circularbuffer.cpp
1.51 KB
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#include "circularbuffer.h"
#include <math.h>
CircularBuffer::CircularBuffer( double interval, size_t numPoints ):
d_y( NULL ),
d_referenceTime( 0.0 ),
d_startIndex( 0 ),
d_offset( 0.0 )
{
fill( interval, numPoints );
}
void CircularBuffer::fill( double interval, size_t numPoints )
{
if ( interval <= 0.0 || numPoints < 2 )
return;
d_values.resize( numPoints );
d_values.fill( 0.0 );
if ( d_y )
{
d_step = interval / ( numPoints - 2 );
for ( size_t i = 0; i < numPoints; i++ )
d_values[i] = d_y( i * d_step );
}
d_interval = interval;
}
void CircularBuffer::setFunction( double( *y )( double ) )
{
d_y = y;
}
void CircularBuffer::setReferenceTime( double timeStamp )
{
d_referenceTime = timeStamp;
const double startTime = ::fmod( d_referenceTime, d_values.size() * d_step );
d_startIndex = int( startTime / d_step ); // floor
d_offset = ::fmod( startTime, d_step );
}
double CircularBuffer::referenceTime() const
{
return d_referenceTime;
}
size_t CircularBuffer::size() const
{
return d_values.size();
}
QPointF CircularBuffer::sample( size_t i ) const
{
const int size = d_values.size();
int index = d_startIndex + i;
if ( index >= size )
index -= size;
const double x = i * d_step - d_offset - d_interval;
const double y = d_values.data()[index];
return QPointF( x, y );
}
QRectF CircularBuffer::boundingRect() const
{
return QRectF( -1.0, -d_interval, 2.0, d_interval );
}