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, 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, 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, QPrintPreviewWidget, 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, QWebEngineUrlSchemeHandler, QWebEngineUrlRequestJob, QWebEngineUrlRequestInterceptor, QWebEngineProfile, QWebEngineNotification, QWebEngineNewWindowRequest, QWebEngineHistory, QWebEngineDownloadRequest, QWebEngineContextMenuRequest, QWebChannelAbstractTransport, QWebChannel, QUiLoader, QSignalSpy, QAbstractItemModelTester, QSvgRenderer, QAbstractTransition, QSignalTransition, QEventTransition, QMouseEventTransition, QKeyEventTransition, QAbstractState, QState, QStateMachine, QHistoryState, QFinalState, QSqlDriver, 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, QSGTextureProvider, QSGTexture, QSGDynamicTexture, QQuickTransform, QQuickTextureFactory, QQuickTextDocument, QQuickRenderControl, QQuickItemGrabResult, QQuickItem, QQuickPaintedItem, QQuickFramebufferObject, QQuickImageResponse, QQmlPropertyMap, QQmlImageProviderBase, QQuickImageProvider, QQuickAsyncImageProvider, QQmlFileSelector, QQmlExtensionPlugin, QQmlExpression, QQmlContext, QQmlComponent, QJSEngine, QQmlEngine, QGeoSatelliteInfoSource, QGeoPositionInfoSource, QNmeaPositionInfoSource, QGeoAreaMonitorSource, QOpenGLVertexArrayObject, QOpenGLTimerQuery, QOpenGLTimeMonitor, QOpenGLShaderProgram, QOpenGLShader, QOpenGLDebugLogger, QAbstractOAuthReplyHandler, QOAuthOobReplyHandler, QNetworkInformation, QNetworkCookieJar, QNetworkAccessManager, QLocalServer, QHttpMultiPart, QDtlsClientVerifier, QDnsLookup, QAbstractNetworkCache, QNetworkDiskCache, QVideoSink, QSoundEffect, QMediaRecorder, QMediaDevices, QMediaCaptureSession, QImageCapture, QCamera, QAudioSource, QAudioSink, QAudioOutput, QAudioInput, QAudioDecoder, QHelpSearchEngine, QHelpFilterEngine, QHelpEngineCore, QHelpEngine, QWindow, QQuickWindow, QQuickView, QPaintDeviceWindow, QOpenGLWindow, QRasterWindow, QAbstract3DGraph, Q3DSurface, Q3DScatter, Q3DBars, 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, QExtensionManager, QDesignerFormWindowToolInterface, QDesignerFormWindowManagerInterface, QDesignerFormEditorInterface, QValue3DAxisFormatter, QLogValue3DAxisFormatter, QCustom3DItem, QCustom3DVolume, QCustom3DLabel, QAbstractDataProxy, QSurfaceDataProxy, QItemModelSurfaceDataProxy, QHeightMapSurfaceDataProxy, QScatterDataProxy, QItemModelScatterDataProxy, QBarDataProxy, QItemModelBarDataProxy, QAbstract3DSeries, QSurface3DSeries, QScatter3DSeries, QBar3DSeries, QAbstract3DInputHandler, Q3DInputHandler, QTouch3DInputHandler, QAbstract3DAxis, QValue3DAxis, QCategory3DAxis, Q3DTheme, Q3DScene, Q3DObject, Q3DLight, Q3DCamera, 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, QProcess, QFutureWatcherBase, QFutureWatcher, QFileSystemWatcher, QFileSelector, QFileDevice, QSaveFile, QFile, QTemporaryFile, QEventLoop, QThread, QCoreApplication, QGuiApplication, QApplication, QWebSocket, QAbstractOAuth, QOAuth1, QAbstractOAuth2, QOAuth2AuthorizationCodeFlow, QSslSocket, QDtls, QMovie, QFileDialog, QWebEngineView, QWebEnginePage, QWebEngineCookieStore, QRemoteObjectHostBase, QRemoteObjectRegistryHost, QRemoteObjectHost, QQmlApplicationEngine, QMediaPlayer, QBuffer, QAbstractItemModel, QFileSystemModel, QAbstractItemModelReplica, QHelpContentModel, QStandardItemModel, QConcatenateTablesProxyModel, QAbstractTableModel, QSqlQueryModel, QSqlTableModel, QSqlRelationalTableModel, QAbstractProxyModel, QTransposeProxyModel