AudioTransport.h

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#pragma once
#include "common/Export.h"
 
 
#include "audio/editing/AudioEditingTypes.h"
 
#include <string>
 
namespace eve::audio { class Source; }
 
namespace eve::audio_editing {
 
enum class AudioTransportState { Stopped, Playing, Paused };
 
struct AudioTransportSnapshot {
    StableId asset;
    Revision sourceRevision = 0;
    AudioTransportState state = AudioTransportState::Stopped;
    double position = 0.0;
    double duration = 0.0;
    bool loopEnabled = false;
    double loopStart = 0.0;
    double loopEnd = 0.0;
};
 
class IAudioTransportBackend {
public:
    virtual ~IAudioTransportBackend() = default;
    virtual void play() = 0;
    virtual void pause() = 0;
    virtual void stop() = 0;
    virtual Result<void> seek(double seconds) = 0;
    virtual double tell() const = 0;
    virtual double duration() const = 0;
    virtual bool playing() const = 0;
    virtual void setNativeLooping(bool enabled) = 0;
};
 
class EVENGINE_API_BACKENDS AudioAuditionTransport {
public:
    Result<void> bind(StableId asset, Revision sourceRevision,
                            IAudioTransportBackend* backend);
    Result<void> setLoop(Revision expectedRevision, bool enabled,
                               double startSeconds = 0.0, double endSeconds = 0.0);
    Result<void> play(Revision expectedRevision);
    Result<void> pause(Revision expectedRevision);
    Result<void> stop(Revision expectedRevision);
    Result<void> seek(Revision expectedRevision, double seconds);
    Result<AudioTransportSnapshot> update(Revision expectedRevision);
    Result<AudioTransportSnapshot> snapshot(Revision expectedRevision) const;
    void unbind();
 
private:
    Result<void> validateRevision(Revision expectedRevision) const;
    AudioTransportSnapshot observe() const;
    StableId asset_;
    Revision revision_ = 0;
    IAudioTransportBackend* backend_ = nullptr;
    AudioTransportState state_ = AudioTransportState::Stopped;
    bool loopEnabled_ = false;
    double loopStart_ = 0.0;
    double loopEnd_ = 0.0;
};
 
class EVENGINE_API_BACKENDS AudioSourceTransportBackend final : public IAudioTransportBackend {
public:
    explicit AudioSourceTransportBackend(audio::Source* source) : source_(source) {}
    void play() override;
    void pause() override;
    void stop() override;
    Result<void> seek(double seconds) override;
    double tell() const override;
    double duration() const override;
    bool playing() const override;
    void setNativeLooping(bool enabled) override;
private:
    audio::Source* source_ = nullptr;
};
 
}  // namespace eve::audio_editing