Use one render loop per QQuickWindow

See the task for the full reasoning behind this patch.

The threaded renderloop has been refactored to have one window per
thread. This is mostly a simplification of the current code path where
for loops over multiple windows are turned into if (window).

The QSGContext has been split into two classes, QSGRenderContext
for which there is one per OpenGLContext.

The rest of the patch is name changes and a couple of cleanups
in the hopes of simplifying this change.

Task-number: QTBUG-33993

Change-Id: I31c81f9694d7da7474a72333169be38de62613c4
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

14 files changed, 58 insertions, 72 deletions

diff --git a/src/quick/items/context2d/qquickcanvasitem.cpp b/src/quick/items/context2d/qquickcanvasitem.cpp
index d9feb8d8eb..ba3592986c 100644
--- a/src/quick/items/context2d/qquickcanvasitem.cpp
+++ b/src/quick/items/context2d/qquickcanvasitem.cpp
@@ -112,7 +112,7 @@ QSGTexture *QQuickCanvasPixmap::texture()
             Q_ASSERT(m_pixmap->textureFactory());
             m_texture = m_pixmap->textureFactory()->createTexture(m_window);
         } else {
-            m_texture = QQuickWindowPrivate::get(m_window)->context->createTexture(m_image);
+            m_texture = m_window->createTextureFromImage(m_image, QQuickWindow::TextureCanUseAtlas);
         }
     }
     return m_texture;
diff --git a/src/quick/items/context2d/qquickcontext2d.cpp b/src/quick/items/context2d/qquickcontext2d.cpp
index 2b2504daf2..3088c41cd7 100644
--- a/src/quick/items/context2d/qquickcontext2d.cpp
+++ b/src/quick/items/context2d/qquickcontext2d.cpp
@@ -4112,7 +4112,7 @@ void QQuickContext2D::init(QQuickCanvasItem *canvasItem, const QVariantMap &args
         m_texture->moveToThread(renderThread);
 
     if (m_renderTarget == QQuickCanvasItem::FramebufferObject && renderThread != sceneGraphThread) {
-         QOpenGLContext *cc = QQuickWindowPrivate::get(window)->context->glContext();
+         QOpenGLContext *cc = QQuickWindowPrivate::get(window)->context->openglContext();
          m_surface = window;
          m_glContext = new QOpenGLContext;
          m_glContext->setFormat(cc->format());
diff --git a/src/quick/items/qquickborderimage.cpp b/src/quick/items/qquickborderimage.cpp
index a2e4e91755..0bed5e96a2 100644
--- a/src/quick/items/qquickborderimage.cpp
+++ b/src/quick/items/qquickborderimage.cpp
@@ -551,7 +551,7 @@ QSGNode *QQuickBorderImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeDat
 {
     Q_D(QQuickBorderImage);
 
-    QSGTexture *texture = d->sceneGraphContext()->textureForFactory(d->pix.textureFactory(), window());
+    QSGTexture *texture = d->sceneGraphRenderContext()->textureForFactory(d->pix.textureFactory(), window());
 
     if (!texture || width() <= 0 || height() <= 0) {
         delete oldNode;
diff --git a/src/quick/items/qquickimage.cpp b/src/quick/items/qquickimage.cpp
index d6be13f3c0..0708304051 100644
--- a/src/quick/items/qquickimage.cpp
+++ b/src/quick/items/qquickimage.cpp
@@ -532,17 +532,17 @@ QRectF QQuickImage::boundingRect() const
 QSGTextureProvider *QQuickImage::textureProvider() const
 {
     Q_D(const QQuickImage);
+
+    if (!d->window || !d->sceneGraphRenderContext() || QThread::currentThread() != d->sceneGraphRenderContext()->thread()) {
+        qWarning("QQuickImage::textureProvider: can only be queried on the rendering thread of an exposed window");
+        return 0;
+    }
+
     if (!d->provider) {
-        // Make sure it gets thread affinity on the rendering thread so deletion works properly..
-        Q_ASSERT_X(d->window
-                   && d->sceneGraphContext()
-                   && QThread::currentThread() == d->sceneGraphContext()->thread(),
-                   "QQuickImage::textureProvider",
-                   "Cannot be used outside the GUI thread");
         QQuickImagePrivate *dd = const_cast<QQuickImagePrivate *>(d);
         dd->provider = new QQuickImageTextureProvider;
         dd->provider->m_smooth = d->smooth;
-        dd->provider->m_texture = d->sceneGraphContext()->textureForFactory(d->pix.textureFactory(), window());
+        dd->provider->m_texture = d->sceneGraphRenderContext()->textureForFactory(d->pix.textureFactory(), window());
     }
 
