- class QObject#
The
QObject
class is the base class of all Qt objects. More…Inherited by:
QWidget
,QWizardPage
,QToolBar
,QTabWidget
,QTabBar
,QStatusBar
,QSplitterHandle
,QSplashScreen
,QSizeGrip
,QRubberBand
,QRhiWidget
,QProgressBar
,QMenuBar
,QMenu
,QMdiSubWindow
,QMainWindow
,QLineEdit
,QKeySequenceEdit
,QGroupBox
,QFrame
,QToolBox
,QStackedWidget
,QSplitter
,QLabel
,QLCDNumber
,QAbstractScrollArea
,QTextEdit
,QTextBrowser
,QScrollArea
,QPlainTextEdit
,QMdiArea
,QGraphicsView
,QAbstractItemView
,QTreeView
,QTreeWidget
,QHelpContentWidget
,QTableView
,QTableWidget
,QListView
,QUndoView
,QListWidget
,QHelpIndexWidget
,QHeaderView
,QColumnView
,QPdfView
,QFocusFrame
,QDockWidget
,QDialogButtonBox
,QDialog
,QWizard
,QProgressDialog
,QMessageBox
,QInputDialog
,QFontDialog
,QErrorMessage
,QColorDialog
,QPrintPreviewDialog
,QPageSetupDialog
,QAbstractPrintDialog
,QPrintDialog
,QComboBox
,QFontComboBox
,QCalendarWidget
,QAbstractSpinBox
,QSpinBox
,QDoubleSpinBox
,QDateTimeEdit
,QTimeEdit
,QDateEdit
,QAbstractSlider
,QSlider
,QScrollBar
,QDial
,QAbstractButton
,QToolButton
,QRadioButton
,QPushButton
,QCommandLinkButton
,QCheckBox
,QSvgWidget
,QQuickWidget
,QAbstract3DGraph
,Q3DSurface
,Q3DScatter
,Q3DBars
,QPrintPreviewWidget
,QPdfPageSelector
,QOpenGLWidget
,QVideoWidget
,QHelpSearchResultWidget
,QHelpSearchQueryWidget
,QHelpFilterSettingsWidget
,QDesignerWidgetBoxInterface
,QDesignerPropertyEditorInterface
,QDesignerObjectInspectorInterface
,QDesignerFormWindowInterface
,QDesignerActionEditorInterface
,QSystemTrayIcon
,QStyle
,QCommonStyle
,QProxyStyle
,QScroller
,QLayout
,QStackedLayout
,QGridLayout
,QFormLayout
,QBoxLayout
,QVBoxLayout
,QHBoxLayout
,QGraphicsTransform
,QGraphicsScale
,QGraphicsRotation
,QGraphicsScene
,QGraphicsObject
,QGraphicsWidget
,QGraphicsProxyWidget
,QGraphicsTextItem
,QGraphicsSvgItem
,QGraphicsVideoItem
,QGraphicsItemAnimation
,QGraphicsEffect
,QGraphicsOpacityEffect
,QGraphicsDropShadowEffect
,QGraphicsColorizeEffect
,QGraphicsBlurEffect
,QGraphicsAnchor
,QGesture
,QTapGesture
,QTapAndHoldGesture
,QSwipeGesture
,QPinchGesture
,QPanGesture
,QDataWidgetMapper
,QCompleter
,QButtonGroup
,QAbstractItemDelegate
,QStyledItemDelegate
,QItemDelegate
,QMaskGenerator
,QQuickWebEngineProfile
,QWebEngineWebAuthUxRequest
,QWebEngineUrlSchemeHandler
,QWebEngineUrlRequestJob
,QWebEngineUrlRequestInterceptor
,QWebEngineProfile
,QWebEngineNotification
,QWebEngineNewWindowRequest
,QWebEngineHistory
,QWebEngineDownloadRequest
,QWebEngineContextMenuRequest
,QWebChannelAbstractTransport
,QWebChannel
,QUiLoader
,QTextToSpeechEngine
,QTextToSpeech
,QSignalSpy
,QAbstractItemModelTester
,QSvgRenderer
,QAbstractTransition
,QSignalTransition
,QEventTransition
,QMouseEventTransition
,QKeyEventTransition
,QAbstractState
,QState
,QStateMachine
,QHistoryState
,QFinalState
,QSqlDriver
,QSpatialSound
,QAudioRoom
,QAudioListener
,QAudioEngine
,QAmbientSound
,QModbusReply
,QModbusDevice
,QModbusServer
,QModbusTcpServer
,QModbusRtuSerialServer
,QModbusClient
,QModbusTcpClient
,QModbusRtuSerialClient
,QCanBusDevice
,QCanBus
,QSensorReading
,QTiltReading
,QTapReading
,QRotationReading
,QProximityReading
,QPressureReading
,QOrientationReading
,QMagnetometerReading
,QLightReading
,QLidReading
,QIRProximityReading
,QHumidityReading
,QGyroscopeReading
,QCompassReading
,QAmbientTemperatureReading
,QAmbientLightReading
,QAccelerometerReading
,QSensorBackend
,QSensor
,QTiltSensor
,QTapSensor
,QRotationSensor
,QProximitySensor
,QPressureSensor
,QOrientationSensor
,QMagnetometer
,QLightSensor
,QLidSensor
,QIRProximitySensor
,QHumiditySensor
,QGyroscope
,QCompass
,QAmbientTemperatureSensor
,QAmbientLightSensor
,QAccelerometer
,QScxmlStateMachine
,QScxmlInvokableServiceFactory
,QScxmlStaticScxmlServiceFactory
,QScxmlDynamicScxmlServiceFactory
,QScxmlInvokableService
,QScxmlDataModel
,QScxmlNullDataModel
,QScxmlCppDataModel
,QRemoteObjectReplica
,QRemoteObjectRegistry
,QRemoteObjectDynamicReplica
,QRemoteObjectPendingCallWatcher
,QRemoteObjectNode
,QRemoteObjectAbstractPersistedStore
,QRemoteObjectSettingsStore
,QQuick3DObject
,QQuick3DTextureData
,QQuick3DRenderExtension
,QQuick3DInstancing
,QQuick3DGeometry
,QSGTextureProvider
,QSGTexture
,QSGDynamicTexture
,QQuickTransform
,QQuickTextureFactory
,QQuickTextDocument
,QQuickRenderControl
,QQuickItemGrabResult
,QQuickItem
,QQuickRhiItem
,QQuickPaintedItem
,QQuickFramebufferObject
,QQuickImageResponse
,QQmlPropertyMap
,QQmlImageProviderBase
,QQuickImageProvider
,QQuickAsyncImageProvider
,QQmlFileSelector
,QQmlExtensionPlugin
,QQmlExpression
,QQmlContext
,QQmlComponent
,QJSEngine
,QQmlEngine
,QGeoSatelliteInfoSource
,QGeoPositionInfoSource
,QNmeaPositionInfoSource
,QGeoAreaMonitorSource
,QPdfPageRenderer
,QPdfPageNavigator
,QPdfDocument
,QOpenGLVertexArrayObject
,QOpenGLTimerQuery
,QOpenGLTimeMonitor
,QOpenGLShaderProgram
,QOpenGLShader
,QOpenGLDebugLogger
,QOpcUaProvider
,QOpcUaNode
,QOpcUaHistoryReadResponse
,QOpcUaGenericStructHandler
,QOpcUaClient
,QNearFieldTarget
,QNearFieldManager
,QAbstractOAuthReplyHandler
,QOAuthOobReplyHandler
,QRestAccessManager
,QNetworkInformation
,QNetworkCookieJar
,QNetworkAccessManager
,QLocalServer
,QHttpMultiPart
,QDtlsClientVerifier
,QDnsLookup
,QAbstractNetworkCache
,QNetworkDiskCache
,QWindowCapture
,QVideoSink
,QSoundEffect
,QScreenCapture
,QMediaRecorder
,QMediaDevices
,QMediaCaptureSession
,QImageCapture
