Merge "Sample code to illustrate how to use the accelerometer" into gingerbread

samples/AccelerometerPlay/Android.mk

@@ -0,0 +1,31 @@
+# Copyright (C) 2010 The Android Open Source Project
+#
+# 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.
+#
+
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_MODULE_TAGS := samples
+
+# Only compile source java files in this apk.
+LOCAL_SRC_FILES := $(call all-java-files-under, src)
+
+LOCAL_PACKAGE_NAME := AccelerometerPlay
+
+LOCAL_SDK_VERSION := current
+
+include $(BUILD_PACKAGE)
+
+# Use the following include to make our test apk.
+include $(call all-makefiles-under,$(LOCAL_PATH))

samples/AccelerometerPlay/AndroidManifest.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2010 The Android Open Source Project
+
+     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.
+-->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+      android:versionCode="1"
+      android:versionName="1.0" package="com.example.android.accelerometerplay">
+    <application android:icon="@drawable/icon" android:label="@string/app_name">
+        <activity android:name=".AccelerometerPlayActivity"
+                  android:label="@string/app_name"
+                  android:screenOrientation="portrait" android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+    </application>
+
+
+<uses-sdk android:minSdkVersion="5"></uses-sdk>
+<uses-permission android:name="android.permission.VIBRATE"></uses-permission>
+
+<uses-permission android:name="android.permission.WAKE_LOCK"></uses-permission>
+
+</manifest> 

samples/AccelerometerPlay/NOTICE

@@ -0,0 +1,190 @@
+
+   Copyright (c) 2005-2008, The Android Open Source Project
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+
+   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.
+
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
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+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
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+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
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+      designated in writing by the copyright owner as "Not a Contribution."
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+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
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+   2. Grant of Copyright License. Subject to the terms and conditions of
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
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+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
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+      (d) If the Work includes a "NOTICE" text file as part of its
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+          of the NOTICE file are for informational purposes only and
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+          notices within Derivative Works that You distribute, alongside
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+          that such additional attribution notices cannot be construed
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+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
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+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
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+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
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+   END OF TERMS AND CONDITIONS
+

samples/AccelerometerPlay/res/layout/main.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2010 The Android Open Source Project
+
+     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.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent"
+    >
+</LinearLayout>

samples/AccelerometerPlay/res/values/strings.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2010 The Android Open Source Project
+
+     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.
+-->
+
+<resources>
+    <string name="app_name">AccelerometerPlay</string>
+</resources>

samples/AccelerometerPlay/src/com/example/android/accelerometerplay/AccelerometerPlayActivity.java

