QQmlParserStatus Class Reference

The QQmlParserStatus class provides updates on the QML parser state. More...

#include <qqmlparserstatus.h>

Inherited by MyObject, MyObject, QDeclarativeCategory, QDeclarativeGeoRouteModel, QDeclarativeGeoRouteQuery, QDeclarativeGeoServiceProvider, QDeclarativeGeocodeModel, QDeclarativePlace, QDeclarativePlaceContentModel, QDeclarativePositionSource, QDeclarativeSatelliteSource, QDeclarativeSearchModelBase, QDeclarativeSupportedCategoriesModel, QPhysicsWorld, QQmlBind, QQmlConnections, QQmlDelegateModel, QQmlInstantiator, QQmlLoggingCategory, QQmlSettings, QQmlSettings, QQmlTableModel, QQmlTimer, QQmlXmlListModel, QQuick3DInfiniteGrid, QQuick3DObject, QQuick3DParticleAbstractShape, QQuick3DParticleEmitBurst, QQuick3DParticleSpriteSequence, QQuick3DXrInputAction, QQuickAbstractAnimation, QQuickAbstractDialog, QQuickBoundaryRule, QQuickButtonGroup, QQuickCalendarModel, QQuickFolderListModel, QQuickFrameAnimation, QQuickImageSelector, QQuickItem, QQuickLabsPlatformDialog, QQuickLabsPlatformMenu, QQuickLabsPlatformMenuBar, QQuickLabsPlatformMenuItem, QQuickLabsPlatformSystemTrayIcon, QQuickParticleGroup, QQuickPath, QQuickPdfDocument, QQuickPlaylist, QQuickPointerHandler, QQuickPopup, QQuickShortcut, QQuickStateGroup, QQuickWindowQmlImpl, QQuickWorkerScript, QWaylandQuickCompositor, QWaylandQuickHardwareLayer, QWaylandQuickOutput, and QWaylandQuickXdgOutputV1.

Collaboration diagram for QQmlParserStatus:

Public Member Functions
	QQmlParserStatus ()
virtual	~QQmlParserStatus ()
virtual void	classBegin ()=0
	Invoked after class creation, but before any properties have been set.
virtual void	componentComplete ()=0
	Invoked after the root component that caused this instantiation has completed construction.

Friends
class	QQmlComponent
class	QQmlComponentPrivate
class	QQmlEnginePrivate
class	QQmlObjectCreator

Detailed Description

The QQmlParserStatus class provides updates on the QML parser state.

Since

5.0 \inmodule QtQml

QQmlParserStatus provides a mechanism for classes instantiated by a QQmlEngine to receive notification at key points in their creation.

This class is often used for optimization purposes, as it allows you to defer an expensive operation until after all the properties have been set on an object. For example, QML's \l {Text} element uses the parser status to defer text layout until all of its properties have been set (we don't want to layout when the text is assigned, and then relayout when the font is assigned, and relayout again when the width is assigned, and so on).

Be aware that QQmlParserStatus methods are only called when a class is instantiated by a QQmlEngine. If you create the same class directly from C++, these methods will not be called automatically. To avoid this problem, it is recommended that you start deferring operations from classBegin instead of from the initial creation of your class. This will still prevent multiple revaluations during initial binding assignment in QML, but will not defer operations invoked from C++.

To use QQmlParserStatus, you must inherit both a QObject-derived class and QQmlParserStatus, and use the Q_INTERFACES() macro.

class MyObject : public QObject, public QQmlParserStatus
{
    Q_OBJECT
    Q_INTERFACES(QQmlParserStatus)
 
public:
    MyObject(QObject *parent = nullptr);
    // ...
    void classBegin() override;
    void componentComplete() override;
};

Definition at line 13 of file qqmlparserstatus.h.

Constructor & Destructor Documentation

QQmlParserStatus()

QQmlParserStatus::QQmlParserStatus

(

)

Definition at line 39 of file qqmlparserstatus.cpp.

