How can I rotate my picture using Pygame?

Question

I want to make the Dragon on the picture rotate softly to the left when he flies to the left and rotate to the right when he flies to the right and up and down also.

How can I do that with the WASD keys? The Dragon can fly already up, down, lef, and right....but he doesn't turn...

My Code:

import pygame, sys
from pygame.locals import *

pygame.init()

size = width, height = 1600, 848
speed = [2, 2]
black = (0, 0, 0)

pygame.mouse.set_cursor(*pygame.cursors.broken_x)

screen = pygame.display.set_mode(size)
background = pygame.image.load("background.PNG")
dragon1 = pygame.image.load("dragon1.gif")
x,y=0,0
clock=pygame.time.Clock()
speed=250
movex, movey=0,0

while True:
screen.blit(background, (0,0))
screen.blit(dragon1, (x,y))

for event in pygame.event.get():
    if event.type == QUIT:
        pygame.quit()
        sys.exit()

if event.type==KEYDOWN:
        if event.key==K_a:
            movex=-4
        elif event.key==K_d:
            movex=+4
        elif event.key==K_w:
            movey=-4
        elif event.key==K_s:
            movey=+4
if event.type==KEYUP:
        if event.key==K_a:
            movex=0
        elif event.key==K_d:
            movex=0
        elif event.key==K_w:
            movey=0
        elif event.key==K_s:
            movey=0
x+=movex
y+=movey

pygame.display.flip()

Answer 1

Use pygame.transform.rotate function:

    screen.blit(background, (0,0))
    angle = None
    if movex == 0 and movey < 0:
        angle = -180
    elif movex > 0 and movey >= 0:
        angle = 20
    elif movex < 0 and movey >= 0:
        angle = -20
    elif movex > 0 and movey < 0:
        angle = 160
    elif movex < 0 and movey < 0:
        angle = -160

    if angle:
        dragon = pygame.transform.rotate(dragon1, angle)
    else:
        dragon = dragon1

    screen.blit(dragon, (x,y))
    ...

You can always keep the original surface dragon1 and transform it when you are going to blit it (like the example), or keep three variations pre-calculated and choose which one you want to blit.