@@ -0,0 +1,450 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package com.example.android.accelerometerplay;
+
+import android.app.Activity;
+import android.content.Context;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.Canvas;
+import android.graphics.BitmapFactory.Options;
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
+import android.os.Bundle;
+import android.os.PowerManager;
+import android.os.PowerManager.WakeLock;
+import android.util.DisplayMetrics;
+import android.view.View;
+
+/**
+ * This is an example of using the accelerometer to integrate the device's
+ * acceleration to a position using the Verlet method. This is illustrated with
+ * a very simple particle system comprised of a few iron balls freely moving on
+ * an inclined wooden table. The inclination of the virtual table is controlled
+ * by the device's accelerometer.
+ * 
+ * @see SensorManager
+ * @see SensorEvent
+ * @see Sensor
+ */
+
+public class AccelerometerPlayActivity extends Activity {
+
+	private SimulationView mSimulationView;
+	private SensorManager mSensorManager;
+	private PowerManager mPowerManager;
+	private WakeLock mWakeLock;
+
+	/** Called when the activity is first created. */
+	@Override
+	public void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		// Get an instance of the SensorManager
+		mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
+
+		// Get an instance of the PowerManager
+		mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);
+
+		// Create a bright wake lock
+		mWakeLock = mPowerManager.newWakeLock(
+				PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass().getName());
+
+		// instantiate our simulation view and set it as the activity's content
+		mSimulationView = new SimulationView(this);
+		setContentView(mSimulationView);
+	}
+
+	@Override
+	protected void onResume() {
+		super.onResume();
+		/*
+		 * when the activity is resumed, we acquire a wake-lock so that the
+		 * screen stays on, since the user will likely not be fiddling with the
+		 * screen or buttons.
+		 */
+		mWakeLock.acquire();
+
+		// Start the simulation
+		mSimulationView.startSimulation();
+	}
+
+	@Override
+	protected void onPause() {
+		super.onPause();
+		/*
+		 * When the activity is paused, we make sure to stop the simulation,
+		 * release our sensor resources and wake locks
+		 */
+
+		// Stop the simulation
+		mSimulationView.stopSimulation();
+
+		// and release our wake-lock
+		mWakeLock.release();
+	}
+
+	class SimulationView extends View implements SensorEventListener {
+		// diameter of the balls in meters
+		private static final float sBallDiameter = 0.004f;
+		private static final float sBallDiameter2 = sBallDiameter
+				* sBallDiameter;
+
+		// friction of the virtual table and air
+		private static final float sFriction = 0.1f;
+
+		private Sensor mAccelerometer;
+		private long mLastT;
+		private float mLastDeltaT;
+
+		private float mXDpi;
+		private float mYDpi;
+		private float mMetersToPixelsX;
+		private float mMetersToPixelsY;
+		private Bitmap mBitmap;
+		private Bitmap mWood;
+		private float mXOrigin;
+		private float mYOrigin;
+		private float mSensorX;
+		private float mSensorY;
+		private long mSensorTimeStamp;
+		private long mCpuTimeStamp;
+		private float mHorizontalBound;
+		private float mVerticalBound;
+		private final ParticleSystem mParticleSystem = new ParticleSystem();
+
+		/*
+		 * Each of our particle holds its previous and current position, its
+		 * acceleration. for added realism each particle has its own friction
+		 * coefficient.
+		 */
+		class Particle {
+			private float mPosX;
+			private float mPosY;
+			private float mAccelX;
+			private float mAccelY;
+			private float mLastPosX;
+			private float mLastPosY;
+			private float mOneMinusFriction;
+
+			Particle() {
+				// make each particle a bit different by randomizing its
+				// coefficient of friction
+				final float r = ((float) Math.random() - 0.5f) * 0.2f;
+				mOneMinusFriction = 1.0f - sFriction + r;
+			}
+
+			public void computePhysics(float sx, float sy, float dT, float dTC) {
+				// Force of gravity applied to our virtual object
+				final float m = 1000.0f; // mass of our virtual object
+				final float gx = -sx * m;
+				final float gy = -sy * m;
+
+				/*
+				 * <20>F = mA <=> A = <20>F / m
+				 * 