~QQmlParserStatus()

QQmlParserStatus::~QQmlParserStatus ( )

virtual

Definition at line 45 of file qqmlparserstatus.cpp.

Member Function Documentation

classBegin()

virtual void QQmlParserStatus::classBegin ( )

pure virtual

Invoked after class creation, but before any properties have been set.

Implemented in MyObject, MyObject, QDeclarativeCategory, QDeclarativeGeocodeModel, QDeclarativeGeoMapItemGroup, QDeclarativeGeoMapItemView, QDeclarativeGeoRouteModel, QDeclarativeGeoRouteQuery, QDeclarativeGeoServiceProvider, QDeclarativePlace, QDeclarativePlaceContentModel, QDeclarativePositionSource, QDeclarativeSatelliteSource, QDeclarativeSearchModelBase, QDeclarativeSupportedCategoriesModel, QPhysicsWorld, QQmlBind, QQmlConnections, QQmlDelegateModel, QQmlInstantiator, QQmlLoggingCategory, QQmlSettings, QQmlSettings, QQmlTableModel, QQmlTimer, QQmlXmlListModel, QQuick3DInfiniteGrid, QQuick3DObject, QQuick3DParticleAbstractShape, QQuick3DParticleEmitBurst, QQuick3DParticleSpriteSequence, QQuick3DXrInputAction, QQuickAbstractAnimation, QQuickAbstractDialog, QQuickApplicationWindow, QQuickBoundaryRule, QQuickButtonGroup, QQuickCalendarModel, QQuickControl, QQuickFolderListModel, QQuickFrameAnimation, QQuickImageSelector, QQuickItem, QQuickLabel, QQuickLabsPlatformDialog, QQuickLabsPlatformMenu, QQuickLabsPlatformMenuBar, QQuickLabsPlatformMenuItem, QQuickLabsPlatformSystemTrayIcon, QQuickParticleGroup, QQuickPath, QQuickPdfDocument, QQuickPlaylist, QQuickPointerHandler, QQuickPopup, QQuickRangeSlider, QQuickScrollBar, QQuickShape, QQuickShortcut, QQuickSpinBox, QQuickStateGroup, QQuickTextArea, QQuickTextField, QQuickWindowContainer, QQuickWindowQmlImpl, QQuickWorkerScript, QWaylandQuickCompositor, QWaylandQuickHardwareLayer, QWaylandQuickOutput, and QWaylandQuickXdgOutputV1.

componentComplete()

virtual void QQmlParserStatus::componentComplete ( )

pure virtual

Invoked after the root component that caused this instantiation has completed construction.

At this point all static values and binding values have been assigned to the class.

