Detect device orientation by gravity sensor
The code demonstrate how to detect device orientation, face-up/face-down, base on gravity sensor data. |
| Detect device orientation by gravity sensor |
We can determine the device orientation(face-up or face-down) from Z value of Gravity sensor. The constant SensorManager.STANDARD_GRAVITY store the value 9.80665, it's the standard gravity (g) on Earth, equivalent to 1G. We can compare Z value with it to determine device orientation.
The code register SensorEventListener for Sensor.TYPE_GRAVITY in onResume() callback method. Once Gravity Sensor changed, the Z value can be retrieved from event.values[2].
Example code:
package com.example.androidgravitysensor;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;
import android.app.Activity;
import android.content.Context;
public class MainActivity extends Activity implements SensorEventListener{
private SensorManager mySensorManager;
private Sensor myGravitySensor;
TextView textFace, textZValue, textStandardGravity, textThreshold;
float standardGravity;
float thresholdGraqvity;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textFace = (TextView)findViewById(R.id.face);
textZValue = (TextView)findViewById(R.id.zvalue);
textStandardGravity = (TextView)findViewById(R.id.standardgravity);
textThreshold = (TextView)findViewById(R.id.threshold);
standardGravity = SensorManager.STANDARD_GRAVITY;
thresholdGraqvity = standardGravity/2;
textFace.setText("");
textZValue.setText("");
textStandardGravity.setText("Standard Gravity = " + standardGravity);
textThreshold.setText("Threshold = " + thresholdGraqvity);
mySensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);
myGravitySensor = mySensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
}
@Override
public void onAccuracyChanged(Sensor arg0, int arg1) {
// TODO Auto-generated method stub
}
@Override
public void onSensorChanged(SensorEvent event) {
Sensor source = event.sensor;
float z = event.values[2];
if(source.getType() == Sensor.TYPE_GRAVITY){
textZValue.setText("Z value = " + z);
if (z >= thresholdGraqvity){
textFace.setText("Face UP");
}else if(z <= -thresholdGraqvity){
textFace.setText("Face DOWN");
}else{
textFace.setText("");
}
}
}
@Override
protected void onPause() {
super.onPause();
mySensorManager.unregisterListener(this);
}
@Override
protected void onResume() {
super.onResume();
mySensorManager.registerListener(
this,
myGravitySensor,
SensorManager.SENSOR_DELAY_NORMAL);
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<TextView
android:id="@+id/face"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold" />
<TextView
android:id="@+id/zvalue"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/standardgravity"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/threshold"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
Related article: Get details of gravity sensor
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