Creating Asha Games: Game Pausing, Orientation, Sensors and Gestures
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This document discusses various techniques for creating games in Asha OS, including game pausing, handling device orientation changes, using mobile sensors, and gestures. It covers pausing a game when the phone rings or the back button is pressed using showNotify() and hideNotify() methods. It also discusses setting the UI orientation, getting sensor data, and handling threading and synchronization for pausing the game loop.
![// NOTICE! This example does not work, all exception handling and synchronized blocks
// are missing
class MyApp {
public static void main(String [] args) {
new MyApp();
}
public MyApp() {
MyThread mythread;
Thread thread = new Thread(mythread = new MyThread());
thread.start();
System.out.println("Sleeping");
Thread.sleep(2000);
// Resume from wait! Calls notify from the object that is in wait…
mythread.notify();
}
}
class MyThread implements Runnable {
public void run() {
// Let's wait until someone calls notify
wait();
System.out.println("Resumed!");
}
}](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-9-320.jpg)
![Finding
and
Iden%fying
a
Sensor
// Find all sensors
SensorInfo[] sensorInfos =
SensorManager.findSensors(null, null);
for(int i=0; i<sensorInfos.length; i++) {
SensorInfo si = sensorInfos[i];
System.out.println(si.getUrl());
}](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-25-320.jpg)
![Finding
and
Iden%fying
a
Sensor
// Sensor type (quantity):
//
acceleration
//
orientation
//
rotation
//
double_tap
//
proximity
//
battery_charge
//
charger_state
//
network_field_intensity
//
null
String type = "acceleration";
// Sensor Context type
//
ambient
//
device
//
user
//
vehicle
//
null
String contextType = "user";
// Fetch all sensors with given information, should find only one.
SensorInfo[] si = SensorManager.findSensors(type, contextType);
// Retrieve the sensor url.
String sensorURL = si[0].getUrl();](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-26-320.jpg)
![Opening
a
sensor
connec%on
{
try {
// This may not be a good idea, fetch the URL from sensorinfo using sensor quantity and
// context type
String sensorURL = "sensor:acceleration;contextType=user;model=Nokia;location=NoLoc";
// How fast data is sent to listener!
final int BUFFER_SIZE = 1;
SensorConnection sensorConnection = (SensorConnection)Connector.open(sensorURL);
// this = any object that implements DataListener
sensorConnection.setDataListener(this, BUFFER_SIZE);
} catch (IOException e) {
e.printStackTrace();
}
}
// Datalistener interface method
public void dataReceived(SensorConnection sensor, Data[] data,
boolean isDataLost) {
System.out.println("Here!");
}](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-27-320.jpg)
![Case:
Accelera%on
listening
public void dataReceived(SensorConnection sensor, Data[] data,
boolean isDataLost) {
// We have three channels.
System.out.println("Channel amount: " + data.length);
// Channel is Data object
Data x = data[0];
// Each channel may hold several values. In this case
// only one.
double [] values = x.getDoubleValues();
System.out.println("Number of values " + values.length);
// And the value is:
System.out.println("x = " + values[0]);
// Let's fetch the rest (y and z) in just on line
System.out.println("y = " + data[1].getDoubleValues()[0]);
System.out.println("z = " + data[2].getDoubleValues()[0]);
}](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-28-320.jpg)
![Case:
Accelera%on
listening
public void dataReceived(SensorConnection sensor, Data[] data,
boolean isDataLost) {
System.out.println("x = " + data[0].getDoubleValues()[0]);
System.out.println("y = " + data[1].getDoubleValues()[0]);
System.out.println("z = " + data[2].getDoubleValues()[0]);
}](https://image.slidesharecdn.com/asha-game-pause-140214025313-phpapp01/85/Creating-Asha-Games-Game-Pausing-Orientation-Sensors-and-Gestures-29-320.jpg)
Creating Asha Games: Game Pausing, Orientation, Sensors and Gestures
- 1. Crea%ng Asha Games: Game Pausing, Device Orienta%on, Sensors, Gestures Jussi Pohjolainen Tampere University of Applied Sciences
- 2. GAME PAUSING
- 3. About Game Pausing • Pause game when – Phone rings – Back – buHon is pressed • Remember that MIDlet's pauseApp – method is never called! • In GameCanvas, implement following – public void showNotify() // resume – public void hideNotify() // pause
- 4. About Gameloop and Threading • Gameloop is implemented using Threading – Thread thread = new Thread(Runnable x); – thread.start(); // calls run() • Gameloop usually: – while(gameIsOn) { …. Thread.sleep(ticks); } • How to pause the current thread in midp?
