host_frame_pump.hpp

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#pragma once

 
#include <atomic>
#include <cstdint>
 
#include <pulp/view/continuous_frames.hpp>
#include <pulp/view/frame_clock.hpp>
 
namespace pulp::view {
 
class View;

class HostFramePump {
public:
    static constexpr float kDefaultNominalDt = 1.0f / 60.0f;
    static constexpr float kDefaultWakeThreshold = 0.25f;

    float measure(double now_seconds);

    void suspend();

    void note_frame_skipped() { skipped_.store(true, std::memory_order_release); }

    void set_nominal_dt(float dt);
    float nominal_dt() const { return nominal_dt_; }

    void set_wake_threshold(float seconds);
    float wake_threshold() const { return wake_threshold_; }

    bool suspended() const {
        return !have_last_ || skipped_.load(std::memory_order_acquire);
    }

    std::uint64_t resumes() const { return resumes_; }

    double last_timestamp() const { return last_; }
 
    void reset();
 
private:
    double last_ = 0;
    bool have_last_ = false;
    float nominal_dt_ = kDefaultNominalDt;
    float wake_threshold_ = kDefaultWakeThreshold;
    std::uint64_t resumes_ = 0;
    // Set on the vsync thread by note_frame_skipped(), consumed on the UI thread
    // by measure(). The only cross-thread state in the pump.
    std::atomic<bool> skipped_{false};
};

struct HostFrameTick {
    float dt = 0.0f;
    bool should_render = false;
    bool continuous = false;
    bool animating = false;
    bool resumed = false;
};

bool should_dispatch_host_frame(HostFramePump& pump, bool needs_repaint,
                                bool continuous, bool has_idle_callback);

HostFrameTick begin_host_frame(View* root, FrameClock& clock, HostFramePump& pump,
                               double now_seconds, bool needs_repaint);

void advance_host_frame(View* root, FrameClock& clock, float dt);

inline bool host_frame_composites(const HostFrameTick& tick, bool damaged) noexcept {
    return damaged || tick.animating;
}

void advance_widget_animations(View* view, float dt);
 
} // namespace pulp::view