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CSS290 : Apps on Mobile Devices

CSS290 : Apps on Mobile Devices. Lecture 6: Thread Safe Event services and Coordinate System. Today: Concepts. Reading: Chapter 5 Sensors and Services Thread invoking functions Delegates Logica l Coordinate Control by Orientation vs. Hardware Coordinate from Accelerometer.

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CSS290 : Apps on Mobile Devices

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  1. CSS290: Apps on Mobile Devices Lecture 6: Thread Safe Event services and Coordinate System

  2. Today: Concepts • Reading: Chapter 5 • Sensors and Services • Thread invoking functions • Delegates • Logical Coordinate Control by Orientation vs. Hardware Coordinate from Accelerometer

  3. Delegate keyword: a function pointer • Define a data type that accepts a function! • delegate returnTypeTypeName(parameter list) • E.g. delegate void MyFuncType(double a, double b) • New datatype is: MyFuncType! • Convenient for passing function pointers around!

  4. Adding a new reference into IDE • The Reference Tab in the Solution Explorer • Finding the right reference • Using the reference in your code • To work with Accelerometer we need • Microsoft.Devices.Sensors

  5. 1. AccTest: Accelerometer • Event service is called form an external thread • SHOULD NOT change our variable from that service routine • Called from external thread, danger of external thread and our own thread trying to change the same variable! • Instead: BeginInvoke()  called sometime later when it is safe. • Accelerometer X/Y/Z • Resting state for Z is -1 (gravitational pull) • Notice: -Y is downwards. • X/Y is associated with the hardware • If you change the phone orientation, X/Y direciton DOES NOT change

  6. 2. Acc Controls Obj: • Accelerometer with Orientation • Phone orientation changes the logical X/Y directions • Accelerometer returns the same X/Y/Z readings regardless of phone orientation! • We must translate the change! • Switch on Orientation changing support • Translate coordinate space depending on phone orientation

  7. 3. Bound Check • Switch off orientation (annoying) • mBall class • Passed in ContentPanel for bound checking • Random position inside the bound • Bound intersection checking • Test for X overlaps • Test for Y overlaps • Must satisfy all conditions for potential collision

  8. Exercise 6: • Integrate Bound checking with Exercise 5 • Check for ball touch net in Timer service (nice central place) • Integrate Music/Sound effect • Integrate Accelerometer for moving the net • No need for orientation support • BECAREFUL!! • mTheNet must be a Shape! (Rectangle)!! • UIImage does _NOT_ work!!

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