- 5. Synchroniza%on • Let's first look at synchroniza5on. • There might be a problem, if two threads accesses the same data – Two people each have a ATM cards that are linked to only one account – What happens when these two people accesses the account at the same %me? • Withdrawal is two-‐step process – Check the balance – If there's enough money int the account, make the withdrawal • What happens if 1 and 2 are separated?
- 6. Locks • We must guarantee that the two steps are never split apart. Use synchronized keyword • Synchroniza%on works with locks. Every object has a lock. If one thread has picked up the lock, no other thread can use the synchronized code.
- 7. Examples • Let's look at some synchroniza%on examples – https://dl.dropboxusercontent.com/u/ 874087/game-programming/examples/ threading/Synchronized1.java • See also – Synchronized2.java -> Synchronized5.java
- 8. wait() • Object class holds a method wait() – Causes the current thread to wait un%l another thread invokes the no%fy() method for this object • So when calling wait() it pauses the current thread and waits that some other thread calls no%fy() or no%fyAll()!
- 9. // NOTICE! This example does not work, all exception handling and synchronized blocks // are missing class MyApp { public static void main(String [] args) { new MyApp(); } public MyApp() { MyThread mythread; Thread thread = new Thread(mythread = new MyThread()); thread.start(); System.out.println("Sleeping"); Thread.sleep(2000); // Resume from wait! Calls notify from the object that is in wait… mythread.notify(); } } class MyThread implements Runnable { public void run() { // Let's wait until someone calls notify wait(); System.out.println("Resumed!"); } }
- 10. wait() • When calling wait and no%fy, it must be inside synchronized block. synchronized(this) { // Before calling notify, the thread calling this must // own a lock. notify(); } synchronized(this) { wait(); }
- 11. Game Pausing in MIDlet • In GameCanvas, following methods are called when phone rings. // Phone rings public void hideNotify() { pause(); // pause game – my own method } // Phone ends public void showNotify() { resume(); // resume game – my own method }
- 12. pause() and resume() public void resume() { isPause = false; synchronized(this) { notify(); // Notify that waiting thread can // continue. } } public void pause() { isPause = true; }
- 13. Game Loop public void run() { int i = 0; while(true) { checkIfPause(); checkCollisions(); moveSprites(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } private void checkIfPause() { synchronized(this) { while(isPause) { // while, just in case try { wait(); // Wait in current thread } catch (InterruptedException e) { e.printStackTrace(); } } } }
- 14. Back BuHon to Game Canvas Command backCommand = new Command("Back", Command.BACK, 0); addCommand(backCommand); setCommandListener(this); // and the listener method public void commandAction(Command c, Displayable d) { if(isPause) { midlet.notifyDestroyed(); } else { pause(); } }
- 16. Adjus%ng Device's Orienta%on • MIDlets can use Orienta5on API to – Change their UI orienta%on – Determine their current UI orienta%on – Determine the current display orienta%on – Receive a no%fica%on whenever the display orienta%on changes • When MIDlet changes it's UI orienta%on, it has to redraw the low-‐level components that it uses.
- 18. Se^ng UI Orienta%on • Add following to JAD file: – Nokia-MIDlet-App-Orientation: manual • Now it supports both portrait and landscape modes • Add orienta%on listener – Orientation.addOrientationListener(orientationListener);
- 19. Orienta%on Listener Callback /** Orientation listener callback */ public void displayOrientationChanged( int newDisplayOrientation ){ /** Check display orientation */ switch( newDisplayOrientation ){ case Orientation.ORIENTATION_PORTRAIT: case Orientation.ORIENTATION_PORTRAIT_180: /** Change MIDlet UI orientation to portrait */ Orientation.setAppOrientation(Orientation.ORIENTATION_PORTRAIT); break; case Orientation.ORIENTATION_LANDSCAPE: case Orientation.ORIENTATION_LANDSCAPE_180: /** Change MIDlet UI orientation to landscape */ Orientation.setAppOrientation(Orientation.ORIENTATION_LANDSCAPE); break; } }
- 20. sizeChanged() • When UI Orienta%on changes: /** Java platform will call this when UI orientation has been changed */ protected void sizeChanged( int w, int h ){ /** Acquiring new Graphics Object since old is not valid anymore */ g = getGraphics( ); canDraw = true; }
- 22. Mobile Sensors • Mobile Sensor API allows MIDlets to fetch data from the sensors of the mobile device • Sensor consists of one or more channels, in accelerometer you will get data from three channels (x, y and z) • Sensors have common proper%es: – accuracy – max and min value
- 23. Available Sensors in Asha 50X • Accelera5on sensor – measures accelera%on in SI units for x, y and z -‐ axis. • Orienta5on sensor – provides informa%on of devices current orienta%on posi%on. • Rota5on sensor – provides informa%on of devices current rota%on degree. • Double tapping sensor – provides informa%on of double taps occurred on the phone sides. • Proximity sensor – indicates if an obstacle is right in front of it • BaLery sensor – shows baHery charge level in percentage. Sensor is always on. • Charger sensor – shows whether charger is connected. Sensor is always on. • Signal strength sensor – shows strength of network connec%on in percentage. Sensor is always on.