,QCamera
,QAudioSource
,QAudioSink
,QAudioOutput
,QAudioInput
,QAudioDecoder
,QMqttSubscription
,QPlaceReply
,QPlaceSearchSuggestionReply
,QPlaceSearchReply
,QPlaceMatchReply
,QPlaceIdReply
,QPlaceDetailsReply
,QPlaceContentReply
,QPlaceManagerEngine
,QPlaceManager
,QGeoServiceProvider
,QGeoRoutingManagerEngine
,QGeoRoutingManager
,QGeoRouteReply
,QGeoCodingManagerEngine
,QGeoCodingManager
,QGeoCodeReply
,QHelpSearchEngine
,QHelpFilterEngine
,QHelpEngineCore
,QHelpEngine
,QWindow
,QQuickWindow
,QQuickView
,QPaintDeviceWindow
,QOpenGLWindow
,QRasterWindow
,QValidator
,QRegularExpressionValidator
,QIntValidator
,QDoubleValidator
,QUndoStack
,QUndoGroup
,QTextObject
,QTextFrame
,QTextTable
,QTextBlockGroup
,QTextList
,QTextDocument
,QSyntaxHighlighter
,QStyleHints
,QShortcut
,QSessionManager
,QScreen
,QPdfWriter
,QOpenGLContextGroup
,QOpenGLContext
,QOffscreenSurface
,QInputMethod
,QInputDevice
,QPointingDevice
,QDrag
,QClipboard
,QActionGroup
,QAction
,QWidgetAction
,QAbstractTextDocumentLayout
,QPlainTextDocumentLayout
,QValue3DAxisFormatter
,QLogValue3DAxisFormatter
,QSeriesTheme
,QGraphTheme
,QCustom3DItem
,QCustom3DVolume
,QCustom3DLabel
,QBarSet
,QAbstractSeries
,QXYSeries
,QScatterSeries
,QLineSeries
,QAbstractBarSeries
,QBarSeries
,QAbstractDataProxy
,QSurfaceDataProxy
,QItemModelSurfaceDataProxy
,QHeightMapSurfaceDataProxy
,QScatterDataProxy
,QItemModelScatterDataProxy
,QBarDataProxy
,QItemModelBarDataProxy
,QAbstractAxis
,QValueAxis
,QBarCategoryAxis
,QAbstract3DSeries
,QSurface3DSeries
,QScatter3DSeries
,QBar3DSeries
,QAbstract3DInputHandler
,Q3DInputHandler
,QTouch3DInputHandler
,QAbstract3DAxis
,QValue3DAxis
,QCategory3DAxis
,Q3DTheme
,Q3DScene
,QExtensionManager
,QDesignerFormWindowToolInterface
,QDesignerFormWindowManagerInterface
,QDesignerFormEditorInterface
,QDBusVirtualObject
,QDBusServiceWatcher
,QDBusServer
,QDBusPendingCallWatcher
,QDBusAbstractInterfaceBase
,QDBusAbstractInterface
,QDBusInterface
,QDBusConnectionInterface
,QDBusAbstractAdaptor
,QTranslator
,QTimer
,QTimeLine
,QThreadPool
,QSocketNotifier
,QSignalMapper
,QSharedMemory
,QSettings
,QPluginLoader
,QMimeData
,QLibrary
,QItemSelectionModel
,QIODevice
,QSerialPort
,QNetworkReply
,QLocalSocket
,QAbstractSocket
,QUdpSocket
,QTcpSocket
,QWebSocketServer
,QOAuthHttpServerReplyHandler
,QTcpServer
,QSslServer
,QAbstractHttpServer
,QHttpServer
,QProcess
,QFutureWatcherBase
,QFutureWatcher
,QFileSystemWatcher
,QFileSelector
,QFileDevice
,QSaveFile
,QFile
,QTemporaryFile
,QEventLoop
,QThread
,QCoreApplication
,QGuiApplication
,QApplication
,QWebSocket
,QAbstractOAuth
,QOAuth1
,QAbstractOAuth2
,QOAuth2AuthorizationCodeFlow
,QSslSocket
,QDtls
,QMqttClient
,QMovie
,QFileDialog
,QWebEngineView
,QWebEnginePage
,QWebEngineCookieStore
,QRemoteObjectHostBase
,QRemoteObjectRegistryHost
,QRemoteObjectHost
,QQmlApplicationEngine
,QMediaPlayer
,QBuffer
,QAbstractItemModel
,QFileSystemModel
,QAbstractItemModelReplica
,QPdfBookmarkModel
,QHelpContentModel
,QStandardItemModel
,QConcatenateTablesProxyModel
,QAbstractTableModel
,QSqlQueryModel
,QSqlTableModel
,QSqlRelationalTableModel
,QAbstractProxyModel
,QTransposeProxyModel
,QSortFilterProxyModel
,QIdentityProxyModel
,QAbstractListModel
,QWebEngineHistoryModel
,QPdfSearchModel
,QPdfLinkModel
,QStringListModel
,QHelpIndexModel
,QAbstractEventDispatcher
,QAbstractAnimation
,QVariantAnimation
,QPropertyAnimation
,QPauseAnimation
,QAnimationGroup
,QSequentialAnimationGroup
,QParallelAnimationGroup
,QFutureWatcherVoid
,QFutureWatcherQString
,QCoapReply
,QCoapResourceDiscoveryReply
,QCoapClient
,QXYModelMapper
,QVXYModelMapper
,QStackedBarSeries
,QSplineSeries
,QPieSlice
,QPieSeries
,QPieModelMapper
,QVPieModelMapper
,QPercentBarSeries
,QLogValueAxis
,QLegendMarker
,QXYLegendMarker
,QPieLegendMarker
,QLegend
,QHorizontalStackedBarSeries
,QHorizontalPercentBarSeries
,QHorizontalBarSeries
,QHXYModelMapper
,QHPieModelMapper
,QDateTimeAxis
,QColorAxis
,QChartView
,QChart
,QPolarChart
,QCategoryAxis
,QCandlestickSet
,QCandlestickSeries
,QCandlestickModelMapper
,QVCandlestickModelMapper
,QHCandlestickModelMapper
,QCandlestickLegendMarker
,QBoxSet
,QBoxPlotSeries
,QBoxPlotModelMapper
,QVBoxPlotModelMapper
,QHBoxPlotModelMapper
,QBoxPlotLegendMarker
,QBarModelMapper
,QVBarModelMapper
,QHBarModelMapper
,QBarLegendMarker
,QAreaSeries
,QAreaLegendMarker
,QLowEnergyService
,QLowEnergyController
,QBluetoothSocket
,QBluetoothServiceDiscoveryAgent
,QBluetoothLocalDevice
,QBluetoothDeviceDiscoveryAgent
,QBluetoothServer
,QTextureWrapMode
,QStencilTestArguments
,QStencilOperationArguments
,QRenderCaptureReply
,QRenderCapabilities
,QPickEvent
,QPickTriangleEvent
,QPickPointEvent
,QPickLineEvent
,QGraphicsApiFilter
,QWheelEvent
,QMouseEvent
,QKeyEvent
,Qt3DWindow
,QNode
,QTechnique
,QShaderProgramBuilder
,QShaderProgram
,QShaderImage
,QRenderTargetOutput
,QRenderState
,QStencilTest
,QStencilOperation
,QStencilMask
,QSeamlessCubemap
,QScissorTest
,QRasterMode
,QPolygonOffset
,QPointSize
,QNoDepthMask
,QMultiSampleAntiAliasing
,QLineWidth
,QFrontFace
,QDithering
,QDepthTest
,QDepthRange
,QCullFace
,QColorMask
,QClipPlane
,QBlendEquationArguments
,QBlendEquation
,QAlphaTest
,QAlphaCoverage
,QRenderPass
,QPickingSettings
,QParameter
,QFrameGraphNode
,QWaitFence
,QViewport
,QTechniqueFilter
,QForwardRenderer
,QSubtreeEnabler
,QSortPolicy
,QSetFence
,QRenderTargetSelector
,QRenderSurfaceSelector
