Android: get device orientation from Azimuth, roll & pitch

Question

I need to get the updated device orientation, but I have to fix my activity to Portrait (which I did in the layout xml file), which prevents me from using this:

int rotation = getWindowManager().getDefaultDisplay().getRotation();

because it always gives me the portrait rotation,

So, I'm trying to rely on the sensors. I found that Sensor.TYPE_ORIENTATION is deprecated, so I'm using a combination of Sensor.TYPE_ACCELEROMETER & Sensor.TYPE_MAGNETIC_FIELD and here is the event listener:

SensorEventListener sensorEventListener = new SensorEventListener() {
    float[] mGravity;
    float[] mGeomagnetic;

    @Override
    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 orientationData[] = new float[3];
                SensorManager.getOrientation(R, orientationData);
                azimuth = orientationData[0];
                pitch = orientationData[1];
                roll = orientationData[2];
                // now how to use previous 3 values to calculate orientation
            }
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

    }
};

Now Question is, how to use the 3 values azimuth, pitch & roll to detect current device orientation as one of these:

• Landscape (rotation 0)
• Portrait (rotation 90)
• Reverse Landscape (rotation 180)
• Reverse Portrait (rotation 270)

Solution

I've found it & here is the calculating function that will be called inside the listener after reading the pitch & roll:

public static final int ORIENTATION_PORTRAIT = 0;
public static final int ORIENTATION_LANDSCAPE_REVERSE = 1;
public static final int ORIENTATION_LANDSCAPE = 2;
public static final int ORIENTATION_PORTRAIT_REVERSE = 3;
public int orientation = ORIENTATION_PORTRAIT;

private int calculateOrientation(int roll, int pitch) {
    if (((orientation == ORIENTATION_PORTRAIT || orientation == ORIENTATION_PORTRAIT_REVERSE)
            && (roll > -30 && roll < 30))) {
        if (averagePitch > 0)
            return ORIENTATION_PORTRAIT_REVERSE;
        else
            return ORIENTATION_PORTRAIT;
    } else {
        // divides between all orientations
        if (Math.abs(pitch) >= 30) {
            if (pitch > 0)
                return ORIENTATION_PORTRAIT_REVERSE;
            else
                return ORIENTATION_PORTRAIT;
        } else {
            if (averageRoll > 0) {
                return ORIENTATION_LANDSCAPE_REVERSE;
            } else {
                return ORIENTATION_LANDSCAPE;
            }
        }
    }
}

-- Update --

& here is my full utility class implementation

-- Update --

Adding this image to help visualizing the azimuth, pitch & roll:

Comments

[agamov]

what is averagePitch and averageRoll in your code?

[AbdelHady]

@agamov sorry for that :), I've updated my answer with a link for my whole implementation.

[GPack]

Please can you shortly explain here or on the gist the logic of calculateOrientation method, thanks?

[AbdelHady]

Well it was a long time ago with a lot of trial and error methodology :). But as far as I remember, when in portrait (my apps default orientation), users could roll the device a little right or left, but if they rolled it too much (more than 30 degrees) then we need to recalculate the new situation. See this image for a better understanding of roll and pitch mathworks.com/matlabcentral/mlc-downloads/downloads/submissi‌​ons/…