How to compile code into a Class with functions - python-3.x

Question

I don't know how to turn this code into a class statement and then run it!
I want to have the same result as this but using class statements.
import pygame
import random
pygame.init()
winh = 500
winl = 500
win = pygame.display.set_mode((winh, winl))
width = 20
vel = 5
y = 250
x = 250
score = 0
direction = "up"
class Dot():
def __init__(self):
self.x = x
self.y = y
self.width = width
self.direction = 'right'
def direction(self):
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
keys = pygame.key.get_pressed()
if keys[pygame.K_w]:
self.direction = "up"
if keys[pygame.K_a]:
self.direction = "left"
if keys[pygame.K_s]:
self.direction = "down"
if keys[pygame.K_d]:
self.direction = "right"
p = True
run = True
while run:
pygame.time.delay(100)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
keys = pygame.key.get_pressed()
if keys[pygame.K_w]:
direction = "up"
if keys[pygame.K_a]:
direction = "left"
if keys[pygame.K_s]:
direction = "down"
if keys[pygame.K_d]:
direction = "right"
if direction == "up":
y -= width
if direction == "down":
y += width
if direction == "left":
x -= width
if direction == "right":
x += width
if y > winh - 20:
y = 20
if y < 20:
y = winh - 20
if x > winl - 20:
x = 20
if x < 0:
x = winl - 20
win.fill((0,0,0))
dot = pygame.draw.rect(win, (0, 255, 0), (x, y, width, width))
pygame.display.update()
pygame.quit()

Answer 1

So you're class was getting there already. A class is an encapsulation of data and functions that are common to that "object". Anything for or about that object should go into this class. But when code for keyboard handling was put into a Dot class, this was going in the wrong direction. A Dot is a thing draw to a screen, it has a size and colour, and position. It should not be responsible for handling user-input. That's outside the scope of what a Dot is.
When updating the class, I chose to base it on the PyGame sprite class. This is a little bit more work at first, and it needs to be written in a particular way - have an image, and a rect, and (hopefully) an update() function. But being a sprite it gets lots of functionality that's already written, including the PyGame collision routines.
Near the main loop, there's a couple of additions. The first is creating the sprite dotty, and a sprite-group sprites to hold it. It's a bit weird to create a sprite group for a single sprite, but I assumed in the future there would be more than one.
Then in the actual loop, the code calls sprites.update(). This is a handy routine that calls the update() function for every sprite in the group. Then later on, there's a call to sprites.draw( win ) which paints every sprite in the group to the screen. This uses the sprite's image and the rect to know where, and what to paint.
import pygame
import random
pygame.init()
WIN_H = 500
WIN_L = 500
win = pygame.display.set_mode((WIN_H, WIN_L))
width = 20
vel = 5
y = 250
x = 250
score = 0
direction = "up"
class Dot( pygame.sprite.Sprite ):
def __init__( self, x,y, size=20, direction='right', colour=(0,255,0) ):
pygame.sprite.Sprite.__init__( self )
self.size = size
self.colour = colour
self.direction = direction
self.image = pygame.Surface( ( size, size ), pygame.SRCALPHA )
self.rect = self.image.get_rect()
self.rect.x = x
self.rect.y = y
self.image.fill( colour )
def move( self, x_dir, y_dir ):
global WIN_H, WIN_L
# Adjust our co-oridinates
self.rect.x += x_dir
self.rect.y += y_dir
# Stay on the screen, and wrap around
if (self.rect.left >= WIN_L ):
self.rect.right = 0
elif (self.rect.right <= 0 ):
self.rect.left = WIN_L
if (self.rect.top >= WIN_H ):
self.rect.bottom = 0
elif (self.rect.bottom <= 0):
self.rect.top = WIN_H
def update( self ):
# TODO - handle animation, collisions, whatever
pass
# make some sprites
dotty = Dot( x,y )
sprites = pygame.sprite.Group() # a group, for a single sprite (or more)
sprites.add( dotty )
p = True
run = True
while run:
pygame.time.delay(100)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
keys = pygame.key.get_pressed()
if keys[pygame.K_w]:
direction = "up"
if keys[pygame.K_a]:
direction = "left"
if keys[pygame.K_s]:
direction = "down"
if keys[pygame.K_d]:
direction = "right"
if direction == "up":
dotty.move( 0, -width )
if direction == "down":
dotty.move( 0, width )
if direction == "left":
dotty.move( -width, 0 )
if direction == "right":
dotty.move( width, 0 )
# update all the sprites
sprites.update()
# repaint the screen
win.fill((0,0,0))
sprites.draw( win )
#dot = pygame.draw.rect(win, (0, 255, 0), (x, y, width, width))
pygame.display.update()
pygame.quit()
The movement code was moved into the Dot class. This allows the Dot to adjust its position, but also take care of screen-wrapping issues. If this sprite was say, some kind of projectile, maybe when it crossed the screen boundary it would call the sprite.kill() function to remove itself from the sprite group. But since a Dot is clearly not a projectile, it can warp to the other side.