Collision detection between ImageViews

Question

I need help getting two ImageViews to collide, I looked around on this website and many youtube videos and think I have found one solution to my problem. I found some code from another person post,

how to detect when a ImageView is in collision with another ImageView?

and I'm just wondering where I should place that code in my program because when it's at the bottom i try to log.d to show if I was succesful on trying to detect whether the imageViews collided and nothing shows. Anyways here is my code and the code I used from the other question is at the very bottom and used as a comment. YOUR HELP IS EXTREMELY APPRECIATED, THANK YOU IF YOU HELPED ME!

Main.java

package com.example.admin.basketball;

import android.graphics.Point;


import android.os.Handler;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.view.Display;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

//Layout
private RelativeLayout myLayout = null;

//Screen Size
private int screenWidth;
private int screenHeight;

//Position
private float ballDownY;
private float ballDownX;

//Initialize Class
private Handler handler = new Handler();
private Timer timer = new Timer();

//Images
private ImageView net = null;
private ImageView ball = null;

//for net movement along x-axis
float x;
float y;

//points
private int points = 0;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myLayout = (RelativeLayout) findViewById(R.id.myLayout);

    //score
    final TextView score = (TextView) findViewById(R.id.score);


    //imageviews
    net = (ImageView) findViewById(R.id.net);
    ball = (ImageView) findViewById(R.id.ball);


    //retrieving screen size
    WindowManager wm = getWindowManager();
    Display disp = wm.getDefaultDisplay();
    Point size = new Point();
    disp.getSize(size);
    screenWidth = size.x;
    screenHeight = size.y;

    //move to out of screen
    ball.setX(-80.0f);
    ball.setY(screenHeight + 80.0f);


    //start timer
    timer.schedule(new TimerTask() {
        @Override
        public void run() {
            handler.post(new Runnable() {
                @Override
                public void run() {
                    changePos();
                }
            });
        }
    }, 0, 20);
}


public void changePos() {
    //down

    ballDownY += 10;
    if (ball.getY() > screenHeight) {
        ballDownX = (float) Math.floor((Math.random() * (screenWidth - 
ball.getWidth())));
        ballDownY = -100.0f;

    }
    ball.setY(ballDownY);
    ball.setX(ballDownX);


    //make net follow finger
    myLayout.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent event) {
            MainActivity.this.x = event.getX();
            y = event.getY();

            if (event.getAction() == MotionEvent.ACTION_MOVE) {
                net.setX(MainActivity.this.x);
                net.setY(y);

            }
            return true;
        }
    });
}

}



/*
private boolean viewsOverlap(ImageView net, ImageView ball) {

    int[] net_coords = new int[2];
    net.getLocationOnScreen(net_coords);
    int net_w = net.getWidth();
    int net_h = net.getHeight();
    Rect net_rect = new Rect(net_coords[0], net_coords[1], net_coords[0] + 
net_w, net_coords[1] + net_h);

    int[] ball_coords = new int[2];
    ball.getLocationOnScreen(ball_coords);
    int ball_w = ball.getWidth();
    int ball_h = ball.getHeight();
    Rect ball_rect = new Rect(ball_coords[0], ball_coords[1], ball_coords[0] 
+ ball_w, ball_coords[1] + ball_h);

    return net_rect.intersect(ball_rect) || net_rect.contains(ball_rect) || 
ball_rect.contains(net_rect);

}*/

score 3 · Accepted Answer · edited Jun 20 '20 at 09:12

Collision detction and score increase ;-)

public class MainActivity extends AppCompatActivity 
{
   //Layout
   private RelativeLayout myLayout = null;

   //Screen Size
   private int screenWidth;
   private int screenHeight;

   //Position
   private float ballDownY;
   private float ballDownX;

   //Initialize Class
   private Handler handler = new Handler();
   private Timer timer = new Timer();

   //Images
   private ImageView net = null;
   private ImageView ball = null;

   //score
   private TextView score = null;

   //for net movement along x-axis
   public float x = 0;
   public float y = 0;

   //points
   private int points = 0;


