diff options
Diffstat (limited to 'src/quick/items/qquickitem.cpp')
| -rw-r--r-- | src/quick/items/qquickitem.cpp | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp index 3907c911b2..08f60aeb1e 100644 --- a/src/quick/items/qquickitem.cpp +++ b/src/quick/items/qquickitem.cpp @@ -1552,7 +1552,7 @@ void QQuickItemPrivate::updateSubFocusItem(QQuickItem *scope, bool focus) You can subclass QQuickItem to provide your own custom visual item that inherits these features. - \section2 Custom Items using Scene Graph + \section1 Custom Scene Graph Items All visual QML items are rendered using the scene graph, a low-level, high-performance rendering stack, closely tied to @@ -1570,7 +1570,7 @@ void QQuickItemPrivate::updateSubFocusItem(QQuickItem *scope, bool focus) To read more about how the scene graph rendering works, see \l{Scene Graph and Rendering} - \section2 Custom Items using QPainter + \section1 Custom QPainter Items The QQuickItem provides a subclass, QQuickPaintedItem, which allows the users to render content using QPainter. @@ -2972,9 +2972,11 @@ void QQuickItem::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeo } /*! - Called by the rendering thread, as a result of - QQuickItem::update(), when it is time to sync the state of the QML - objects with the scene graph objects. + Called on the render thread when it is time to sync the state + of the item with the scene graph. + + The function is called as a result of QQuickItem::update(), if + the user has set the QQuickItem::ItemHasContents flag on the item. The function should return the root of the scene graph subtree for this item. Most implementations will return a single @@ -3005,11 +3007,17 @@ void QQuickItem::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeo the visual outcome is identical. \warning It is crucial that OpenGL operations and interaction with - the scene graph happens exclusively on the rendering thread, + the scene graph happens exclusively on the render thread, primarily during the QQuickItem::updatePaintNode() call. The best rule of thumb is to only use classes with the "QSG" prefix inside the QQuickItem::updatePaintNode() function. + \warning This function is called on the render thread. This means any + QObjects or thread local storage that is created will have affinity to the + render thread, so apply caution when doing anything other than rendering + in this function. Similarily for signals, these will be emitted on the render + thread and will thus often be delivered via queued connections. + \sa QSGMaterial, QSGSimpleMaterial, QSGGeometryNode, QSGGeometry, QSGFlatColorMaterial, QSGTextureMaterial, QSGNode::markDirty() */ |