     return d->provider;
@@ -552,7 +552,7 @@ QSGNode *QQuickImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
 {
     Q_D(QQuickImage);
 
-    QSGTexture *texture = d->sceneGraphContext()->textureForFactory(d->pix.textureFactory(), window());
+    QSGTexture *texture = d->sceneGraphRenderContext()->textureForFactory(d->pix.textureFactory(), window());
 
     // Copy over the current texture state into the texture provider...
     if (d->provider) {
diff --git a/src/quick/items/qquickitem_p.h b/src/quick/items/qquickitem_p.h
index f731acabbb..7faf39f8e5 100644
--- a/src/quick/items/qquickitem_p.h
+++ b/src/quick/items/qquickitem_p.h
@@ -468,6 +468,7 @@ public:
     QQuickWindow *window;
     int windowRefCount;
     inline QSGContext *sceneGraphContext() const;
+    inline QSGRenderContext *sceneGraphRenderContext() const;
 
     QQuickItem *parentItem;
     QQmlNotifier parentNotifier;
@@ -840,6 +841,12 @@ Qt::MouseButtons QQuickItemPrivate::acceptedMouseButtons() const
 QSGContext *QQuickItemPrivate::sceneGraphContext() const
 {
     Q_ASSERT(window);
+    return static_cast<QQuickWindowPrivate *>(QObjectPrivate::get(window))->context->sceneGraphContext();
+}
+
+QSGRenderContext *QQuickItemPrivate::sceneGraphRenderContext() const
+{
+    Q_ASSERT(window);
     return static_cast<QQuickWindowPrivate *>(QObjectPrivate::get(window))->context;
 }
 
diff --git a/src/quick/items/qquickshadereffectsource.cpp b/src/quick/items/qquickshadereffectsource.cpp
index e86550d731..c05545c292 100644
--- a/src/quick/items/qquickshadereffectsource.cpp
+++ b/src/quick/items/qquickshadereffectsource.cpp
@@ -45,6 +45,7 @@
 #include "qquickwindow_p.h"
 #include <private/qsgadaptationlayer_p.h>
 #include <QtQuick/private/qsgrenderer_p.h>
+#include <qsgsimplerectnode.h>
 
 #include "qopenglframebufferobject.h"
 #include "qmath.h"
@@ -143,7 +144,7 @@ QQuickShaderEffectTexture::QQuickShaderEffectTexture(QQuickItem *shaderSource)
 #ifdef QSG_DEBUG_FBO_OVERLAY
     , m_debugOverlay(0)
 #endif
-    , m_context(QQuickItemPrivate::get(shaderSource)->sceneGraphContext())
+    , m_context(QQuickItemPrivate::get(shaderSource)->sceneGraphRenderContext())
     , m_mipmap(false)
     , m_live(true)
     , m_recursive(false)
@@ -326,7 +327,7 @@ void QQuickShaderEffectTexture::grab()
         || (!m_fbo->format().mipmap() && m_mipmap))
     {
         if (!m_multisamplingChecked) {
-            if (m_context->glContext()->format().samples() <= 1) {
+            if (m_context->openglContext()->format().samples() <= 1) {
                 m_multisampling = false;
             } else {
                 QList<QByteArray> extensions = QByteArray((const char *)glGetString(GL_EXTENSIONS)).split(' ');
@@ -342,7 +343,7 @@ void QQuickShaderEffectTexture::grab()
             QOpenGLFramebufferObjectFormat format;
 
