1 <?xml version="1.0" encoding="UTF-8"?> 2 <!-- 3 Copyright 2013 The Android Open Source Project 4 5 Licensed under the Apache License, Version 2.0 (the "License"); 6 you may not use this file except in compliance with the License. 7 You may obtain a copy of the License at 8 9 http://www.apache.org/licenses/LICENSE-2.0 10 11 Unless required by applicable law or agreed to in writing, software 12 distributed under the License is distributed on an "AS IS" BASIS, 13 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 See the License for the specific language governing permissions and 15 limitations under the License. 16 --> 17 18 19 20 <sample> 21 <name>JumpingJack</name> 22 <group>Wearable</group> 23 <package>com.example.android.wearable.jumpingjack</package> 24 25 26 27 <!-- change minSdk if needed--> 28 <minSdk>18</minSdk> 29 30 31 <strings> 32 <intro> 33 <![CDATA[ 34 Uses the Gravity sensor to count how many jumping jacks you have performed. 35 ]]> 36 </intro> 37 </strings> 38 39 <template src="base"/> 40 <template src="Wear"/> 41 <common src="logger"/> 42 <common src="activities"/> 43 44 <metadata> 45 <status>PUBLISHED</status> 46 <categories>Wearable</categories> 47 <technologies>Android</technologies> 48 <languages>Java</languages> 49 <solutions>Mobile</solutions> 50 <level>INTERMEDIATE</level> 51 <icon>screenshots/web-icon.png</icon> 52 <screenshots> 53 <img>screenshots/jumping_jack.gif</img> 54 </screenshots> 55 <api_refs> 56 <android>android.hardware.SensorEvent</android> 57 <android>android.hardware.SensorEventManager</android> 58 </api_refs> 59 60 <description> 61 <![CDATA[ 62 A basic sample showing how to use the Gravity sensor on the wearable device 63 by counting how many jumping jacks you have performed. 64 ]]> 65 </description> 66 67 <intro> 68 <![CDATA[ 69 [SensorEventListener][1] offers you methods used for receiving notifications from the 70 [SensorManager][2] when sensor values have changed. 71 72 This example counts how many times Jumping Jakcs are performed by detecting the value 73 of the Gravity sensor by the following code: 74 75 ```java 76 @Override 77 public void onSensorChanged(SensorEvent event) { 78 detectJump(event.values[0], event.timestamp); 79 } 80 81 private void detectJump(float xValue, long timestamp) { 82 if ((Math.abs(xValue) > GRAVITY_THRESHOLD)) { 83 if(timestamp - mLastTime < TIME_THRESHOLD_NS && mUp != (xValue > 0)) { 84 onJumpDetected(!mUp); 85 } 86 mUp = xValue > 0; 87 mLastTime = timestamp; 88 } 89 } 90 ``` 91 92 The detectJump method above assumes that when a person is wearing the watch, the x-component of gravity 93 as measured by the Gravity Sensor is +9.8 when the hand is downward and -9.8 when the hand 94 is upward (signs are reversed if the watch is worn on the right hand). Since the upward or 95 downward may not be completely accurate, we leave some room and instead of 9.8, we use 96 GRAVITY_THRESHOLD (7.0f). We also consider the up <-> down movement successful if it takes less than 97 TIME_THRESHOLD_NS (2000000000 nanoseconds). 98 99 [1]: http://developer.android.com/reference/android/hardware/SensorEventListener.html 100 [2]: http://developer.android.com/reference/android/hardware/SensorManager.html 101 ]]> 102 </intro> 103 </metadata> 104 </sample> 105
