My character doesn't stay inside the screen

Question

I'm new to programming and my character goes out of the screen when I run the code. How can I make it stay inside the screen? Also, I have this wall.png which will work as the wall. How do I put the wall as the limit of the screen so it doesn't go away from the screen?

code:

import os, sys
import pygame
from pygame.locals import *
from ayuda import *

pygame.init
 class PyManMain:    

    def __init__(self, width=600,height=600):

        pygame.init()
        self.width = width
        self.height = height
        self.screen = pygame.display.set_mode((self.width
                                           , self.height))

    def MainLoop(self):
        self.LoadSprites();
        pygame.key.set_repeat(500, 30)

        self.background = pygame.Surface(self.screen.get_size())
        self.background = self.background.convert()
        self.background.fill((50,85,40))

        while 1:
            for event in pygame.event.get():
                if event.type == pygame.QUIT: 
                    sys.exit()
                elif event.type == KEYDOWN:
                    if ((event.key == K_RIGHT)
                    or (event.key == K_LEFT)
                    or (event.key == K_UP)
                    or (event.key == K_DOWN)):
                        self.snake.move(event.key)

            lstCols = pygame.sprite.spritecollide(self.snake
                                                 , self.pellet_sprites
                                                 , True)

            self.snake.pellets = self.snake.pellets + len(lstCols)


            self.screen.blit(self.background, (0, 0))     

            self.pellet_sprites.draw(self.screen)
            self.snake_sprites.draw(self.screen)
            pygame.display.flip()

    def LoadSprites(self):
        self.snake = Snake()
        self.snake_sprites = pygame.sprite.RenderPlain((self.snake))

        nNumHorizontal = int(self.width/64)
        nNumVertical = int(self.height/64)       
        self.pellet_sprites = pygame.sprite.Group()
        for x in range(nNumHorizontal):
            for y in range(nNumVertical):
                self.pellet_sprites.add(Pellet(pygame.Rect(x*64, y*64, 64, 64)))        

class Snake(pygame.sprite.Sprite):


    def __init__(self):
        pygame.sprite.Sprite.__init__(self) 
        self.image, self.rect = load_image('personaje.png',-1)
        self.pellets = 0

        self.x_dist = 5
        self.y_dist = 5 

    def move(self, key):

        xMove = 0;
        yMove = 0;

        if (key == K_RIGHT):
            xMove = self.x_dist
        elif (key == K_LEFT):
            xMove = -self.x_dist
        elif (key == K_UP):
            yMove = -self.y_dist
        elif (key == K_DOWN):
            yMove = self.y_dist
        self.rect.move_ip(xMove,yMove);



class Pellet(pygame.sprite.Sprite):

    def __init__(self, rect=None):
        pygame.sprite.Sprite.__init__(self) 
        self.image, self.rect = load_image('cofrefront.png',-1)
        if rect != None:
            self.rect = rect


if __name__ == "__main__":
    MainWindow = PyManMain()
    MainWindow.MainLoop()

Answer 1

I think I know what your problem is. You would like your character (snake) to stay inside the screen when he reaches the edges of the window. To achieve this, you need to modify the move function of the Snake class :). My modifications would look like this:

def move(self, key):

    xMove = 0;
    yMove = 0;

    if (key == K_RIGHT) and self.rect.right + self.x_dist <= 600 :
        xMove = self.x_dist
    elif (key == K_LEFT) and self.rect.left - self.x_dist >= 0:
        xMove = -self.x_dist
    elif (key == K_UP) and self.rect.top - self.y_dist >= 0:
        yMove = -self.y_dist
    elif (key == K_DOWN) and self.rect.bottom + self.y_dist <= 600:
        yMove = self.y_dist

    self.rect.move_ip(xMove,yMove);

Essentially what I did above, is before I let the character move left,right,up and down, I check whether he would be outside the visible screen. If after the movement he still is inside the screen, I let him move. If not, I block he's movement :)

Hope that helped,

Cheers!

Alex