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

         this.setContentView(R.layout.activity_main);
         this.myLayout = (RelativeLayout) findViewById(R.id.myLayout);

         this.score = (TextView) findViewById(R.id.score);

         this.net = (ImageView) findViewById(R.id.net);
         this.ball = (ImageView) findViewById(R.id.ball);

         //retrieving screen size
         WindowManager wm = getWindowManager();
         Display disp = wm.getDefaultDisplay();
         Point size = new Point();
         disp.getSize(size);
         screenWidth = size.x;
         screenHeight = size.y;

         //move to out of screen
         this.ball.setX(-80.0f);
         this.ball.setY(screenHeight + 80.0f);

          //Error here
         /*//Run constantly
         new Handler().postDelayed(new Runnable()
         {
           @Override
           public void run()
           {
              Render();
           }
         }, 100); //100 is miliseconds interval than sleep this process, 1000 miliseconds is 1 second*/

     Thread t = new Thread() {
     @Override
     public void run() {
     try {
        while (!isInterrupted()) {
             Thread.sleep(100);
             runOnUiThread(new Runnable() {
             @Override
             public void run(){Render();}});}
             }catch (InterruptedException e) {}}};

     t.start();

    }

    public void Render()
    {
        changePos();
        if(Collision(net, ball))
        {
          points++; //You dont need findView Textview score for that exists in OnCreate Method
          this.score.setText("Score:" + points);
        }
    }

    public void changePos() 
    {

        //down
        ballDownY += 10;
        if (ball.getY() > screenHeight) {
        ballDownX = (float) Math.floor((Math.random() * (screenWidth - ball.getWidth())));
        ballDownY = -100.0f;

    }
    ball.setY(ballDownY);
    ball.setX(ballDownX);

      //make net follow finger
      myLayout.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent event) {
            x = event.getX();
            y = event.getY();

            if (event.getAction() == MotionEvent.ACTION_MOVE) {
                net.setX(x);
                net.setY(y);
            }
            return true;
        }

    });

    public boolean Collision(ImageView net, ImageView ball)
    {
       Rect BallRect = new Rect();
       ball.getHitRect(BallRect);
       Rect NetRect = new Rect();
       net.getHitRect(NetRect);
       return BallRect.intersect(NetRect);
    }
}

score -1 · Answer 2 · answered Mar 14 '18 at 23:23

Let me give you an example how I implemented working collision detection in only 10 rows of code. It is not exactly the same problem but it can give you an idea how to manipulate objects based on coordinates.

 // update the canvas in order to display the game action
    @Override
    public void onDraw(Canvas canvas) {

        super.onDraw(canvas);
        int xx = 200;
        int yy = 0;
        if (persons != null) {
            synchronized (persons) {
                Iterator<Person> iterate = persons.iterator();
                while (iterate.hasNext()) {
                    Person p = iterate.next();
                    if (p.getImage() != 0) {
                        bitmap = BitmapFactory.decodeResource(getResources(), p.getImage()); //load a character image
                        // Draw the visible person's appearance
                        if(xx > canvas.getWidth())
                            xx = 0;
                        canvas.drawBitmap(bitmap, xx , canvas.getHeight()- bitmap.getHeight() , null);
                        // Draw the name
                        Paint paint = new Paint();
                        paint.setStyle(Paint.Style.FILL);
                        canvas.save();
                        paint.setStrokeWidth(1);
                        paint.setColor(Color.WHITE);
                        paint.setTextSize(50);
                        canvas.drawText(p.name, (float)(xx+0.25*bitmap.getWidth()), (float) (canvas.getHeight() ), paint);
                        xx += bitmap.getWidth()*0.75;
                    }
                }
            }
        }
        canvas.save(); //Save the position of the canvas.
        canvas.restore();
        //Call the next frame.
        invalidate();
    }
}

In the above code, I just check if xx collides with an array of other images, then I just update xx accordingly. You are welcome to check out my open source repository with this code.

Collision detection between ImageViews

2 Answers2

Collision detction and score increase ;-)