qplatformmediaintegration.cpp

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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
 
#include <qtmultimediaglobal_p.h>
#include "qplatformmediaintegration_p.h"
#include <qatomic.h>
#include <qmutex.h>
#include <qplatformaudioinput_p.h>
#include <qplatformaudiooutput_p.h>
#include <qplatformvideodevices_p.h>
#include <qmediadevices.h>
#include <qcameradevice.h>
#include <qloggingcategory.h>
 
#include "qplatformcapturablewindows_p.h"
#include "QtCore/private/qfactoryloader_p.h"
#include "qplatformmediaplugin_p.h"
 
class QDummyIntegration : public QPlatformMediaIntegration
{
public:
    QDummyIntegration()
    {
        qCritical("QtMultimedia is not currently supported on this platform or compiler.");
    }
    QPlatformMediaFormatInfo *formatInfo() override { return nullptr; }
};
 
static Q_LOGGING_CATEGORY(qLcMediaPlugin, "qt.multimedia.plugin")
 
Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
                          (QPlatformMediaPlugin_iid,
                           QLatin1String("/multimedia")))
 
static const auto FFmpegBackend = QStringLiteral("ffmpeg");
 
static QStringList availableBackends()
{
    QStringList list;
 
    if (QFactoryLoader *fl = loader()) {
        const auto keyMap = fl->keyMap();
        for (auto it = keyMap.constBegin(); it != keyMap.constEnd(); ++it)
            if (!list.contains(it.value()))
                list << it.value();
    }
 
    qCDebug(qLcMediaPlugin) << "Available backends" << list;
    return list;
}
 
static QString defaultBackend(const QStringList &backends)
{
#ifdef QT_DEFAULT_MEDIA_BACKEND
    auto backend = QString::fromUtf8(QT_DEFAULT_MEDIA_BACKEND);
    if (backends.contains(backend))
        return backend;
#endif
 
#if defined(Q_OS_DARWIN) || defined(Q_OS_LINUX) || defined(Q_OS_WINDOWS) || defined(Q_OS_ANDROID)
    // Return ffmpeg backend by default.
    // Platform backends for the OS list are optionally available but have limited support.
    if (backends.contains(FFmpegBackend))
        return FFmpegBackend;
#else
    // Return platform backend (non-ffmpeg) by default.
    if (backends.size() > 1 && backends[0] == FFmpegBackend)
        return backends[1];
#endif
 
    return backends[0];
}
 
QT_BEGIN_NAMESPACE
 
struct QPlatformMediaIntegration::InstanceHolder
{
    // TODO: replace the mutex with std::once
    QBasicMutex mutex;
    std::unique_ptr<QPlatformMediaIntegration> instance;
    Factory factory;
} instanceHolder;
 
QPlatformMediaIntegration *QPlatformMediaIntegration::instance()
{
    QMutexLocker locker(&instanceHolder.mutex);
    if (instanceHolder.instance)
        return instanceHolder.instance.get();
 
    if (instanceHolder.factory) {
        instanceHolder.instance = instanceHolder.factory();
        return instanceHolder.instance.get();
    }
 
    const auto backends = availableBackends();
    QString backend = QString::fromUtf8(qgetenv("QT_MEDIA_BACKEND"));
    if (backend.isEmpty() && !backends.isEmpty())
        backend = defaultBackend(backends);
 
    qCDebug(qLcMediaPlugin) << "loading backend" << backend;
    instanceHolder.instance.reset(
            qLoadPlugin<QPlatformMediaIntegration, QPlatformMediaPlugin>(loader(), backend));
 
    if (!instanceHolder.instance) {
        qWarning() << "could not load multimedia backend" << backend;
        instanceHolder.instance = std::make_unique<QDummyIntegration>();
    }
 
    return instanceHolder.instance.get();
}
 
/*
    This API is there to be able to test with a mock backend.
*/
void QPlatformMediaIntegration::setPlatformFactory(Factory factory)
{
    Q_ASSERT((factory == nullptr) ^ (instanceHolder.factory == nullptr));
    instanceHolder.instance.reset();
    instanceHolder.factory = std::move(factory);
}
 
QList<QCameraDevice> QPlatformMediaIntegration::videoInputs()
{
    return m_videoDevices ? m_videoDevices->videoDevices() : QList<QCameraDevice>{};
}
 
QMaybe<QPlatformAudioInput *> QPlatformMediaIntegration::createAudioInput(QAudioInput *q)
{
    return new QPlatformAudioInput(q);
}
 
QMaybe<QPlatformAudioOutput *> QPlatformMediaIntegration::createAudioOutput(QAudioOutput *q)
{
    return new QPlatformAudioOutput(q);
}
 
QList<QCapturableWindow> QPlatformMediaIntegration::capturableWindows()
{
    return m_capturableWindows ? m_capturableWindows->windows() : QList<QCapturableWindow>{};
}
 
bool QPlatformMediaIntegration::isCapturableWindowValid(const QCapturableWindowPrivate &window)
{
    return m_capturableWindows && m_capturableWindows->isWindowValid(window);
}
 
QPlatformMediaIntegration::QPlatformMediaIntegration() = default;
 
QPlatformMediaIntegration::~QPlatformMediaIntegration() = default;
 
QT_END_NAMESPACE