gui_fps_counter.hpp

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#pragma once
 
#include "gui_element_types.hpp"
namespace ui {
 
class fps_counter_text_box : public simple_text_element_base {
private:
    std::chrono::time_point<std::chrono::steady_clock> last_render_time{};
    std::chrono::time_point<std::chrono::steady_clock> last_compute_time{};
 
public:
    void on_create(sys::state& state) noexcept override {
        simple_text_element_base::on_create(state);
        set_text(state, "0");
    }
 
    void render(sys::state& state, int32_t x, int32_t y) noexcept override {
        std::chrono::time_point<std::chrono::steady_clock> now = std::chrono::steady_clock::now();
        if(last_render_time == std::chrono::time_point<std::chrono::steady_clock>{}) {
            last_render_time = now;
        }
        auto microseconds_since_last_render = std::chrono::duration_cast<std::chrono::microseconds>(now - last_render_time);
        auto microseconds_since_last_compute = std::chrono::duration_cast<std::chrono::microseconds>(now - last_compute_time);
        if(microseconds_since_last_render.count() > 0.f && microseconds_since_last_compute.count() > 1e5) {
            auto frames_per_second = 1.f / float(microseconds_since_last_render.count() / 1e6);
            set_text(state, std::to_string(int32_t(frames_per_second)));
            last_compute_time = now;
        }
        last_render_time = now;
 
        simple_text_element_base::render(state, x, y);
    }
};
 
} // namespace ui