,QRenderStateSet
,QRenderPassFilter
,QRenderCapture
,QProximityFilter
,QNoPicking
,QNoDraw
,QMemoryBarrier
,QLayerFilter
,QFrustumCulling
,QDispatchCompute
,QClearBuffers
,QCameraSelector
,QBufferCapture
,QBlitFramebuffer
,QFilterKey
,QEffect
,QAbstractTextureImage
,QTextureImage
,QPaintedTextureImage
,QAbstractTexture
,QTextureRectangle
,QTextureLoader
,QTextureCubeMapArray
,QTextureCubeMap
,QTextureBuffer
,QTexture3D
,QTexture2DMultisampleArray
,QTexture2DMultisample
,QTexture2DArray
,QTexture2D
,QTexture1DArray
,QTexture1D
,QSharedGLTexture
,QAxisSetting
,QAxis
,QAction
,QAbstractPhysicalDevice
,QMouseDevice
,QKeyboardDevice
,QAbstractAxisInput
,QButtonAxisInput
,QAnalogAxisInput
,QAbstractActionInput
,QInputSequence
,QInputChord
,QActionInput
,QSpriteSheetItem
,QAbstractSpriteSheet
,QSpriteSheet
,QSpriteGrid
,QJoint
,QGeometryView
,QTorusGeometryView
,QSphereGeometryView
,QPlaneGeometryView
,QCylinderGeometryView
,QCuboidGeometryView
,QConeGeometryView
,QGeometry
,QTorusGeometry
,QSphereGeometry
,QPlaneGeometry
,QExtrudedTextGeometry
,QCylinderGeometry
,QCuboidGeometry
,QConeGeometry
,QEntity
,QCamera
,QText2DEntity
,QSkyboxEntity
,QAbstractCameraController
,QOrbitCameraController
,QFirstPersonCameraController
,QComponent
,QShaderData
,QSceneLoader
,QRenderTarget
,QRenderSettings
,QObjectPicker
,QMaterial
,QTextureMaterial
,QPhongMaterial
,QPhongAlphaMaterial
,QPerVertexColorMaterial
,QNormalDiffuseSpecularMapMaterial
,QNormalDiffuseMapMaterial
,QNormalDiffuseMapAlphaMaterial
,QMorphPhongMaterial
,QMetalRoughMaterial
,QGoochMaterial
,QDiffuseSpecularMaterial
,QDiffuseSpecularMapMaterial
,QDiffuseMapMaterial
,QLevelOfDetail
,QLevelOfDetailSwitch
,QLayer
,QEnvironmentLight
,QComputeCommand
,QCameraLens
,QAbstractRayCaster
,QScreenRayCaster
,QRayCaster
,QAbstractLight
,QSpotLight
,QPointLight
,QDirectionalLight
,QFrameAction
,QMouseHandler
,QLogicalDevice
,QKeyboardHandler
,QInputSettings
,QAxisAccumulator
,QTransform
,QCoreSettings
,QBuffer
,QBoundingVolume
,QPickingProxy
,QGeometryRenderer
,QMesh
,QTorusMesh
,QSphereMesh
,QPlaneMesh
,QExtrudedTextMesh
,QCylinderMesh
,QCuboidMesh
,QConeMesh
,QAttribute
,QAspectEngine
,QArmature
,QAbstractSkeleton
,QSkeletonLoader
,QSkeleton
,QAbstractAspect
,QRenderAspect
,QLogicAspect
,QInputAspect
,QMorphTarget
,QClock
,QChannelMapper
,QAnimationGroup
,QAnimationController
,QAnimationAspect
,QAbstractClipBlendNode
,QLerpClipBlend
,QClipBlendValue
,QAdditiveClipBlend
,QAbstractClipAnimator
,QClipAnimator
,QBlendedClipAnimator
,QAbstractChannelMapping
,QSkeletonMapping
,QChannelMapping
,QAbstractAnimationClip
,QAnimationClipLoader
,QAnimationClip
,QAbstractAnimation
,QVertexBlendAnimation
,QMorphingAnimation
,QKeyframeAnimation
Synopsis#
Properties#
objectNameᅟ
- The name of this object
Methods#
def
__init__()
def
blockSignals()
def
children()
def
connect()
def
disconnect()
def
dumpObjectInfo()
def
dumpObjectTree()
def
emit()
def
findChild()
def
findChildren()
def
inherits()
def
isWidgetType()
def
isWindowType()
def
killTimer()
def
moveToThread()
def
objectName()
def
parent()
def
property()
def
receivers()
def
sender()
def
setObjectName()
def
setParent()
def
setProperty()
def
signalsBlocked()
def
startTimer()
def
thread()
def
tr()
Virtual methods#
def
childEvent()
def
connectNotify()
def
customEvent()
def
event()
def
eventFilter()
def
metaObject()
def
timerEvent()
Slots#
def
deleteLater()
Signals#
def
destroyed()
Static functions#
def
connect()
def
disconnect()
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
QObject
is the heart of the Qt Object Model . The central feature in this model is a very powerful mechanism for seamless object communication called signals and slots . You can connect a signal to a slot withconnect()
and destroy the connection withdisconnect()
. To avoid never ending notification loops you can temporarily block signals withblockSignals()
. The protected functionsconnectNotify()
anddisconnectNotify()
make it possible to track connections.QObjects organize themselves in object trees . When you create a
QObject
with another object as parent, the object will automatically add itself to the parent’schildren()
list. The parent takes ownership of the object; i.e., it will automatically delete its children in its destructor. You can look for an object by name and optionally type usingfindChild()
orfindChildren()
.Every object has an
objectName()
and its class name can be found via the correspondingmetaObject()
(seeclassName()
). You can determine whether the object’s class inherits another class in theQObject
inheritance hierarchy by using theinherits()
function.When an object is deleted, it emits a
destroyed()
signal. You can catch this signal to avoid dangling references to QObjects.QObjects can receive events through
event()
and filter the events of other objects. SeeinstallEventFilter()
andeventFilter()
for details. A convenience handler,childEvent()
, can be reimplemented to catch child events.Last but not least,
QObject
provides the basic timer support in Qt; seeQTimer
for high-level support for timers.Notice that the
Q_OBJECT
macro is mandatory for any object that implements signals, slots or properties. You also need to run the Meta Object Compiler on the source file. We strongly recommend the use of this macro in all subclasses ofQObject
