QT5 -- Add Qwt 6.1-multiaxes

qwt/examples/refreshtest/circularbuffer.cpp

@@ -0,0 +1,73 @@
+#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 );
+}