I was trying to learn surface view and i did read about it.
So , i tried making a game, i thought it would help learn me a bit better.
I created a surface view class which looks like this :
class SnakeEngine extends SurfaceView implements Runnable,View.OnTouchListener {
private Thread thread = null;
private Context context;
private SoundPool soundPool;
private int eat_bob = -1;
private int snake_crash = -1;
private Rect rect2;
private Rect rect1;
private boolean snakeHungry=true;
private boolean runThread=true;
public enum Heading {UP, RIGHT, DOWN, LEFT}
private Heading heading = Heading.RIGHT;
private int screenX;
private int screenY;
private int snakeLength=1;
private float x;
private float y;
private float bobX=0;
private float bobY=0;
private final int blockSize=40;
private final int FPS = 10;
private int score=0;
private int[] snakeXs;
private int[] snakeYs;
private int xSpeed=FPS;
private int yspeed=FPS;
private boolean foodOnTable=false;
private volatile boolean isPlaying=true;
private SurfaceHolder surfaceHolder;
private Paint paint;
public SnakeEngine(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SnakeEngine(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public SnakeEngine(Context context) {
super(context);
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = null;
if (wm != null) {
display = wm.getDefaultDisplay();
}
Point size = new Point();
if (display != null) {
display.getSize(size);
}
screenX = size.x;
screenY = size.y;
surfaceHolder=getHolder();
setOnTouchListener(this);
paint=new Paint();
paint.setColor(Color.GREEN);
snakeXs=new int[200];
snakeYs=new int[200];
}
@Override
public void run() {
while (runThread) {
try {
long MILLIS_PER_SECOND = 20;
Thread.sleep(MILLIS_PER_SECOND);
} catch (InterruptedException e) {
e.printStackTrace();
thread.interrupt();
}
if(!surfaceHolder.getSurface().isValid())
continue;
Canvas canvas = surfaceHolder.lockCanvas();
update();
draw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
public void resume() {
thread=new Thread(this);
thread.start();
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
canvas.drawColor(Color.argb(255, 26, 128, 182));
int foodSize = 20;
canvas.drawRect(x, y, (int) (x + foodSize), y + foodSize, paint);
for (int i = 0; i < snakeLength; i++) {
canvas.drawRect(snakeXs[i], snakeYs[i], snakeXs[i] + blockSize, snakeYs[i] + blockSize, paint);
}
}
public void getLocation() {
Random random = new Random();
x= random.nextInt(screenX-blockSize);
y= random.nextInt(screenY-blockSize);
}
private void update() {
Log.e("here","here");
if(!foodOnTable){
getLocation();
foodOnTable=true;
}
if(bobX<x && bobY<y && (bobX+blockSize)>x && (bobY+blockSize)>y){
eatFood();
getLocation();
foodOnTable=true;
}
bobX+=xSpeed;
bobY+=yspeed;
moveSnake((int)bobX,(int)bobY);
if(bobX+blockSize>=screenX || bobY+blockSize>=screenY ||
(bobY+FPS<=0 && bobX!=0) || (bobX!=0 && bobY>=screenY) || (bobX==0 && bobY+FPS==0)
||(bobX+FPS==0 && bobY==0)|| (bobY!=0 && bobX+FPS<=0)){
bobX-=xSpeed;
bobY-=yspeed;
}
}
private void moveSnake(int bobX,int bobY) {
if (snakeHungry) {
for (int i = 0; i < snakeLength - 1; i++) {
snakeXs[i] = snakeXs[i + 1];
snakeYs[i] = snakeYs[i + 1];
}
}else snakeHungry=!snakeHungry;
snakeXs[snakeLength - 1] = bobX;
snakeYs[snakeLength - 1] = bobY;
}
private void eatFood() {
snakeLength++;
snakeHungry=false;
}
public void pause() {
if(thread!=null){
runThread=false;
try {
thread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void directSnake(Heading heading){
switch (heading){
case UP:
xSpeed=0;
yspeed=-FPS;
break;
case DOWN:
xSpeed=0;
yspeed=FPS;
break;
case LEFT:
xSpeed=-FPS;
yspeed=0;
break;
case RIGHT:
xSpeed=FPS;
yspeed=0;
break;
}
}
@Override
public boolean onTouch(View v, MotionEvent event) {
int x=(int)event.getX();
int y=(int)event.getY();
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:{
if(heading==Heading.LEFT || heading ==Heading.RIGHT){
if(y>(bobY+blockSize)){
directSnake(Heading.DOWN);
heading=Heading.DOWN;
}else {
directSnake(Heading.UP);
heading=Heading.UP;
}
break;
}else if(heading==Heading.DOWN || heading==Heading.UP) {
if(x<(bobX+blockSize)){
directSnake(Heading.LEFT);
heading=Heading.LEFT;
}else {
directSnake(Heading.RIGHT);
heading=Heading.RIGHT;
}
break;
}
break;
}
}
return true;
}
}
My mainactivity file looks like this:
public class MainActivity extends AppCompatActivity {
SnakeEngine snakeEngine;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
snakeEngine=new SnakeEngine(this);
setContentView(R.layout.activity_main);
}
@Override
protected void onResume() {
super.onResume();
snakeEngine.resume();
}
@Override
protected void onPause() {
super.onPause();
snakeEngine.pause();
}
}
Layout file:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.snake.tilak.myapplication.MainActivity">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.snake.tilak.myapplication.SnakeEngine
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/surfaceView">
</com.snake.tilak.myapplication.SnakeEngine>
<LinearLayout android:id="@+id/linearLayout1" android:layout_width="wrap_content" android:layout_height="wrap_content">
<ImageButton android:contentDescription="@string/down_button" android:id="@+id/buttonDown" android:background="@mipmap/ic_keyboard_arrow_down_black_24dp" android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<ImageButton android:contentDescription="@string/up_button" android:id="@+id/buttonUp" android:background="@mipmap/ic_keyboard_arrow_up_black_24dp" android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<ImageButton android:contentDescription="@string/left_button" android:id="@+id/buttonLeft" android:background="@mipmap/ic_keyboard_arrow_left_black_24dp" android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<ImageButton android:contentDescription="@string/right_button" android:id="@+id/buttonRight" android:background="@mipmap/ic_keyboard_arrow_right_black_24dp" android:layout_width="wrap_content" android:layout_height="wrap_content"/>
</LinearLayout>
</FrameLayout>
</android.support.constraint.ConstraintLayout>
Now when i run it, all i see is a black screen?
Where did i go wrong ? what should i change in it?
I read various questions here on this topic and can't seem to make anything working.
That's because you trying to instantiate new SnakeEngine, but you should find an instance of it by id because you already add it to XML file:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// snakeEngine = new SnakeEngine(this);
setContentView(R.layout.activity_main);
snakeEngine = findViewById(R.id.surfaceView);
}
Then, when you will fix it, you should move all your initiating logic from public SnakeEngine(Context context) constructor to separate method and call it from each constructor of SnakeEngine:
public SnakeEngine(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public SnakeEngine(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public SnakeEngine(Context context) {
super(context);
init(context);
}
private void init(Context context) {
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = null;
if (wm != null) {
display = wm.getDefaultDisplay();
}
Point size = new Point();
if (display != null) {
display.getSize(size);
}
screenX = size.x;
screenY = size.y;
surfaceHolder = getHolder();
setOnTouchListener(this);
paint = new Paint();
paint.setColor(Color.GREEN);
snakeXs = new int[200];
snakeYs = new int[200];
}