qsurfacecapturegrabber_p.h

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// Copyright (C) 2021 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#ifndef QSURFACECAPTUREGRABBER_P_H

#define QSURFACECAPTUREGRABBER_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API. It exists purely as an

// implementation detail. This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

//

#include <QtMultimedia/qvideoframe.h>

#include <QtMultimedia/private/qplatformsurfacecapture_p.h>

#include <QtMultimedia/qtmultimediaglobal.h>

#include <QtCore/qmutex.h>

#include <chrono>

#include <memory>

#include <optional>

QT_BEGIN_NAMESPACE

class QThread;

static constexpr qreal DefaultScreenCaptureFrameRate = 60.f;

static constexpr qreal MinScreenCaptureFrameRate = 1.f;

class Q_MULTIMEDIA_EXPORT QSurfaceCaptureGrabber : public QObject

    Q_OBJECT

public:

    enum ThreadPolicy {

        UseCurrentThread,

        CreateGrabbingThread,

};

    ~QSurfaceCaptureGrabber() override;

    void start();

    void stop();

    template<typename Object, typename Method>

    void addFrameCallback(Object *object, Method method)

        connect(this, &QSurfaceCaptureGrabber::frameGrabbed, object, method,

                Qt::DirectConnection);

    void setFrameRate(std::optional<qreal>);

    qreal frameRate() const;

    // Owning thread before start(), grabbing thread after.

    qreal activeFrameRate() const;

Q_SIGNALS:

    void frameGrabbed(const QVideoFrame&);

    void errorUpdated(QPlatformSurfaceCapture::Error error, const QString &description);

protected:

    QSurfaceCaptureGrabber(ThreadPolicy threadPolicy = CreateGrabbingThread);

    void updateError(QPlatformSurfaceCapture::Error error, const QString &description = {});

    virtual QVideoFrame grabFrame() = 0;

    void updateTimerInterval();

    void setTimerInterval(std::chrono::nanoseconds interval, quint64 generation);

    virtual void initializeGrabbingContext();

    virtual void finalizeGrabbingContext();

    bool isGrabbingContextInitialized() const;

    void injectContextToGrabbingThread(QObject *context);

private:

    class GrabbingProfiler;

    struct GrabbingContext;

    class GrabbingThread;

    mutable QMutex m_mutex;

    std::unique_ptr<GrabbingContext> m_context;

    std::optional<QPlatformSurfaceCapture::Error> m_prevError;

    std::unique_ptr<QThread> m_thread;

    std::chrono::nanoseconds m_timerInterval{ 0 };

    quint64 m_contextGeneration{ 0 };

    qreal m_rate{ DefaultScreenCaptureFrameRate };

    // Locked in start()/updateTimerInterval(); lock-free on the grabbing thread.

    qreal m_activeRate{ DefaultScreenCaptureFrameRate };

};

QT_END_NAMESPACE

#endif // QSURFACECAPTUREGRABBER_P_H