Snake-Game: Having problems with continious movement of the snake

Question

The cube is only moving once.

import time
import pygame

pygame.init()


class Window(object):
    def __init__(self, width, height, bg):
        self.width = width
        self.height = height
        self.bg = bg

    def create(self):
        return pygame.display.set_mode((self.width, self.height))

The problem is somewhere here

class Cube(object):
    def __init__(self, surface, x, y, width, height, color):
        self.surface = surface
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.color = color

    def move(self, lead_x_change=0, lead_y_change=0):
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                lead_x_change = -20
            elif event.key == pygame.K_RIGHT:
                lead_x_change = 20
            elif event.key == pygame.K_UP:
                lead_y_change = -20
            elif event.key == pygame.K_DOWN:
                lead_y_change = 20
        self.x += lead_x_change
        self.y += lead_y_change

    def draw(self):
        pygame.draw.rect(self.surface, self.color, (self.x, self.y, self.width, self.height))


window = Window(800, 600, (0, 0, 0))
surface = window.create()

head = Cube(surface, 400, 300, 20, 20, (255, 255, 255))

starting gameloop

gameloop = True
while gameloop:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()

        head.move()

        surface.fill((0, 0, 0))
        head.draw()
        pygame.display.update()

The Cube moves, but only one time after a keypress. it should continiously move in one direction though, after pressing the direction. I dont know how to make it move continiously, even watched ton of videos about it and still dont understand.

Answer 1

Based on the comment that OP wants the movement to occur until another key is pressed, as opposed to whether a key is held down, there is an entirely separate solution involved. Instead, the code must be refactored to instead include a variable for the last direction that was pressed, and a timed loop to continuously move in that direction.

In the Cube's __init__ method, add:

self.lastDir = null

Make a new method in the Cube class for handling the key event:

def updateDir(self, event):
    if event.type == pygame.KEYDOWN and event.key in [pygame.K_LEFT, pygame.K_RIGHT, pygame.K_UP, pygame.K_DOWN]:
        self.lastDir = event.key

Modify the move method to instead be based on self.lastDir instead of event.key:

if self.lastDir != null:
    if self.lastDir == pygame.K_LEFT:
        lead_x_change = -20
...

And finally, modify the main loop to call the move method on a regular basis, as opposed to waiting for a new move:

gameloop = True
while gameloop:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            quit()
        head.updateDir(event)
    head.move()
    surface.fill((0, 0, 0))
    head.draw()
    pygame.display.update()
    # Insert time.sleep(seconds) here if too fast