             format.setInternalTextureFormat(m_format);
-            format.setSamples(m_context->glContext()->format().samples());
+            format.setSamples(m_context->openglContext()->format().samples());
             m_secondaryFbo = new QOpenGLFramebufferObject(m_size, format);
             m_depthStencilBuffer = m_context->depthStencilBufferForFbo(m_secondaryFbo);
         } else {
@@ -385,20 +386,16 @@ void QQuickShaderEffectTexture::grab()
 #ifdef QSG_DEBUG_FBO_OVERLAY
     if (qmlFboOverlay()) {
         if (!m_debugOverlay)
-            m_debugOverlay = m_context->createRectangleNode();
+            m_debugOverlay = new QSGSimpleRectNode();
         m_debugOverlay->setRect(QRectF(0, 0, m_size.width(), m_size.height()));
         m_debugOverlay->setColor(QColor(0xff, 0x00, 0x80, 0x40));
-        m_debugOverlay->setPenColor(QColor());
-        m_debugOverlay->setPenWidth(0);
-        m_debugOverlay->setRadius(0);
-        m_debugOverlay->update();
         root->appendChildNode(m_debugOverlay);
     }
 #endif
 
     m_dirtyTexture = false;
 
-    QOpenGLContext *ctx = m_context->glContext();
+    QOpenGLContext *ctx = m_context->openglContext();
     m_renderer->setDeviceRect(m_size);
     m_renderer->setViewportRect(m_size);
     QRectF mirrored(m_rect.left(), m_rect.bottom(), m_rect.width(), -m_rect.height());
@@ -591,8 +588,8 @@ void QQuickShaderEffectSource::ensureTexture()
         return;
 
     Q_ASSERT_X(QQuickItemPrivate::get(this)->window
-               && QQuickItemPrivate::get(this)->sceneGraphContext()
-               && QThread::currentThread() == QQuickItemPrivate::get(this)->sceneGraphContext()->thread(),
+               && QQuickItemPrivate::get(this)->sceneGraphRenderContext()
+               && QThread::currentThread() == QQuickItemPrivate::get(this)->sceneGraphRenderContext()->thread(),
                "QQuickShaderEffectSource::ensureTexture",
                "Cannot be used outside the rendering thread");
 
@@ -603,13 +600,13 @@ void QQuickShaderEffectSource::ensureTexture()
 
 QSGTextureProvider *QQuickShaderEffectSource::textureProvider() const
 {
+    const QQuickItemPrivate *d = QQuickItemPrivate::get(this);
+    if (!d->window || !d->sceneGraphRenderContext() || QThread::currentThread() != d->sceneGraphRenderContext()->thread()) {
+        qWarning("QQuickShaderEffectSource::textureProvider: can only be queried on the rendering thread of an exposed window");
+        return 0;
+    }
+
     if (!m_provider) {
-        // Make sure it gets thread affinity on the rendering thread so deletion works properly..
-        Q_ASSERT_X(QQuickItemPrivate::get(this)->window
-                   && QQuickItemPrivate::get(this)->sceneGraphContext()
-                   && QThread::currentThread() == QQuickItemPrivate::get(this)->sceneGraphContext()->thread(),
-                   "QQuickShaderEffectSource::textureProvider",
-                   "Cannot be used outside the rendering thread");
         const_cast<QQuickShaderEffectSource *>(this)->m_provider = new QQuickShaderEffectSourceTextureProvider();
         const_cast<QQuickShaderEffectSource *>(this)->ensureTexture();
         connect(m_texture, SIGNAL(updateRequested()), m_provider, SIGNAL(textureChanged()));
diff --git a/src/quick/items/qquickshadereffectsource_p.h b/src/quick/items/qquickshadereffectsource_p.h
index 7d1a9b7304..85b58e67e4 100644
--- a/src/quick/items/qquickshadereffectsource_p.h
+++ b/src/quick/items/qquickshadereffectsource_p.h
@@ -60,6 +60,7 @@ QT_BEGIN_NAMESPACE
 class QSGNode;
 class UpdatePaintNodeData;
 class QOpenGLFramebufferObject;
+class QSGSimpleRectNode;
 
 class QQuickShaderEffectSourceTextureProvider;
 
