public class  DragDrop extends Activity{


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        //for no title
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        // draw the view
        setContentView(new DrawView(this));


     }

    public class DrawView extends View
    {
       Context context;
       private ColorBall[] colorballs = new ColorBall[3]; // array that holds the balls
       private int balID = 0; // variable to know what ball is being dragged

       int sx,sy,tx,ty;
       Bitmap aa,pp,ppp,ll,ee,trans,nn,tt;

       int a;

       Point point1 = new Point();
       Point point2 = new Point();
       Point point3 = new Point();

        public DrawView(Context context)
        {
            super(context);
            setFocusable(true); //necessary for getting the touch events
            //getting the screen size

            Display display = getWindowManager().getDefaultDisplay();

            sx = display.getWidth();
            sy = display.getHeight();

            a=R.drawable.a;
            trans=BitmapFactory.decodeResource(getResources(), R.drawable.trans);

            aa=BitmapFactory.decodeResource(getResources(), R.drawable.aa);
            nn=BitmapFactory.decodeResource(getResources(), R.drawable.nn);
            tt=BitmapFactory.decodeResource(getResources(), R.drawable.tt);


            // setting the start point for the balls

            point1.x = sx-200;
            point1.y = 250;

            point2.x = sx/2-50;
            point2.y = 250;

            point3.x = 100;
            point3.y = 250;

            // declare each ball with the ColorBall class
            colorballs[0] = new ColorBall(context,a, point1);
            colorballs[1] = new ColorBall(context,R.drawable.n, point2);
            colorballs[2] = new ColorBall(context,R.drawable.t, point3);


        }

        // the method that draws the balls
        @Override protected void onDraw(Canvas canvas)
        {

            canvas.drawBitmap(tt,100, 50, null);
            canvas.drawBitmap(nn,sx/2-50, 50, null);
            canvas.drawBitmap(aa,sx-200, 50, null);

            if(set_a)
            {
                a=R.drawable.trans;
            }

            //draw the balls on the canvas
            for (ColorBall ball : colorballs)
            {

                tx=ball.getX();
                ty=ball.getY();

                canvas.drawBitmap(ball.getBitmap(),tx, ty, null);

                  if(tx>sx/2-50 && tx<((sx/2)-50)+20 && ty>50  && ty<70 && balID==2)
                  {
                        nn=BitmapFactory.decodeResource(getResources(), R.drawable.n);
                   }

                  if(tx>sx-200 && tx<(sx-200)+20 && ty>50 && ty<=75 && balID==1)
                  {
                      aa=BitmapFactory.decodeResource(getResources(), R.drawable.a1);
                      set_a=true;
                  }

                  if(tx>100 && tx<120 && ty>50 && ty<=75 && balID==3)
                  {
                      tt=BitmapFactory.decodeResource(getResources(), R.drawable.t);
                  }

            }


        }

        // events when touching the screen
        public boolean onTouchEvent(MotionEvent event)
        {
            int eventaction = event.getAction();

            int X = (int)event.getX();
            int Y = (int)event.getY();

            switch (eventaction )
            {

            case MotionEvent.ACTION_DOWN: // touch down so check if the finger is on a ball
                balID = 0;
                for (ColorBall ball : colorballs)
                {
                    // check if inside the bounds of the ball (circle)
                    // get the center for the ball
                    int centerX = ball.getX() + 25;
                    int centerY = ball.getY() + 25;

                    // calculate the radius from the touch to the center of the ball
                    double radCircle  = Math.sqrt( (double) (((centerX-X)*(centerX-X)) + (centerY-Y)*(centerY-Y)));

                    // if the radius is smaller then 23 (radius of a ball is 22), then it must be on the ball
                    if (radCircle < 23)
                    {
                        balID = ball.getID();
                        break;
                    }

                    // check all the bounds of the ball (square)
                    //if (X > ball.getX() && X < ball.getX()+50 && Y > ball.getY() && Y < ball.getY()+50){
                    //  balID = ball.getID();
                    //  break;
                    //}
               }

                 break;


            case MotionEvent.ACTION_MOVE:   // touch drag with the ball
                // move the balls the same as the finger
                if (balID > 0)
                {
                    colorballs[balID-1].setX(X-25);
                    colorballs[balID-1].setY(Y-25);
                }

                break;

            case MotionEvent.ACTION_UP:
                // touch drop - just do things here after dropping

                 break;
            }
            // redraw the canvas
            invalidate();
            return true;

        }
    }

}

public class ColorBall{
     private Bitmap img; // the image of the ball
     private int coordX = 0; // the x coordinate at the canvas
     private int coordY = 0; // the y coordinate at the canvas
     private int id; // gives every ball his own id, for now not necessary
     private static int count = 1;
     private boolean goRight = true;
     private boolean goDown = true;

    public ColorBall(Context context, int drawable)
    {

        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inJustDecodeBounds = true;
        img = BitmapFactory.decodeResource(context.getResources(), drawable);
        id=count;
        count++;

    }

    public ColorBall(Context context, int drawable, Point point)
    {

        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inJustDecodeBounds = true;
        img = BitmapFactory.decodeResource(context.getResources(), drawable);
        id=count;
        count++;
        coordX= point.x;
        coordY = point.y;

    }

    public static int getCount()
    {
        return count;
    }

    void setX(int newValue)
    {
        coordX = newValue;
    }

    public int getX()
    {
        return coordX;
    }

    void setY(int newValue)
    {
        coordY = newValue;
   }

    public int getY()
    {
        return coordY;
    }

    public int getID()
    {
        return id;
    }

    public Bitmap getBitmap()
    {
        return img;
    }

    public void moveBall(int goX, int goY)
    {
        // check the borders, and set the direction if a border has reached
        if (coordX > 270){
            goRight = false;
        }
        if (coordX < 0){
            goRight = true;
        }
        if (coordY > 400){
            goDown = false;
        }
        if (coordY < 0){
            goDown = true;
        }
        // move the x and y
        if (goRight){
            coordX += goX;
        }else
        {
            coordX -= goX;
        }
        if (goDown){
            coordY += goY;
        }else
        {
            coordY -= goY;
        }

    }

}