motion_preferences.hpp

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#pragma once

 
#include <functional>
#include <mutex>
#include <optional>
#include <string>
#include <string_view>
 
namespace pulp::view {

enum class MotionPolicy {
    Full,     
    Reduced,  
    Off,      
};

class MotionPreferences {
public:
    static MotionPreferences& instance();

    static MotionPolicy current() { return instance().policy(); }

    static double current_duration_scale() {
        return instance().duration_scale();
    }

    MotionPolicy policy() const;

    double duration_scale() const;

    void set_duration_scale(double scale);

    void set_override(std::optional<MotionPolicy> p);

    bool has_override() const noexcept;

    bool poll();

    void on_policy_changed(std::function<void(MotionPolicy)> callback);

    void reset_for_tests();
 
private:
    MotionPreferences();
    ~MotionPreferences();
    MotionPreferences(const MotionPreferences&) = delete;
    MotionPreferences& operator=(const MotionPreferences&) = delete;

    static MotionPolicy detect_system_policy();

    MotionPolicy policy_locked() const;

    void notify_changed(MotionPolicy p);

    mutable std::mutex mtx_;
    MotionPolicy last_os_ = MotionPolicy::Full;
    std::optional<MotionPolicy> override_;
    double duration_scale_ = 1.0;
    std::function<void(MotionPolicy)> callback_;
};
 
// ── Free-function convenience shims ──────────────────────────────────
//
// Animation primitives use these to keep the call site cheap and avoid
// pulling the full singleton header into hot paths in the future.

inline float apply_motion_policy_to_duration(float configured_seconds) {
    auto& prefs = MotionPreferences::instance();
    switch (prefs.policy()) {
        case MotionPolicy::Off:
            return 0.0f;
        case MotionPolicy::Reduced:
            return configured_seconds *
                   static_cast<float>(prefs.duration_scale());
        case MotionPolicy::Full:
        default:
            return configured_seconds;
    }
}

inline bool motion_policy_is_off() {
    return MotionPreferences::instance().policy() == MotionPolicy::Off;
}

inline const char* motion_policy_to_string(MotionPolicy p) {
    switch (p) {
        case MotionPolicy::Off:     return "off";
        case MotionPolicy::Reduced: return "reduced";
        case MotionPolicy::Full:
        default:                    return "full";
    }
}

inline MotionPolicy motion_policy_from_string(const std::string_view s) {
    if (s == "off")     return MotionPolicy::Off;
    if (s == "reduced") return MotionPolicy::Reduced;
    return MotionPolicy::Full;
}
 
} // namespace pulp::view