Qt 5.13 | Qt Designer Manual | C++ Classes | QDesignerMemberSheetExtension

Qt 5.13.2 Reference Documentation

# QDesignerMemberSheetExtension Class

The QDesignerMemberSheetExtension class allows you to manipulate a widget's member functions which is displayed when configuring connections using Qt Designer's mode for editing signals and slots. More...

Header: | #include <QDesignerMemberSheetExtension>
qmake: | QT += designer

- List of all members, including inherited members

## Public Functions

virtual | ~QDesignerMemberSheetExtension()
virtual int | count() const = 0
virtual QString | declaredInClass(int index) const = 0
virtual int | indexOf(const QString &name) const = 0
virtual bool | inheritedFromWidget(int index) const = 0
virtual bool | isSignal(int index) const = 0
virtual bool | isSlot(int index) const = 0
virtual bool | isVisible(int index) const = 0
virtual QString | memberGroup(int index) const = 0
virtual QString | memberName(int index) const = 0
int | parameterNames(int) const
int | parameterTypes(int) const
virtual void | setMemberGroup(int index, const QString &group) = 0
virtual void | setVisible(int index, bool visible) = 0
virtual QString | signature(int index) const = 0

## Detailed Description

QDesignerMemberSheetExtension is a collection of functions that is typically used to query a widget's member functions, and to manipulate the member functions' appearance in Qt Designer's signals and slots editing mode. For example:

      QDesignerMemberSheetExtension *memberSheet  = 0;
      QExtensionManager manager = formEditor->extensionManager();

      memberSheet = qt_extension<QDesignerMemberSheetExtension*>(manager, widget);
      int index = memberSheet->indexOf(setEchoMode);
      memberSheet->setVisible(index, false);

      delete memberSheet;

When implementing a custom widget plugin, a pointer to Qt Designer's current QDesignerFormEditorInterface object (`formEditor` in the example above) is provided by the QDesignerCustomWidgetInterface::initialize() function's parameter.

The member sheet (and any other extension), can be retrieved by querying Qt Designer's extension manager using the qt_extension() function. When you want to release the extension, you only need to delete the pointer.

All widgets have a default member sheet used in Qt Designer's signals and slots editing mode with the widget's member functions. But QDesignerMemberSheetExtension also provides an interface for creating custom member sheet extensions.

Warning: Qt Designer uses the QDesignerMemberSheetExtension to facilitate the signal and slot editing mode. Whenever a connection between two widgets is requested, Qt Designer will query for the widgets' member sheet extensions. If a widget has an implemented member sheet extension, this extension will override the default member sheet.

To create a member sheet extension, your extension class must inherit from both QObject and QDesignerMemberSheetExtension. Then, since we are implementing an interface, we must ensure that it's made known to the meta object system using the Q_INTERFACES() macro:

      class MyMemberSheetExtension : public QObject,
              public QDesignerMemberSheetExtension
      {
          Q_OBJECT
          Q_INTERFACES(QDesignerMemberSheetExtension)

      public:
          ...
      }

This enables Qt Designer to use qobject_cast() to query for supported interfaces using nothing but a QObject pointer.

In Qt Designer the extensions are not created until they are required. For that reason, when implementing a member sheet extension, 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 widget's member sheet 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 member sheet extension for that widget, is found. This factory will then make an instance of the extension. If no such factory is found, Qt Designer will use the default member sheet.

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.

The 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(QDesignerMemberSheetExtension))
              return 0;

          if (MyCustomWidget *widget = qobject_cast<MyCustomWidget*>
                 (object))
              return new MyMemberSheetExtension(widget, parent);

          return 0;
      }

Or you can use an existing factory, expanding the QExtensionFactory::createExtension() function to make the factory able to create a member sheet 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(QDesignerMemberSheetExtension))) {
              return new MyMemberSheetExtension(widget, parent);

          } else {
              return 0;
          }
      }

For a complete example using an extension class, see Task Menu Extension example. The example shows how to create a custom widget plugin for Qt Designer, and how to to use the QDesignerTaskMenuExtension class to add custom items to Qt Designer's task menu.

See also QExtensionFactory, QExtensionManager, and Creating Custom Widget Extensions.

## Member Function Documentation

### `[virtual]` QDesignerMemberSheetExtension::~QDesignerMemberSheetExtension()

Destroys the member sheet extension.

### `[pure virtual]` int QDesignerMemberSheetExtension::count() const

Returns the extension's number of member functions.

### `[pure virtual]` QString QDesignerMemberSheetExtension::declaredInClass(int index) const

Returns the name of the class in which the member function with the given index is declared.

See also indexOf().

### `[pure virtual]` int QDesignerMemberSheetExtension::indexOf(const QString &name) const

Returns the index of the member function specified by the given name.

See also memberName().

### `[pure virtual]` bool QDesignerMemberSheetExtension::inheritedFromWidget(int index) const

Returns true if the member function with the given index is inherited from QWidget, otherwise false.

See also indexOf().

### `[pure virtual]` bool QDesignerMemberSheetExtension::isSignal(int index) const

Returns true if the member function with the given index is a signal, otherwise false.

See also indexOf().

### `[pure virtual]` bool QDesignerMemberSheetExtension::isSlot(int index) const

Returns true if the member function with the given index is a slot, otherwise false.

See also indexOf().

### `[pure virtual]` bool QDesignerMemberSheetExtension::isVisible(int index) const

Returns true if the member function with the given index is visible in Qt Designer's signal and slot editor, otherwise false.

See also indexOf() and setVisible().

### `[pure virtual]` QString QDesignerMemberSheetExtension::memberGroup(int index) const

Returns the name of the member group specified for the function with the given index.

See also indexOf() and setMemberGroup().

### `[pure virtual]` QString QDesignerMemberSheetExtension::memberName(int index) const

Returns the name of the member function with the given index.

See also indexOf().

### int QDesignerMemberSheetExtension::parameterNames(int) const

Returns the parameter names of the member function with the given index, as a QByteArray list.

See also indexOf() and parameterTypes().

### int QDesignerMemberSheetExtension::parameterTypes(int) const

Returns the parameter types of the member function with the given index, as a QByteArray list.

See also indexOf() and parameterNames().

### `[pure virtual]` void QDesignerMemberSheetExtension::setMemberGroup(int index, const QString &group)

Sets the member group of the member function with the given index, to group.

See also indexOf() and memberGroup().

### `[pure virtual]` void QDesignerMemberSheetExtension::setVisible(int index, bool visible)

If visible is true, the member function with the given index is visible in Qt Designer's signals and slots editing mode; otherwise the member function is hidden.

See also indexOf() and isVisible().

### `[pure virtual]` QString QDesignerMemberSheetExtension::signature(int index) const

Returns the signature of the member function with the given index.

See also indexOf().