, QSortFilterProxyModel, QIdentityProxyModel, QAbstractListModel, QWebEngineHistoryModel, QStringListModel, QHelpIndexModel, QAbstractEventDispatcher, QAbstractAnimation, QVariantAnimation, QPropertyAnimation, QPauseAnimation, QAnimationGroup, QSequentialAnimationGroup, QParallelAnimationGroup, QFutureWatcherVoid, QFutureWatcherQString, QXYModelMapper, QVXYModelMapper, QPieSlice, QPieModelMapper, QVPieModelMapper, QLegendMarker, QXYLegendMarker, QPieLegendMarker, QLegend, QHXYModelMapper, QHPieModelMapper, QChartView, QChart, QPolarChart, QCandlestickSet, QCandlestickModelMapper, QVCandlestickModelMapper, QHCandlestickModelMapper, QCandlestickLegendMarker, QBoxSet, QBoxPlotModelMapper, QVBoxPlotModelMapper, QHBoxPlotModelMapper, QBoxPlotLegendMarker, QBarSet, QBarModelMapper, QVBarModelMapper, QHBarModelMapper, QBarLegendMarker, QAreaLegendMarker, QAbstractSeries, QXYSeries, QScatterSeries, QLineSeries, QSplineSeries, QPieSeries, QCandlestickSeries, QBoxPlotSeries, QAreaSeries, QAbstractBarSeries, QStackedBarSeries, QPercentBarSeries, QHorizontalStackedBarSeries, QHorizontalPercentBarSeries, QHorizontalBarSeries, QBarSeries, QAbstractAxis, QValueAxis, QCategoryAxis, QLogValueAxis, QDateTimeAxis, QBarCategoryAxis, 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¶
Functions¶
def
blockSignals
(b)def
children
()def
connect
(arg__1, arg__2, arg__3[, type=Qt.AutoConnection])def
connect
(arg__1, arg__2[, type=Qt.AutoConnection])def
connect
(sender, signal, member[, type=Qt.AutoConnection])def
disconnect
(arg__1, arg__2)def
disconnect
(receiver[, member=None])def
disconnect
(signal, receiver, member)def
dumpObjectInfo
()def
dumpObjectTree
()def
dynamicPropertyNames
()def
emit
(arg__1, arg__2)def
findChild
(type[, name={}[, options=Qt.FindChildrenRecursively]])def
findChildren
(type, pattern[, options=Qt.FindChildrenRecursively])def
findChildren
(type[, name={}[, options=Qt.FindChildrenRecursively]])def
inherits
(classname)def
installEventFilter
(filterObj)def
isSignalConnected
(signal)def
isWidgetType
()def
isWindowType
()def
killTimer
(id)def
moveToThread
(thread)def
objectName
()def
parent
()def
property
(name)def
receivers
(signal)def
removeEventFilter
(obj)def
sender
()def
senderSignalIndex
()def
setObjectName
(name)def
setParent
(parent)def
setProperty
(name, value)def
signalsBlocked
()def
startTimer
(interval[, timerType=Qt.CoarseTimer])def
thread
()def
tr
(sourceText[, disambiguation=None[, n=-1]])
Virtual functions¶
def
childEvent
(event)def
connectNotify
(signal)def
customEvent
(event)def
disconnectNotify
(signal)def
event
(event)def
eventFilter
(watched, event)def
metaObject
()def
timerEvent
(event)
Slots¶
def
deleteLater
()
Signals¶
def
destroyed
([object=None])
Static functions¶
def
connect
(arg__1, arg__2, arg__3[, type=Qt.AutoConnection])def
connect
(sender, signal, receiver, member[, type=Qt.AutoConnection])def
connect
(sender, signal, receiver, method[, type=Qt.AutoConnection])def
disconnect
(arg__1)def
disconnect
(arg__1, arg__2, arg__3)def
disconnect
(sender, signal, receiver, member)def
disconnect
(sender, signal, receiver, member)
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 with connect()
and destroy the connection with disconnect()
. To avoid never ending notification loops you can temporarily block signals with blockSignals()
. The protected functions connectNotify()
and disconnectNotify()
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’s children()
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 using findChild()
or findChildren()
.