regardless of whether or not they actually use signals, slots and properties, since failure to do so may lead certain functions to exhibit strange behavior.All Qt widgets inherit
QObject
. The convenience functionisWidgetType()
returns whether an object is actually a widget. It is much faster thanqobject_cast
<QWidget *>(obj) or obj->inherits
(“QWidget”).Some
QObject
functions, e.g.children()
, return aQObjectList
.QObjectList
is a typedef forQList
<QObject
*>.Thread Affinity#
A
QObject
instance is said to have a thread affinity, or that it lives in a certain thread. When aQObject
receives aqueued signal
or a posted event , the slot or event handler will run in the thread that the object lives in.Note
If a
QObject
has no thread affinity (that is, ifthread()
returns zero), or if it lives in a thread that has no running event loop, then it cannot receive queued signals or posted events.By default, a
QObject
lives in the thread in which it is created. An object’s thread affinity can be queried usingthread()
and changed usingmoveToThread()
.All QObjects must live in the same thread as their parent. Consequently:
setParent()
will fail if the two QObjects involved live in different threads.When a
QObject
is moved to another thread, all its children will be automatically moved too.moveToThread()
will fail if theQObject
has a parent.If QObjects are created within
run()
, they cannot become children of theQThread
object because theQThread
does not live in the thread that callsrun()
.
Note
A
QObject
‘s member variables do not automatically become its children. The parent-child relationship must be set by either passing a pointer to the child’sconstructor
, or by callingsetParent()
. Without this step, the object’s member variables will remain in the old thread whenmoveToThread()
is called.No Copy Constructor or Assignment Operator#
QObject
has neither a copy constructor nor an assignment operator. This is by design. Actually, they are declared, but in aprivate
section with the macroQ_DISABLE_COPY()
. In fact, all Qt classes derived fromQObject
(direct or indirect) use this macro to declare their copy constructor and assignment operator to be private. The reasoning is found in the discussion on Identity vs Value on the Qt Object Model page.The main consequence is that you should use pointers to
QObject
(or to yourQObject
subclass) where you might otherwise be tempted to use yourQObject
subclass as a value. For example, without a copy constructor, you can’t use a subclass ofQObject
as the value to be stored in one of the container classes. You must store pointers.Auto-Connection#
Qt’s meta-object system provides a mechanism to automatically connect signals and slots between
QObject
subclasses and their children. As long as objects are defined with suitable object names, and slots follow a simple naming convention, this connection can be performed at run-time by theconnectSlotsByName()
function.uic generates code that invokes this function to enable auto-connection to be performed between widgets on forms created with Qt Designer. More information about using auto-connection with Qt Designer is given in the Using a Designer UI File in Your Application section of the Qt Designer manual.
Dynamic Properties#
Dynamic properties can be added to and removed from
QObject
instances at run-time. Dynamic properties do not need to be declared at compile-time, yet they provide the same advantages as static properties and are manipulated using the same API - usingproperty()
to read them andsetProperty()
to write them.Dynamic properties are supported by Qt Designer, and both standard Qt widgets and user-created forms can be given dynamic properties.
Internationalization (I18n)#
All
QObject
subclasses support Qt’s translation features, making it possible to translate an application’s user interface into different languages.To make user-visible text translatable, it must be wrapped in calls to the
tr()
function. This is explained in detail in the Writing Source Code for Translation document.See also
QMetaObject
QPointer
QObjectCleanupHandler
Q_DISABLE_COPY()
Object Trees & OwnershipNote
Properties can be used directly when
from __feature__ import true_property
is used or via accessor functions otherwise.- property objectNameᅟ: str#
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
This property holds the name of this object.
You can find an object by name (and type) using
findChild()
. You can find a set of objects withfindChildren()
.qDebug("MyClass.setPrecision(): (%s) invalid precision %f", qPrintable(objectName()), newPrecision)
By default, this property contains an empty string.
See also
- Access functions:
Constructs an object with parent object
parent
.The parent of an object may be viewed as the object’s owner. For instance, a dialog box is the parent of the OK and Cancel buttons it contains.
The destructor of a parent object destroys all child objects.
Setting
parent
toNone
constructs an object with no parent. If the object is a widget, it will become a top-level window.See also
- blockSignals(b)#
- Parameters:
b – bool
- Return type:
bool
If
block
is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). Ifblock
is false, no such blocking will occur.The return value is the previous value of
signalsBlocked()
.Note that the
destroyed()
signal will be emitted even if the signals for this object have been blocked.Signals emitted while being blocked are not buffered.
