historykeeper.h

#ifndef HISTORYKEEPER_H
#define HISTORYKEEPER_H

// Class which handles recording of history of changes of some variable
// In order to use it - call "valueChanged(double newValue)" every time your variable changes its value
// Call "double rollBack()" to do "Ctrl+z". You will get previous recorded value of variable
// Author: Dmytro Pavlichenko <dm.mark999@gmail.com>

#include <QObject>
#include <QStack>
#include <QElapsedTimer>
#include <QTimer>
#include <QEvent>
#include <QKeyEvent>

#include <QSlider>
#include <QDoubleSpinBox>

class HistoryKeeper : public QObject
{
    Q_OBJECT
public:
    HistoryKeeper(unsigned int maxStackSize_, double minElapsedTime_);
    HistoryKeeper(unsigned int maxStackSize_, double minElapsedTime_, QDoubleSpinBox *spin_);
    HistoryKeeper(unsigned int maxStackSize_, double minElapsedTime_, QDoubleSpinBox *spin_, QSlider *slider_);
    ~HistoryKeeper();
    
    void setRecorded(bool recorded);
    
    void clearHistory();
    void valueChanged(double newValue);
    double rollBack(); // Returns previously recorded value. If there is no recorded value - returns -999
    double rollForward();
    
    virtual bool eventFilter(QObject *object, QEvent *event);
    
Q_SIGNALS:
    
private Q_SLOTS:
    void loop(); // Main loop. Is called every 0.2 seconds
    
private:
    void init(unsigned int maxStackSize_, double minElapsedTime_);
    
    void handleUndo();
    void handleRedo();
    
private:
    QTimer        *mainLoopTimer; // TODO: reimplement it without this instant loop
    QElapsedTimer *elapsedTimer; // Counts elapsed time since last edit
    double minElapsedTime; // Time which must be elapsed before recording new changes
    
    QStack<double> stack; // Stack to record history of changes
    int maxStackSize;     // How deep the history will be recorded
    int currentPosition;  // Current position in the stack of changes
    
    double currentValue;
    bool   wasRecorded; // True if currentValue was already stored into stack
    
    QDoubleSpinBox *spin;
    QSlider *slider;
    bool spinOnly;
};

#endif // HISTORYKEEPER_H