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#include "qsgdefaultrendercontext_p.h"

#include <QtGui/QGuiApplication>
#include <QtGui/QOpenGLFramebufferObject>

#include <QtQuick/private/qsgbatchrenderer_p.h>
#include <QtQuick/private/qsgrenderer_p.h>
#include <QtQuick/private/qsgatlastexture_p.h>
#include <QtQuick/private/qsgcompressedtexture_p.h>
#include <QtQuick/private/qsgdefaultdistancefieldglyphcache_p.h>

QT_BEGIN_NAMESPACE

#define QSG_RENDERCONTEXT_PROPERTY "_q_sgrendercontext"

QSGDefaultRenderContext::QSGDefaultRenderContext(QSGContext *context)
    : QSGRenderContext(context)
    , m_gl(nullptr)
    , m_depthStencilManager(nullptr)
    , m_maxTextureSize(0)
    , m_brokenIBOs(false)
    , m_serializedRender(false)
    , m_attachToGLContext(true)
    , m_atlasManager(nullptr)
{

}

/*!
    Initializes the scene graph render context with the GL context \a context. This also
    emits the ready() signal so that the QML graph can start building scene graph nodes.
 */
void QSGDefaultRenderContext::initialize(void *context)
{
    if (!m_sg)
        return;

    QOpenGLContext *openglContext = static_cast<QOpenGLContext *>(context);

    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
    funcs->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &m_maxTextureSize);

    // Sanity check the surface format, in case it was overridden by the application
    QSurfaceFormat requested = m_sg->defaultSurfaceFormat();
    QSurfaceFormat actual = openglContext->format();
    if (requested.depthBufferSize() > 0 && actual.depthBufferSize() <= 0)
        qWarning("QSGContext::initialize: depth buffer support missing, expect rendering errors");
    if (requested.stencilBufferSize() > 0 && actual.stencilBufferSize() <= 0)
        qWarning("QSGContext::initialize: stencil buffer support missing, expect rendering errors");

    if (!m_atlasManager)
        m_atlasManager = new QSGAtlasTexture::Manager();

    Q_ASSERT_X(!m_gl, "QSGRenderContext::initialize", "already initialized!");
    m_gl = openglContext;
    if (m_attachToGLContext) {
        Q_ASSERT(!openglContext->property(QSG_RENDERCONTEXT_PROPERTY).isValid());
        openglContext->setProperty(QSG_RENDERCONTEXT_PROPERTY, QVariant::fromValue(this));
    }
    m_sg->renderContextInitialized(this);

#ifdef Q_OS_LINUX
    const char *vendor = (const char *) funcs->glGetString(GL_VENDOR);
    if (vendor && strstr(vendor, "nouveau"))
        m_brokenIBOs = true;
    const char *renderer = (const char *) funcs->glGetString(GL_RENDERER);
    if (renderer && strstr(renderer, "llvmpipe"))
        m_serializedRender = true;
    if (vendor && renderer && strstr(vendor, "Hisilicon Technologies") && strstr(renderer, "Immersion.16"))
        m_brokenIBOs = true;
#endif

    emit initialized();
}


void QSGDefaultRenderContext::invalidate()
{
    if (!m_gl)
        return;

    qDeleteAll(m_texturesToDelete);
    m_texturesToDelete.clear();

    qDeleteAll(m_textures);
    m_textures.clear();

    /* The cleanup of the atlas textures is a bit intriguing.
       As part of the cleanup in the threaded render loop, we
       do:
       1. call this function
       2. call QCoreApp::sendPostedEvents() to immediately process
          any pending deferred deletes.
       3. delete the GL context.

       As textures need the atlas manager while cleaning up, the
       manager needs to be cleaned up after the textures, so
       we post a deleteLater here at the very bottom so it gets
       deferred deleted last.

