pygame dragging a background image - pygame

Question

This is a follow up question to the code below.
I commented out the y imgPos so the image can only be dragged left or right. But you can drag the image forever in either direction. How can you put a stopping point so you can not drag it any further left and right.
I have tried imgPos.clamp_ip(screen)
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)

Answer 1

Why not just do this
if e.type == MOUSEMOTION:
if e.buttons[LeftButton]:
# clicked and moving
rel = e.rel
imgPos.x += rel[0]
if imgPos.x < MIN_X:
imgPos.x = MIN_X
elif imgPos.x > MAX_X:
imgPos.x = MAX_X
If you want to make this a little neater, you could wrap it up in a pygame.Rect object, which would also make it easier to add the same functionality to the imgPos.y
border = pygame.Rect(MIN_X, MIN_Y, WIDTH, HEIGHT)
if e.type == MOUSEMOTION:
if e.buttons[LeftButton]:
# clicked and moving
rel = e.rel
imgPos.x += rel[0]
if imgPos.left < border.left:
imgPos.left = border.left
elif imgPos.right > border.right:
imgPos.right = border.right