如何获取Android设备旋转的角度？

Question

我想为我的Android手机制作一个指南针应用程序，其中的指南针图像会旋转并显示方向变化，我在Google上搜索并找到了一些类似codeofninja.com和javadecodegeeks.com的教程，但它们都无法在我的设备上正常工作（我有三星S3手机）。 我完全陷入如何获取旋转角度并显示图像旋转方向变化的问题。 请帮帮我。

Answer 1

您可以看到此http://developer.android.com/reference/android/hardware/SensorEvent.html

http://www.workingfromhere.com/blog/2009/03/30/orientation-sensor-tips-in-android/

https://thenewcircle.com/s/post/43/using_the_sensors_api

并参阅https : //stackoverflow.com/a/13817444/2771869 ...。

您可以像这样获取屏幕方向（例如，在onResume（）方法中）：

private static final int ORIENTATION_0 = 0;
private static final int ORIENTATION_90 = 3;
private static final int ORIENTATION_270 = 1;


Display display = ((WindowManager)
          getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
int screenOrientation = display.getRotation();

switch (screenOrientation)
{
default:
case ORIENTATION_0: // Portrait
   // do smth.
break;
case ORIENTATION_90: // Landscape right
   // do smth.
break;
case ORIENTATION_270: // Landscape left
   // do smth.
break;
}

Answer 2

您需要使用设备的方向传感器，这是一个简单的类，说明如何使用它：

package com.samplecompass;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.View;

public class CompassActivity extends Activity implements SensorEventListener {

  Float azimut;  // View to draw a compass

  public class CustomDrawableView extends View {
    Paint paint = new Paint();
    public CustomDrawableView(Context context) {
      super(context);
      paint.setColor(0xff00ff00);
      paint.setStyle(Style.STROKE);
      paint.setStrokeWidth(2);
      paint.setAntiAlias(true);
    };

    protected void onDraw(Canvas canvas) {
      int width = getWidth();
      int height = getHeight();
      int centerx = width/2;
      int centery = height/2;
      canvas.drawLine(centerx, 0, centerx, height, paint);
      canvas.drawLine(0, centery, width, centery, paint);
      // Rotate the canvas with the azimut      
      if (azimut != null)
        canvas.rotate(-azimut*360/(2*3.14159f), centerx, centery);
      paint.setColor(0xff0000ff);
      canvas.drawLine(centerx, -1000, centerx, +1000, paint);
      canvas.drawLine(-1000, centery, 1000, centery, paint);
      canvas.drawText("N", centerx+5, centery-10, paint);
      canvas.drawText("S", centerx-10, centery+15, paint);
      paint.setColor(0xff00ff00);
    }
  }

  CustomDrawableView mCustomDrawableView;
  private SensorManager mSensorManager;
  Sensor accelerometer;
  Sensor magnetometer;

  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mCustomDrawableView = new CustomDrawableView(this);
    setContentView(mCustomDrawableView);    // Register the sensor listeners
    mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
      accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
  }

  protected void onResume() {
    super.onResume();
    mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_UI);
    mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_UI);
  }

  protected void onPause() {
    super.onPause();
    mSensorManager.unregisterListener(this);
  }

  public void onAccuracyChanged(Sensor sensor, int accuracy) {  }

  float[] mGravity;
  float[] mGeomagnetic;
  public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
      mGravity = event.values;
    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
      mGeomagnetic = event.values;
    if (mGravity != null && mGeomagnetic != null) {
      float R[] = new float[9];
      float I[] = new float[9];
      boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);
      if (success) {
        float orientation[] = new float[3];
        SensorManager.getOrientation(R, orientation);
        azimut = orientation[0]; // orientation contains: azimut, pitch and roll
      }
    }
    mCustomDrawableView.invalidate();
  }
}

您需要此权限才能进行此工作：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

然后，如果要使用设备的方向旋转图像，则需要使用Matrix，这是一个简单的示例：

Matrix matrix=new Matrix();
imageView.setScaleType(ScaleType.MATRIX);   //required
matrix.postRotate((float) angle, pivX, pivY);
imageView.setImageMatrix(matrix); 

因此，使用SensorManager获取方向，使用Matrix旋转图像。 我没有真正尝试过，但是在这方面，祝您好运