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examples/oscilloscope/SignalData.cpp

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+/*****************************************************************************
+ * Qwt Examples - Copyright (C) 2002 Uwe Rathmann
+ * This file may be used under the terms of the 3-clause BSD License
+ *****************************************************************************/
+
+#include "SignalData.h"
+
+#include <QVector>
+#include <QMutex>
+#include <QReadWriteLock>
+
+class SignalData::PrivateData
+{
+  public:
+    PrivateData()
+        : boundingRect( 1.0, 1.0, -2.0, -2.0 ) // invalid
+    {
+        values.reserve( 1000 );
+    }
+
+    inline void append( const QPointF& sample )
+    {
+        values.append( sample );
+
+        // adjust the bounding rectangle
+
+        if ( boundingRect.width() < 0 || boundingRect.height() < 0 )
+        {
+            boundingRect.setRect( sample.x(), sample.y(), 0.0, 0.0 );
+        }
+        else
+        {
+            boundingRect.setRight( sample.x() );
+
+            if ( sample.y() > boundingRect.bottom() )
+                boundingRect.setBottom( sample.y() );
+
+            if ( sample.y() < boundingRect.top() )
+                boundingRect.setTop( sample.y() );
+        }
+    }
+
+    QReadWriteLock lock;
+
+    QVector< QPointF > values;
+    QRectF boundingRect;
+
+    QMutex mutex; // protecting pendingValues
+    QVector< QPointF > pendingValues;
+};
+
+SignalData::SignalData()
+{
+    m_data = new PrivateData();
+}
+
+SignalData::~SignalData()
+{
+    delete m_data;
+}
+
+int SignalData::size() const
+{
+    return m_data->values.size();
+}
+
+QPointF SignalData::value( int index ) const
+{
+    return m_data->values[index];
+}
+
+QRectF SignalData::boundingRect() const
+{
+    return m_data->boundingRect;
+}
+
+void SignalData::lock()
+{
+    m_data->lock.lockForRead();
+}
+
+void SignalData::unlock()
+{
+    m_data->lock.unlock();
+}
+
+void SignalData::append( const QPointF& sample )
+{
+    m_data->mutex.lock();
+    m_data->pendingValues += sample;
+
+    const bool isLocked = m_data->lock.tryLockForWrite();
+    if ( isLocked )
+    {
+        const int numValues = m_data->pendingValues.size();
+        const QPointF* pendingValues = m_data->pendingValues.data();
+
+        for ( int i = 0; i < numValues; i++ )
+            m_data->append( pendingValues[i] );
+
+        m_data->pendingValues.clear();
+
+        m_data->lock.unlock();
+    }
+
+    m_data->mutex.unlock();
+}
+
+void SignalData::clearStaleValues( double limit )
+{
+    m_data->lock.lockForWrite();
+
+    m_data->boundingRect = QRectF( 1.0, 1.0, -2.0, -2.0 ); // invalid
+
+    const QVector< QPointF > values = m_data->values;
+    m_data->values.clear();
+    m_data->values.reserve( values.size() );
+
+    int index;
+    for ( index = values.size() - 1; index >= 0; index-- )
+    {
+        if ( values[index].x() < limit )
+            break;
+    }
+
+    if ( index > 0 )
+        m_data->append( values[index++] );
+
+    while ( index < values.size() - 1 )
+        m_data->append( values[index++] );
+
+    m_data->lock.unlock();
+}
+
+SignalData& SignalData::instance()
+{
+    static SignalData valueVector;
+    return valueVector;
+}