Cleanup: Separate the sub-tree layering out of QtQuick into the scene graph

This basically renames QQuickShaderEffectTexture to QSGDefaultLayer and
introduces QSGLayer as interface to be used. QQuickShaderEffectTexture is
generic for the scene graph and has no QtQuick dependencies. The interface
separation allows scene graph backends to customize layers.

Change-Id: I9a7f37addaa4b80a34ff9a1456b0cb9b16d4e9f3
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

1 files changed, 445 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgdefaultlayer.cpp b/src/quick/scenegraph/qsgdefaultlayer.cpp
new file mode 100644
index 0000000000..c93517fe3f
--- /dev/null
+++ b/src/quick/scenegraph/qsgdefaultlayer.cpp
@@ -0,0 +1,445 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "qsgdefaultlayer_p.h"
+
+#include <private/qqmlglobal_p.h>
+#include <private/qsgrenderer_p.h>
+
+#include <QOpenGLFramebufferObject>
+
+#ifdef QSG_DEBUG_FBO_OVERLAY
+DEFINE_BOOL_CONFIG_OPTION(qmlFboOverlay, QML_FBO_OVERLAY)
+#endif
+DEFINE_BOOL_CONFIG_OPTION(qmlFboFlushBeforeDetach, QML_FBO_FLUSH_BEFORE_DETACH)
+
+namespace
+{
+    class BindableFbo : public QSGBindable
+    {
+    public:
+        BindableFbo(QOpenGLFramebufferObject *fbo, QSGDepthStencilBuffer *depthStencil);
+        virtual ~BindableFbo();
+        virtual void bind() const;
+    private:
+        QOpenGLFramebufferObject *m_fbo;
+        QSGDepthStencilBuffer *m_depthStencil;
+    };
+
+    BindableFbo::BindableFbo(QOpenGLFramebufferObject *fbo, QSGDepthStencilBuffer *depthStencil)
+        : m_fbo(fbo)
+        , m_depthStencil(depthStencil)
+    {
+    }
+
+    BindableFbo::~BindableFbo()
+    {
+        if (qmlFboFlushBeforeDetach())
+            QOpenGLContext::currentContext()->functions()->glFlush();
+        if (m_depthStencil)
+            m_depthStencil->detach();
+    }
+
+    void BindableFbo::bind() const
+    {
+        m_fbo->bind();
+        if (m_depthStencil)
+            m_depthStencil->attach();
+    }
+}
+
+QSGDefaultLayer::QSGDefaultLayer(QSGRenderContext *context)
+    : QSGLayer()
+    , m_item(0)
+    , m_shaderSourceNode(0)
+    , m_device_pixel_ratio(1)
+    , m_format(GL_RGBA)
+    , m_renderer(0)
+    , m_fbo(0)
+    , m_secondaryFbo(0)
+    , m_transparentTexture(0)
+#ifdef QSG_DEBUG_FBO_OVERLAY
+    , m_debugOverlay(0)
+#endif
+    , m_context(context)
+    , m_mipmap(false)
+    , m_live(true)
+    , m_recursive(false)
+    , m_dirtyTexture(true)
+    , m_multisamplingChecked(false)
+    , m_multisampling(false)
+    , m_grab(false)
+{
+}
+
+QSGDefaultLayer::~QSGDefaultLayer()
+{
+    invalidated();
+}
+
+void QSGDefaultLayer::invalidated()
+{
+    delete m_renderer;
+    m_renderer = 0;
+    delete m_fbo;
+    delete m_secondaryFbo;
+    m_fbo = m_secondaryFbo = 0;
+#ifdef QSG_DEBUG_FBO_OVERLAY
+    delete m_debugOverlay;
+    m_debugOverlay = 0;
+#endif
+    if (m_transparentTexture) {
+        QOpenGLContext::currentContext()->functions()->glDeleteTextures(1, &m_transparentTexture);
+        m_transparentTexture = 0;
+    }
+}
+
+int QSGDefaultLayer::textureId() const
+{
+    return m_fbo ? m_fbo->texture() : 0;
+}
+
+bool QSGDefaultLayer::hasAlphaChannel() const
+{
+    return m_format != GL_RGB;
+}
+
+bool QSGDefaultLayer::hasMipmaps() const
+{
+    return m_mipmap;
+}
+
+
+void QSGDefaultLayer::bind()
+{
+#ifndef QT_NO_DEBUG
+    if (!m_recursive && m_fbo && ((m_multisampling && m_secondaryFbo->isBound()) || m_fbo->isBound()))
+        qWarning("ShaderEffectSource: \'recursive\' must be set to true when rendering recursively.");
+#endif
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    if (!m_fbo && m_format == GL_RGBA) {
+        if (m_transparentTexture == 0) {
+            funcs->glGenTextures(1, &m_transparentTexture);
+            funcs->glBindTexture(GL_TEXTURE_2D, m_transparentTexture);
+            const uint zero = 0;
+            funcs->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, &zero);
+        } else {
+            funcs->glBindTexture(GL_TEXTURE_2D, m_transparentTexture);
+        }
+    } else {