+				 * We could simplify the code by completely eliminating "m" (the
+				 * mass) from all the equations, but it would hide the concepts
+				 * from this sample code.
+				 */
+				final float invm = 1.0f / m;
+				final float ax = gx * invm;
+				final float ay = gy * invm;
+
+				/*
+				 * Time-corrected Verlet integration
+				 * 
+				 * The position Verlet integrator is defined as
+				 * 
+				 * x(t+<2B>t) = x(t) + x(t) - x(t-<2D>t) + a(t)<29>t<EFBFBD>2
+				 * 
+				 * However, the above equation doesn't handle variable <20>t very
+				 * well, a time-corrected version is needed:
+				 * 
+				 * x(t+<2B>t) = x(t) + (x(t) - x(t-<2D>t)) * (<28>t/<2F>t_prev) + a(t)<29>t<EFBFBD>2
+				 * 
+				 * 
+				 * We also add a simple friction term (f) to the equation:
+				 * 
+				 * x(t+<2B>t) = x(t) + (1-f) * (x(t) - x(t-<2D>t)) * (<28>t/<2F>t_prev) +
+				 * a(t)<29>t<EFBFBD>2
+				 */
+				final float dTdT = dT * dT;
+				final float x = mPosX + mOneMinusFriction * dTC
+						* (mPosX - mLastPosX) + mAccelX * dTdT;
+				final float y = mPosY + mOneMinusFriction * dTC
+						* (mPosY - mLastPosY) + mAccelY * dTdT;
+				mLastPosX = mPosX;
+				mLastPosY = mPosY;
+				mPosX = x;
+				mPosY = y;
+				mAccelX = ax;
+				mAccelY = ay;
+			}
+
+			/*
+			 * Resolving constraints and collisions with the Verlet integrator
+			 * can be very simple, we simply need to move a colliding or
+			 * constrained particle in such way that the constraint is
+			 * satisfied.
+			 */
+			public void resolveCollisionWithBounds() {
+				final float xmax = mHorizontalBound;
+				final float ymax = mVerticalBound;
+				final float x = mPosX;
+				final float y = mPosY;
+				if (x > xmax) {
+					mPosX = xmax;
+				} else if (x < -xmax) {
+					mPosX = -xmax;
+				}
+				if (y > ymax) {
+					mPosY = ymax;
+				} else if (y < -ymax) {
+					mPosY = -ymax;
+				}
+			}
+		}
+
+		/*
+		 * A particle system is just a collection of particles
+		 */
+		class ParticleSystem {
+			static final int NUM_PARTICLES = 15;
+			private Particle mBalls[] = new Particle[NUM_PARTICLES];
+
+			ParticleSystem() {
+				/*
+				 * Initially our particles have no speed or acceleration
+				 */
+				for (int i = 0; i < mBalls.length; i++) {
+					mBalls[i] = new Particle();
+				}
+			}
+
+			/*
+			 * Update the position of each particle in the system using the
+			 * Verlet integrator.
+			 */
+			private void updatePositions(float sx, float sy, long timestamp) {
+				final long t = timestamp;
+				if (mLastT != 0) {
+					final float dT = (float) (t - mLastT)
+							* (1.0f / 1000000000.0f);
+					if (mLastDeltaT != 0) {
+						final float dTC = dT / mLastDeltaT;
+						final int count = mBalls.length;
+						for (int i = 0; i < count; i++) {
+							Particle ball = mBalls[i];
+							ball.computePhysics(sx, sy, dT, dTC);
+						}
+					}
+					mLastDeltaT = dT;
+				}
+				mLastT = t;
+			}
+
+			/*
+			 * Performs one iteration of the simulation. First updating the
+			 * position of all the particles and resolving the constraints and
+			 * collisions.
+			 */
+			public void update(float sx, float sy, long now) {
+				// update the system's positions
+				updatePositions(sx, sy, now);
+
+				// We do no more than a limited number of iterations
+				final int NUM_MAX_ITERATIONS = 10;
+
+				/*
+				 * Resolve collisions, each particle is tested against every
+				 * other particle for collision. If a collision is detected the
+				 * particle is moved away using a virtual spring of infinite
+				 * stiffness.
+				 */
+				boolean more = true;
+				final int count = mBalls.length;
+				for (int k = 0; k < NUM_MAX_ITERATIONS && more; k++) {
+					more = false;
+					for (int i = 0; i < count; i++) {
+						Particle curr = mBalls[i];
+						for (int j = i + 1; j < count; j++) {
+							Particle ball = mBalls[j];
+							float dx = ball.mPosX - curr.mPosX;
+							float dy = ball.mPosY - curr.mPosY;
+							float dd = dx * dx + dy * dy;
+							// Check for collisions
+							if (dd <= sBallDiameter2) {
+								/*
+								 * add a little bit of entropy, after nothing is
+								 * perfect in the universe.
+								 */
+								dx += ((float) Math.random() - 0.5f) * 0.0001f;
+								dy += ((float) Math.random() - 0.5f) * 0.0001f;
+								dd = dx * dx + dy * dy;
+								// simulate the spring
+								final float d = (float) Math.sqrt(dd);