@@ -139,10 +140,10 @@ private:
     QSharedPointer<QSGDepthStencilBuffer> m_depthStencilBuffer;
 
 #ifdef QSG_DEBUG_FBO_OVERLAY
-    QSGRectangleNode *m_debugOverlay;
+    QSGSimpleRectNode *m_debugOverlay;
 #endif
 
-    QSGContext *m_context;
+    QSGRenderContext *m_context;
 
     uint m_mipmap : 1;
     uint m_live : 1;
diff --git a/src/quick/items/qquicktext.cpp b/src/quick/items/qquicktext.cpp
index fbda2df2dc..6335c83b2b 100644
--- a/src/quick/items/qquicktext.cpp
+++ b/src/quick/items/qquicktext.cpp
@@ -2241,11 +2241,10 @@ QSGNode *QQuickText::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *data
     const qreal dy = QQuickTextUtil::alignedY(d->layedOutTextRect.height(), height(), d->vAlign);
 
     QQuickTextNode *node = 0;
-    if (!oldNode) {
-        node = new QQuickTextNode(QQuickItemPrivate::get(this)->sceneGraphContext(), this);
-    } else {
+    if (!oldNode)
+        node = new QQuickTextNode(this);
+    else
         node = static_cast<QQuickTextNode *>(oldNode);
-    }
 
     node->setUseNativeRenderer(d->renderType == NativeRendering && d->window->devicePixelRatio() <= 1);
     node->deleteContent();
diff --git a/src/quick/items/qquicktextedit.cpp b/src/quick/items/qquicktextedit.cpp
index be2cd37dee..ffc732621d 100644
--- a/src/quick/items/qquicktextedit.cpp
+++ b/src/quick/items/qquicktextedit.cpp
@@ -2370,7 +2370,7 @@ void QQuickTextEditPrivate::addCurrentTextNodeToRoot(QSGTransformNode *root, QQu
 QQuickTextNode *QQuickTextEditPrivate::createTextNode()
 {
     Q_Q(QQuickTextEdit);
-    QQuickTextNode* node = new QQuickTextNode(QQuickItemPrivate::get(q)->sceneGraphContext(), q);
+    QQuickTextNode* node = new QQuickTextNode(q);
     node->setUseNativeRenderer(renderType == QQuickTextEdit::NativeRendering && window->devicePixelRatio() <= 1);
     node->initEngine(color, selectedTextColor, selectionColor);
     return node;
diff --git a/src/quick/items/qquicktextinput.cpp b/src/quick/items/qquicktextinput.cpp
index 1848fbb80b..93ea677d2c 100644
--- a/src/quick/items/qquicktextinput.cpp
+++ b/src/quick/items/qquicktextinput.cpp
@@ -1834,7 +1834,7 @@ QSGNode *QQuickTextInput::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData
 
     QQuickTextNode *node = static_cast<QQuickTextNode *>(oldNode);
     if (node == 0)
-        node = new QQuickTextNode(QQuickItemPrivate::get(this)->sceneGraphContext(), this);
+        node = new QQuickTextNode(this);
     d->textNode = node;
 
     if (!d->textLayoutDirty && oldNode != 0) {
diff --git a/src/quick/items/qquicktextnode.cpp b/src/quick/items/qquicktextnode.cpp
index 1f4ca34b13..6acfaaf396 100644
--- a/src/quick/items/qquicktextnode.cpp
+++ b/src/quick/items/qquicktextnode.cpp
@@ -47,6 +47,7 @@
 #include <private/qsgadaptationlayer_p.h>
 #include <private/qsgdistancefieldglyphnode_p.h>
 #include <private/qquickclipnode_p.h>
+#include <private/qquickitem_p.h>
 #include <QtQuick/private/qsgcontext_p.h>
 
