qsurfacecapturegrabber_p.h

Go to the documentation of this file.

// 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