state_view.hpp

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#ifndef EAGINE_APPLICATION_STATE_VIEW_HPP
#define EAGINE_APPLICATION_STATE_VIEW_HPP
 
#include "../quantities.hpp"
#include "../value_with_history.hpp"
#include <chrono>
 
namespace eagine::application {
//------------------------------------------------------------------------------
template <typename T>
using state_value = value_with_history<T, 3>;
 
template <typename T>
using state_variable = variable_with_history<T, 3>;
//------------------------------------------------------------------------------
class context_state_view {
public:
    using clock_type = std::chrono::steady_clock;
 
    auto run_time() const noexcept -> clock_type::duration {
        return clock_type::now() - _start_time;
    }
 
    auto user_idle_time() const noexcept -> clock_type::duration {
        return clock_type::now() - _user_active_time;
    }
 
    auto frame_time() const noexcept -> seconds_t<float> {
        return seconds_(_frame_time.value());
    }
 
    auto frame_duration() const noexcept -> seconds_t<float> {
        return seconds_(_frame_time.delta());
    }
 
    auto is_active() const noexcept -> bool {
        return !_new_user_idle || _has_activity;
    }
 
    auto user_is_idle() const noexcept -> value_with_history<bool, 2> {
        return {_new_user_idle, _old_user_idle};
    }
 
    auto user_became_idle() const noexcept -> bool {
        return user_is_idle().delta() > 0;
    }
 
    auto user_became_active() const noexcept -> bool {
        return user_is_idle().delta() < 0;
    }
 
    auto user_idle_too_long() const noexcept -> bool {
        // TODO: configurable interval?
        return user_idle_time() > std::chrono::seconds{1};
    }
 
protected:
    const clock_type::time_point _start_time{clock_type::now()};
    clock_type::time_point _user_active_time{clock_type::now()};
    state_variable<float> _frame_time{0.0F};
 
    bool _has_activity{false};
    bool _old_user_idle{false};
    bool _new_user_idle{false};
};
//------------------------------------------------------------------------------
} // namespace eagine::application
 
#endif