Every object has an objectName()
and its class name can be found via the corresponding metaObject()
(see className()
). You can determine whether the object’s class inherits another class in the QObject
inheritance hierarchy by using the inherits()
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. See installEventFilter()
and eventFilter()
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; see QTimer
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 of QObject
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 function isWidgetType()
returns whether an object is actually a widget. It is much faster than qobject_cast
< QWidget
*>(obj) or obj-> inherits
(” QWidget
“).
Some QObject
functions, e.g. children()
, return a QObjectList
. QObjectList
is a typedef for QList
< QObject
*>.
Thread Affinity¶
A QObject
instance is said to have a thread affinity, or that it lives in a certain thread. When a QObject
receives a queued 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, if thread()
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 using thread()
and changed using moveToThread()
.
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’s constructor
, or by calling setParent()
. Without this step, the object’s member variables will remain in the old thread when moveToThread()
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 a private
section with the macro Q_DISABLE_COPY()
. In fact, all Qt classes derived from QObject
(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 your QObject
subclass) where you might otherwise be tempted to use your QObject
subclass as a value. For example, without a copy constructor, you can’t use a subclass of QObject
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 the connectSlotsByName()
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¶
From Qt 4.2, 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 - using property()
to read them and setProperty()
to write them.
From Qt 4.3, 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 & Ownership
- class PySide6.QtCore.QObject([parent=None])¶
- Parameters
parent –
PySide6.QtCore.QObject
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
to None
constructs an object with no parent. If the object is a widget, it will become a top-level window.
See also
- PySide6.QtCore.QObject.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). If block
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
- PySide6.QtCore.QObject.childEvent(event)¶
- Parameters
event –
PySide6.QtCore.QChildEvent
This event handler can be reimplemented in a subclass to receive child events. The event is passed in the event
parameter.
ChildAdded
and ChildRemoved
events are sent to objects when children are added or removed. In both cases you can only rely on the child being a QObject
, or if isWidgetType()
returns true
, a QWidget
. (This is because, in the ChildAdded
case, the child is not yet fully constructed, and in the ChildRemoved
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 more ChildPolished
events, and one ChildRemoved
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
- PySide6.QtCore.QObject.children()¶
- Return type
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 the last
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
- static PySide6.QtCore.QObject.connect(arg__1, arg__2, arg__3[, type=Qt.AutoConnection])¶
- Parameters
arg__1 –
PySide6.QtCore.QObject
arg__2 – str
arg__3 –
PyCallable
type –
ConnectionType
- Return type
- static PySide6.QtCore.QObject.connect(sender, signal, receiver, method[, type=Qt.AutoConnection])
- Parameters
sender –
PySide6.QtCore.QObject
signal –
PySide6.QtCore.QMetaMethod
receiver –
PySide6.QtCore.QObject
method –
PySide6.QtCore.QMetaMethod
type –
ConnectionType
- Return type
Creates a connection of the given type
from the signal
in the sender
object to the method
in the receiver
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 uses QMetaMethod
to specify signal and method.
See also
ConnectionType type)
- static PySide6.QtCore.QObject.connect(sender, signal, receiver, member[, type=Qt.AutoConnection])
- Parameters
sender –
PySide6.QtCore.QObject
signal – str
receiver –
PySide6.QtCore.QObject
member – str
type –
ConnectionType
- Return type
Creates a connection of the given type
from the signal
in the sender
object to the method
in the receiver
object. Returns a handle to the connection that can be used to disconnect it later.
You must use the SIGNAL()
and SLOT()
macros when specifying the signal
and the method
, 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 to MyWidget
.
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, if QObject
is unable to verify the existence of either signal
or method
, 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 the UniqueConnection
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 invalid Connection
.
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 message
QObject.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
- PySide6.QtCore.QObject.connect(sender, signal, member[, type=Qt.AutoConnection])
- Parameters
sender –
PySide6.QtCore.QObject
signal – str
member – str
type –
ConnectionType
- Return type
This function overloads connect()
.
Connects signal
from the sender
object to this object’s method
.
