docs: Add AccelerometerPlay sample to prebuilts

am: ef51b0db8e

Change-Id: I15925d602cf36ec591c5acf554998d0102fcb45d

samples/browseable/AccelerometerPlay/AndroidManifest.xml

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+<?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="@mipmap/ic_launcher" 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/browseable/AccelerometerPlay/_index.jd

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+
+page.tags="AccelerometerPlay"
+sample.group=Sensors
+@jd:body
+
+<p>
+            
+            <p>This sample demonstrates how to use an accelerometer sensor as input for
+            a physics-based view. The input from the accelerometer is used to simulate a
+            virtual surface, and a number of free-moving objects placed on top of it.</p>
+
+            <p>Any effects from the device's acceleration vector (including both gravity and
+            temporary movement) will be translated to the on-screen particles.</p>
+            
+        </p>

samples/browseable/AccelerometerPlay/res/layout/main.xml

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+<?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.
+-->
+
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent"
+    android:background="@drawable/wood"
+    >
+</FrameLayout>

samples/browseable/AccelerometerPlay/res/values/strings.xml

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+<?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/browseable/AccelerometerPlay/src/com.example.android.accelerometerplay/AccelerometerPlayActivity.java

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+/*
+ * 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.annotation.TargetApi;
+import android.app.Activity;
+import android.content.Context;
+import android.graphics.Bitmap;
+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.Build;
+import android.os.Bundle;
+import android.os.PowerManager;
+import android.os.PowerManager.WakeLock;
+import android.util.AttributeSet;
+import android.util.DisplayMetrics;
+import android.view.Display;
+import android.view.Surface;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.WindowManager;
+import android.widget.FrameLayout;
+
+/**
+ * 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 WindowManager mWindowManager;
+    private Display mDisplay;
+    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);
+
+        // Get an instance of the WindowManager
+        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
+        mDisplay = mWindowManager.getDefaultDisplay();
+
+        // 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);
+        mSimulationView.setBackgroundResource(R.drawable.wood);
+        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 FrameLayout implements SensorEventListener {
+        // diameter of the balls in meters
+        private static final float sBallDiameter = 0.004f;
+        private static final float sBallDiameter2 = sBallDiameter * sBallDiameter;
+
+        private final int mDstWidth;
+        private final int mDstHeight;
+
+        private Sensor mAccelerometer;
+        private long mLastT;
+
+        private float mXDpi;
+        private float mYDpi;
+        private float mMetersToPixelsX;
+        private float mMetersToPixelsY;
+        private float mXOrigin;
+        private float mYOrigin;
+        private float mSensorX;
+        private float mSensorY;
+        private float mHorizontalBound;
+        private float mVerticalBound;
+        private final ParticleSystem mParticleSystem;
+        /*
+         * Each of our particle holds its previous and current position, its
+         * acceleration. for added realism each particle has its own friction
+         * coefficient.
+         */
+        class Particle extends View {
+            private float mPosX = (float) Math.random();
+            private float mPosY = (float) Math.random();
+            private float mVelX;
+            private float mVelY;
+
+            public Particle(Context context) {
+                super(context);
+            }
+
+            public Particle(Context context, AttributeSet attrs) {
+                super(context, attrs);
+            }
+
+            public Particle(Context context, AttributeSet attrs, int defStyleAttr) {
+                super(context, attrs, defStyleAttr);
+            }
+
+            @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+            public Particle(Context context, AttributeSet attrs, int defStyleAttr,
+                            int defStyleRes) {
+                super(context, attrs, defStyleAttr, defStyleRes);
+            }
+
+            public void computePhysics(float sx, float sy, float dT) {
+
+                final float ax = -sx/5;
+                final float ay = -sy/5;
+
+                mPosX += mVelX * dT + ax * dT * dT / 2;
+                mPosY += mVelY * dT + ay * dT * dT / 2;
+
+                mVelX += ax * dT;
+                mVelY += ay * dT;
+            }
+
+            /*
+             * 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;
+                    mVelX = 0;
+                } else if (x < -xmax) {
+                    mPosX = -xmax;
+                    mVelX = 0;
+                }
+                if (y > ymax) {
+                    mPosY = ymax;
+                    mVelY = 0;
+                } else if (y < -ymax) {
+                    mPosY = -ymax;
+                    mVelY = 0;
+                }
+            }
+        }
+
+        /*
+         * A particle system is just a collection of particles
+         */
+        class ParticleSystem {
+            static final int NUM_PARTICLES = 5;
+            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(getContext());
+                    mBalls[i].setBackgroundResource(R.drawable.ball);
+                    mBalls[i].setLayerType(LAYER_TYPE_HARDWARE, null);
+                    addView(mBalls[i], new ViewGroup.LayoutParams(mDstWidth, mDstHeight));
+                }
+            }
+
+            /*
+             * 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) / 1000.f /** (1.0f / 1000000000.0f)*/;
+                        final int count = mBalls.length;
+                        for (int i = 0; i < count; i++) {
+                            Particle ball = mBalls[i];
+                            ball.computePhysics(sx, sy, 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;
+                                final float effectX = dx * c;
+                                final float effectY = dy * c;
+                                curr.mPosX -= effectX;
+                                curr.mPosY -= effectY;
+                                ball.mPosX += effectX;
+                                ball.mPosY += effectY;
+                                more = true;
+                            }
+                        }
+                        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_GAME);
+        }
+
+        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
+            mDstWidth = (int) (sBallDiameter * mMetersToPixelsX + 0.5f);
+            mDstHeight = (int) (sBallDiameter * mMetersToPixelsY + 0.5f);
+            mParticleSystem = new ParticleSystem();
+
+            Options opts = new Options();
+            opts.inDither = true;
+            opts.inPreferredConfig = Bitmap.Config.RGB_565;
+        }
+
+        @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 - mDstWidth) * 0.5f;
+            mYOrigin = (h - mDstHeight) * 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. In this application, we need to
+             * take into account how the screen is rotated with respect to the
+             * sensors (which always return data in a coordinate space aligned
+             * to with the screen in its native orientation).
+             */
+
+            switch (mDisplay.getRotation()) {
+                case Surface.ROTATION_0:
+                    mSensorX = event.values[0];
+                    mSensorY = event.values[1];
+                    break;
+                case Surface.ROTATION_90:
+                    mSensorX = -event.values[1];
+                    mSensorY = event.values[0];
+                    break;
+                case Surface.ROTATION_180:
+                    mSensorX = -event.values[0];
+                    mSensorY = -event.values[1];
+                    break;
+                case Surface.ROTATION_270:
+                    mSensorX = event.values[1];
+                    mSensorY = -event.values[0];
+                    break;
+            }
+        }
+
+        @Override
+        protected void onDraw(Canvas canvas) {
+            /*
+             * Compute the new position of our object, based on accelerometer
+             * data and present time.
+             */
+            final ParticleSystem particleSystem = mParticleSystem;
+            final long now = System.currentTimeMillis();
+            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 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;
+                particleSystem.mBalls[i].setTranslationX(x);
+                particleSystem.mBalls[i].setTranslationY(y);
+            }
+
+            // and make sure to redraw asap
+            invalidate();
+        }
+
+        @Override
+        public void onAccuracyChanged(Sensor sensor, int accuracy) {
+        }
+    }
+}