Qt Reference Documentation

# accelerometerfilter.cpp Example File

demos/mobile/qtbubblelevel/accelerometerfilter.cpp

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     #include <math.h>
     #include "accelerometerfilter.h"

     #define RADIANS_TO_DEGREES 57.2957795

     AccelerometerFilter::AccelerometerFilter()
         : x(0), y(0), z(0)
     {
     }

     bool AccelerometerFilter::filter(QAccelerometerReading *reading)
     {
         qreal rx = reading->x();
         qreal ry = reading->y();
         qreal rz = reading->z();

         qreal divider = sqrt(rx * rx + ry * ry + rz * rz);

         // Lowpass factor
     #ifdef Q_OS_SYMBIAN
         float lowPassFactor = 0.10;
     #else
         float lowPassFactor = 0.05;
     #endif

         // Calculate the axis angles in degrees and reduce the noise in sensor
         // readings.
         x += (acos(rx / divider) * RADIANS_TO_DEGREES - 90 - x) * lowPassFactor;
         y += (acos(ry / divider) * RADIANS_TO_DEGREES - 90 - y) * lowPassFactor;
         z += (acos(rz / divider) * RADIANS_TO_DEGREES - 90 - z) * lowPassFactor;

         // The orientations of the accelerometers are different between
         // Symbian and Maemo devices so we use the different axes
         // depending on the platform.
     #if defined(Q_OS_SYMBIAN)
         emit rotationChanged(-y);
     #else
         emit rotationChanged(x);
     #endif

         // Don't store the reading in the sensor.
         return false;
     }