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
- PySide6.QtCore.QObject.connect(arg__1, arg__2[, type=Qt.AutoConnection])
- Parameters
arg__1 – str
arg__2 –
PyCallable
type –
ConnectionType
- Return type
- PySide6.QtCore.QObject.connect(arg__1, arg__2, arg__3[, type=Qt.AutoConnection])
- Parameters
arg__1 – str
arg__2 –
PySide6.QtCore.QObject
arg__3 – str
type –
ConnectionType
- Return type
- PySide6.QtCore.QObject.connectNotify(signal)¶
- Parameters
signal –
PySide6.QtCore.QMetaMethod
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 use fromSignal()
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.
See also
- PySide6.QtCore.QObject.customEvent(event)¶
- Parameters
event –
PySide6.QtCore.QEvent
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 the Type
enum, and is typically a QEvent
subclass. The event is passed in the event
parameter.
- PySide6.QtCore.QObject.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. is called on an object before exec()
), the object will be deleted once the event loop is started. If is called after the main event loop has stopped, the object will not be deleted. Since Qt 4.8, if 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 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.
Note
It is safe to call this function more than once; when the first deferred deletion event is delivered, any pending events for the object are removed from the event queue.
See also
destroyed()
QPointer
- PySide6.QtCore.QObject.destroyed([object=None])¶
- Parameters
object –
PySide6.QtCore.QObject
- static PySide6.QtCore.QObject.disconnect(arg__1, arg__2, arg__3)¶
- Parameters
arg__1 –
PySide6.QtCore.QObject
arg__2 – str
arg__3 –
PyCallable
- Return type
bool
- PySide6.QtCore.QObject.disconnect(signal, receiver, member)
- Parameters
signal – str
receiver –
PySide6.QtCore.QObject
member – str
- Return type
bool
This function overloads disconnect()
.
Disconnects signal
from method
of receiver
.
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.
- PySide6.QtCore.QObject.disconnect(arg__1, arg__2)
- Parameters
arg__1 – str
arg__2 –
PyCallable
- Return type
bool
- static PySide6.QtCore.QObject.disconnect(sender, signal, receiver, member)
- Parameters
sender –
PySide6.QtCore.QObject
signal – str
receiver –
PySide6.QtCore.QObject
member – str
- Return type
bool
Disconnects signal
in object sender
from method
in object receiver
. Returns true
if the connection is successfully broken; otherwise returns false
.
A signal-slot connection is removed when either of the objects involved are destroyed.
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 be None
. (You cannot disconnect signals from more than one object in a single call.)
If signal
is None
, it disconnects receiver
and method
from any signal. If not, only the specified signal is disconnected.
If receiver
is None
, it disconnects anything connected to signal
. If not, slots in objects other than receiver
are not disconnected.
If method
is None
, it disconnects anything that is connected to receiver
. If not, only slots named method
will be disconnected, and all other slots are left alone. The method
must be None
if receiver
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 PySide6.QtCore.QObject.disconnect(sender, signal, receiver, member)
- Parameters
sender –
PySide6.QtCore.QObject
signal –
PySide6.QtCore.QMetaMethod
receiver –
PySide6.QtCore.QObject
member –
PySide6.QtCore.QMetaMethod
- Return type
bool
Disconnects signal
in object sender
from method
in object receiver
. Returns true
if the connection is successfully broken; otherwise returns false
.
This function provides the same possibilities like disconnect(const QObject *sender, const char *signal, const QObject *receiver, const char *method)
but uses QMetaMethod
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 for receiver
in the meaning “any receiving object”. In this case method should also be QMetaMethod(). sender
parameter should be never None
.
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)
- PySide6.QtCore.QObject.disconnect(receiver[, member=None])
- Parameters
receiver –
PySide6.QtCore.QObject
member – str
- Return type
bool
This function overloads disconnect()
.
Disconnects all signals in this object from receiver
's method
.
A signal-slot connection is removed when either of the objects involved are destroyed.
- static PySide6.QtCore.QObject.disconnect(arg__1)
- Parameters
- Return type
bool
Disconnect a connection.
If the connection
is invalid or has already been disconnected, do nothing and return false.
See also
- PySide6.QtCore.QObject.disconnectNotify(signal)¶
- Parameters
signal –
PySide6.QtCore.QMetaMethod
This virtual function is called when something has been disconnected from signal
in this object.
See connectNotify()
for an example of how to compare signal
with a specific signal.