+        funcs->glBindTexture(GL_TEXTURE_2D, m_fbo ? m_fbo->texture() : 0);
+        updateBindOptions();
+    }
+}
+
+bool QSGDefaultLayer::updateTexture()
+{
+    bool doGrab = (m_live || m_grab) && m_dirtyTexture;
+    if (doGrab)
+        grab();
+    if (m_grab)
+        emit scheduledUpdateCompleted();
+    m_grab = false;
+    return doGrab;
+}
+
+void QSGDefaultLayer::setHasMipmaps(bool mipmap)
+{
+    if (mipmap == m_mipmap)
+        return;
+    m_mipmap = mipmap;
+    if (m_mipmap && m_fbo && !m_fbo->format().mipmap())
+        markDirtyTexture();
+}
+
+
+void QSGDefaultLayer::setItem(QSGNode *item)
+{
+    if (item == m_item)
+        return;
+    m_item = item;
+
+    if (m_live && !m_item) {
+        delete m_fbo;
+        delete m_secondaryFbo;
+        m_fbo = m_secondaryFbo = 0;
+        m_depthStencilBuffer.clear();
+    }
+
+    markDirtyTexture();
+}
+
+void QSGDefaultLayer::setRect(const QRectF &rect)
+{
+    if (rect == m_rect)
+        return;
+    m_rect = rect;
+    markDirtyTexture();
+}
+
+void QSGDefaultLayer::setSize(const QSize &size)
+{
+    if (size == m_size)
+        return;
+    m_size = size;
+
+    if (m_live && m_size.isNull()) {
+        delete m_fbo;
+        delete m_secondaryFbo;
+        m_fbo = m_secondaryFbo = 0;
+        m_depthStencilBuffer.clear();
+    }
+
+    markDirtyTexture();
+}
+
+void QSGDefaultLayer::setFormat(GLenum format)
+{
+    if (format == m_format)
+        return;
+    m_format = format;
+    markDirtyTexture();
+}
+
+void QSGDefaultLayer::setLive(bool live)
+{
+    if (live == m_live)
+        return;
+    m_live = live;
+
+    if (m_live && (!m_item || m_size.isNull())) {
+        delete m_fbo;
+        delete m_secondaryFbo;
+        m_fbo = m_secondaryFbo = 0;
+        m_depthStencilBuffer.clear();
+    }
+
+    markDirtyTexture();
+}
+
+void QSGDefaultLayer::scheduleUpdate()
+{
+    if (m_grab)
+        return;
+    m_grab = true;
+    if (m_dirtyTexture) {
+        emit updateRequested();
+        if (m_shaderSourceNode)
+            m_shaderSourceNode->markDirty(QSGNode::DirtyMaterial);
+    }
+}
+
+void QSGDefaultLayer::setRecursive(bool recursive)
+{
+    m_recursive = recursive;
+}
+
+void QSGDefaultLayer::markDirtyTexture()
+{
+    m_dirtyTexture = true;
+    if (m_live || m_grab) {
+        emit updateRequested();
+        if (m_shaderSourceNode)
+            m_shaderSourceNode->markDirty(QSGNode::DirtyMaterial);
+    }
+}
+
+void QSGDefaultLayer::grab()
+{
+    if (!m_item || m_size.isNull()) {
+        delete m_fbo;
+        delete m_secondaryFbo;
+        m_fbo = m_secondaryFbo = 0;
+        m_depthStencilBuffer.clear();
+        m_dirtyTexture = false;
+        return;
+    }
+    QSGNode *root = m_item;
+    while (root->firstChild() && root->type() != QSGNode::RootNodeType)
+        root = root->firstChild();
+    if (root->type() != QSGNode::RootNodeType)
+        return;
+
+    if (!m_renderer) {
+        m_renderer = m_context->createRenderer();
+        connect(m_renderer, SIGNAL(sceneGraphChanged()), this, SLOT(markDirtyTextureLater()));
+    }
+    m_renderer->setDevicePixelRatio(m_device_pixel_ratio);
+    m_renderer->setRootNode(static_cast<QSGRootNode *>(root));
+
+    QOpenGLFunctions *funcs = QOpenGLContext::currentContext()->functions();
+    bool deleteFboLater = false;
+    if (!m_fbo || m_fbo->size() != m_size || m_fbo->format().internalTextureFormat() != m_format
+        || (!m_fbo->format().mipmap() && m_mipmap))
+    {
+        if (!m_multisamplingChecked) {
+            if (m_context->openglContext()->format().samples() <= 1) {
+                m_multisampling = false;
+            } else {
+                const QSet<QByteArray> extensions = m_context->openglContext()->extensions();
+                m_multisampling = extensions.contains(QByteArrayLiteral("GL_EXT_framebuffer_multisample"))
+                    && extensions.contains(QByteArrayLiteral("GL_EXT_framebuffer_blit"));
+            }
+            m_multisamplingChecked = true;
+        }
+        if (m_multisampling) {
+            // Don't delete the FBO right away in case it is used recursively.
