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# QDeclarativeProperty Class Reference
[QtDeclarative module]

The QDeclarativeProperty class abstracts accessing properties on objects created from QML. More...

### Types

- enum PropertyTypeCategory { InvalidCategory, List, Object, Normal }
- enum Type { Invalid, Property, SignalProperty }

### Methods

- __init__ (self)
- __init__ (self, QObject)
- __init__ (self, QObject, QDeclarativeContext)
- __init__ (self, QObject, QDeclarativeEngine)
- __init__ (self, QObject, QString)
- __init__ (self, QObject, QString, QDeclarativeContext)
- __init__ (self, QObject, QString, QDeclarativeEngine)
- __init__ (self, QDeclarativeProperty)
- bool connectNotifySignal (self, QObject dest, object slot)
- bool connectNotifySignal (self, object slot)
- bool connectNotifySignal (self, QObject dest, int method)
- bool hasNotifySignal (self)
- int index (self)
- bool isDesignable (self)
- bool isProperty (self)
- bool isResettable (self)
- bool isSignalProperty (self)
- bool isValid (self)
- bool isWritable (self)
- QMetaMethod method (self)
- QString name (self)
- bool needsNotifySignal (self)
- QObject object (self)
- QMetaProperty property (self)
- int propertyType (self)
- PropertyTypeCategory propertyTypeCategory (self)
- str propertyTypeName (self)
- QVariant read (self)
- bool reset (self)
- Type type (self)
- bool write (self, QVariant)

### Static Methods

- QVariant read (QObject, QString)
- QVariant read (QObject, QString, QDeclarativeContext)
- QVariant read (QObject, QString, QDeclarativeEngine)
- bool write (QObject, QString, QVariant)
- bool write (QObject, QString, QVariant, QDeclarativeContext)
- bool write (QObject, QString, QVariant, QDeclarativeEngine)

### Special Methods

- bool __eq__ (self, QDeclarativeProperty)
- int __hash__ (self)
- bool __ne__ (self, QDeclarativeProperty)

## Detailed Description

The QDeclarativeProperty class abstracts accessing properties on objects created from QML.

As QML uses Qt's meta-type system all of the existing QMetaObject classes can be used to introspect and interact with objects created by QML. However, some of the new features provided by QML - such as type safety and attached properties - are most easily used through the QDeclarativeProperty class that simplifies some of their natural complexity.

Unlike QMetaProperty which represents a property on a class type, QDeclarativeProperty encapsulates a property on a specific object instance. To read a property's value, programmers create a QDeclarativeProperty instance and call the read() method. Likewise to write a property value the write() method is used.

For example, for the following QML code:

     // MyItem.qml
     import QtQuick 1.0

     Text { text: "A bit of text" }

The Text object's properties could be accessed using QDeclarativeProperty, like this:

     #include <QDeclarativeProperty>
     #include <QGraphicsObject>

     ...

     QDeclarativeView view(QUrl.fromLocalFile("MyItem.qml"));
     QDeclarativeProperty property(view.rootObject(), "font.pixelSize");
     qWarning() << "Current pixel size:" << property.read().toInt();
     property.write(24);
     qWarning() << "Pixel size should now be 24:" << property.read().toInt();

## Type Documentation

### QDeclarativeProperty.PropertyTypeCategory

This enum specifies a category of QML property.

Constant | Value | Description
--- | --- | ---
`QDeclarativeProperty.InvalidCategory` | `0` | The property is invalid, or is a signal property.
`QDeclarativeProperty.List` | `1` | The property is a QDeclarativeListProperty list property
`QDeclarativeProperty.Object` | `2` | The property is a QObject derived type pointer
`QDeclarativeProperty.Normal` | `3` | The property is a normal value property.

### QDeclarativeProperty.Type

This enum specifies a type of QML property.

Constant | Value | Description
--- | --- | ---
`QDeclarativeProperty.Invalid` | `0` | The property is invalid.
`QDeclarativeProperty.Property` | `1` | The property is a regular Qt property.
`QDeclarativeProperty.SignalProperty` | `2` | The property is a signal property.

## Method Documentation

### QDeclarativeProperty.__init__ (self)

Create an invalid QDeclarativeProperty.

### QDeclarativeProperty.__init__ (self, QObject)

Creates a QDeclarativeProperty for the default property of obj. If there is no default property, an invalid QDeclarativeProperty will be created.

### QDeclarativeProperty.__init__ (self, QObject, QDeclarativeContext)

Creates a QDeclarativeProperty for the default property of obj using the context ctxt. If there is no default property, an invalid QDeclarativeProperty will be created.

### QDeclarativeProperty.__init__ (self, QObject, QDeclarativeEngine)

Creates a QDeclarativeProperty for the default property of obj using the environment for instantiating QML components that is provided by engine. If there is no default property, an invalid QDeclarativeProperty will be created.

### QDeclarativeProperty.__init__ (self, QObject, QString)

Creates a QDeclarativeProperty for the property name of obj.

### QDeclarativeProperty.__init__ (self, QObject, QString, QDeclarativeContext)

Creates a QDeclarativeProperty for the property name of obj using the context ctxt.