If all signals were disconnected from this object (e.g., the signal argument to disconnect()
was None
), is only called once, and the signal
will be an invalid QMetaMethod
( isValid()
returns false
).
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 any of any QObject
functions from your reimplementation and if you lock a mutex in your reimplementation, make sure that you don’t call QObject
functions with that mutex held in other places or it will result in a deadlock.
See also
- PySide6.QtCore.QObject.dumpObjectInfo()¶
Dumps information about signal connections, etc. for this object to the debug output.
- PySide6.QtCore.QObject.dumpObjectTree()¶
Dumps a tree of children to the debug output.
- PySide6.QtCore.QObject.dynamicPropertyNames()¶
- Return type
Returns the names of all properties that were dynamically added to the object using setProperty()
.
- PySide6.QtCore.QObject.emit(arg__1, arg__2)¶
- Parameters
arg__1 – str
arg__2 – :any:``
- Return type
bool
- PySide6.QtCore.QObject.event(event)¶
- Parameters
event –
PySide6.QtCore.QEvent
- Return type
bool
This virtual function receives events to an object and should return true if the event e
was recognized and processed.
The 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() event = bool(QEvent* ev) 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)
- PySide6.QtCore.QObject.eventFilter(watched, event)¶
- Parameters
watched –
PySide6.QtCore.QObject
event –
PySide6.QtCore.QEvent
- Return type
bool
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: eventFilter = bool(QObject obj, QEvent ev) # 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 function, since the base class might have reimplemented for its own internal purposes.
Some events, such as ShortcutOverride
must be explicitly accepted (by calling accept()
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
- PySide6.QtCore.QObject.findChild(type[, name={}[, options=Qt.FindChildrenRecursively]])¶
- Parameters
type –
PyTypeObject
name – str
options –
FindChildOptions
- Return type
object
- PySide6.QtCore.QObject.findChildren(type, pattern[, options=Qt.FindChildrenRecursively])¶
- Parameters
type –
PyTypeObject
pattern –
PySide6.QtCore.QRegularExpression
options –
FindChildOptions
- Return type
PySequence
- PySide6.QtCore.QObject.findChildren(type[, name={}[, options=Qt.FindChildrenRecursively]])
- Parameters
type –
PyTypeObject
name – str
options –
FindChildOptions
- Return type
PySequence
- PySide6.QtCore.QObject.inherits(classname)¶
- Parameters
classname – str
- Return type
bool
Returns true
if this object is an instance of a class that inherits className
or a QObject
subclass that inherits className
; otherwise returns false
.
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()
- PySide6.QtCore.QObject.installEventFilter(filterObj)¶
- Parameters
filterObj –
PySide6.QtCore.QObject
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 its eventFilter()
function. The eventFilter()
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.
Here’s a KeyPressEater
class that eats the key presses of its monitored objects:
class KeyPressEater(QObject): Q_OBJECT ... protected: eventFilter = bool(QObject obj, QEvent event) 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 either filterObj
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
- PySide6.QtCore.QObject.isSignalConnected(signal)¶
- Parameters
signal –
PySide6.QtCore.QMetaMethod
- Return type
bool
Returns true
if the signal
is connected to at least one receiver, otherwise returns false
.
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 emitting a signal that nobody listens to.
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.
- PySide6.QtCore.QObject.isWidgetType()¶
- Return type
bool
Returns true
if the object is a widget; otherwise returns false
.
Calling this function is equivalent to calling inherits("QWidget")
, except that it is much faster.
- PySide6.QtCore.QObject.isWindowType()¶
- Return type
bool
Returns true
if the object is a window; otherwise returns false
.
Calling this function is equivalent to calling inherits("QWindow")
, except that it is much faster.
- PySide6.QtCore.QObject.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
- PySide6.QtCore.QObject.metaObject()¶
- Return type
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. Every QObject
subclass that contains the Q_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
- PySide6.QtCore.QObject.moveToThread(thread)¶
- Parameters
thread –
PySide6.QtCore.QThread
Changes the thread affinity for this object and its children. The object cannot be moved if it has a parent. Event processing will continue in the targetThread
.
