canvas_traverser.h

#ifndef CANVAS_TRAVERSER_H
#define CANVAS_TRAVERSER_H
 
// Project Includes
#include "medium_io/sequence/px_sequence_generator.h"
#include "medium_io/sequence/ch_sequence_generator.h"
 
namespace PxCryptPrivate
{
 
class MetaAccess;
 
class CanvasTraverser
{
//-Inner Struct-----------------------------------------------------------------------------------------------------------
private:
    struct Position
    {
        quint64 px;
        int ch;
        int bit;
 
        static quint64 channelsBeteween(const Position& a, const Position& b);
        static Position fromBits(quint64 bitPos, quint8 bpc);
        quint64 toBits(quint8 bpc) const;
        bool operator==(const Position& other) const = default;
        auto operator<=>(const Position& other) const noexcept = default;
    };
 
    struct Selection
    {
        qint64 px;
        Channel ch;
        //int bit; Always the same as linear position bit so just share that
 
        bool operator==(const Selection& other) const = default;
    };
 
    struct State
    {
        PxSequenceGenerator::State pxState;
        ChSequenceGenerator::State chState;
        Position linearPosition;
        Selection currentSelection;
    };
 
//-Instance Variables------------------------------------------------------------------------------------------------------
private:
    // Meta
    MetaAccess& mMeta;
 
    // Generator
    std::unique_ptr<PxSequenceGenerator> mPxSequence;
    std::unique_ptr<ChSequenceGenerator> mChSequence;
 
    // Location
    Position mLinearPosition;
    Selection mCurrentSelection;
    Position mLinearEnd;
 
    // State
    std::unique_ptr<State> mInitialState;
 
//-Constructor---------------------------------------------------------------------------------------------------------
public:
    CanvasTraverser(MetaAccess& meta);
 
//-Instance Functions----------------------------------------------------------------------------------------------
private:
    void restoreState(const State& state);
    void calculateEnd();
    void advanceChannel();
    void advancePixel();
 
public:
    void init();
 
    // Stat
    State state() const;
    bool atEnd() const;
 
    quint64 pixelIndex() const;
    Channel channel() const;
    int channelBitIndex() const;
    int remainingChannelBits() const;
 
    // Manipulation
    void advanceBits(int bitCount);
    bool bitAdvanceWillChangePixel(int bitCount);
    qint64 skip(qint64 bytes);
 
//-Operators----------------------------------------------------------------------------------------------------------------
public:
    bool operator==(const State& state) const;
};
 
}
 
#endif // CANVAS_TRAVERSER_H