Android Open Source - GameWorker Game Engine

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License

The source code is released under:

Apache License

Java Source Code

package com.al.gameengine;
/*w  w  w.  j av a2  s.c  o  m*/
import android.graphics.Canvas;
import android.util.Log;
import android.view.SurfaceHolder;

import com.al.gameengine.sprite.GameView;

/**
 * Game Loop for the game view, this will update the position of the images in the view.
 * @author AL
 *
 */
public class GameEngine extends Thread
{

    private static final String TAG = GameEngine.class.getSimpleName();
    private boolean running;
    private SurfaceHolder surfaceHolder;
    private GameView gamePanel;

    // desired fps
    private final static int   MAX_FPS = 50;
    // maximum number of frames to be skipped
    private final static int  MAX_FRAME_SKIPS = 5;
    // the frame period
    private final static int  FRAME_PERIOD = 1000 / MAX_FPS;  

    //    @Override
    //    public void run()
    //    {
    //  super.run();
    //  SpriteManager.update();
    //    }

    public GameEngine()
    {
  running = false;
    }

    public GameEngine(SurfaceHolder surfaceHolder, GameView gamePanel)
    {
  super();
  //Lock for the canvas.
  this.surfaceHolder = surfaceHolder;
  //Pointer to the game view, where the images will be displayed.
  this.gamePanel = gamePanel;
    }

    @Override
    public void run() {
  //Pointer to the canvas where things will be displayed.
  Canvas canvas;
  Log.d(TAG, "Starting game loop");

  // the time when the cycle begun
  long beginTime;
  // the time it took for the cycle to execute
  long timeDiff;
  // ms to sleep (<0 if we're behind)
  int sleepTime;
  // number of frames being skipped 
  int framesSkipped;

  sleepTime = 0;

  //Loops the game if the running flag is true.
  while (running) {
      canvas = null;
      // try locking the canvas for exclusive pixel editing
      // in the surface
      try {
    canvas = this.surfaceHolder.lockCanvas();
    synchronized (surfaceHolder) {
        beginTime = System.currentTimeMillis();
        // resetting the frames skipped
        framesSkipped = 0;  
        // update game state
        this.gamePanel.update();
        // render state to the screen
        // draws the canvas on the panel
        this.gamePanel.render(canvas);
        // calculate how long did the cycle take
        timeDiff = System.currentTimeMillis() - beginTime;
        // calculate sleep time
        sleepTime = (int)(FRAME_PERIOD - timeDiff);

        if (sleepTime > 0) {
      // if sleepTime > 0 we're OK
      try {
          // send the thread to sleep for a short period
          // very useful for battery saving
          Thread.sleep(sleepTime);
      } catch (InterruptedException e) {}
        }

        while (sleepTime < 0 && framesSkipped < MAX_FRAME_SKIPS) {
      // we need to catch up
      // update without rendering
      this.gamePanel.update();
      // add frame period to check if in next frame
      sleepTime += FRAME_PERIOD;
      framesSkipped++;
        }
    }
      } finally {
    // in case of an exception the surface is not left in
    // an inconsistent state
    if (canvas != null) {
        surfaceHolder.unlockCanvasAndPost(canvas);
    }
      }  // end finally
  }
    }

    public boolean isRunning()
    {
        return running;
    }

    /**
     * Sets the running state of the engine.
     * @param running
     */
    public void setRunning(boolean running)
    {
        this.running = running;
    }

}

Java Source Code List

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