qmacscreencapturekit_p.h

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// Copyright (C) 2026 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 QMACSCREENCAPTUREKIT_P_H

#define QMACSCREENCAPTUREKIT_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 <QtCore/qobject.h>

#include <QtCore/qloggingcategory.h>

#include <QtCore/private/qexpected_p.h>

#include <QtMultimedia/qvideoframe.h>

#include <QtMultimedia/private/qavfcamerautility_p.h>

#import <ScreenCaptureKit/ScreenCaptureKit.h>

#include <functional>

#include <future>

#include <memory>

#include <optional>

#include <vector>

// Error-handling for on-going stream

@interface QT_MANGLE_NAMESPACE(QMacScreenCaptureStreamDelegate) : NSObject <SCStreamDelegate>

@end

// Receives frame callbacks

@interface QT_MANGLE_NAMESPACE(QMacScreenCaptureStreamOutput) : NSObject <SCStreamOutput>

@end

QT_BEGIN_NAMESPACE

namespace QFFmpeg {

Q_DECLARE_LOGGING_CATEGORY(qLcMacScreenCapture);

using QMacScreenCaptureStreamDelegate = QT_MANGLE_NAMESPACE(QMacScreenCaptureStreamDelegate);

using QMacScreenCaptureStreamOutput = QT_MANGLE_NAMESPACE(QMacScreenCaptureStreamOutput);

// Helper class for managing a ScreenCaptureKit stream.

//

// TODO: This class has very few FFmpeg specific components. Move this out of FFmpeg media backend

// in the future.

class QMacScreenCaptureKit : public QObject {

    Q_OBJECT

public:

    enum class StreamId : int64_t{};

    // TODO: May become a runtime parameter in the future.

    // For now we only support BGRA32.

    static constexpr FourCharCode cvPixelFormat = kCVPixelFormatType_32BGRA;

    static constexpr QVideoFrameFormat::PixelFormat pixelFormat =

        QVideoFrameFormat::PixelFormat::Format_BGRA8888;

    // How many frames can be queued up on the background thread before we start dropping frames

    // ScreenCaptureKit default is 3.

    // https://developer.apple.com/documentation/screencapturekit/scstreamconfiguration/queuedepth?language=objc

    static constexpr int queueDepth = 3;

    [[nodiscard]] static CFStringRef cgColorSpace() { return kCGColorSpaceSRGB; }

    static constexpr QVideoFrameFormat::ColorSpace colorSpace =

        QVideoFrameFormat::ColorSpace::ColorSpace_BT709;

    static constexpr QVideoFrameFormat::ColorRange colorRange =

        QVideoFrameFormat::ColorRange::ColorRange_Full;

    static constexpr QVideoFrameFormat::ColorTransfer colorTransfer =

        QVideoFrameFormat::ColorTransfer::ColorTransfer_BT709;

    struct CapturableItems {

        std::vector<AVFScopedPointer<SCDisplay>> displays;

        std::vector<AVFScopedPointer<SCWindow>> windows;

};

    struct StreamSettings {

        std::optional<qreal> frameRate;

        bool overrideIgnoreCursor = false;

};

    struct CreateStreamInfo {

        StreamId streamId = {};

        std::function<void(QMacScreenCaptureKit&)> connectionSetupFn;

        StreamSettings streamSettings = {};

};

    QMacScreenCaptureKit() = default;

    ~QMacScreenCaptureKit();

    QMacScreenCaptureKit(const QMacScreenCaptureKit &) = delete;

    QMacScreenCaptureKit &operator=(const QMacScreenCaptureKit &) = delete;

    QMacScreenCaptureKit(QMacScreenCaptureKit &&other) noexcept = delete;

    QMacScreenCaptureKit &operator=(QMacScreenCaptureKit &&other) = delete;

    [[nodiscard]] StreamId streamId() const noexcept { return m_streamId; }

    [[nodiscard]] static std::future<q23::expected<CapturableItems, QString>> enumerateCapturableItems();

    [[nodiscard]] static std::future<q23::expected<std::unique_ptr<QMacScreenCaptureKit>, QString>>

    createStreamFromDisplay(

        CreateStreamInfo const &,

        SCDisplay *);

    [[nodiscard]] static std::future<q23::expected<std::unique_ptr<QMacScreenCaptureKit>, QString>>

    createStreamFromFilter(

        CreateStreamInfo const &,

        SCContentFilter *);

    [[nodiscard]] static std::future<q23::expected<std::unique_ptr<QMacScreenCaptureKit>, QString>>

    createStreamFromWindow(

        CreateStreamInfo const &,

        SCWindow *);

    // Called from background thread when stream needs to be configured with new

    // output resolution. Don't call directly.

    void updateStream(QSize resolutionPx);

Q_SIGNALS:

    void newVideoFrameGenerated(StreamId streamId, QVideoFrame);

    // This is commonly signaled if the user stops the stream by

    // interacting with the system UI, or the stream has stopped

    // for unknown reasons.

    // Message is not suitable for forwarding to UI.

    void streamStoppedWithError(StreamId streamId, QString);

private:

    StreamId m_streamId = {};

    // A copy of the stream settings when this class was created. Does

    // not change after stream has started. Used for auto-reconfiguring

    // our stream with new size when needed.

    StreamSettings m_streamSettings = {};

    AVFScopedPointer<SCStream> m_stream;

    AVFScopedPointer<dispatch_queue_t> m_dispatchQueue;

    AVFScopedPointer<QMacScreenCaptureStreamDelegate> m_streamDelegate;

    AVFScopedPointer<QMacScreenCaptureStreamOutput> m_streamOutput;

    static void startStreamReconfigure(

        SCStream *scStream,

        QSize resolutionPx,

        StreamSettings const &);

};

QT_END_NAMESPACE

#endif // QMACSCREENCAPTUREKIT_P_H