cachedplotcurvedatamodel.h

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#ifndef CACHEDPLOTCURVEDATAMODEL_H
#define CACHEDPLOTCURVEDATAMODEL_H

struct DataPoint
{
    DataPoint() : time_t(0), data(0){}
    DataPoint(int time_t, float data){
        this->time_t = time_t;
        this->data = data;
    }
    unsigned int time_t;
    float data; //conversion from float to double is implicit and very fast (<15ms for 1M conversions)
};

#include "basequerymodel.h"

#include <qwt_data.h>
#include <QObject>
#include <QPointer>

class CachedPlotCurveDataModel : public QObject, public QwtData
{
    Q_OBJECT
public:
    CachedPlotCurveDataModel(QAbstractItemModel *model, int xColumn, int yColumn);
    size_t size() const;
    double x(size_t i) const;
    double y(size_t i) const;
    QwtData *copy() const;

private:
    void setModel(QAbstractItemModel *model, int xColumn, int yColumn);
    QAbstractItemModel *model() const;
    DataPoint updateCache(size_t i) const;
    const DataPoint previousNotNull(size_t i) const;
    void updateRowsSkip();

private slots:
    void resetCache();

signals:
    void signal_dataChanged();

private:
    mutable QHash<unsigned int, DataPoint> cache;
    QPointer<QAbstractItemModel> sourceModel;
    int xColumn;
    int yColumn;
    size_t m_size;
};

#endif // CACHEDPLOTCURVEDATAMODEL_H