1 2 Android JumpingJack Sample 3 =================================== 4 5 A basic sample showing how to use the Gravity sensor on the wearable device 6 by counting how many jumping jacks you have performed. 7 8 Introduction 9 ------------ 10 11 [SensorEventListener][1] offers you methods used for receiving notifications from the 12 [SensorManager][2] when sensor values have changed. 13 14 This example counts how many times Jumping Jacks are performed by detecting the value 15 of the Gravity sensor by the following code: 16 17 ```java 18 @Override 19 public void onSensorChanged(SensorEvent event) { 20 detectJump(event.values[0], event.timestamp); 21 } 22 23 private void detectJump(float xValue, long timestamp) { 24 if ((Math.abs(xValue) > GRAVITY_THRESHOLD)) { 25 if(timestamp - mLastTime < TIME_THRESHOLD_NS && mUp != (xValue > 0)) { 26 onJumpDetected(!mUp); 27 } 28 mUp = xValue > 0; 29 mLastTime = timestamp; 30 } 31 } 32 ``` 33 34 The detectJump method above assumes that when a person is wearing the watch, the x-component of gravity 35 as measured by the Gravity Sensor is +9.8 when the hand is downward and -9.8 when the hand 36 is upward (signs are reversed if the watch is worn on the right hand). Since the upward or 37 downward may not be completely accurate, we leave some room and instead of 9.8, we use 38 GRAVITY_THRESHOLD (7.0f). We also consider the up <-> down movement successful if it takes less than 39 TIME_THRESHOLD_NS (2000000000 nanoseconds). 40 41 [1]: http://developer.android.com/reference/android/hardware/SensorEventListener.html 42 [2]: http://developer.android.com/reference/android/hardware/SensorManager.html 43 44 Pre-requisites 45 -------------- 46 47 - Android SDK 27 48 - Android Build Tools v27.0.2 49 - Android Support Repository 50 51 Screenshots 52 ------------- 53 54 <img src="screenshots/jumping_jack.gif" height="400" alt="Screenshot"/> 55 56 Getting Started 57 --------------- 58 59 This sample uses the Gradle build system. To build this project, use the 60 "gradlew build" command or use "Import Project" in Android Studio. 61 62 Support 63 ------- 64 65 - Google+ Community: https://plus.google.com/communities/105153134372062985968 66 - Stack Overflow: http://stackoverflow.com/questions/tagged/android 67 68 If you've found an error in this sample, please file an issue: 69 https://github.com/googlesamples/android-JumpingJack 70 71 Patches are encouraged, and may be submitted by forking this project and 72 submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details. 73 74 License 75 ------- 76 77 Copyright 2017 The Android Open Source Project, Inc. 78 79 Licensed to the Apache Software Foundation (ASF) under one or more contributor 80 license agreements. See the NOTICE file distributed with this work for 81 additional information regarding copyright ownership. The ASF licenses this 82 file to you under the Apache License, Version 2.0 (the "License"); you may not 83 use this file except in compliance with the License. You may obtain a copy of 84 the License at 85 86 http://www.apache.org/licenses/LICENSE-2.0 87 88 Unless required by applicable law or agreed to in writing, software 89 distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 90 WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 91 License for the specific language governing permissions and limitations under 92 the License. 93
