using sensors in java me apps on series 40
DESCRIPTION
This webinar will introduce you to the sensors embedded on Nokia Asha phones and how to use them in Java ME apps and games. The structure and usage of the Mobile Sensor API (JSR-256) will be covered. Attila Csipa, technology wizard at Nokia in Tampere, Finland, will give you a short overview that will be followed by plenty of examples and live coding demos. He’ll use the Nokia IDE for Java™ ME (Eclipse-based) to show you how to build your code. He’ll also share best practices and user-experience recommendations based on the most common use cases.TRANSCRIPT
Attila Csipa [@achipa] Technology Wizard, Nokia
1 © 2012 Nokia Using accelerometers and other sensors in Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
USING ACCELEROMETERS AND OTHER SENSORS IN JAVA ME ON SERIES 40
CONTENTS • Introduction
– Platforms & Versions • Sensors
– Physical vs virtual – JSR-256 – Measurables – Accelerometers – Usage – UI considerations – Performance – App Compatibility
• Resources
2 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
PLATFORMS
3 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Developer Platform 2.0 DP 1.1 DP 1.0 6th Ed., FP1 6th Ed. 6th Ed., Lite 5th Ed., FP1
API Differences: bit.ly/S40Apis
http://www.developer.nokia.com/Devices/Device_specifications/Comparison.xhtml?dev=Asha_306,Nokia_Asha_309,Asha_311
DP 2.0 – NEW APIS
4 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Full touch UI
Virtual Keyboard
Multipoint Touch APIs
Gestures: Pinch
Sensors & Orientation
...
5 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS
Etymology Originated 1925–30 from sense + -or. Noun sensor (plural sensors) A device or organ that detects certain external stimuli and responds in a distinctive manner.
SENSORS: PHYSICAL VS VIRTUAL
• Physical sensors (physical values, g or m/s, mbar, etc)
– Acceleration – Light – ...
• Virtual sensors (combined or interpreted values, %, enum-s)
– Battery level – Orientation – …
6 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: JSR-256
• JSR 256 Sensor API – Generic: designed also for temperature, blood pressure, etc.
– Support on Series40 from DP2.0 (Asha Full Touch)
– Also available on Symbian (from S60 5th edition onwards)
• Two packages javax.microedition.sensor (read information)
javax.microedition.sensor.control (settings, start/stop)
7 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
JSR page at http://bit.ly/VdZDlG
SENSORS: WHAT TO LOOK FOR
• Currently supported – Battery Charge: 0 .. 100, charge percentage – Network Field Intensity: 0 .. 100, signal strength – Charger State: 0 .. 1, charger connected – Acceleration: –2g .. +2g, x / y / z axis – Double Tap: 1 .. 63, phone sides – Orientation: 0 .. 6, phone orientation
8 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: ACCELEROMETERS ARE COOL
• Enrich user interaction – Doesn’t suffer from finger size limits
– Doesn’t suffer from screen size limits
– Doesn’t interfere with what the user sees on the screen
– Natural interaction
• Ideal for games!
