1. Mobile Game Framework

2. Stuff You Should Know… Genres Paper Prototyping Mechanics Theme/Backstory Don’t Code!

3. General Game API Window/scene management Input File I/O – Playback recording (event logging) – Audio Graphics General game framework/loop (w/ timing)

4. Window Management Handle basic Android OS events – Create – Pause – Resume

5. Input Polling – Code asks, “what is the current state?” – Info lost between polling Event-based – Queue of events stored Touch down, drag/move, up Key down, up

6. Input Polling isKeyPressed(keyCode) isTouchDown(id) getTouchX(id) getTouchY(id) getAccelX() getAccelY() getAccelZ()

7. Event-based Input getKeyEvents() – Returns List getTouchEvents() – Returns List

8. File I/O Manage Java InputStream and OutputStream instances Load/use assets (audio, graphics, etc.) Save data (state, high score, settings)

9. Audio Assets Music – Ambient/background – Streamed (open stream and play) – Play, pause, stop, looping (bool), volume (float) Sound – Shorter – Typically event-driven – Load entirely in memory – Play Dispose when not needed

10. Graphics Handle typical APIs like color, pixel maps, compression, double buffering, and alpha compositing Load/store imgs Framebuffer – Clear – DrawSprite – Primitives – Swap – Height/width

11. Game Loop Input input = new Input(); Graphics graphics = new Graphics(); Audio audio = new Audio(); Screen currentScreen = new MainMenu(); Float lastFrameTime = currentTime(); while (!userQuit() ) { float deltaTime = currentTime() – lastFrameTime; lastFrameTime = currentTime(); currentScreen.updateState(input, deltaTime); currentScreen.present(graphics, audio, deltaTime); } cleanupResources();

12. Frame Rate Management vs

13. Java/ADK Specifics

14. XML and the Manifest

15. Best Practices Utilize latest SDKs but be compatible back to 1.5 Install to SD whenever possible Single main activity that handles all events – Debatable relative to general Android App dev Portrait or landscape (or both?) Access SD Obtain a wake lock (keep from sleeping)

16. Defining Multi-Resolution Assets Handle difference devices – ldpi=36x36 – mdpi=48x48 – hdpi=72x72 – xhdpi=96x96 /res/drawable/ic_launcher.png – Same as mdpi – For Android 1.5 compatibility

17. Core Android Activity Events Create – Set up window/UI Resume – (Re)start game loop Pause – Pause game loop – Check isFinishing Save state

18. Test Your Understanding LogCat (debugging event list) – Utilize debugging view in Eclipse Define new class that extends Activity – Override onCreate onResume onPause – Check isFinishing()

19. Handling Touch Events setOnTouchListener(this) onTouch(view, event) – Handle types of touch events – switch(event.getAction()) MotionEvent.ACTION_DOWN MotionEvent.ACTION_UP … – event.getX() Multitouch involves handling array of touch data

20. Handling Key Events setOnKeyListener(this) onKey(view, keyCode, event) – Handle KeyEvent.ACTION_DOWN – Handle KeyEvent.ACTION_UP

21. Accelerometer Input Check if accelerometer present on device – getSensorList(Sensor.TYPE_ACCELEROMETER) Register activity as listener to accelerometer events – registerListener(this, accel, m.SENSOR_DELAY_GAME) onSensorChanged(event) – event.values[0] <- x – event.values[1] <- y – event.values[2] <- z Deal with orientation by axis swapping

22. Asset File I/O assets/ folder quite useful via AssetManager AssetManager am = getAssets(); InputStream is = am.open(filename); … is.close();

23. External/SD Access Use in manifest Check if external storage exists – Environment.getExternalStorageState(); Get directory root – Environment.getExternalStorageDirectory(); Utilize standard Java file I/O APIs Beware: complete SD access to read/write!

24. Shared Preferences Stores key-value pairs p = getPreferences(Context.MODE_PRIVATE); e = p.edit(); e.putString(key, value); e.putInt(key, value); e.commit(); String s = p.getString(key, null); int i = p.getInt(key, 0);

25. Sound Effect Audio Setup… setVolumeControlStream(AudioManager.STREA_MUSIC); soundPool = new SoundPool(max, AudioManager.STREAM_MUSIC, 0); Get file descriptor and id: d = assetManager.openFd(“soundEffect.ogg”); int id =soundPool.load(d, 1); Then play… soundPool.play(id, left, right, 0, loop, playback); Finally… soundPool.unload(id);

26. Streaming Audio MediaPlayer mp = new MediaPlayer(); AssetFileDescriptor afd = am.openFd(“ambient.ogg”); mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength()); mp.prepare(); mp.start(); … mp.setVolume(left, right); mp.pause(); mp.stop(); mp.setLooping(bool); Handle when completed: mp.isPlaying() mp.setOnCompletionListener(listener); mp.release();

27. Well-Lit Graphics Keep screen completely on with wake lock… Setup – in manifest onCreate – PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE); – WakeLock wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Lock"); onResume – wl.acquire(); onPause – wl.release();

28. Full Screen Graphics Remove the title bars Get full resolution for graphics/display In onCreate: requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags( WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); NOTE: do this before setting the content view of activity!

29. FPS++ Heretofore, the application only refreshes/draws itself in response to events This is good given battery considerations But we can increase the FPS/draw rate Inherit from View Define onDraw(Canvas) method Invoke ‘invalidate’ at the end of onDraw Don’t forget to set the content view to a new instance of this derived class

30. The Limitless Possibilities of Canvas Canvas (parameter to onDraw) provides a wealth of options – getWidth(); – getHeight(); – drawPoint(x,y,paint); – drawLine(x1,y1,x2,y2,paint); – drawRect(x1,y1,x2,y2,paint); – drawCircle(x,y,radius,paint); Paint – setARGB(a,r,g,b); – setColor(0xaarrggbb);

31. Drawing Bitmaps/Sprites Bitmap – InputStream is = assetManager.open(file); – Bitmap bmp = BitmapFactory.decodeStream(is); – getWidth(); – getHeight(); – When done, bmp.recycle(); Drawing the Bitmap – canvas.drawBitmap(bmp, x, y, paint); – canvas.drawBitmap(bmp, srcRect, dstRect, paint);

32. Drawing Text Fonts are placed in the assets/ directory Then loaded – Typeface font = Typeface.createFromAsset(context.getAssets(), fontFileName); Set the paint instance – paint.setTypeFace(font); – paint.setTextSize(x); – paint.setTextAlign(Paint.Align.LEFT|CENTER|RIGHT); Draw using canvas – canvas.drawText(string, x, y, paint);

33. Problem with onDraw/invalidate This presumes nothing else in the game runs UI dominates View vs SurfaceView We want to have a thread running to do rendering Create new class that inherits SurfaceView – Maintain thread – Implement run, pause methods To draw – Canvas c = holder.lockCanvas(); – c.draw… – holder.unlockCanvasAndPost(c);

34. SurfaceView Subclass

35. Using SurfaceView Subclass