance[0], screen_size[1] - this_crop_distance[1]
                    next_zoom_resolution = screen_size[0] - next_crop_distance[0], screen_size[1] - next_crop_distance[1]

                    factor = this_zoom_resolution[0] / next_zoom_resolution[0]

                    updated_x = (event.pos[0] - pos[0]) * (factor - 1)
                    updated_y = (event.pos[1] - pos[1]) * (factor - 1)

                    pos[0] += updated_x
                    pos[1] += updated_y

                    zoom += 1

            elif event.button == 5:
                if zoom > 0:
                    
                    this_crop_distance = zoom * aspect_ratio[0], zoom * aspect_ratio[1]
                    next_crop_distance = (zoom-1) * aspect_ratio[0], (zoom-1) * aspect_ratio[1]

                    this_zoom_resolution = screen_size[0] - this_crop_distance[0], screen_size[1] - this_crop_distance[1]
                    next_zoom_resolution = screen_size[0] - next_crop_distance[0], screen_size[1] - next_crop_distance[1]

                    factor = this_zoom_resolution[0] / next_zoom_resolution[0]

                    updated_x = (event.pos[0] - pos[0]) * (factor - 1)
                    updated_y = (event.pos[1] - pos[1]) * (factor - 1)

                    pos[0] += updated_x
                    pos[1] += updated_y

                    zoom -= 1


    crop_distance = zoom * aspect_ratio[0], zoom * aspect_ratio[1]
    cropped_region = pos[0], pos[1] , screen_size[0] - crop_distance[0], screen_size[1] - crop_distance[1]

    blit_output = pygame.transform.scale(original_image.subsurface(cropped_region), screen_size)
    screen.blit(blit_output, (0,0))

    pygame.display.update()
    clock.tick(60)

pygame.quit()
quit()