Contents

• Public Functions
• Detailed Description

Detailed Description

TheQDesignerContainerExtension class allows you to add pages to a custom multi-page container in Qt Designer's workspace.

QDesignerContainerExtension provide an interface for creating custom container extensions. A container extension consists of a collection of functions thatQt Designer needs to manage a multi-page container plugin, and a list of the container's pages.

Warning: This isnot an extension for container plugins in general, only custommulti-page containers.

To create a container extension, your extension class must inherit from bothQObject andQDesignerContainerExtension. For example:

class MyContainerExtension :publicQObject,publicQDesignerContainerExtension{    Q_OBJECT    Q_INTERFACES(QDesignerContainerExtension)public:    MyContainerExtension(MyCustomWidget*widget,QObject*parent=0);int count()const;QWidget*widget(int index)const;int currentIndex()const;void setCurrentIndex(int index);void addWidget(QWidget*widget);void insertWidget(int index,QWidget*widget);void remove(int index);private:    MyCustomWidget*myWidget;};

Since we are implementing an interface, we must ensure that it's made known to the meta object system using theQ_INTERFACES() macro. This enablesQt Designer to use theqobject_cast() function to query for supported interfaces using nothing but aQObject pointer.

You must reimplement several functions to enableQt Designer to manage a custom multi-page container widget:Qt Designer usescount() to keep track of the number pages in your container,widget() to return the page at a given index in the list of the container's pages, andcurrentIndex() to return the list index of the selected page.Qt Designer uses theaddWidget() function to add a given page to the container, expecting it to be appended to the list of pages, while it expects theinsertWidget() function to add a given page to the container by inserting it at a given index.

InQt Designer the extensions are not created until they are required. For that reason you must also create aQExtensionFactory, i.e a class that is able to make an instance of your extension, and register it usingQt Designer'sextension manager.

When a container extension is required,Qt Designer'sextension manager will run through all its registered factories callingQExtensionFactory::createExtension() for each until the first one that is able to create a container extension, is found. This factory will then create the extension for the plugin.

There are four available types of extensions inQt Designer:QDesignerContainerExtension ,QDesignerMemberSheetExtension,QDesignerPropertySheetExtension andQDesignerTaskMenuExtension.Qt Designer's behavior is the same whether the requested extension is associated with a multi page container, a member sheet, a property sheet or a task menu.

TheQExtensionFactory class provides a standard extension factory, and can also be used as an interface for custom extension factories. You can either create a newQExtensionFactory and reimplement theQExtensionFactory::createExtension() function. For example:

QObject*ANewExtensionFactory::createExtension(QObject*object,constQString&iid,QObject*parent)const{if (iid!= Q_TYPEID(QDesignerContainerExtension))return0;if (MyCustomWidget*widget= qobject_cast<MyCustomWidget*>           (object))returnnew MyContainerExtension(widget, parent);return0;}

Or you can use an existing factory, expanding theQExtensionFactory::createExtension() function to make the factory able to create a container extension as well. For example:

QObject*AGeneralExtensionFactory::createExtension(QObject*object,constQString&iid,QObject*parent)const{    MyCustomWidget*widget= qobject_cast<MyCustomWidget*>(object);if (widget&& (iid== Q_TYPEID(QDesignerTaskMenuExtension))) {returnnew MyTaskMenuExtension(widget, parent);    }elseif (widget&& (iid== Q_TYPEID(QDesignerContainerExtension))) {returnnew MyContainerExtension(widget, parent);    }else {return0;    }}

For a complete example using theQDesignerContainerExtension class, see theContainer Extension example. The example shows how to create a custom multi-page plugin forQt Designer.

Member Function Documentation

[virtual]QDesignerContainerExtension::~QDesignerContainerExtension()

Destroys the extension.

[pure virtual]void QDesignerContainerExtension::addWidget(QWidget * page)

Adds the givenpage to the container by appending it to the extension's list of pages.

See alsoinsertWidget(),remove(), andwidget().

[pure virtual]int QDesignerContainerExtension::count() const

Returns the number of pages in the container.

[pure virtual]int QDesignerContainerExtension::currentIndex() const

Returns the index of the currently selected page in the container.

See alsosetCurrentIndex().

[pure virtual]void QDesignerContainerExtension::insertWidget(int index,QWidget * page)

Adds the givenpage to the container by inserting it at the givenindex in the extension's list of pages.

See alsoaddWidget(),remove(), andwidget().

[pure virtual]void QDesignerContainerExtension::remove(int index)

Removes the page at the givenindex from the extension's list of pages.

See alsoaddWidget() andinsertWidget().

[pure virtual]void QDesignerContainerExtension::setCurrentIndex(int index)

Sets the currently selected page in the container to be the page at the givenindex in the extension's list of pages.

See alsocurrentIndex().

[pure virtual]QWidget * QDesignerContainerExtension::widget(int index) const

Returns the page at the givenindex in the extension's list of pages.

See alsoaddWidget() andinsertWidget().