+								final float c = (0.5f * (sBallDiameter - d))
+										/ d;
+								curr.mPosX -= dx * c;
+								curr.mPosY -= dy * c;
+								ball.mPosX += dx * c;
+								ball.mPosY += dy * c;
+								more = true;
+							}
+						}
+						/*
+						 * Finally make sure the particle doesn't intersects
+						 * with the walls.
+						 */
+						curr.resolveCollisionWithBounds();
+					}
+				}
+			}
+
+			public int getParticleCount() {
+				return mBalls.length;
+			}
+
+			public float getPosX(int i) {
+				return mBalls[i].mPosX;
+			}
+
+			public float getPosY(int i) {
+				return mBalls[i].mPosY;
+			}
+		}
+
+		public void startSimulation() {
+			/*
+			 * It is not necessary to get accelerometer events at a very high
+			 * rate, by using a slower rate (SENSOR_DELAY_UI), we get an
+			 * automatic low-pass filter, which "extracts" the gravity component
+			 * of the acceleration. As an added benefit, we use less power and
+			 * CPU resources.
+			 */
+			mSensorManager.registerListener(this, mAccelerometer,
+					SensorManager.SENSOR_DELAY_UI);
+		}
+
+		public void stopSimulation() {
+			mSensorManager.unregisterListener(this);
+		}
+
+		public SimulationView(Context context) {
+			super(context);
+			mAccelerometer = mSensorManager
+					.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+
+			DisplayMetrics metrics = new DisplayMetrics();
+			getWindowManager().getDefaultDisplay().getMetrics(metrics);
+			mXDpi = metrics.xdpi;
+			mYDpi = metrics.ydpi;
+			mMetersToPixelsX = mXDpi / 0.0254f;
+			mMetersToPixelsY = mYDpi / 0.0254f;
+
+			// rescale the ball so it's about 0.5 cm on screen
+			Bitmap ball = BitmapFactory.decodeResource(getResources(),
+					R.drawable.ball);
+			final int dstWidth = (int) (sBallDiameter * mMetersToPixelsX + 0.5f);
+			final int dstHeight = (int) (sBallDiameter * mMetersToPixelsY + 0.5f);
+			mBitmap = Bitmap
+					.createScaledBitmap(ball, dstWidth, dstHeight, true);
+
+			Options opts = new Options();
+			opts.inDither = true;
+			opts.inPreferredConfig = Bitmap.Config.RGB_565;
+			mWood = BitmapFactory.decodeResource(getResources(),
+					R.drawable.wood, opts);
+		}
+
+		@Override
+		protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+			// compute the origin of the screen relative to the origin of
+			// the bitmap
+			mXOrigin = (w - mBitmap.getWidth()) * 0.5f;
+			mYOrigin = (h - mBitmap.getHeight()) * 0.5f;
+			mHorizontalBound = ((w / mMetersToPixelsX - sBallDiameter) * 0.5f);
+			mVerticalBound = ((h / mMetersToPixelsY - sBallDiameter) * 0.5f);
+		}
+
+		@Override
+		public void onSensorChanged(SensorEvent event) {
+			if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER)
+				return;
+			/*
+			 * record the accelerometer data, the event's timestamp as well as
+			 * the current time. The latter is needed so we can calculate the
+			 * "present" time during rendering.
+			 */
+			mSensorX = event.values[0];
+			mSensorY = event.values[1];
+			mSensorTimeStamp = event.timestamp;
+			mCpuTimeStamp = System.nanoTime();
+		}
+
+		@Override
+		protected void onDraw(Canvas canvas) {
+
+			/*
+			 * draw the background
+			 */
+
+			canvas.drawBitmap(mWood, 0, 0, null);
+
+			/*
+			 * compute the new position of our object, based on accelerometer
+			 * data and present time.
+			 */
+
+			final ParticleSystem particleSystem = mParticleSystem;
+			final long now = mSensorTimeStamp
+					+ (System.nanoTime() - mCpuTimeStamp);
+			final float sx = mSensorX;
+			final float sy = mSensorY;
+
+			particleSystem.update(sx, sy, now);
+
+			final float xc = mXOrigin;
+			final float yc = mYOrigin;
+			final float xs = mMetersToPixelsX;
+			final float ys = mMetersToPixelsY;
+			final Bitmap bitmap = mBitmap;
+			final int count = particleSystem.getParticleCount();
+			for (int i = 0; i < count; i++) {
+				/*
+				 * We transform the canvas so that the coordinate system matches
+				 * the sensors coordinate system with the origin in the center
+				 * of the screen and the unit is the meter.
+				 */
+
+				final float x = xc + particleSystem.getPosX(i) * xs;
+				final float y = yc - particleSystem.getPosY(i) * ys;
+				canvas.drawBitmap(bitmap, x, y, null);
+			}
+
+			// and make sure to redraw asap
+			invalidate();
+		}
+
+		@Override
+		public void onAccuracyChanged(Sensor sensor, int accuracy) {
+		}
+	}
+}