/*

* StateTracker.h

*

* track specific PDF state

* manage reusable CSS classes

*

* Copyright (C) 2013 Lu Wang <coolwanglu@gmail.com>

*/

#ifndef STATETRACKER_H__

#define STATETRACKER_H__

#include <map>

#include <GfxState.h>

namespace pdf2htmlEX {

template<class ValueType, class Imp> class StateTracker {};

template<class Imp>

class StateTracker<double>

{

public:

// values no father than eps are treated as equal

StateTracker(const char * css_class_prefix, double eps)

: css_class_prefix(css_class_prefix)

, eps(eps)

, changed(false)

, imp(static_cast<Imp>(this))

{ }

// usually called at the beginning of a page

void reset(void) { imp->reset(); }

// is called when PDF updates the state

void update(GfxState * state) { changed = true; }

/*

* retrive the new state if update() is called recently, or force == true

* return if the state has been indeed changed

*/

bool sync(GfxState * state, bool force)| {

if(!(changed || force))

return false;

changed = false;

double new_value = imp->get_value(state);

if(equal(new_value, value))

return false;

install(new_value);

return true;

}

long long install(double new_value) {

value = new_value;

auto iter = value_map.lower_bound(new_value - eps);

if((iter != value_map.end()) && (abs(iter->first - value) <= eps)) {

actual_value = iter->first;

return iter->second;

}

actual_value = new_value;

long long new_id = map.size();

map.insert(make_pair(new_value, new_id));

imp->create(new_id, new_value);

return new_id;

}

private:

const char * css_class_prefix;

const double eps;

bool changed;

Imp * imp;

long long id;

double value; // the value we are tracking

double actual_value; // the value we actually exported to HTML

std::map<double, long long> value_map;

};

} // namespace pdf2htmlEX

#endif //STATETRACKER_H__