See also
- childEvent(event)#
- Parameters:
event –
QChildEvent
This event handler can be reimplemented in a subclass to receive child events. The event is passed in the
event
parameter.ChildAdded
andChildRemoved
events are sent to objects when children are added or removed. In both cases you can only rely on the child being aQObject
, or ifisWidgetType()
returnstrue
, a QWidget. (This is because, in theChildAdded
case, the child is not yet fully constructed, and in theChildRemoved
case it might have been destructed already).ChildPolished
events are sent to widgets when children are polished, or when polished children are added. If you receive a child polished event, the child’s construction is usually completed. However, this is not guaranteed, and multiple polish events may be delivered during the execution of a widget’s constructor.For every child widget, you receive one
ChildAdded
event, zero or moreChildPolished
events, and oneChildRemoved
event.The
ChildPolished
event is omitted if a child is removed immediately after it is added. If a child is polished several times during construction and destruction, you may receive several child polished events for the same child, each time with a different virtual table.See also
Returns a list of child objects. The
QObjectList
class is defined in the<QObject>
header file as the following:The first child added is the
first
object in the list and the last child added is thelast
object in the list, i.e. new children are appended at the end.Note that the list order changes when QWidget children are raised or lowered. A widget that is raised becomes the last object in the list, and a widget that is lowered becomes the first object in the list.
See also
- connect(signal, receiver, method[, type=Qt.AutoConnection])#
- Parameters:
signal – str
receiver –
QObject
method – str
type –
ConnectionType
- Return type:
Connection
- connect(signal, functor[, type=Qt.AutoConnection])
- Parameters:
signal – str
functor –
PyCallable
type –
ConnectionType
- Return type:
Connection
- connect(sender, signal, member[, type=Qt.AutoConnection])
- Parameters:
sender –
QObject
signal – str
member – str
type –
ConnectionType
- Return type:
Connection
This function overloads
connect()
.Connects
signal
from thesender
object to this object’smethod
.Equivalent to connect(
sender
,signal
,this
,method
,type
).Every connection you make emits a signal, so duplicate connections emit two signals. You can break a connection using
disconnect()
.See also
- static connect(sender, signal, receiver, member[, type=Qt.AutoConnection])
- Parameters:
sender –
QObject
signal – str
receiver –
QObject
member – str
type –
ConnectionType
- Return type:
Connection
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Creates a connection of the given
type
from thesignal
in thesender
object to themethod
in thereceiver
object. Returns a handle to the connection that can be used to disconnect it later.You must use the
SIGNAL()
andSLOT()
macros when specifying thesignal
and themethod
, for example:label = QLabel() scrollBar = QScrollBar() QObject.connect(scrollBar, SIGNAL(valueChanged(int)), label, SLOT(setNum(int)))
This example ensures that the label always displays the current scroll bar value. Note that the signal and slots parameters must not contain any variable names, only the type. E.g. the following would not work and return false:
# WRONG QObject.connect(scrollBar, SIGNAL(valueChanged(int value)), label, SLOT(setNum(int value)))
A signal can also be connected to another signal:
class MyWidget(QWidget): Q_OBJECT # public MyWidget() # signals def buttonClicked(): # private myButton = QPushButton() def __init__(self): myButton = QPushButton(self) connect(myButton, SIGNAL(clicked()), self, SIGNAL(buttonClicked()))
In this example, the
MyWidget
constructor relays a signal from a private member variable, and makes it available under a name that relates toMyWidget
.A signal can be connected to many slots and signals. Many signals can be connected to one slot.
If a signal is connected to several slots, the slots are activated in the same order in which the connections were made, when the signal is emitted.
The function returns a
Connection
that represents a handle to a connection if it successfully connects the signal to the slot. The connection handle will be invalid if it cannot create the connection, for example, ifQObject
is unable to verify the existence of eithersignal
ormethod
, or if their signatures aren’t compatible. You can check if the handle is valid by casting it to a bool.By default, a signal is emitted for every connection you make; two signals are emitted for duplicate connections. You can break all of these connections with a single
disconnect()
call. If you pass theUniqueConnection
type
, the connection will only be made if it is not a duplicate. If there is already a duplicate (exact same signal to the exact same slot on the same objects), the connection will fail and connect will return an invalidConnection
.Note
Qt::UniqueConnections do not work for lambdas, non-member functions and functors; they only apply to connecting to member functions.
The optional
type
parameter describes the type of connection to establish. In particular, it determines whether a particular signal is delivered to a slot immediately or queued for delivery at a later time. If the signal is queued, the parameters must be of types that are known to Qt’s meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes. If you try to use a queued connection and get the error messageQObject.connect: Cannot queue arguments of type 'MyType' (Make sure 'MyType' is registered using qRegisterMetaType().)
call
qRegisterMetaType()
to register the data type before you establish the connection.See also
disconnect()
sender()
qRegisterMetaType()
Q_DECLARE_METATYPE()
Differences between String-Based and Functor-Based Connections
- static connect(sender, signal, context, functor[, type=Qt.AutoConnection])
- Parameters:
sender –
QObject
signal – str
context –
QObject
functor –
PyCallable
type –
ConnectionType
- Return type:
Connection
- static connect(sender, signal, functor[, type=Qt.AutoConnection])
- Parameters:
sender –
QObject
signal – str
functor –
PyCallable
type –
ConnectionType
- Return type:
Connection
- static connect(sender, signal, receiver, method[, type=Qt.AutoConnection])
- Parameters:
sender –
QObject
signal –
QMetaMethod
receiver –
QObject
method –
QMetaMethod
type –
ConnectionType
- Return type:
Connection
Creates a connection of the given
type
from thesignal
in thesender
object to themethod
in thereceiver
object. Returns a handle to the connection that can be used to disconnect it later.The Connection handle will be invalid if it cannot create the connection, for example, the parameters were invalid. You can check if the
Connection
is valid by casting it to a bool.This function works in the same way as
connect(const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type)
but it usesQMetaMethod
to specify signal and method.See also
ConnectionType type)
- connectNotify(signal)#
- Parameters:
signal –
QMetaMethod
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
This virtual function is called when something has been connected to
signal
in this object.If you want to compare
signal
with a specific signal, you can usefromSignal()
as follows:if signal == QMetaMethod.fromSignal(MyObject.valueChanged): # signal is valueChanged
Warning
This function violates the object-oriented principle of modularity. However, it might be useful when you need to perform expensive initialization only if something is connected to a signal.
Warning
This function is called from the thread which performs the connection, which may be a different thread from the thread in which this object lives. This function may also be called with a
QObject
internal mutex locked. It is therefore not allowed to re-enter anyQObject
functions, includingisSignalConnected()
, from your reimplementation. If you lock a mutex in your reimplementation, make sure that you don’t callQObject
functions with that mutex held in other places or it will result in a deadlock.See also
This event handler can be reimplemented in a subclass to receive custom events. Custom events are user-defined events with a type value at least as large as the
User
item of theType
enum, and is typically aQEvent
subclass. The event is passed in theevent
parameter.- deleteLater()#
Schedules this object for deletion.