       Another alternative would be to use a QPointer in
       QSGAtlasTexture::Texture, but this seemed simpler.
     */
    m_atlasManager->invalidate();
    m_atlasManager->deleteLater();
    m_atlasManager = nullptr;

    // The following piece of code will read/write to the font engine's caches,
    // potentially from different threads. However, this is safe because this
    // code is only called from QQuickWindow's shutdown which is called
    // only when the GUI is blocked, and multiple threads will call it in
    // sequence. (see qsgdefaultglyphnode_p.cpp's init())
    for (QSet<QFontEngine *>::const_iterator it = m_fontEnginesToClean.constBegin(),
         end = m_fontEnginesToClean.constEnd(); it != end; ++it) {
        (*it)->clearGlyphCache(m_gl);
        if (!(*it)->ref.deref())
            delete *it;
    }
    m_fontEnginesToClean.clear();

    delete m_depthStencilManager;
    m_depthStencilManager = nullptr;

    qDeleteAll(m_glyphCaches);
    m_glyphCaches.clear();

    if (m_gl->property(QSG_RENDERCONTEXT_PROPERTY) == QVariant::fromValue(this))
        m_gl->setProperty(QSG_RENDERCONTEXT_PROPERTY, QVariant());
    m_gl = nullptr;

    if (m_sg)
        m_sg->renderContextInvalidated(this);
    emit invalidated();
}

static QBasicMutex qsg_framerender_mutex;

void QSGDefaultRenderContext::renderNextFrame(QSGRenderer *renderer, uint fboId)
{
    if (m_serializedRender)
        qsg_framerender_mutex.lock();

    renderer->renderScene(fboId);

    if (m_serializedRender)
        qsg_framerender_mutex.unlock();
}

/*!
    Returns a shared pointer to a depth stencil buffer that can be used with \a fbo.
*/
QSharedPointer<QSGDepthStencilBuffer> QSGDefaultRenderContext::depthStencilBufferForFbo(QOpenGLFramebufferObject *fbo)
{
    if (!m_gl)
        return QSharedPointer<QSGDepthStencilBuffer>();
    QSGDepthStencilBufferManager *manager = depthStencilBufferManager();
    QSGDepthStencilBuffer::Format format;
    format.size = fbo->size();
    format.samples = fbo->format().samples();
    format.attachments = QSGDepthStencilBuffer::DepthAttachment | QSGDepthStencilBuffer::StencilAttachment;
    QSharedPointer<QSGDepthStencilBuffer> buffer = manager->bufferForFormat(format);
    if (buffer.isNull()) {
        buffer = QSharedPointer<QSGDepthStencilBuffer>(new QSGDefaultDepthStencilBuffer(m_gl, format));
        manager->insertBuffer(buffer);
    }
    return buffer;
}

/*!
    Returns a pointer to the context's depth/stencil buffer manager. This is useful for custom
    implementations of \l depthStencilBufferForFbo().
*/
QSGDepthStencilBufferManager *QSGDefaultRenderContext::depthStencilBufferManager()
{
    if (!m_gl)
        return nullptr;
    if (!m_depthStencilManager)
        m_depthStencilManager = new QSGDepthStencilBufferManager(m_gl);
    return m_depthStencilManager;
}

QSGTexture *QSGDefaultRenderContext::createTexture(const QImage &image, uint flags) const
{
    bool atlas = flags & CreateTexture_Atlas;
    bool mipmap = flags & CreateTexture_Mipmap;
    bool alpha = flags & CreateTexture_Alpha;

    // The atlas implementation is only supported from the render thread and
    // does not support mipmaps.
    if (!mipmap && atlas && openglContext() && QThread::currentThread() == openglContext()->thread()) {
        QSGTexture *t = m_atlasManager->create(image, alpha);
        if (t)
            return t;
    }

    QSGPlainTexture *texture = new QSGPlainTexture();
    texture->setImage(image);
    if (texture->hasAlphaChannel() && !alpha)
        texture->setHasAlphaChannel(false);

    return texture;
}

QSGRenderer *QSGDefaultRenderContext::createRenderer()
{
    return new QSGBatchRenderer::Renderer(this);
}

QSGTexture *QSGDefaultRenderContext::compressedTextureForFactory(const QSGCompressedTextureFactory *factory) const
{
    // The atlas implementation is only supported from the render thread
    if (openglContext() && QThread::currentThread() == openglContext()->thread())
        return m_atlasManager->create(factory);
    return nullptr;
}

/*!
    Compile \a shader, optionally using \a vertexCode and \a fragmentCode as
    replacement for the source code supplied by \a shader.

