Pygame issue while using scrolling to "zoom in/out".

[Jory R Ferrell]

i am attempting to use the scroll wheel to enlarge or shrink everything on the screen. But after I enlarge the images and try to shrink them, the images disappear completely and I can no longer "scroll in". Obviously I am not updating everything correctly, but I'm not sure what I did wrong.

Also, I can't scroll in more than once...I was under the impression that I could make multiple calls to the function the way it's written, and each call would reassign something to the width and height. This is not happening. I suspect again because I am not updating the images correctly?

background_image_filename = 'C:\Users\office\Documents\Portable Python 2.7.2.1\App\Background.jpg'
sprite_image_filename = 'C:\Users\office\Documents\Portable Python 2.7.2.1\App\Neuron_On_2.png'
sprite_image_filename_2 = 'C:\Users\office\Documents\Portable Python 2.7.2.1\App\Neuron_Off_2.png'

import pygame
from pygame.locals import *
from sys import exit

pygame.init()

screen = pygame.display.set_mode((600, 600), 0, 32)

background = pygame.image.load(background_image_filename).convert()

sprite = pygame.image.load(sprite_image_filename).convert_alpha()
sprite_2 = pygame.image.load(sprite_image_filename_2).convert_alpha()
display_Sprite = sprite_2
clock = pygame.time.Clock()

# The x coordinate of our sprite
x = 290.0
y = 290.0

h = 0
w = 0


while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()

        pressed_mouse = pygame.mouse.get_pressed()

        if pressed_mouse[0]:
            newX, newY = pygame.mouse.get_pos()
            x = newX
            y = newY
            display_Sprite = sprite
            pygame.display.update()

        if not pressed_mouse[0]:
            display_Sprite = sprite_2
            pygame.display.update()

        if event.type == pygame.MOUSEBUTTONDOWN:
            print event.button
            w, h = sprite.get_size()
            if event.button == 4:
                sprite = pygame.transform.scale(sprite, ((w/100)*150, (h/100)*150))
                sprite_2 = pygame.transform.scale(sprite_2, ((w/100)*150, (h/100)*150))
            elif event.button == 5:
                sprite = pygame.transform.scale(sprite, ((w/100)*90, (h/100)*90))
                sprite_2 = pygame.transform.scale(sprite_2, ((w/100)*90, (h/100)*90))
           
            pygame.display.update()

    
    screen.blit(background, (0,0))
    screen.blit(display_Sprite, (x-w/2, y-h/2))

    clock.tick(120)

[Jory R Ferrell]

Nevermind on the updating each time I scroll. For some reason the image won't scale any longer past just a certain size. I started with larger images and it's scrolling fine...till I hit a threshold. I Still don't know why that is.

Again, I just need to figure out why the image disappears past a certain size (only does it when shrinking).