 #include <QtCore/qpoint.h>
@@ -80,8 +81,8 @@ namespace {
 /*!
   Creates an empty QQuickTextNode
 */
-QQuickTextNode::QQuickTextNode(QSGContext *context, QQuickItem *ownerElement)
-    : m_context(context), m_cursorNode(0), m_ownerElement(ownerElement), m_useNativeRenderer(false)
+QQuickTextNode::QQuickTextNode(QQuickItem *ownerElement)
+    : m_cursorNode(0), m_ownerElement(ownerElement), m_useNativeRenderer(false)
 {
 #ifdef QSG_RUNTIME_DESCRIPTION
     qsgnode_set_description(this, QLatin1String("text"));
@@ -141,9 +142,10 @@ QSGGlyphNode *QQuickTextNode::addGlyphs(const QPointF &position, const QGlyphRun
                                      QQuickText::TextStyle style, const QColor &styleColor,
                                      QSGNode *parentNode)
 {
+    QSGRenderContext *sg = QQuickItemPrivate::get(m_ownerElement)->sceneGraphRenderContext();
     QSGGlyphNode *node = m_useNativeRenderer
-            ? m_context->createNativeGlyphNode()
-            : m_context->createGlyphNode();
+            ? sg->sceneGraphContext()->createNativeGlyphNode(sg)
+            : sg->sceneGraphContext()->createGlyphNode(sg);
     node->setOwnerElement(m_ownerElement);
     node->setGlyphs(position + QPointF(0, glyphs.rawFont().ascent()), glyphs);
     node->setStyle(style);
@@ -189,8 +191,9 @@ void QQuickTextNode::initEngine(const QColor& textColor, const QColor& selectedT
 
 void QQuickTextNode::addImage(const QRectF &rect, const QImage &image)
 {
-    QSGImageNode *node = m_context->createImageNode();
-    QSGTexture *texture = m_context->createTexture(image);
+    QSGRenderContext *sg = QQuickItemPrivate::get(m_ownerElement)->sceneGraphRenderContext();
+    QSGImageNode *node = sg->sceneGraphContext()->createImageNode();
+    QSGTexture *texture = sg->createTexture(image);
     m_textures.append(texture);
     node->setTargetRect(rect);
     node->setInnerTargetRect(rect);
diff --git a/src/quick/items/qquicktextnode_p.h b/src/quick/items/qquicktextnode_p.h
index 64f396eb10..0bff0d5cff 100644
--- a/src/quick/items/qquicktextnode_p.h
+++ b/src/quick/items/qquicktextnode_p.h
@@ -77,7 +77,7 @@ public:
     };
     Q_DECLARE_FLAGS(Decorations, Decoration)
 
-    QQuickTextNode(QSGContext *, QQuickItem *ownerElement);
+    QQuickTextNode(QQuickItem *ownerElement);
     ~QQuickTextNode();
 
     static bool isComplexRichText(QTextDocument *);
@@ -110,7 +110,6 @@ private:
     void initEngine(const QColor &textColor, const QColor &selectedTextColor, const QColor &selectionColor, const QColor& anchorColor = QColor()
             , const QPointF &position = QPointF());
 
-    QSGContext *m_context;
     QSGSimpleRectNode *m_cursorNode;
     QList<QSGTexture *> m_textures;
     QQuickItem *m_ownerElement;
diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index fd0313aed5..ed97325c85 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -50,8 +50,6 @@
 
 #include <QtQuick/private/qsgrenderer_p.h>
 #include <QtQuick/private/qsgtexture_p.h>
-#include <QtQuick/private/qsgflashnode_p.h>
-
 #include <private/qsgrenderloop_p.h>
 #include <private/qquickanimatorcontroller_p.h>
 
