Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Toutes les classes  ·  Toutes les fonctions  ·  Vues d'ensemble  · 

Creating Custom Widget Extensions

Once you have a custom widget plugin for Qt Designer, you can provide it with the expected behavior and functionality within Qt Designer's workspace, using custom widget extensions.

Extension Types

There are several available types of extensions in Qt Designer. You can use all of these extensions in the same pattern, only replacing the respective extension base class.

QDesignerContainerExtension is necessary when implementing a custom multi-page container.

QDesignerTaskMenuExtension

QDesignerTaskMenuExtension is useful for custom widgets. It provides an extension that allows you to add custom menu entries to Qt Designer's task menu.

The Task Menu Extension example illustrates how to use this class.

QDesignerContainerExtension

QDesignerContainerExtension is necessary when implementing a custom multi-page container. It provides an extension that allows you to add and delete pages for a multi-page container plugin in Qt Designer.

The Container Extension example further explains how to use this class.

Note: It is not possible to add custom per-page properties for some widgets (e.g., QTabWidget) due to the way they are implemented.

QDesignerMemberSheetExtension

The QDesignerMemberSheetExtension class allows you to manipulate a widget's member functions displayed when connecting signals and slots.

QDesignerPropertySheetExtension, QDesignerDynamicPropertySheetExtension

These extension classes allow you to control how a widget's properties are displayed in Qt Designer's property editor.

Qt Designer uses the QDesignerPropertySheetExtension and the QDesignerMemberSheetExtension classes to feed its property and signal and slot editors. Whenever a widget is selected in its workspace, Qt Designer will query for the widget's property sheet extension; likewise, whenever a connection between two widgets is requested, Qt Designer will query for the widgets' member sheet extensions.

Warning: All widgets have default property and member sheets. If you implement custom property sheet or member sheet extensions, your custom extensions will override the default sheets.

Creating an Extension

To create an extension you must inherit both QObject and the appropriate base class, and reimplement its functions. Since we are implementing an interface, we must ensure that it is made known to the meta object system using the Q_INTERFACES() macro in the extension class's definition. For example:

 class MyExtension: public QObject,
                    public QdesignerContainerExtension
 {
     Q_OBJECT
     Q_INTERFACE(QDesignerContainerExtension)

     ...
 }

This enables Qt Designer to use the qobject_cast() function to query for supported interfaces using a QObject pointer only.

Exposing an Extension to Qt Designer

In Qt Designer the extensions are not created until they are required. For this reason, when implementing extensions, you must subclass QExtensionFactory to create a class that is able to make instances of your extensions. Also, you must register your factory with Qt Designer's extension manager; the extension manager handles the construction of extensions.

When an extension is requested, Qt Designer's extension manager will run through its registered factories calling QExtensionFactory::createExtension() for each of them until it finds one that is able to create the requested extension for the selected widget. This factory will then make an instance of the extension.

Creating an Extension Factory

The QExtensionFactory class provides a standard extension factory, but it can also be used as an interface for custom extension factories.

The purpose is to reimplement the QExtensionFactory::createExtension() function, making it able to create your extension, such as a MultiPageWidget container extension.

You can either create a new QExtensionFactory and reimplement the QExtensionFactory::createExtension() function:

 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 enable the factory to create your custom extension as well:

 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;
     }
 }

Accessing Qt Designer's Extension Manager

When implementing a custom widget plugin, you must subclass the QDesignerCustomWidgetInterface to expose your plugin to Qt Designer. This is covered in more detail in the Creating Custom Widgets for Qt Designer section. The registration of an extension factory is typically made in the QDesignerCustomWidgetInterface::initialize() function:

 void MyPlugin::initialize(QDesignerFormEditorInterface *formEditor)
 {
     if (initialized)
         return;

     QExtensionManager *manager = formEditor->extensionManager();
     Q_ASSERT(manager != 0);

     manager->registerExtensions(new MyExtensionFactory(manager),
                                 Q_TYPEID(QDesignerTaskMenuExtension));

     initialized = true;
 }

The formEditor parameter in the QDesignerCustomWidgetInterface::initialize() function is a pointer to Qt Designer's current QDesignerFormEditorInterface object. You must use the QDesignerFormEditorInterface::extensionManager() function to retrieve an interface to Qt Designer's extension manager. Then you use the QExtensionManager::registerExtensions() function to register your custom extension factory.

Related Examples

For more information on creating custom widget extensions in Qt Designer, refer to the Task Menu Extension and Container Extension examples.

[Previous: Creating Custom Widgets for Qt Designer] [Contents] [Next: Qt Designer's UI File Format]

Publicité

Best Of

Actualités les plus lues

Semaine
Mois
Année
  1. « Quelque chose ne va vraiment pas avec les développeurs "modernes" », un développeur à "l'ancienne" critique la multiplication des bibliothèques 64
  2. Apercevoir la troisième dimension ou l'utilisation multithreadée d'OpenGL dans Qt, un article des Qt Quarterly traduit par Guillaume Belz 0
  3. Les développeurs ignorent-ils trop les failles découvertes dans leur code ? Prenez-vous en compte les remarques des autres ? 17
  4. BlackBerry 10 : premières images du prochain OS de RIM qui devrait intégrer des widgets et des tuiles inspirées de Windows Phone 0
  5. Quelles nouveautés de C++11 Visual C++ doit-il rapidement intégrer ? Donnez-nous votre avis 10
  6. Adieu qmake, bienvenue qbs : Qt Building Suite, un outil déclaratif et extensible pour la compilation de projets Qt 17
  7. La rubrique Qt a besoin de vous ! 1
Page suivante

Le Qt Developer Network au hasard

Logo

Combiner licence, à propos et fermer

Le Qt Developer Network est un réseau de développeurs Qt anglophone, où ils peuvent partager leur expérience sur le framework. Lire l'article.

Communauté

Ressources

Liens utiles

Contact

  • Vous souhaitez rejoindre la rédaction ou proposer un tutoriel, une traduction, une question... ? Postez dans le forum Contribuez ou contactez-nous par MP ou par email (voir en bas de page).

Qt dans le magazine

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 4.6
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web