/**
* AccelerometerDemo.java
*
* Copyright � 1998-2011 Research In Motion Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Note: For the sake of simplicity, this sample application may not leverage
* resource bundles and resource strings. However, it is STRONGLY recommended
* that application developers make use of the localization features available
* within the BlackBerry development platform to ensure a seamless application
* experience across a variety of languages and geographies. For more information
* on localizing your application, please refer to the BlackBerry Java Development
* Environment Development Guide associated with this release.
*/
package com.rim.samples.device.accelerometerdemo;
import java.util.Random;
import net.rim.device.api.command.Command;
import net.rim.device.api.command.CommandHandler;
import net.rim.device.api.command.ReadOnlyCommandMetadata;
import net.rim.device.api.system.AccelerometerSensor;
import net.rim.device.api.system.AccelerometerSensor.Channel;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.DeviceInfo;
import net.rim.device.api.system.Display;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.MenuItem;
import net.rim.device.api.ui.Screen;
import net.rim.device.api.ui.Ui;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.Dialog;
import net.rim.device.api.ui.component.Menu;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.util.StringProvider;
/**
* This sample demonstrates the Accelerometer API. The DrawThread opens the
* accelerometer channel and periodically queries for the current data reading.
* The data is then used to apply corresponding force to a ball drawn on the
* screen.
*/
public final class AccelerometerDemo extends UiApplication {
private AccelerometerDemoScreen _screen;
private DrawThread _thread;
private Bitmap _ball;
private int _ballWidth;
private int _ballHeight;
private int _x;
private int _y;
private float _xSpeed;
private float _ySpeed;
private Random _r;
private boolean _simulated;
private Channel _accChannel;
private final short[] _xyz = new short[3];
private static final float G_NORM =
9.8066f / AccelerometerSensor.G_FORCE_VALUE;
private static final float TABLE_FRICTION = 0.98f;
private static final float BOUNCE_SLOWDOWN = 0.6f;
private static final int DEFAULT_ORIENTATION = Display.DIRECTION_NORTH;
private int _tick = 0;
private MenuItem _startMenuItem;
private MenuItem _stopMenuItem;
/**
* Entry point for application
*
* @param args
* Command line arguments (not used)
*/
public static void main(final String[] args) {
// Create a new instance of the application and make the currently
// running thread the application's event dispatch thread.
final AccelerometerDemo app = new AccelerometerDemo();
app.enterEventDispatcher();
}
/**
* Creates a new AccelerometerDemo object
*/
public AccelerometerDemo() {
if (AccelerometerSensor.isSupported()) {
// Menu item to start the ball moving
_startMenuItem =
new MenuItem(new StringProvider("Start"), 0x230010, 0);
_startMenuItem.setCommand(new Command(new CommandHandler() {
/**
* @see net.rim.device.api.command.CommandHandler#execute(ReadOnlyCommandMetadata,
* Object)
*/
public void execute(final ReadOnlyCommandMetadata metadata,
final Object context) {
if (_thread == null) {
// Start drawing
_thread = new DrawThread();
_thread.start();
}
}
}));
// Menu item to stop the ball moving
_stopMenuItem =
new MenuItem(new StringProvider("Stop"), 0x230010, 0);
_stopMenuItem.setCommand(new Command(new CommandHandler() {
/**
* @see net.rim.device.api.command.CommandHandler#execute(ReadOnlyCommandMetadata,
* Object)
*/
public void execute(final ReadOnlyCommandMetadata metadata,
final Object context) {
if (_thread != null) {
synchronized (_thread) {