@@ -416,9 +414,10 @@ void QQuickWindowPrivate::init(QQuickWindow *c)
     contentItemPrivate->flags |= QQuickItem::ItemIsFocusScope;
 
     windowManager = QSGRenderLoop::instance();
-    context = windowManager->sceneGraphContext();
+    QSGContext *sg = windowManager->sceneGraphContext();
+    context = windowManager->createRenderContext(sg);
     q->setSurfaceType(QWindow::OpenGLSurface);
-    q->setFormat(context->defaultSurfaceFormat());
+    q->setFormat(sg->defaultSurfaceFormat());
 
     animationController = new QQuickAnimatorController();
     animationController->window = q;
@@ -2319,10 +2318,6 @@ void QQuickWindowPrivate::updateDirtyNodes()
 
 void QQuickWindowPrivate::updateDirtyNode(QQuickItem *item)
 {
-#ifdef QML_RUNTIME_TESTING
-    bool didFlash = false;
-#endif
-
     QQuickItemPrivate *itemPriv = QQuickItemPrivate::get(item);
     quint32 dirty = itemPriv->dirtyAttributes;
     itemPriv->dirtyAttributes = 0;
@@ -2546,19 +2541,6 @@ void QQuickWindowPrivate::updateDirtyNode(QQuickItem *item)
     }
 #endif
 
-#ifdef QML_RUNTIME_TESTING
-    if (itemPriv->sceneGraphContext()->isFlashModeEnabled()) {
-        QSGFlashNode *flash = new QSGFlashNode();
-        flash->setRect(item->boundingRect());
-        itemPriv->childContainerNode()->appendChildNode(flash);
-        didFlash = true;
-    }
-    Q_Q(QQuickWindow);
-    if (didFlash) {
-        q->maybeUpdate();
-    }
-#endif
-
 }
 
 void QQuickWindow::maybeUpdate()
@@ -2598,9 +2580,7 @@ void QQuickWindow::setTransientParent_helper(QQuickWindow *window)
 QOpenGLContext *QQuickWindow::openglContext() const
 {
     Q_D(const QQuickWindow);
-    if (d->context->isReady())
-        return d->context->glContext();
-    return 0;
+    return d->context->openglContext();
 }
 
 /*!
@@ -2796,7 +2776,7 @@ QImage QQuickWindow::grabWindow()
     Q_D(QQuickWindow);
     if (!isVisible()) {
 
-        if (d->context->isReady()) {
+        if (d->context->openglContext()) {
             qWarning("QQuickWindow::grabWindow: scene graph already in use");
             return QImage();
         }
@@ -2993,7 +2973,7 @@ QSGTexture *QQuickWindow::createTextureFromImage(const QImage &image) const
 QSGTexture *QQuickWindow::createTextureFromImage(const QImage &image, CreateTextureOptions options) const
 {
     Q_D(const QQuickWindow);
-    if (d->context && d->context->isReady()) {
+    if (d->context && d->context->openglContext()) {
         if (options & TextureCanUseAtlas)
             return d->context->createTexture(image);
         else
@@ -3021,7 +3001,7 @@ QSGTexture *QQuickWindow::createTextureFromImage(const QImage &image, CreateText
 QSGTexture *QQuickWindow::createTextureFromId(uint id, const QSize &size, CreateTextureOptions options) const
 {
     Q_D(const QQuickWindow);
-    if (d->context && d->context->isReady()) {
+    if (d->context && d->context->openglContext()) {
         QSGPlainTexture *texture = new QSGPlainTexture();
         texture->setTextureId(id);
         texture->setHasAlphaChannel(options & TextureHasAlphaChannel);
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index c02f7107d4..2cf98bfe21 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/src/quick/items/qquickwindow_p.h
@@ -194,7 +194,7 @@ public:
 
     void fireFrameSwapped() { Q_EMIT q_func()->frameSwapped(); }
 
-    QSGContext *context;
+    QSGRenderContext *context;
     QSGRenderer *renderer;
 
     QSGRenderLoop *windowManager;