To move an object to the main thread, use instance()
to retrieve a pointer to the current application, and then use thread()
to retrieve the thread in which the application lives. For example:
myObject.moveToThread(QApplication.instance().thread())
If targetThread
is None
, 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 the targetThread
, provided it is not None
: when it is None
, 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
- PySide6.QtCore.QObject.objectName()¶
- Return type
str
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 with findChildren()
.
qDebug("MyClass::setPrecision(): (%s) invalid precision %f", qPrintable(objectName()), newPrecision)
By default, this property contains an empty string.
See also
- PySide6.QtCore.QObject.parent()¶
- Return type
Returns a pointer to the parent object.
See also
- PySide6.QtCore.QObject.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()
and dynamicPropertyNames()
.
See also
setProperty()
isValid()
metaObject()
dynamicPropertyNames()
- PySide6.QtCore.QObject.receivers(signal)¶
- Parameters
signal – str
- Return type
int
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
- PySide6.QtCore.QObject.removeEventFilter(obj)¶
- Parameters
obj –
PySide6.QtCore.QObject
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
- PySide6.QtCore.QObject.sender()¶
- Return type
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
- PySide6.QtCore.QObject.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 signal destroyed(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
- PySide6.QtCore.QObject.setObjectName(name)¶
- Parameters
name – str
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 with findChildren()
.
qDebug("MyClass::setPrecision(): (%s) invalid precision %f", qPrintable(objectName()), newPrecision)
By default, this property contains an empty string.
See also
- PySide6.QtCore.QObject.setParent(parent)¶
- Parameters
parent –
PySide6.QtCore.QObject
Makes the object a child of parent
.
See also
- PySide6.QtCore.QObject.setProperty(name, value)¶
- Parameters
name – str
value – object
- Return type
bool
Sets the value of the object’s name
property to value
.
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 using Q_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()
and dynamicPropertyNames()
.
Dynamic properties can be queried again using property()
and can be removed by setting the property value to an invalid QVariant
. Changing the value of a dynamic property causes a QDynamicPropertyChangeEvent
to be sent to the object.
Note
Dynamic properties starting with “_q_” are reserved for internal purposes.
- PySide6.QtCore.QObject.signalsBlocked()¶
- Return type
bool
Returns true
if signals are blocked; otherwise returns false
.
Signals are not blocked by default.
See also
- PySide6.QtCore.QObject.startTimer(interval[, timerType=Qt.CoarseTimer])¶
- Parameters
interval – int
timerType –
TimerType
- Return type
int
Starts a timer and returns a timer identifier, or returns zero if it could not start a timer.
A timer event will occur every interval
milliseconds until killTimer()
is called. If interval
is 0, then the timer event occurs once every time there are no more window system events to process.
The virtual timerEvent()
function is called with the QTimerEvent
event parameter class when a timer event occurs. Reimplement this function to get timer events.
If multiple timers are running, the timerId()
can be used to find out which timer was activated.
Example:
class MyObject(QObject): Q_OBJECT # public MyObject(QObject parent = None) protected: def timerEvent(event): def __init__(self, parent): QObject.__init__(self, parent) startTimer(50) # 50-millisecond timer startTimer(1000) # 1-second timer startTimer(60000) # 1-minute timer namespace = using() startTimer(milliseconds(50)) startTimer(seconds(1)) startTimer(minutes(1)) # since C++14 we can use std::chrono::duration literals, e.g.: startTimer(100ms) startTimer(5s) startTimer(2min) startTimer(1h) def timerEvent(self, event): print("Timer ID:", event.timerId())
Note that QTimer
‘s accuracy depends on the underlying operating system and hardware. The timerType
argument allows you to customize the accuracy of the timer. See TimerType
for information on the different timer types. Most platforms support an accuracy of 20 milliseconds; some provide more. If Qt is unable to deliver the requested number of timer events, it will silently discard some.
The QTimer
class provides a high-level programming interface with single-shot timers and timer signals instead of events. There is also a QBasicTimer
class that is more lightweight than QTimer
and less clumsy than using timer IDs directly.
See also
- PySide6.QtCore.QObject.thread()¶
- Return type
Returns the thread in which the object lives.
See also
- PySide6.QtCore.QObject.timerEvent(event)¶
- Parameters
event –
PySide6.QtCore.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 the event
parameter.
See also
- PySide6.QtCore.QObject.tr(sourceText[, disambiguation=None[, n=-1]])¶
- Parameters
sourceText – str
disambiguation – str
n – int
- Return type
str
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