    If \a vertexCode or \a fragmentCode is supplied, the caller is responsible
    for setting up attribute bindings.

    \a material is supplied in case the implementation needs to take the
    material flags into account.
 */
void QSGDefaultRenderContext::compileShader(QSGMaterialShader *shader, QSGMaterial *material, const char *vertexCode, const char *fragmentCode)
{
    Q_UNUSED(material);
    if (vertexCode || fragmentCode) {
        Q_ASSERT_X((material->flags() & QSGMaterial::CustomCompileStep) == 0,
                   "QSGRenderContext::compile()",
                   "materials with custom compile step cannot have modified vertex or fragment code");
        QOpenGLShaderProgram *p = shader->program();
        p->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, vertexCode ? vertexCode : shader->vertexShader());
        p->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment, fragmentCode ? fragmentCode : shader->fragmentShader());
        p->link();
        if (!p->isLinked())
            qWarning() << "shader compilation failed:" << endl << p->log();
    } else {
        shader->compile();
    }
}

QString QSGDefaultRenderContext::fontKey(const QRawFont &font)
{
    QFontEngine *fe = QRawFontPrivate::get(font)->fontEngine;
    if (!fe->faceId().filename.isEmpty()) {
        QByteArray keyName = fe->faceId().filename;
        if (font.style() != QFont::StyleNormal)
            keyName += QByteArray(" I");
        if (font.weight() != QFont::Normal)
            keyName += ' ' + QByteArray::number(font.weight());
        keyName += QByteArray(" DF");
        return QString::fromUtf8(keyName);
    } else {
        return QString::fromLatin1("%1_%2_%3_%4")
            .arg(font.familyName())
            .arg(font.styleName())
            .arg(font.weight())
            .arg(font.style());
    }
}

void QSGDefaultRenderContext::initializeShader(QSGMaterialShader *shader)
{
    shader->program()->bind();
    shader->initialize();
}

void QSGDefaultRenderContext::setAttachToGraphicsContext(bool attach)
{
    Q_ASSERT(!isValid());
    m_attachToGLContext = attach;
}

QSGDefaultRenderContext *QSGDefaultRenderContext::from(QOpenGLContext *context)
{
    return qobject_cast<QSGDefaultRenderContext *>(context->property(QSG_RENDERCONTEXT_PROPERTY).value<QObject *>());
}

bool QSGDefaultRenderContext::separateIndexBuffer() const
{
    // WebGL: A given WebGLBuffer object may only be bound to one of
    // the ARRAY_BUFFER or ELEMENT_ARRAY_BUFFER target in its
    // lifetime. An attempt to bind a buffer object to the other
    // target will generate an INVALID_OPERATION error, and the
    // current binding will remain untouched.
    static const bool isWebGL = qGuiApp->platformName().compare(QLatin1String("webgl")) == 0;
    return isWebGL;
}

QSGDistanceFieldGlyphCache *QSGDefaultRenderContext::distanceFieldGlyphCache(const QRawFont &font)
{
    QString key = fontKey(font);
    QSGDistanceFieldGlyphCache *cache = m_glyphCaches.value(key, 0);
    if (!cache) {
        cache = new QSGDefaultDistanceFieldGlyphCache(openglContext(), font);
        m_glyphCaches.insert(key, cache);
    }

    return cache;
}

QT_END_NAMESPACE

#include "moc_qsgdefaultrendercontext_p.cpp"
