DrawView.java

package com.zeroeightysix.android.bluegreen;

import java.util.ArrayList;

//import com.zeroeightysix.android.bluegreen.Point.Coordinates;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class DrawView extends SurfaceView implements SurfaceHolder.Callback {

	ArrayList<Point> points = new ArrayList<Point>();
	Paint paint = new Paint();
	private DrawViewThread _thread;

	//Interaction is handled by the DrawView class
	public DrawView(Context context) {
		super(context);
		getHolder().addCallback(this);//add DrawView to SurfaceHolder
		_thread = new DrawViewThread(getHolder(), this);
		setFocusable(true);
		//setFocusableInTouchMode(true);
		//this.setOnTouchListener(this);

		paint.setColor(Color.WHITE);
		paint.setAntiAlias(true);

	}

	@Override
	public void onDraw(Canvas canvas) {
		for (Point point : points) {
			if(point.x <150){
				paint.setColor(Color.BLUE);
			}
			else if(point.x <300 && point.x > 150){
				paint.setColor(Color.GREEN);
			}
			canvas.drawCircle(point.x, point.y, 5, paint);
		}
	}

	public boolean onTouchEvent(MotionEvent event){
		//Synchronization with the SurfaceHolder to avoid changing 
		//the number in the list while reading the list
		synchronized(_thread.getSurfaceHolder()){
			Point point = new Point();
			point.x = event.getX();
			point.y = event.getY();
			invalidate();

			return points.add(point);

		}
	}

	@Override
	public void surfaceChanged(SurfaceHolder holder, int format, int width,
			int height) {
		// TODO Auto-generated method stub
	}

	@Override
	public void surfaceCreated(SurfaceHolder holder) {
		_thread.setRunning(true);
		_thread.start();

	}


	@Override
	public void surfaceDestroyed(SurfaceHolder holder) {
		boolean retry = true;
		_thread.setRunning(false);
		while(retry){
			try {
				_thread.join();
				retry = false;
			} catch (InterruptedException e) {
				// keep trying to join
			}

		}
	}

	public void UpdatePhysics(){
		Point.Speed speed;

		for(Point point : points){
			speed = point.getSpeed();

			//X and Y DIRECTION//
			if(speed.getXDirection() == Point.Speed.X_DIRECTION_RIGHT){
				point.x = point.x + point.getSpeed().getX();
			}else{
				point.x = point.x - point.getSpeed().getX();
			}

			if(speed.getYDirection() == Point.Speed.Y_DIRECTION_UP){
				point.y = point.y + point.getSpeed().getY();
			}else{
				point.y = point.y + point.getSpeed().getY();
			}

			//BOARDERS//
			if(point.x > getWidth()){
				speed.toggleXDirection();	
			}else if(point.x < 0){
				speed.toggleXDirection();
			}

			if(point.y > getHeight()){
				speed.toggleYDirection();
			}else if(point.y < 0){
				speed.toggleYDirection();
			}
		}
	}

	//Thread to control drawings
	class DrawViewThread extends Thread {
		private SurfaceHolder _surfaceHolder;
		private DrawView _drawView;
		private boolean _run = false;

		public SurfaceHolder getSurfaceHolder(){
			return _surfaceHolder;
		}
		public DrawViewThread(SurfaceHolder surfaceHolder, DrawView drawView) {
			_surfaceHolder = surfaceHolder;
			_drawView = drawView;
		}

		public void setRunning(boolean run) {
			_run = run;
		}

		@Override
		public void run() {
			Canvas c;
			while (_run) {
				c = null;
				try {
					c = _surfaceHolder.lockCanvas(null);
					synchronized (_surfaceHolder) {
						_drawView.UpdatePhysics();
						_drawView.onDraw(c);
					}
				} finally {
					// do this in a finally so that if an exception is thrown
					// during the above, it doesn't leave the Surface in an
					// inconsistent state
					if (c != null) {
						_surfaceHolder.unlockCanvasAndPost(c);
					}
				}
			}
		}

	}



}

Point.java

package com.zeroeightysix.android.bluegreen;

public class Point {
	float x, y;
	
	@Override
	public String toString() {
		return x + ", " + y;
	}

	
	/*
	 * SPEED CLASS
	 */
	public class Speed{
		public static final int X_DIRECTION_LEFT = -1;
		public static final int X_DIRECTION_RIGHT = 1;
		public static final int Y_DIRECTION_UP = 1;
		public static final int Y_DIRECTION_DOWN = -1;
		
		private int _x = 1;
		private int _y = 1;
		
		private int _xDirection = X_DIRECTION_RIGHT;
		private int _yDirection = Y_DIRECTION_DOWN;
		
		public int getXDirection(){
			return _xDirection;
		}
		
		public int getYDirection(){
			return _yDirection;
		}
	
		//set direction
		public void setXDirection(int direction){
			_xDirection = direction;
		}
		
		public void setYDirection(int direction){
			_yDirection = direction;
		}
		
		//toggle direction
		public void toggleXDirection(){
			
			if(_xDirection == X_DIRECTION_RIGHT){
				_xDirection = X_DIRECTION_LEFT;
			}else{
				_xDirection = X_DIRECTION_RIGHT;
			}
		}
		
		public void toggleYDirection(){
			if(_yDirection == Y_DIRECTION_DOWN){
				_yDirection = Y_DIRECTION_UP;
			}else{
				_yDirection = Y_DIRECTION_DOWN;
			}
		}
		
		//getters
		public int getX(){
			return _x;
		}
		
		public int getY(){
			return _y;
		}
		
		//setters
		public void setX(int speed){
			_x = speed;
		}
		
		public void setY(int speed){
			_y = speed;
		}
		
		public String toString(){
			String xDirection;
			String yDirection;
			if (_yDirection == Y_DIRECTION_UP){
				yDirection = "up";
			}else{
				yDirection = "down";
			}
			if (_xDirection == X_DIRECTION_RIGHT){
				xDirection = "right";
			}else{
				xDirection = "left";
			}
			//Speed x: 5 | 6 xDirection: left
			return "Speed x: "+_x+" | y: "+_y+"| xDirection: "+xDirection+" | yDirection: "+yDirection;
		}
			
	}
	
	/*
	 * Getters and Setters for Speed
	 */
	
	private Speed _speed;

	public Point(){
		_speed = new Speed();
	}

	public Speed getSpeed(){
		return _speed;
	}
	
	
}