python - How to make an image grow in size with pygame

Question

This question already has an answer here: question from:https://stackoverflow.com/questions/65545404/how-to-make-an-image-grow-in-size-with-pygame

Answer 1

The image isn't really moving. It might look like its moving towards the bottom-right corner because its getting bigger i.e. its width and height are increasing, which remember, starts at the top left corner of the image. That is where it is drawn as well. So to make it look like its growing, you can offset where its drawn my half the width and the height, which basically means offset it so that it is drawn at the centre. Replace

background.blit(self.image, (self.x_pos, self.y_pos))

with

background.blit(self.image, (self.x_pos - (self.width/2), self.y_pos - (self.height/2)))

Working Example

import pygame

class GrowingImage:

    def __init__(self, image_path, x, y, width, height):
        self.width = width
        self.height = height

        self.object_image = image_path

        self.image = pygame.transform.scale(self.object_image, (self.width, self.height))

        self.x_pos = x
        self.y_pos = y

    def draw(self, background):
        background.blit(self.image, (self.x_pos - (self.width/2), self.y_pos - (self.height/2)))

    def grow(self):
        self.image = pygame.transform.smoothscale(self.object_image, (self.width, self.height))
        self.width += 1
        self.height += 1


pygame.init()

d = pygame.display.set_mode((600, 600))
image = pygame.Surface((1, 1))
growingImage = GrowingImage(image, 300, 300, 20, 20)

while True:
    d.fill((255, 255, 255))
    pygame.event.get()

    growingImage.draw(d)
    growingImage.grow()

    pygame.display.update()