Implemented in MyObject, MyObject, QDeclarativeCategory, QDeclarativeGeocodeModel, QDeclarativeGeoMap, QDeclarativeGeoMapItemGroup, QDeclarativeGeoMapItemView, QDeclarativeGeoRouteModel, QDeclarativeGeoRouteQuery, QDeclarativeGeoServiceProvider, QDeclarativePlace, QDeclarativePlaceContentModel, QDeclarativePositionSource, QDeclarativeSatelliteSource, QDeclarativeSearchModelBase, QDeclarativeSupportedCategoriesModel, QPhysicsWorld, QQmlBind, QQmlConnections, QQmlDelegateModel, QQmlInstantiator, QQmlLoggingCategory, QQmlSettings, QQmlSettings, QQmlTableModel, QQmlTimer, QQmlXmlListModel, QQuick3DInfiniteGrid, QQuick3DLoader, QQuick3DNode, QQuick3DObject, QQuick3DParticle, QQuick3DParticleAbstractShape, QQuick3DParticleAffector, QQuick3DParticleEmitBurst, QQuick3DParticleEmitter, QQuick3DParticleModelBlendParticle, QQuick3DParticleModelParticle, QQuick3DParticleSpriteParticle, QQuick3DParticleSpriteSequence, QQuick3DParticleSystem, QQuick3DRepeater, QQuick3DRuntimeLoader, QQuick3DViewport, QQuick3DXrHandModel, QQuick3DXrInputAction, QQuick3DXrItem, QQuickAbstractAnimation, QQuickAbstractButton, QQuickAbstractColorPicker, QQuickAbstractDialog, QQuickAnimatedImage, QQuickAnimatedSprite, QQuickApplicationWindow, QQuickBasePositioner, QQuickBoundaryRule, QQuickButtonGroup, QQuickCalendarModel, QQuickCanvasItem, QQuickComboBox, QQuickContainer, QQuickControl, QQuickDayOfWeekRow, QQuickDial, QQuickDialogButtonBox, QQuickFileDialogImpl, QQuickFlickable, QQuickFolderBreadcrumbBar, QQuickFolderDialogImpl, QQuickFolderListModel, QQuickFrameAnimation, QQuickGridLayoutBase, QQuickGroupBox, QQuickHoverHandler, QQuickIconImage, QQuickIconLabel, QQuickImageBase, QQuickImageSelector, QQuickItem, QQuickItemView, QQuickLabel, QQuickLabsPlatformDialog, QQuickLabsPlatformMenu, QQuickLabsPlatformMenuBar, QQuickLabsPlatformMenuItem, QQuickLabsPlatformSystemTrayIcon, QQuickLayout, QQuickLoader, QQuickMaterialPlaceholderText, QQuickMaterialTextContainer, QQuickMenu, QQuickMenuBar, QQuickMenuItem, QQuickMonthGrid, QQuickMultiEffect, QQuickPage, QQuickPane, QQuickParticleAffector, QQuickParticleEmitter, QQuickParticleGroup, QQuickParticlePainter, QQuickParticleSystem, QQuickPath, QQuickPathView, QQuickPdfDocument, QQuickPlaceholderText, QQuickPlaylist, QQuickPointerHandler, QQuickPopup, QQuickProgressBar, QQuickRangeSlider, QQuickRectangularShadow, QQuickRepeater, QQuickScrollBar, QQuickScrollView, QQuickShaderEffect, QQuickShape, QQuickShortcut, QQuickSlider, QQuickSpinBox, QQuickSplitView, QQuickStackLayout, QQuickStackView, QQuickStateGroup, QQuickStyleItem, QQuickSwipeDelegate, QQuickSwipeView, QQuickTabBar, QQuickText, QQuickTextArea, QQuickTextEdit, QQuickTextField, QQuickTextInput, QQuickTreeViewDelegate, QQuickTumbler, QQuickTumblerView, QQuickWeekNumberColumn, QQuickWindowContainer, QQuickWindowQmlImpl, QQuickWorkerScript, QWaylandQuickCompositor, QWaylandQuickHardwareLayer, QWaylandQuickOutput, and QWaylandQuickXdgOutputV1.

Friends And Related Symbol Documentation

QQmlComponent

friend class QQmlComponent

friend

Definition at line 23 of file qqmlparserstatus.h.

QQmlComponentPrivate

friend class QQmlComponentPrivate

friend

Definition at line 24 of file qqmlparserstatus.h.

QQmlEnginePrivate

friend class QQmlEnginePrivate

friend

Definition at line 25 of file qqmlparserstatus.h.

QQmlObjectCreator

friend class QQmlObjectCreator

friend

Definition at line 26 of file qqmlparserstatus.h.

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The documentation for this class was generated from the following files:

• qtdeclarative/src/qml/qml/qqmlparserstatus.h (0dc4fd240a2897c5c443a0ef6d84c416843e4938)
• qtdeclarative/src/qml/qml/qqmlparserstatus.cpp (0dc4fd240a2897c5c443a0ef6d84c416843e4938)