The object will be deleted when control returns to the event loop. If the event loop is not running when this function is called (e.g. deleteLater() is called on an object before
exec()
), the object will be deleted once the event loop is started. If deleteLater() is called after the main event loop has stopped, the object will not be deleted. If deleteLater() is called on an object that lives in a thread with no running event loop, the object will be destroyed when the thread finishes.Note that entering and leaving a new event loop (e.g., by opening a modal dialog) will not perform the deferred deletion; for the object to be deleted, the control must return to the event loop from which deleteLater() was called. This does not apply to objects deleted while a previous, nested event loop was still running: the Qt event loop will delete those objects as soon as the new nested event loop starts.
In situations where Qt is not driving the event dispatcher via e.g.
exec()
orexec()
, deferred deletes will not be processed automatically. To ensure deferred deletion in this scenario, the following workaround can be used:const auto *eventDispatcher = QThread::currentThread()->eventDispatcher(); QObject::connect(eventDispatcher, &QAbstractEventDispatcher::aboutToBlock, QThread::currentThread(), []{ if (QThread::currentThread()->loopLevel() == 0) QCoreApplication::sendPostedEvents(nullptr, QEvent::DeferredDelete); } );
See also
destroyed()
QPointer
This signal is emitted immediately before the object
obj
is destroyed, after any instances ofQPointer
have been notified, and cannot be blocked.All the objects’s children are destroyed immediately after this signal is emitted.
See also
deleteLater()
QPointer
- static disconnect(connection)#
- Parameters:
connection –
Connection
- Return type:
bool
Disconnect a connection.
If the
connection
is invalid or has already been disconnected, do nothing and return false.See also
- disconnect(signal, receiver, member)
- Parameters:
signal – str
receiver –
QObject
member – str
- Return type:
bool
This function overloads
disconnect()
.Disconnects
signal
frommethod
ofreceiver
.A signal-slot connection is removed when either of the objects involved are destroyed.
Note
Disconnecting all signal-slot connections will also disconnect the
destroyed()
signal if it is connected. Doing so can adversely affect classes that rely on this signal for cleaning up resources. It is recommended to disconnect only the specific signals that were connected by application code.- disconnect(signal, functor)
- Parameters:
signal – str
functor –
PyCallable
- Return type:
bool
- static disconnect(sender, signal, receiver, member)
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Disconnects
signal
in objectsender
frommethod
in objectreceiver
. Returnstrue
if the connection is successfully broken; otherwise returnsfalse
.A signal-slot connection is removed when either of the objects involved are destroyed.
disconnect() is typically used in three ways, as the following examples demonstrate.
Disconnect everything connected to an object’s signals:
disconnect(myObject, None, None, None)
equivalent to the non-static overloaded function
myObject.disconnect()
Disconnect everything connected to a specific signal:
disconnect(myObject, SIGNAL(mySignal()), None, None)
equivalent to the non-static overloaded function
myObject.disconnect(SIGNAL(mySignal()))
Disconnect a specific receiver:
disconnect(myObject, None, myReceiver, None)
equivalent to the non-static overloaded function
myObject.disconnect(myReceiver)
None
may be used as a wildcard, meaning “any signal”, “any receiving object”, or “any slot in the receiving object”, respectively.The
sender
may never beNone
. (You cannot disconnect signals from more than one object in a single call.)If
signal
isNone
, it disconnectsreceiver
andmethod
from any signal. If not, only the specified signal is disconnected.If
receiver
isNone
, it disconnects anything connected tosignal
. If not, slots in objects other thanreceiver
are not disconnected.If
method
isNone
, it disconnects anything that is connected toreceiver
. If not, only slots namedmethod
will be disconnected, and all other slots are left alone. Themethod
must beNone
ifreceiver
is left out, so you cannot disconnect a specifically-named slot on all objects.Note
Disconnecting all signal-slot connections will also disconnect the
destroyed()
signal if it is connected. Doing so can adversely affect classes that rely on this signal for cleaning up resources. It is recommended to disconnect only the specific signals that were connected by application code.See also
- static disconnect(sender, signal, functor)
- Parameters:
sender –
QObject
signal – str
functor –
PyCallable
- Return type:
bool
- static disconnect(sender, signal, receiver, member)
- Parameters:
sender –
QObject
signal –
QMetaMethod
receiver –
QObject
member –
QMetaMethod
- Return type:
bool
Disconnects
signal
in objectsender
frommethod
in objectreceiver
. Returnstrue
if the connection is successfully broken; otherwise returnsfalse
.This function provides the same possibilities like
disconnect(const QObject *sender, const char *signal, const QObject *receiver, const char *method)
but usesQMetaMethod
to represent the signal and the method to be disconnected.Additionally this function returns false and no signals and slots disconnected if:
signal
is not a member of sender class or one of its parent classes.method
is not a member of receiver class or one of its parent classes.signal
instance represents not a signal.
QMetaMethod() may be used as wildcard in the meaning “any signal” or “any slot in receiving object”. In the same way
None
can be used forreceiver
in the meaning “any receiving object”. In this case method should also be QMetaMethod().sender
parameter should be neverNone
.Note
Disconnecting all signal-slot connections will also disconnect the
destroyed()
signal if it is connected. Doing so can adversely affect classes that rely on this signal for cleaning up resources. It is recommended to disconnect only the specific signals that were connected by application code.See also
disconnect(const QObject *sender, const char *signal, const QObject *receiver, const char *method)
- disconnect(receiver[, member=None])
- Parameters:
receiver –
QObject
member – str
- Return type:
bool
This function overloads
disconnect()
.Disconnects all signals in this object from
receiver
'smethod
.A signal-slot connection is removed when either of the objects involved are destroyed.
- disconnectNotify(signal)#
- Parameters:
signal –
QMetaMethod
This virtual function is called when something has been disconnected from
signal
in this object.See
connectNotify()
for an example of how to comparesignal
with a specific signal.If all signals were disconnected from this object (e.g., the signal argument to
disconnect()
wasNone
), disconnectNotify() is only called once, and thesignal
will be an invalidQMetaMethod
(isValid()
returnsfalse
).Warning
This function violates the object-oriented principle of modularity. However, it might be useful for optimizing access to expensive resources.
Warning
This function is called from the thread which performs the disconnection, which may be a different thread from the thread in which this object lives. This function may also be called with a
QObject
internal mutex locked. It is therefore not allowed to re-enter anyQObject
functions, includingisSignalConnected()
, from your reimplementation. If you lock a mutex in your reimplementation, make sure that you don’t callQObject
functions with that mutex held in other places or it will result in a deadlock.See also
- dumpObjectInfo()#
Dumps information about signal connections, etc. for this object to the debug output.
