SnakeGame Game Activity

SnakeGame_GameActivity.java

package com.mjuaji.snake1720;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.AssetFileDescriptor;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.media.AudioManager;
import android.media.SoundPool;
import android.os.Bundle;
import android.util.Log;
import android.view.Display;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.io.IOException;
import java.util.Random;

public class GameActivity extends Activity {
    Canvas canvas;
    SnakeView snakeView;
    Bitmap headBitmap;
    Bitmap bodyBitmap;
    Bitmap tailBitmap;
    Bitmap appleBitmap;

    //Initialize sound variables
    private SoundPool soundPool;
    int sample1 = -1;
    int sample2 = -1;
    int sample3 = -1;
    int sample4 = -1;

    //for snake movement 0 = up, 1 = right, 2 = down, 3 = left
    int directionOfTravel = 0;

    int screenWidth;
    int screenHeight;
    int topGap;

    //stats
    long lastFrameTime;
    int fps;
    int score;
    int hi;

    //Game Objects
    int [] snakeX;
    int [] snakeY;
    int snakeLength;
    int appleX;
    int appleY;

    //the size in pixels of a place on the game board
    int blockSize;
    int numBlocksWide;
    int numBlocksHigh;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        loadSound();
        configureDisplay();
        snakeView = new SnakeView(this);
        setContentView(snakeView);
    }

    class SnakeView extends SurfaceView implements Runnable{
        Thread ourThread = null;
        SurfaceHolder ourHolder;
        volatile boolean playingSnake;
        Paint paint;

        public SnakeView(Context context){
            super(context);
            ourHolder = getHolder();
            paint = new Paint();

            //snake length
            snakeX = new int[200];
            snakeY = new int[200];

            //our starting snake
            getSnake();

            //get an apple to much
            getApple();
        }
        public void getSnake(){
            snakeLength = 3;
            //start snake head in the middle of screen
            snakeX[0] = numBlocksWide/2;
            snakeY[0] = numBlocksHigh/2;

            //then the body
            snakeX[1] = snakeX[0]-1;
            snakeY[1] = snakeY[0];

            //and the tail
            snakeX[1] = snakeX[1]-1;
            snakeY[1] = snakeY[0];
        }

        public void getApple(){
            Random random = new Random();
            appleX = random.nextInt(numBlocksWide-1)+1;
            appleY = random.nextInt(numBlocksHigh-1)+1;
        }

        @Override
        public void run() {
            while(playingSnake){
                updateGame();
                drawGame();
                controlFPS();
            }
        }

        public void updateGame(){
            //did the player get the apple
            if(snakeX[0] == appleX && snakeY[0] == appleY){
                //grow the snake
                snakeLength++;
                //replace the apple
                getApple();
                //add to the score
                score = score + snakeLength;
                soundPool.play(sample1,1,1,0,0,1);
            }
            //move the snake starting at the back
            for(int i = snakeLength; i>0 ; i--){
                snakeX[i] = snakeX[i-1];
                snakeY[i] = snakeY[i-1];
            }

            //move the head in the appropriate direction
            switch(directionOfTravel){
                case 0://up
                    snakeY[0] --;
                    break;

                case 1://right
                    snakeX[0] ++;
                    break;

                case 2://down
                    snakeY[0] ++;
                    break;

                case 3://left
                    snakeX[0] --;
                    break;
            }

            //have we had an accident?
            boolean dead = false;

            //with a wall
            if(snakeX[0] == -1) dead = true;
            if(snakeX[0] >= numBlocksWide) dead = true;
            if(snakeY[0] == -1) dead = true;
            if(snakeY[0] == numBlocksHigh) dead = true;

            //have we eaten ourselves
            for(int i = snakeLength -1; i > 0; i--){
                if((i > 4) && (snakeX[0] == snakeX[i]) && (snakeY[0] == snakeY[i])){
                    dead = true;
                }
            }

            if(dead){
                //start again
                soundPool.play(sample4, 1, 1, 0, 0,1);
                score = 0;
                getSnake();
            }
        }

        public void drawGame(){
            if(ourHolder.getSurface().isValid()){
                canvas = ourHolder.lockCanvas();
                //Paint paint = new Paint();
                canvas.drawColor(Color.BLACK);//the background

                paint.setColor(Color.argb(255,255,255,255));
                paint.setTextSize(topGap/2);
                canvas.drawText("Score:" + score + " Hi:" + hi, 10, topGap-6, paint);

                //draw a border - 4 lines, top right, bottom, left
                paint.setStrokeWidth(3);//3 pixel border
                canvas.drawLine(1, topGap, screenWidth-1, topGap, paint);
                canvas.drawLine(screenWidth-1, topGap, screenWidth-1, topGap+(numBlocksHigh*blockSize), paint);
                canvas.drawLine(screenWidth-1, topGap+(numBlocksHigh*blockSize),1, topGap+(numBlocksHigh*blockSize), paint);
                canvas.drawLine(1, topGap, 1,topGap+(numBlocksHigh*blockSize), paint);