_thread._running = false;
_thread.notifyAll();
_thread = null;
}
}
}
}));
_screen = new AccelerometerDemoScreen();
pushScreen(_screen);
_ball = Bitmap.getBitmapResource("img/ball.png");
_r = new Random();
if (_ball != null) {
_ballWidth = _ball.getWidth();
_ballHeight = _ball.getHeight();
}
// Prevent UI from rotating the screen
Ui.getUiEngineInstance().setAcceptableDirections(
DEFAULT_ORIENTATION);
} else {
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.alert("This device does not support accelerometer.");
System.exit(0);
}
});
}
}
/**
* Calculates ball position
*
* @param xAcc
* x axis acceleration
* @param yAcc
* y axis acceleration
*/
private void applyForce(final int xAcc, final int yAcc) {
// Calculate new speed
_xSpeed += xAcc * G_NORM;
_ySpeed += yAcc * G_NORM;
// Apply table friction
_xSpeed *= TABLE_FRICTION;
_ySpeed *= TABLE_FRICTION;
// Move the ball
_x += _xSpeed;
_y += _ySpeed;
if (_x < 0) {
_x = 0;
_xSpeed = -(_xSpeed * BOUNCE_SLOWDOWN);
} else {
final int screenWidth = _screen.getWidth();
if (_x > screenWidth - _ballWidth) {
_x = screenWidth - _ballHeight;
_xSpeed = -(_xSpeed * BOUNCE_SLOWDOWN);
}
}
if (_y < 0) {
_y = 0;
_ySpeed = -(_ySpeed * BOUNCE_SLOWDOWN);
} else {
final int screenHeight = _screen.getHeight();
if (_y > screenHeight - _ballHeight) {
_y = screenHeight - _ballHeight;
_ySpeed = -(_ySpeed * BOUNCE_SLOWDOWN);
}
}
}
/**
* A thread class to handle screen updates
*/
private class DrawThread extends Thread {
private boolean _running;
public void run() {
_running = true;
// Start querying the accelerometer sensor
openAccelerometerConnection();
while (_running) {
_tick++;
// Get current acceleration
readAcceleration();
// Apply force to the ball
applyForce(-_xyz[0], _xyz[1]);
try {
synchronized (this) {
wait(50);
}
} catch (final InterruptedException e) {
UiApplication.getUiApplication().invokeLater(
new Runnable() {
public void run() {
Dialog.alert("wait(long) threw InterruptedException");
}
});
}
if (!_running) {
break;
}
_screen.invalidate();
}
// Stop querying the sensor to save battery charge
closeAccelerometerConnection();
}
/**
* Returns running state of thread
*
* @return True if this thread is running, otherwise false
*/
public boolean isRunning() {
return _running;
}
}
/**
* Opens the data channel
*/
private void openAccelerometerConnection() {
if (DeviceInfo.isSimulator()) {
_simulated = true;
} else {
_accChannel =
AccelerometerSensor
.openRawDataChannel(AccelerometerDemo.this);
_simulated = false;
}
}
/**
* Gets the latest acceleromenter data
*/
private void readAcceleration() {
if (_simulated) {
// Running in a simulator, simulate random
if (_tick % 10 == 0) {
_xyz[0] = (short) (_r.nextInt(400) - 200);
_xyz[1] = (short) (_r.nextInt(400) - 200);
}
} else {
// Real device, call the API for samples
_accChannel.getLastAccelerationData(_xyz);
}
}
/**
* Closes the data channel
*/
private void closeAccelerometerConnection() {
if (_accChannel != null) {
_accChannel.close();
_accChannel = null;
}
}
/**
* A screen on which to display the ball
*/
private class AccelerometerDemoScreen extends MainScreen {
/**
* @see Screen#paint(Graphics)
*/
protected void paint(final Graphics graphics) {
if (_ball != null) {
graphics.drawBitmap(_x, _y, _ballWidth, _ballHeight, _ball, 0,
0);
}
}
/**
* @see MainScreen#makeMenu(Menu, int)
*/
protected void makeMenu(final Menu menu, final int instance) {
if (_thread == null || !_thread.isRunning()) {
menu.add(_startMenuItem);
} else {
menu.add(_stopMenuItem);
}
super.makeMenu(menu, instance);
}
/**
* @see Screen#onClose()
*/
public boolean onClose() {
if (_thread != null) {
synchronized (_thread) {
_thread._running = false;
_thread.notifyAll();
}
Thread.yield();
}
return super.onClose();
}
}
}