+            deleteFboLater = true;
+            delete m_secondaryFbo;
+            QOpenGLFramebufferObjectFormat format;
+
+            format.setInternalTextureFormat(m_format);
+            format.setSamples(m_context->openglContext()->format().samples());
+            m_secondaryFbo = new QOpenGLFramebufferObject(m_size, format);
+            m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_secondaryFbo);
+        } else {
+            QOpenGLFramebufferObjectFormat format;
+            format.setInternalTextureFormat(m_format);
+            format.setMipmap(m_mipmap);
+            if (m_recursive) {
+                deleteFboLater = true;
+                delete m_secondaryFbo;
+                m_secondaryFbo = new QOpenGLFramebufferObject(m_size, format);
+                funcs->glBindTexture(GL_TEXTURE_2D, m_secondaryFbo->texture());
+                updateBindOptions(true);
+                m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_secondaryFbo);
+            } else {
+                delete m_fbo;
+                delete m_secondaryFbo;
+                m_fbo = new QOpenGLFramebufferObject(m_size, format);
+                m_secondaryFbo = 0;
+                funcs->glBindTexture(GL_TEXTURE_2D, m_fbo->texture());
+                updateBindOptions(true);
+                m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_fbo);
+            }
+        }
+    }
+
+    if (m_recursive && !m_secondaryFbo) {
+        // m_fbo already created, m_recursive was just set.
+        Q_ASSERT(m_fbo);
+        Q_ASSERT(!m_multisampling);
+
+        m_secondaryFbo = new QOpenGLFramebufferObject(m_size, m_fbo->format());
+        funcs->glBindTexture(GL_TEXTURE_2D, m_secondaryFbo->texture());
+        updateBindOptions(true);
+    }
+
+    // Render texture.
+    root->markDirty(QSGNode::DirtyForceUpdate); // Force matrix, clip and opacity update.
+    m_renderer->nodeChanged(root, QSGNode::DirtyForceUpdate); // Force render list update.
+
+#ifdef QSG_DEBUG_FBO_OVERLAY
+    if (qmlFboOverlay()) {
+        if (!m_debugOverlay)
+            m_debugOverlay = new QSGSimpleRectNode();
+        m_debugOverlay->setRect(QRectF(0, 0, m_size.width(), m_size.height()));
+        m_debugOverlay->setColor(QColor(0xff, 0x00, 0x80, 0x40));
+        root->appendChildNode(m_debugOverlay);
+    }
+#endif
+
+    m_dirtyTexture = false;
+
+    m_renderer->setDeviceRect(m_size);
+    m_renderer->setViewportRect(m_size);
+    QRectF mirrored(m_rect.left(), m_rect.bottom(), m_rect.width(), -m_rect.height());
+    m_renderer->setProjectionMatrixToRect(mirrored);
+    m_renderer->setClearColor(Qt::transparent);
+
+    if (m_multisampling) {
+        m_renderer->renderScene(BindableFbo(m_secondaryFbo, m_depthStencilBuffer.data()));
+
+        if (deleteFboLater) {
+            delete m_fbo;
+            QOpenGLFramebufferObjectFormat format;
+            format.setInternalTextureFormat(m_format);
+            format.setAttachment(QOpenGLFramebufferObject::NoAttachment);
+            format.setMipmap(m_mipmap);
+            format.setSamples(0);
+            m_fbo = new QOpenGLFramebufferObject(m_size, format);
+            funcs->glBindTexture(GL_TEXTURE_2D, m_fbo->texture());
+            updateBindOptions(true);
+        }
+
+        QRect r(QPoint(), m_size);
+        QOpenGLFramebufferObject::blitFramebuffer(m_fbo, r, m_secondaryFbo, r);
+    } else {
+        if (m_recursive) {
+            m_renderer->renderScene(BindableFbo(m_secondaryFbo, m_depthStencilBuffer.data()));
+
+            if (deleteFboLater) {
+                delete m_fbo;
+                QOpenGLFramebufferObjectFormat format;
+                format.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil);
+                format.setInternalTextureFormat(m_format);
+                format.setMipmap(m_mipmap);
+                m_fbo = new QOpenGLFramebufferObject(m_size, format);
+                funcs->glBindTexture(GL_TEXTURE_2D, m_fbo->texture());
+                updateBindOptions(true);
+            }
+            qSwap(m_fbo, m_secondaryFbo);
+        } else {
+            m_renderer->renderScene(BindableFbo(m_fbo, m_depthStencilBuffer.data()));
+        }
+    }
+
+    if (m_mipmap) {
+        funcs->glBindTexture(GL_TEXTURE_2D, textureId());
+        funcs->glGenerateMipmap(GL_TEXTURE_2D);
+    }
+
+    root->markDirty(QSGNode::DirtyForceUpdate); // Force matrix, clip, opacity and render list update.
+
+#ifdef QSG_DEBUG_FBO_OVERLAY
+    if (qmlFboOverlay())
+        root->removeChildNode(m_debugOverlay);
+#endif
+    if (m_recursive)
+        markDirtyTexture(); // Continuously update if 'live' and 'recursive'.
+}
+
+QImage QSGDefaultLayer::toImage() const
+{
+    if (m_fbo)
+        return m_fbo->toImage();
+
+    return QImage();
+}