- dumpObjectTree()#
Dumps a tree of children to the debug output.
- dynamicPropertyNames()#
- Return type:
.list of QByteArray
Returns the names of all properties that were dynamically added to the object using
setProperty()
.- emit(arg__1, arg__2)#
- Parameters:
arg__1 – str
arg__2 –
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
This virtual function receives events to an object and should return true if the event
e
was recognized and processed.The event() function can be reimplemented to customize the behavior of an object.
Make sure you call the parent event class implementation for all the events you did not handle.
Example:
class MyClass(QWidget): Q_OBJECT # public MyClass(QWidget parent = None) ~MyClass() bool event(QEvent* ev) override if ev.type() == QEvent.PolishRequest: # overwrite handling of PolishRequest if any doThings() return True else:if (ev.type() == QEvent.Show) { # complement handling of Show if any doThings2() QWidget.event(ev) return True # Make sure the rest of events are handled return QWidget.event(ev)
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Filters events if this object has been installed as an event filter for the
watched
object.In your reimplementation of this function, if you want to filter the
event
out, i.e. stop it being handled further, return true; otherwise return false.Example:
class MainWindow(QMainWindow): # public MainWindow() # protected bool eventFilter(QObject obj, QEvent ev) override # private textEdit = QTextEdit() def __init__(self): textEdit = QTextEdit() setCentralWidget(textEdit) textEdit.installEventFilter(self) def eventFilter(self, QObject obj, QEvent event): if obj == textEdit: if event.type() == QEvent.KeyPress: keyEvent = QKeyEvent(event) print("Ate key press", keyEvent.key()) return True else: return False else: # pass the event on to the parent class return QMainWindow.eventFilter(obj, event)
Notice in the example above that unhandled events are passed to the base class’s eventFilter() function, since the base class might have reimplemented eventFilter() for its own internal purposes.
Some events, such as
ShortcutOverride
must be explicitly accepted (by callingaccept()
on them) in order to prevent propagation.Warning
If you delete the receiver object in this function, be sure to return true. Otherwise, Qt will forward the event to the deleted object and the program might crash.
See also
- findChild(type[, name={}[, options=Qt.FindChildrenRecursively]])#
- Parameters:
type –
PyTypeObject
name – str
options – Combination of
FindChildOption
- Return type:
object
To find the child of a certain QObject, the first argument of this function should be the child’s type, and the second the name of the child:
... parent = QWidget() ... # The first argument must be the child type child1 = parent.findChild(QPushButton, "child_button") child2 = parent.findChild(QWidget, "child_widget")
- findChildren(type, pattern[, options=Qt.FindChildrenRecursively])#
- Parameters:
type –
PyTypeObject
pattern –
QRegularExpression
options – Combination of
FindChildOption
- Return type:
PySequence
- findChildren(type[, name={}[, options=Qt.FindChildrenRecursively]])
- Parameters:
type –
PyTypeObject
name – str
options – Combination of
FindChildOption
- Return type:
PySequence
Like the method findChild, the first parameter should be the child’s type.
- inherits(classname)#
- Parameters:
classname – str
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns
true
if this object is an instance of a class that inheritsclassName
or aQObject
subclass that inheritsclassName
; otherwise returnsfalse
.A class is considered to inherit itself.
Example:
timer = QTimer() # QTimer inherits QObject() timer.inherits("QTimer") # returns true timer.inherits("QObject") # returns true timer.inherits("QAbstractButton") # returns false # QVBoxLayout inherits QObject and QLayoutItem layout = QVBoxLayout() layout.inherits("QObject") # returns true layout.inherits("QLayoutItem") # returns true (even though QLayoutItem is not a QObject)
If you need to determine whether an object is an instance of a particular class for the purpose of casting it, consider using
qobject_cast
<Type *>(object) instead.See also
metaObject()
qobject_cast()
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Installs an event filter
filterObj
on this object. For example:monitoredObj.installEventFilter(filterObj)
An event filter is an object that receives all events that are sent to this object. The filter can either stop the event or forward it to this object. The event filter
filterObj
receives events via itseventFilter()
function. TheeventFilter()
function must return true if the event should be filtered, (i.e. stopped); otherwise it must return false.If multiple event filters are installed on a single object, the filter that was installed last is activated first.
If
filterObj
has already been installed for this object, this function moves it so it acts as if it was installed last.Here’s a
KeyPressEater
class that eats the key presses of its monitored objects:class KeyPressEater(QObject): Q_OBJECT ... # protected bool eventFilter(QObject obj, QEvent event) override def eventFilter(self, QObject obj, QEvent event): if event.type() == QEvent.KeyPress: keyEvent = QKeyEvent(event) qDebug("Ate key press %d", keyEvent.key()) return True else: # standard event processing return QObject.eventFilter(obj, event)
And here’s how to install it on two widgets:
keyPressEater = KeyPressEater(self) pushButton = QPushButton(self) listView = QListView(self) pushButton.installEventFilter(keyPressEater) listView.installEventFilter(keyPressEater)
The QShortcut class, for example, uses this technique to intercept shortcut key presses.
Warning
If you delete the receiver object in your
eventFilter()
function, be sure to return true. If you return false, Qt sends the event to the deleted object and the program will crash.Note that the filtering object must be in the same thread as this object. If
filterObj
is in a different thread, this function does nothing. If eitherfilterObj
or this object are moved to a different thread after calling this function, the event filter will not be called until both objects have the same thread affinity again (it is not removed).See also
- isQuickItemType()#
- Return type:
bool
Returns
true
if the object is a QQuickItem; otherwise returnsfalse
.Calling this function is equivalent to calling
inherits("QQuickItem")
, except that it is much faster.- isSignalConnected(signal)#
- Parameters:
signal –
QMetaMethod
- Return type:
bool
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns
true
if thesignal
is connected to at least one receiver, otherwise returnsfalse
.signal
must be a signal member of this object, otherwise the behaviour is undefined.valueChangedSignal = QMetaMethod.fromSignal(MyObject.valueChanged) if isSignalConnected(valueChangedSignal): data = QByteArray() data = get_the_value() # expensive operation valueChanged.emit(data)
As the code snippet above illustrates, you can use this function to avoid expensive initialization or emitting a signal that nobody listens to. However, in a multithreaded application, connections might change after this function returns and before the signal gets emitted.