9 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: UNDERSTANDING ACCELEROMETERS
• Acceleration is CHANGE of the speed vector • Standstill normalized value is 1.0, why? GRAVITY • Nitpick - accelerometers measure translation not rotation • Rotation can still be measured indirectly (we measure
gravity vector hopping from one axis to the other)
10 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: API AVAILABILITY
• No System property for the API version? – Check Class availability
– ClassNotFoundException? → API not supported
11 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
// Virtual keyboard support try { // Check if class is available Class.forName("javamicroedition.sensor.SensorConnection"); // SensorManager.findSensors("acceleration", null); useSensors = true; } catch (ClassNotFoundException e) { // Class not available: -> no Sensor API support. useSensors = false; } catch (Exception e) { }
Example: Racer, aMaze
SENSORS: USING THEM – ROLL YOUR OWN
• Establish sensor connection
• Check data in game loop
12 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
// Find all acceleration sensors, the contextType is left undefined SensorInfo[] sensorInfos = SensorManager.findSensors("acceleration", null); // Find an acceleration sensor that returns double values for (int i = 0; i < sensorInfos.length; i++) { if (sensorInfos[i].getChannelInfos()[0].getDataType() == ChannelInfo.TYPE_DOUBLE) { accSensor = (SensorConnection) Connector.open(sensorInfos[i].getUrl()); } }
// Use 1 as a buffer size to get exactly 1 value for each axis Data[] data = accSensor.getData(1); speedX = -data[0].getDoubleValues()[0]; // data[0] => x-axis speedY = data[1].getDoubleValues()[0]; // data[1] => y-axis
Example: MovingBall
SENSORS: USING THEM – COPY WITH PRIDE
• Use the wrapping classes from Nokia Developer examples
13 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
private void enableSensors() { if (accelerationProvider != null) { accelerationProvider.close(); } accelerationProvider = AccelerationProvider.getProvider( new AccelerationProvider.Listener() { public void dataReceived(double ax, double ay, double az) { if (isSensorTurning()) { tilt = (int) ay; } } }); if (accelerationProvider != null) { Main.sensorsSupported = true; } else { Main.sensorsSupported = false; } }
SENSORS: UI CONSIDERATIONS
• Calibrate! (see aMaze example) • Look for change, not particular values • Which axis is which (portrait vs landscape) • Anticipate noise in readings (average values if needed) • Don’t force accelerometer usage if it doesn’t add to the
user experience
14 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: PERFORMANCE
• Filter (LimitCondition) for values you’re really interested in • Separate from mainloop – use Threads (see Cottage360
video and source) • Responsiveness is more critical than with keyboard input • Choose right frequency (is 100 reads/sec really needed?)
15 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
16 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
COMPATIBILITY
COMPATIBILITY? CODE CONSIDERATIONS
• Source & binary compatible – xx years old Java ME apps run on
full touch phones (and vice versa)!
• Downwards compatibility – Check API support of target phones – Lowest common denominator:
→ Nokia Java SDK 2.0 compiled app runs on old phones
17 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
COMPATIBILITY? USE-CASE CONSIDERATIONS
• Input type – Sensors complementing buttons (universal)
– Discrete input CAN be easier with buttons (f.ex Snake)!
– Sensors complementing touch controls (touch&type) – Most common
– Accelerometer only (no pre-DP2.0) – Rarer than you think, but possible! (f.ex wire loop game)
18 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
DYNAMIC API USAGE
• Single code base for different phones – Code that uses new APIs
– Externalize to extra class
– Check API support at runtime – Instantiate class if supported – Different methods for checking available
19 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
22 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
RESOURCES & TIPS
NOKIA IDE FOR JAVA ME
23 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Device SDK Manager
Integrated SDK + Toolchain
App Templates
JAD Editor
CODE EXAMPLES • Nokia IDE
– Nokia Hub → Nokia Series 40 Code Examples
• Online – bit.ly/JavaMeExamples
• Emulator – Help → MIDlet Samples
• Maps & LWUIT – C:\Nokia\devices\Nokia_SDK_2_0_Java\plugins
24 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
CODE EXAMPLES SHOWN TODAY
• Wiki • aMaze • Racer • Cottage360 (episode 19)
25 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
GET STARTED • Overview
– www.developer.nokia.com/Develop/Java/Getting_started/ • Downloads
– SDK: www.developer.nokia.com/Develop/Java/ – LWUIT: projects.developer.nokia.com/LWUIT_for_Series_40
• Guides – Design & User Experience – Porting from Android – www.developer.nokia.com/Develop/Java/Documentation/ – Training Videos: www.developer.nokia.com/Develop/Java/Learning/ – Code Examples: www.developer.nokia.com/Develop/Java/Code_examples/
27 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Want to learn more? www.developer.nokia.com Attila Csipa [@achipa] Technology Wizard, Nokia
28 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
THANK YOU! QUESTIONS?