FPSMeter.java

/****************************************************************************
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 ** This demo file is part of yFiles for Java (Swing) 3.6.
 **
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 ** 72070 Tuebingen, Germany. All rights reserved.
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package viewer.largegraphs;

import com.yworks.yfiles.view.GraphComponent;

import java.awt.EventQueue;
import java.time.Duration;
import java.time.Instant;
import java.util.Timer;
import java.util.TimerTask;

/**
 * Helper class that calculates the Frames per second.
 */
public class FPSMeter {
  private final GraphComponent control;
  private final Runnable callback;

  private boolean recording;
  private boolean isRunning = false;
  private Instant first;
  private Instant last;
  private int frameCount;
  private int[] frameCountHistory = new int[10];
  private Instant[] timeStameHistory = new Instant[10];
  private int updateCount = 0;
  private Timer timer;

  // region FPS property

  private String fps = "";

  public String getFps() {
    return fps;
  }

  public int getFrameCount() {
    return frameCount;
  }

  // endregion

  public boolean isRecording() {
    return recording;
  }

  public void setRecording(boolean recording) {
    this.recording = recording;
    if (!recording) {
      reset();
    }
  }

  public FPSMeter(GraphComponent control, Runnable callback) {
    this.control = control;
    this.callback = callback;
    control.addUpdatedListener((source, args) -> calcFps());
  }

  /**
   * Calculates and shows the frame rate. To be called once on each new frame.
   */
  private void calcFps() {
    if (!this.recording) {
      if (isRunning) {
        reset();
      }
      return;
    }
    if (!isRunning) {
      frameCount = 0;
      first = last = Instant.now();
      isRunning = true;
      timer = new Timer();
      timer.scheduleAtFixedRate(new TimerTask() {
        @Override
        public void run() {
          long d = Duration.between(first, last).toMillis();
          int currentFps = d == 0 ? 0 : (int) Math.floor(frameCount * 1000.0 / d);
          int index = updateCount % 10;
          if (updateCount >= 10) {
            Instant historic = timeStameHistory[index];
            double delay = historic != null ? Duration.between(historic, last).toMillis() / 1000.0 : 0;
            if (delay <= 0) {
              // threading problems
              delay = 1;
            }
            currentFps = (int) Math.floor((frameCount - frameCountHistory[index]) / delay);
          }
          frameCountHistory[index] = frameCount;
          timeStameHistory[index] = last;
          updateCount++;

          fps = Integer.toString(currentFps);

          EventQueue.invokeLater(callback);
        }
      }, 0, 100);
      return;
    }

    last = Instant.now();
    frameCount++;
  }

  private void reset() {
    timer.cancel();
    first = null;
    last = null;
    frameCountHistory = new int[10];
    timeStameHistory = new Instant[10];
    updateCount = 0;
    isRunning = false;
  }
}