Warning
This function violates the object-oriented principle of modularity. In particular, this function must not be called from an override of
connectNotify()
ordisconnectNotify()
, as those might get called from any thread.- isWidgetType()#
- Return type:
bool
Returns
true
if the object is a widget; otherwise returnsfalse
.Calling this function is equivalent to calling
inherits("QWidget")
, except that it is much faster.- isWindowType()#
- Return type:
bool
Returns
true
if the object is a window; otherwise returnsfalse
.Calling this function is equivalent to calling
inherits("QWindow")
, except that it is much faster.- killTimer(id)#
- Parameters:
id – int
Kills the timer with timer identifier,
id
.The timer identifier is returned by
startTimer()
when a timer event is started.See also
- metaObject()#
- Return type:
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns a pointer to the meta-object of this object.
A meta-object contains information about a class that inherits
QObject
, e.g. class name, superclass name, properties, signals and slots. EveryQObject
subclass that contains theQ_OBJECT
macro will have a meta-object.The meta-object information is required by the signal/slot connection mechanism and the property system. The
inherits()
function also makes use of the meta-object.If you have no pointer to an actual object instance but still want to access the meta-object of a class, you can use staticMetaObject .
Example:
obj = QPushButton() obj.metaObject().className() # returns "QPushButton" QPushButton.staticMetaObject.className() # returns "QPushButton"
See also
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Changes the thread affinity for this object and its children and returns
true
on success. The object cannot be moved if it has a parent. Event processing will continue in thetargetThread
.To move an object to the main thread, use QApplication::instance() to retrieve a pointer to the current application, and then use QApplication::thread() to retrieve the thread in which the application lives. For example:
myObject.moveToThread(QApplication.instance().thread())
If
targetThread
isNone
, all event processing for this object and its children stops, as they are no longer associated with any thread.Note that all active timers for the object will be reset. The timers are first stopped in the current thread and restarted (with the same interval) in the
targetThread
. As a result, constantly moving an object between threads can postpone timer events indefinitely.A
ThreadChange
event is sent to this object just before the thread affinity is changed. You can handle this event to perform any special processing. Note that any new events that are posted to this object will be handled in thetargetThread
, provided it is notNone
: when it isNone
, no event processing for this object or its children can happen, as they are no longer associated with any thread.Warning
This function is not thread-safe; the current thread must be same as the current thread affinity. In other words, this function can only “push” an object from the current thread to another thread, it cannot “pull” an object from any arbitrary thread to the current thread. There is one exception to this rule however: objects with no thread affinity can be “pulled” to the current thread.
See also
- objectName()#
- Return type:
str
See also
Getter of property
objectNameᅟ
.- objectNameChanged(objectName)#
- Parameters:
objectName – str
This signal is emitted after the object’s name has been changed. The new object name is passed as
objectName
.See also
Notification signal of property
objectNameᅟ
.Returns a pointer to the parent object.
See also
- property(name)#
- Parameters:
name – str
- Return type:
object
Returns the value of the object’s
name
property.If no such property exists, the returned variant is invalid.
Information about all available properties is provided through the
metaObject()
anddynamicPropertyNames()
.See also
setProperty()
isValid()
metaObject()
dynamicPropertyNames()
- receivers(signal)#
- Parameters:
signal – str
- Return type:
int
Warning
This section contains snippets that were automatically translated from C++ to Python and may contain errors.
Returns the number of receivers connected to the
signal
.Since both slots and signals can be used as receivers for signals, and the same connections can be made many times, the number of receivers is the same as the number of connections made from this signal.
When calling this function, you can use the
SIGNAL()
macro to pass a specific signal:if receivers(SIGNAL(valueChanged(QByteArray))) > 0: data = QByteArray() get_the_value(data) # expensive operation valueChanged.emit(data)
Warning
This function violates the object-oriented principle of modularity. However, it might be useful when you need to perform expensive initialization only if something is connected to a signal.
See also
Removes an event filter object
obj
from this object. The request is ignored if such an event filter has not been installed.All event filters for this object are automatically removed when this object is destroyed.
It is always safe to remove an event filter, even during event filter activation (i.e. from the
eventFilter()
function).See also
Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns
None
. The pointer is valid only during the execution of the slot that calls this function from this object’s thread context.The pointer returned by this function becomes invalid if the sender is destroyed, or if the slot is disconnected from the sender’s signal.
Warning
This function violates the object-oriented principle of modularity. However, getting access to the sender might be useful when many signals are connected to a single slot.
Warning
As mentioned above, the return value of this function is not valid when the slot is called via a
DirectConnection
from a thread different from this object’s thread. Do not use this function in this type of scenario.See also
- senderSignalIndex()#
- Return type:
int
Returns the meta-method index of the signal that called the currently executing slot, which is a member of the class returned by
sender()
. If called outside of a slot activated by a signal, -1 is returned.For signals with default parameters, this function will always return the index with all parameters, regardless of which was used with
connect()
. For example, the signaldestroyed(QObject *obj = \nullptr)
will have two different indexes (with and without the parameter), but this function will always return the index with a parameter. This does not apply when overloading signals with different parameters.Warning
This function violates the object-oriented principle of modularity. However, getting access to the signal index might be useful when many signals are connected to a single slot.
Warning
The return value of this function is not valid when the slot is called via a
DirectConnection
from a thread different from this object’s thread. Do not use this function in this type of scenario.See also
- setObjectName(name)#
- Parameters:
name – str
This is an overloaded function.
Makes the object a child of
parent
.See also
- setProperty(name, value)#
- Parameters:
name – str
value – object
- Return type:
bool
Sets the value of the object’s
name
property tovalue
.If the property is defined in the class using
Q_PROPERTY
then true is returned on success and false otherwise. If the property is not defined usingQ_PROPERTY
, and therefore not listed in the meta-object, it is added as a dynamic property and false is returned.Information about all available properties is provided through the
metaObject()
anddynamicPropertyNames()
.Dynamic properties can be queried again using
property()
and can be removed by setting the property value to an invalidQVariant
. Changing the value of a dynamic property causes aQDynamicPropertyChangeEvent
to be sent to the object.Note
Dynamic properties starting with “_q_” are reserved for internal purposes.
- signalsBlocked()#
- Return type:
bool
Returns
true
if signals are blocked; otherwise returnsfalse
.Signals are not blocked by default.
See also
- startTimer(interval[, timerType=Qt.CoarseTimer])#
- Parameters:
interval – int
timerType –
TimerType
- Return type:
int
This is an overloaded function that will start a timer of type
timerType
and a timeout ofinterval
milliseconds. This is equivalent to calling:startTimer(std::chrono::milliseconds{interval}, timerType);
See also
Returns the thread in which the object lives.
See also
- timerEvent(event)#
- Parameters:
event –
QTimerEvent
This event handler can be reimplemented in a subclass to receive timer events for the object.
QTimer
provides a higher-level interface to the timer functionality, and also more general information about timers. The timer event is passed in theevent
parameter.See also
- tr(sourceText[, disambiguation=None[, n=-1]])#
- Parameters:
sourceText – str
disambiguation – str
n – int
- Return type:
str