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• 公共函数
• 信号
• 详细描述

QDeclarativePropertyMap Class

The QDeclarativePropertyMap class allows you to set key-value pairs that can be used in QML bindings. 更多...

头：	#include <QDeclarativePropertyMap>
Since:	Qt 4.7
继承：	QObject

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公共函数

	QDeclarativePropertyMap (QObject * parent = 0)
virtual	~QDeclarativePropertyMap ()
void	clear (const QString & key )
bool	contains (const QString & key ) const
int	count () const
void	insert (const QString & key , const QVariant & value )
bool	isEmpty () const
QStringList	keys () const
int	size () const
QVariant	value (const QString & key ) const
QVariant &	operator[] (const QString & key )
QVariant	operator[] (const QString & key ) const

• 29 公共函数继承自 QObject

信号

void	valueChanged (const QString & key , const QVariant & value )

• 1 信号继承自 QObject

额外继承成员

• 1 特性继承自 QObject
• 1 公共槽继承自 QObject
• 7 静态公共成员继承自 QObject
• 8 保护函数继承自 QObject

详细描述

The QDeclarativePropertyMap class allows you to set key-value pairs that can be used in QML bindings.

QDeclarativePropertyMap provides a convenient way to expose domain data to the UI layer. The following example shows how you might declare data in C++ and then access it in QML.

在 C++ 文件：

// create our data
QDeclarativePropertyMap ownerData;
ownerData.insert("name", QVariant(QString("John Smith")));
ownerData.insert("phone", QVariant(QString("555-5555")));
// expose it to the UI layer
QDeclarativeView view;
QDeclarativeContext *ctxt = view.rootContext();
ctxt->setContextProperty("owner", &ownerData);
view.setSource(QUrl::fromLocalFile("main.qml"));
view.show();
					

Then, in main.qml :

Text { text: owner.name + " " + owner.phone }
					

The binding is dynamic - whenever a key's value is updated, anything bound to that key will be updated as well.

To detect value changes made in the UI layer you can connect to the valueChanged () signal. However, note that valueChanged () 是 NOT emitted when changes are made by calling insert () 或 clear () - it is only emitted when a value is updated from QML.

注意： It is not possible to remove keys from the map; once a key has been added, you can only modify or clear its associated value.

成员函数文档编制

QDeclarativePropertyMap:: QDeclarativePropertyMap ( QObject * parent = 0)

Constructs a bindable map with parent object parent .

[虚拟] QDeclarativePropertyMap:: ~QDeclarativePropertyMap ()

销毁可绑定映射。

void QDeclarativePropertyMap:: clear (const QString & key )

Clears the value (if any) associated with key .

bool QDeclarativePropertyMap:: contains (const QString & key ) const

Returns true if the map contains key .

另请参阅 size ().

int QDeclarativePropertyMap:: count () const

这是重载函数。

如同 size ().

void QDeclarativePropertyMap:: insert (const QString & key , const QVariant & value )

Sets the value associated with key to value .

If the key doesn't exist, it is automatically created.

bool QDeclarativePropertyMap:: isEmpty () const

Returns true if the map contains no keys; otherwise returns false.

另请参阅 size ().

QStringList QDeclarativePropertyMap:: keys () const

Returns the list of keys.

Keys that have been cleared will still appear in this list, even though their associated values are invalid QVariants .

int QDeclarativePropertyMap:: size () const

Returns the number of keys in the map.

另请参阅 isEmpty () 和 count ().

QVariant QDeclarativePropertyMap:: value (const QString & key ) const

Returns the value associated with key .

If no value has been set for this key (or if the value has been cleared), an invalid QVariant 被返回。

[signal] void QDeclarativePropertyMap:: valueChanged (const QString & key , const QVariant & value )

This signal is emitted whenever one of the values in the map is changed. key is the key corresponding to the value that was changed.

注意： valueChanged() NOT emitted when changes are made by calling insert () 或 clear () - it is only emitted when a value is updated from QML.

QVariant & QDeclarativePropertyMap:: operator[] (const QString & key )

Returns the value associated with the key key 作为可修改引用。

If the map contains no item with key key , the function inserts an invalid QVariant into the map with key key , and returns a reference to it.

另请参阅 insert () 和 value ().

QVariant QDeclarativePropertyMap:: operator[] (const QString & key ) const

这是重载函数。

如同 value ().