- 24. Using Sensors
- 25. Finding and Iden%fying a Sensor // Find all sensors SensorInfo[] sensorInfos = SensorManager.findSensors(null, null); for(int i=0; i<sensorInfos.length; i++) { SensorInfo si = sensorInfos[i]; System.out.println(si.getUrl()); }
- 26. Finding and Iden%fying a Sensor // Sensor type (quantity): // acceleration // orientation // rotation // double_tap // proximity // battery_charge // charger_state // network_field_intensity // null String type = "acceleration"; // Sensor Context type // ambient // device // user // vehicle // null String contextType = "user"; // Fetch all sensors with given information, should find only one. SensorInfo[] si = SensorManager.findSensors(type, contextType); // Retrieve the sensor url. String sensorURL = si[0].getUrl();
- 27. Opening a sensor connec%on { try { // This may not be a good idea, fetch the URL from sensorinfo using sensor quantity and // context type String sensorURL = "sensor:acceleration;contextType=user;model=Nokia;location=NoLoc"; // How fast data is sent to listener! final int BUFFER_SIZE = 1; SensorConnection sensorConnection = (SensorConnection)Connector.open(sensorURL); // this = any object that implements DataListener sensorConnection.setDataListener(this, BUFFER_SIZE); } catch (IOException e) { e.printStackTrace(); } } // Datalistener interface method public void dataReceived(SensorConnection sensor, Data[] data, boolean isDataLost) { System.out.println("Here!"); }
- 28. Case: Accelera%on listening public void dataReceived(SensorConnection sensor, Data[] data, boolean isDataLost) { // We have three channels. System.out.println("Channel amount: " + data.length); // Channel is Data object Data x = data[0]; // Each channel may hold several values. In this case // only one. double [] values = x.getDoubleValues(); System.out.println("Number of values " + values.length); // And the value is: System.out.println("x = " + values[0]); // Let's fetch the rest (y and z) in just on line System.out.println("y = " + data[1].getDoubleValues()[0]); System.out.println("z = " + data[2].getDoubleValues()[0]); }
- 29. Case: Accelera%on listening public void dataReceived(SensorConnection sensor, Data[] data, boolean isDataLost) { System.out.println("x = " + data[0].getDoubleValues()[0]); System.out.println("y = " + data[1].getDoubleValues()[0]); System.out.println("z = " + data[2].getDoubleValues()[0]); }
- 30. Closing connec%on • Remember to close the connec%on if not needed! – sensorConnection.close();
- 31. GESTURES API
- 32. Really Easy to Use // STEP 1: Defines a GestureInteractiveZone for the // whole screen and all Gesture types. GestureInteractiveZone giz = new GestureInteractiveZone( GestureInteractiveZone.GESTURE_ALL ); // STEP 2: Register the GestureInteractiveZones for the // GameCanvas object this. GestureRegistrationManager.register( this, giz ); // STEP 3: Set the listener, source is this gamecanvas // and listener is this also GestureRegistrationManager.setListener(this, this);
- 33. Listener public void gestureAction(Object container, GestureInteractiveZone gestureInteractiveZone, GestureEvent gestureEvent) { switch(gestureEvent.getType()) { case GestureInteractiveZone.GESTURE_TAP: Debug.printInfo("MyGameCanvas", "gestureAction", "TAP", 2); break; ... case GestureInteractiveZone.GESTURE_LONG_PRESS: Debug.printInfo("MyGameCanvas", "gestureAction", "LONG PRESS", 2); break; } }
- 34. Listener public void gestureAction(Object container, GestureInteractiveZone gestureInteractiveZone, GestureEvent gestureEvent) { switch(gestureEvent.getType()) { ... case GestureInteractiveZone.GESTURE_FLICK: Debug.printInfo("MyGameCanvas", "gestureAction", "FLICK", 2); Debug.printInfo("MyGameCanvas", "gestureAction", "flick speed = " + gestureEvent.getFlickSpeed(), 2); Debug.printInfo("MyGameCanvas", "gestureAction", "flick direction = " + gestureEvent.getFlickDirection(), 2); break; } }