Question

I am trying to make my background image move in the opposite direction as the mouse is moving when it is clicked. So it looks like you are dragging the screen left and right, like you can see in many mobile apps. Does anyone have a simple way of doing this?

Answer 1

What you need is to detect the event type, such as MOUSEBUTTONDOWN, MOUSEBUTTONUP, MOUSEMOTION.
When you detected a mouse motion, check if it’s clicked using the event.buttons attribute.
Here’s my implement:

import pygame
from pygame.locals import *

pygame.display.init()
screen = pygame.display.set_mode((800, 600))
img = pygame.image.load('sky.png')

imgPos = pygame.Rect((0, 0), (0, 0))

LeftButton = 0
while 1:
    for e in pygame.event.get():
        if e.type == QUIT: exit(0)
        if e.type == MOUSEMOTION:
            if e.buttons[LeftButton]:
                # clicked and moving
                rel = e.rel
                imgPos.x += rel[0]
                imgPos.y += rel[1]
    screen.fill(0)
    screen.blit(img, imgPos)
    pygame.display.flip()
    pygame.time.delay(30)

---

You may need to read: Pygame event document