                //draw the snake
                canvas.drawBitmap(headBitmap, snakeX[0]*blockSize, (snakeY[0]*blockSize)+topGap, paint);

                //draw the body
                for(int i = 1; i<snakeLength-1; i++){
                    canvas.drawBitmap(bodyBitmap, snakeX[i]*blockSize, (snakeY[i]*blockSize)+topGap, paint);
                }

                //draw the tail
                canvas.drawBitmap(tailBitmap, snakeX[snakeLength-1]*blockSize,(snakeY[snakeLength-1]*blockSize)+topGap, paint);

                //draw the apple
                canvas.drawBitmap(appleBitmap, appleX*blockSize,(appleY*blockSize)+topGap, paint);

                ourHolder.unlockCanvasAndPost(canvas);
            }
        }

        public void controlFPS(){
            long timeThisFrame = (System.currentTimeMillis() - lastFrameTime);
            long timeToSleep = 100 - timeThisFrame;
            if(timeThisFrame > 0){
                fps = (int)(1000/timeThisFrame);
            }
            if(timeToSleep > 0){
                try{
                    ourThread.sleep(timeToSleep);
                } catch(InterruptedException e){

                }
            }
            lastFrameTime = System.currentTimeMillis();
        }

        public void pause(){
            playingSnake = false;
            try{
                ourThread.join();
            }catch(InterruptedException e){

            }
        }

        public void resume(){
            playingSnake = true;
            ourThread = new Thread(this);
            ourThread.start();
        }

        @Override
        public boolean onTouchEvent(MotionEvent motionEvent){
            switch(motionEvent.getAction() & MotionEvent.ACTION_MASK){
                case MotionEvent.ACTION_UP:
                    if(motionEvent.getX() >= screenWidth/2){
                        //turn right
                        directionOfTravel ++;
                        //no such direction
                        if(directionOfTravel ==4)
                            //loop back up to 0
                            directionOfTravel = 0;
                    }else {
                        //turn left
                        directionOfTravel --;
                        if(directionOfTravel == -1){//no such direction
                            //loop back up to 0
                            directionOfTravel = 3;
                        }
                    }
            }
            return true;
        }
    }

    @Override
    protected void onStop(){
        super.onStop();
        while(true){
            snakeView.pause();
            break;
        }
        finish();
    }

    @Override
    protected void onResume(){
        super.onResume();
        snakeView.resume();
    }

    @Override
    protected void onPause(){
        super.onPause();
        snakeView.pause();
    }

    public boolean onKeyDown(int keyCode, KeyEvent event){
        if(keyCode == KeyEvent.KEYCODE_BACK){
            snakeView.pause();
            Intent i = new Intent(this, MainActivity.class);
            startActivity(i);
            finish();
            return true;
        }
        return false;
    }

    public void loadSound(){
        soundPool = new SoundPool(10, AudioManager.STREAM_MUSIC, 0);
        try{
            //Create objects of the 2 required classes
            AssetManager assetManager = getAssets();
            AssetFileDescriptor descriptor;

            //create our three fx in memory ready for use
            descriptor = assetManager.openFd("sample1.ogg");
            sample1 = soundPool.load(descriptor, 0);

            descriptor = assetManager.openFd("sample2.ogg");
            sample2 = soundPool.load(descriptor, 0);

            descriptor = assetManager.openFd("sample3.ogg");
            sample3 = soundPool.load(descriptor, 0);

            descriptor = assetManager.openFd("sample4.ogg");
            sample4 = soundPool.load(descriptor, 0);
        } catch(IOException e){
            //print an error message to the console
            Log.e("error", "failed to load sound files");
        }
    }

    public void configureDisplay(){
        //find out the width and height of the screen
        Display display = getWindowManager().getDefaultDisplay();
        Point size = new Point();
        display.getSize(size);
        screenWidth = size.x;
        screenHeight = size.y;
        topGap = screenHeight/14;

        //determine the size of each block/place on the game board
        blockSize = screenWidth/40;

        //determine how many game blocks will fit into the height
        //and width of the game screen
        // leaving one block for the score at the top
        numBlocksWide = 40;
        numBlocksHigh = ((screenHeight - topGap))/blockSize;

        //load and scale bitmaps
        headBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.head);
        bodyBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.body);
        tailBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.tail);
        appleBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.apple);
        //scale the bitmap to match the block size
        headBitmap = Bitmap.createScaledBitmap(headBitmap, blockSize, blockSize, false);
        bodyBitmap = Bitmap.createScaledBitmap(bodyBitmap, blockSize, blockSize, false);
        tailBitmap = Bitmap.createScaledBitmap(tailBitmap, blockSize, blockSize, false);
        appleBitmap = Bitmap.createScaledBitmap(appleBitmap, blockSize, blockSize, false);
    }


}