Creating a QDeclarativeProperty without a context will render some properties - like attached properties - inaccessible.

### QDeclarativeProperty.__init__ (self, QObject, QString, QDeclarativeEngine)

Creates a QDeclarativeProperty for the property name of obj using the environment for instantiating QML components that is provided by engine.

### QDeclarativeProperty.__init__ (self, QDeclarativeProperty)

Create a copy of other.

### bool QDeclarativeProperty.connectNotifySignal (self, QObject dest, object slot)

Connects the property's change notifier signal to the specified slot of the dest object and returns true. Returns false if this metaproperty does not represent a regular Qt property or if it has no change notifier signal, or if the dest object does not have the specified slot.

### bool QDeclarativeProperty.connectNotifySignal (self, object slot)

Connects the property's change notifier signal to the specified method of the dest object and returns true. Returns false if this metaproperty does not represent a regular Qt property or if it has no change notifier signal, or if the dest object does not have the specified method.

### bool QDeclarativeProperty.connectNotifySignal (self, QObject dest, int method)

### bool QDeclarativeProperty.hasNotifySignal (self)

Returns true if the property has a change notifier signal, otherwise false.

### int QDeclarativeProperty.index (self)

Return the Qt metaobject index of the property.

### bool QDeclarativeProperty.isDesignable (self)

Returns true if the property is designable, otherwise false.

### bool QDeclarativeProperty.isProperty (self)

Returns true if this QDeclarativeProperty represents a regular Qt property.

### bool QDeclarativeProperty.isResettable (self)

Returns true if the property is resettable, otherwise false.

### bool QDeclarativeProperty.isSignalProperty (self)

Returns true if this QDeclarativeProperty represents a QML signal property.

### bool QDeclarativeProperty.isValid (self)

Returns true if the QDeclarativeProperty refers to a valid property, otherwise false.

### bool QDeclarativeProperty.isWritable (self)

Returns true if the property is writable, otherwise false.

### QMetaMethod QDeclarativeProperty.method (self)

Return the QMetaMethod for this property if it is a SignalProperty, otherwise returns an invalid QMetaMethod.

### QString QDeclarativeProperty.name (self)

Return the name of this QML property.

### bool QDeclarativeProperty.needsNotifySignal (self)

Returns true if the property needs a change notifier signal for bindings to remain upto date, false otherwise.

Some properties, such as attached properties or those whose value never changes, do not require a change notifier.

### QObject QDeclarativeProperty.object (self)

Returns the QDeclarativeProperty's QObject.

### QMetaProperty QDeclarativeProperty.property (self)

Returns the Qt property associated with this QML property.

### int QDeclarativeProperty.propertyType (self)

Returns the QVariant type of the property, or QVariant.Invalid if the property has no QVariant type.

### PropertyTypeCategory QDeclarativeProperty.propertyTypeCategory (self)

Returns the property category.

### str QDeclarativeProperty.propertyTypeName (self)

Returns the type name of the property, or 0 if the property has no type name.

### QVariant QDeclarativeProperty.read (self)

Returns the property value.

### QVariant QDeclarativeProperty.read (QObject, QString)

Return the name property value of object. This method is equivalent to:

     QDeclarativeProperty p(object, name);
     p.read();

### QVariant QDeclarativeProperty.read (QObject, QString, QDeclarativeContext)

Return the name property value of object using the context ctxt. This method is equivalent to:

     QDeclarativeProperty p(object, name, context);
     p.read();

### QVariant QDeclarativeProperty.read (QObject, QString, QDeclarativeEngine)

Return the name property value of object using the environment for instantiating QML components that is provided by engine. . This method is equivalent to:

     QDeclarativeProperty p(object, name, engine);
     p.read();

### bool QDeclarativeProperty.reset (self)

Resets the property and returns true if the property is resettable. If the property is not resettable, nothing happens and false is returned.

### Type QDeclarativeProperty.type (self)

Returns the type of the property.

### bool QDeclarativeProperty.write (self, QVariant)

Sets the property value to value and returns true. Returns false if the property can't be set because the value is the wrong type, for example.

### bool QDeclarativeProperty.write (QObject, QString, QVariant)

Writes value to the name property of object. This method is equivalent to:

     QDeclarativeProperty p(object, name);
     p.write(value);

### bool QDeclarativeProperty.write (QObject, QString, QVariant, QDeclarativeContext)

Writes value to the name property of object using the context ctxt. This method is equivalent to:

     QDeclarativeProperty p(object, name, ctxt);
     p.write(value);

### bool QDeclarativeProperty.write (QObject, QString, QVariant, QDeclarativeEngine)

Writes value to the name property of object using the environment for instantiating QML components that is provided by engine. This method is equivalent to:

     QDeclarativeProperty p(object, name, engine);
     p.write(value);

### bool QDeclarativeProperty.__eq__ (self, QDeclarativeProperty)

### int QDeclarativeProperty.__hash__ (self)

### bool QDeclarativeProperty.__ne__ (self, QDeclarativeProperty)