qopenglvideobuffer.cpp

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// Copyright (C) 2024 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 "qopenglvideobuffer_p.h"
 
#include <qoffscreensurface.h>
#include <qthread.h>
#include <private/qimagevideobuffer_p.h>
 
#include <QtOpenGL/private/qopenglcompositor_p.h>
#include <QtOpenGL/private/qopenglframebufferobject_p.h>
 
QT_BEGIN_NAMESPACE
 
static QOpenGLContext *createContext(QOpenGLContext *shareContext)
{
    // Create an OpenGL context for the current thread. The lifetime of the context is tied to the
    // lifetime of the current thread.
    auto context = std::make_unique<QOpenGLContext>();
    context->setShareContext(shareContext);
 
    if (!context->create()) {
        qWarning() << "Couldn't create an OpenGL context for QOpenGLVideoBuffer";
        return nullptr;
    }
 
    QObject::connect(QThread::currentThread(), &QThread::finished,
                     context.get(), &QOpenGLContext::deleteLater);
    return context.release();
}
 
static bool setCurrentOpenGLContext()
{
    auto compositorContext = QOpenGLCompositor::instance()->context();
 
    // A thread-local variable is used to avoid creating a new context if we're called on the same
    // thread. The context lifetime is tied to the current thread lifetime (see createContext()).
    static thread_local QOpenGLContext *context = nullptr;
    static thread_local QOffscreenSurface *surface = nullptr;
 
    if (!context) {
        context = compositorContext->thread()->isCurrentThread() ? compositorContext
                                                                 : createContext(compositorContext);
 
        if (!context)
            return false;
 
        surface = new QOffscreenSurface(nullptr, context);
        surface->setFormat(context->format());
        surface->create();
    }
 
    return context->makeCurrent(surface);
}
 
QOpenGLVideoBuffer::QOpenGLVideoBuffer(std::unique_ptr<QOpenGLFramebufferObject> fbo)
    : m_fbo(std::move(fbo))
{
    Q_ASSERT(m_fbo);
}
 
QOpenGLVideoBuffer::~QOpenGLVideoBuffer() = default;
 
QAbstractVideoBuffer::MapData QOpenGLVideoBuffer::map(QVideoFrame::MapMode mode)
{
    return ensureImageBuffer().map(mode);
}
 
void QOpenGLVideoBuffer::unmap()
{
    if (m_imageBuffer)
        m_imageBuffer->unmap();
}
 
quint64 QOpenGLVideoBuffer::textureHandle(QRhi &, int plane)
{
    Q_UNUSED(plane);
    return m_fbo->texture();
}
 
QImageVideoBuffer &QOpenGLVideoBuffer::ensureImageBuffer()
{
    // Create image buffer if not yet created.
    // This is protected by mapMutex in QVideoFrame::map.
    if (!m_imageBuffer) {
        if (!setCurrentOpenGLContext())
            qWarning() << "Failed to set current OpenGL context";
 
        m_imageBuffer = std::make_unique<QImageVideoBuffer>(m_fbo->toImage(false));
    }
 
    return *m_imageBuffer;
}
 
QT_END_NAMESPACE