FrameCounter.java

package vooga.rts.util;

import java.awt.Color;
import java.awt.Graphics2D;
import java.util.LinkedList;
import java.util.Queue;
import util.Location;
import util.Text;
import vooga.rts.IGameLoop;


/**
 * This class is used to monitor the frame rate of the application.
 * It keeps track of how long it takes between each update cycle.
 * 
 * To use the class, make sure you update it with the elapsed time per
 * frame and then call paint in order to paint it on the screen.
 * 
 * @author Jonathan Schmidt
 * 
 */
public class FrameCounter implements IGameLoop {

    private static final int COUNT_PER_CYCLE = 10;

    private Queue<Long> myTimes;

    private double myRate;

    private Location myScreenLocation;

    /**
     * Creates a new Frame Counter.
     * 
     * @param screenLoc The location to paint the FPS
     */
    public FrameCounter (Location screenLoc) {
        myTimes = new LinkedList<Long>();
        myScreenLocation = new Location(screenLoc);
    }

    @Override
    public void update (double elapsedTime) {

        myTimes.add(System.currentTimeMillis());
        if (myTimes.size() > COUNT_PER_CYCLE) {
            long change = System.currentTimeMillis() - myTimes.poll();
            double inS = ((double) change) / 1000;
            myRate = COUNT_PER_CYCLE / inS;
        }
    }

    @Override
    public void paint (Graphics2D pen) {
        Text f = new Text("FPS: " + String.format("%.2f", myRate));
        f.paint(pen, myScreenLocation, Color.RED);
    }
}