main.py

import sys
import random
from PIL import Image,ImageTk
from tkinter import Tk,Frame,Canvas,ALL,NW


class Cons:
    BOARD_WIDTH = 300
    BOARD_HEIGHT = 300
    DELAY = 100
    DOT_SIZE = 10
    MAX_RAND_POS = 27

class Board(Canvas):
    def __init__(self):
        super().__init__(width=Cons.BOARD_WIDTH,height=Cons.BOARD_HEIGHT,
        background="black", highlightthickness=0)

        self.initGame()
        self.pack()
    
    def initGame(self):
        self.inGame = True
        self.dots = 3
        self.score = 0

        self.moveX = Cons.DOT_SIZE
        self.moveY = 0

        self.appleX = 100
        self.appleY = 190

        self.loadImages()

        self.createObjects()
        self.locateApple()
        self.bind_all('<Key>', self.onKeyPressed)
        self.after(Cons.DELAY, self.onTimer)

    def loadImages(self):

        try:
            self.idot = Image.open('dot.png')
            self.dot = ImageTk.PhotoImage(self.idot)
            self.ihead = Image.open('head.png')
            self.head = ImageTk.PhotoImage(self.ihead)
            self.iapple = Image.open('apple.png')
            self.apple = ImageTk.PhotoImage(self.iapple)

        except IOError as e:
            print(e)
            sys.exit(1)
    

    def createObjects(self):

        self.create_text(30,10,text='Score: {0}'.format(self.score),
                         tag='score', fill='white')
        self.create_image(self.appleX, self.appleY, image=self.apple, 
                         anchor=NW, tag='apple')
        
        self.create_image(50,50, image=self.head, anchor=NW, tag='head')
        self.create_image(30,50, image=self.dot, anchor=NW, tag='dot')
        self.create_image(40,50, image=self.dot, anchor=NW, tag='dot')

    def checkAppleCollision(self):
        apple = self.find_withtag('apple')
        head = self.find_withtag('head')

        x1,y1,x2,y2 = self.bbox(head)
        overlap = self.find_overlapping(x1,y1,x2,y2)

        for ovr in overlap:
            if apple[0] == ovr:
                self.score += 1
                x,y = self.coords(apple)
                self.create_image(x,y,image=self.dot, anchor=NW,tag='dot')
                self.locateApple()

    def moveSnake(self):

        dots = self.find_withtag('dot')
        head = self.find_withtag('head')

        items = dots+head

        z=0
        while z < len(items)-1:
            c1 = self.coords(items[z])
            c2 = self.coords(items[z+1])
            self.move(items[z], c2[0]-c1[0], c2[1]-c1[1])
            z += 1
        self.move(head, self.moveX, self.moveY)

    def checkCollisions(self):

        dots = self.find_withtag('dot')
        head = self.find_withtag('head')

        x1,y1,x2,y2 = self.bbox(head)
        overlap = self.find_overlapping(x1,y1,x2,y2)

        for dot in dots:
            for over in overlap:
                if over == dot:
                    self.inGame = True
        
        if x1 < 0 or x1 > Cons.BOARD_WIDTH - Cons.DOT_SIZE:
            self.inGame = False
        if y1 < 0 or y1 > Cons.BOARD_HEIGHT - Cons.DOT_SIZE: 
            self.inGame = False
        

    def locateApple(self):

        apple = self.find_withtag('apple')
        self.delete(apple[0])

        r = random.randint(0,Cons.MAX_RAND_POS)
        self.appleX = r * Cons.DOT_SIZE
        r = random.randint(0, Cons.MAX_RAND_POS)
        self.appleY = r * Cons.DOT_SIZE

        self.create_image(self.appleX, self.appleY, anchor=NW, imag=self.apple, tag = 'apple')

    def onKeyPressed(self,e):

        key = e.keysym

        LEFT_CURSOR_KEY = 'Left'
        if key == LEFT_CURSOR_KEY and self.moveX <= 0:
            self.moveX = -Cons.DOT_SIZE
            self.moveY = 0
        
        RIGHT_CURSOR_KEY = 'Right'
        if key == RIGHT_CURSOR_KEY and self.moveX >= 0:
            self.moveX = Cons.DOT_SIZE
            self.moveY = 0
        
        UP_CURSOR_KEY = 'Up'
        if key == UP_CURSOR_KEY and self.moveY <= 0:
            self.moveX = 0
            self.moveY = - Cons.DOT_SIZE
        
        DOWN_CURSOR_KEY = 'Down'
        if key == DOWN_CURSOR_KEY and self.moveY >= 0:
            self.moveX = 0
            self.moveY = Cons.DOT_SIZE
        
    def onTimer(self):

        self.drawScore()
        self.checkCollisions()

        if self.inGame:
            self.checkAppleCollision()
            self.moveSnake()
            self.after(Cons.DELAY, self.onTimer)
        else:
            self.gameOver()
    
    def drawScore(self):

        score = self.find_withtag('score')
        self.itemconfigure(score,text='Score: {0}'.format(self.score))

    def gameOver(self):

        self.delete(ALL)
        self.create_text(self.winfo_width() / 2, self.winfo_height() / 2, 
                        text='Game Over with score {0}'.format(self.score), fill='white')


class Snake(Frame):
    def __init__(self):
        super().__init__()

        self.master.title('Snake')
        self.board= Board()
        self.pack()


def main():
    root = Tk()
    nib = Snake()
    root.mainloop()


if __name__ == '__main__':
    main()