QDesignerContainerExtension Class Reference
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The QDesignerContainerExtension class allows you to add pages to a custom multi-page container in Qt Designer's workspace. 更多...

Inherited by QPyDesignerContainerExtension .

方法

__init__ ( self )
__init__ ( self , QDesignerContainerExtension)
addWidget ( self , QWidget widget )
int count ( self )
int currentIndex ( self )
insertWidget ( self , int index , QWidget widget )
remove ( self , int index )
setCurrentIndex ( self , int index )
QWidget widget ( self , int index )

Special Methods

__len__ ( self )

详细描述

The QDesignerContainerExtension 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 that Qt Designer needs to manage a multi-page container plugin, and a list of the container's 页面。

警告： This is not an extension for container plugins in general, only custom multi-page containers.

To create a container extension, your extension class must inherit from both QObject and QDesignerContainerExtension. For example:

 class MyContainerExtension : public QObject,
        public QDesignerContainerExtension
 {
     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 the Q_INTERFACES () macro. This enables Qt Designer 要使用 qobject_cast () function to query for supported interfaces using nothing but a QObject pointer.

You must reimplement several functions to enable Qt Designer to manage a custom multi-page container widget: Qt Designer 使用 count () 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, and currentIndex () to return the list index of the selected page. Qt Designer 使用 addWidget () function to add a given page to the container, expecting it to be appended to the list of pages, while it expects the insertWidget () function to add a given page to the container by inserting it at a given index.

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

When a container extension is required, Qt Designer 's extension manager will run through all its registered factories calling QExtensionFactory.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 in Qt Designer : QDesignerContainerExtension , QDesignerMemberSheetExtension , QDesignerPropertySheetExtension and QDesignerTaskMenuExtension . 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.

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

 QObject *ANewExtensionFactory.createExtension(QObject *object,
         const QString &iid, QObject *parent) const
 {
     if (iid != Q_TYPEID(QDesignerContainerExtension))
         return 0;
     if (MyCustomWidget *widget = qobject_cast<MyCustomWidget*>
            (object))
         return new MyContainerExtension(widget, parent);
     return 0;
 }

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

 QObject *AGeneralExtensionFactory.createExtension(QObject *object,
         const QString &iid, QObject *parent) const
 {
     MyCustomWidget *widget = qobject_cast<MyCustomWidget*>(object);
     if (widget && (iid == Q_TYPEID(QDesignerTaskMenuExtension))) {
         return new MyTaskMenuExtension(widget, parent);
     } else if (widget && (iid == Q_TYPEID(QDesignerContainerExtension))) {
         return new MyContainerExtension(widget, parent);
     } else {
         return 0;
     }
 }

For a complete example using the QDesignerContainerExtension class, see the Container Extension example . The example shows how to create a custom multi-page plugin for Qt Designer .