# class KPanelExtension | KDE Panel Extension class. More...
Definition | `#include <kpanelextension.h>`
Inherits | QFrame (qt) [public ]
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#### Public Types

- enum Type { Normal = 0, Stretch }
- enum Action { About = 1, Help = 2, Preferences = 4, ReportBug =8 }
- enum Position { Left = 0, Right, Top, Bottom }

#### Public Methods

- KPanelExtension (const QString& configFile, Type t = Normal, int actions = 0, QWidget *parent = 0, const char *name = 0)
- ~KPanelExtension ()
- virtual QSize sizeHint (Position , QSize maxsize) const
- KConfig* config () const
- Type type () const
- int actions () const
- virtual void action ( Action a )
- virtual Position preferedPosition () const

#### Public Slots

- void slotSetPosition (Position p)

#### Signals

- void updateLayout ()

#### Protected Methods

- virtual void about ()
- virtual void help ()
- virtual void preferences ()
- Position position () const
- Orientation orientation ()
- virtual void positionChange ( Position )

## Detailed Description

Implement a panel extension.

Panel extensions

- Are small applications living in the Window Manager dock managed by the panel.
- Are implemented as DSOs (Dynamic Shared Objects).

Note: For security and stability reasons the panel won't load untrusted third party extensions directly into its namespace but via an external wrapper process.

The panel locates available extensions by searching for extension desktop files in (ALL_KDEDIRS)/share/apps/kicker/extensions. Every panel extension should install a desktop file there to be recognised by the panel.

Besides standard keys like "Name", "Comment" and "Icon" there are two panel extension specific keys:

### X-KDE-Library

Used by the panel to locate the extension DSO (Dynamic Shared Object) Example: X-KDE-Library=libexampleextension

### X-KDE-UniqueExtension

Similar to KApplication and KUniqueApplication there are two types of panel extensions. Use unique extensions when it makes no sence to run more than one instance of an extension in the panel. A good example for unique extensions is the taskbar extension. Use normal extensions when you need instance specific configuration. An example is a subpanel extension where you might want to run more than one instances. X-KDE-UniqueExtension is a boolean key which defaults to "false". Example: X-KDE-UniqueExtension=true

Back to panel extension DSOs, the following conventions are used for KDE: Name: lib<extensionname>extension.la LDFLAGS: -module -no-undefined

To implement a panel extension it is not enough to write a class inheriting from KPanelExtension but you also have to provide a factory function in your DSO. A sample factory function could look like this:

     extern "C"
     {
         KPanelExtension* init(QWidget *parent, const QString& configFile)
         {
             KGlobal::locale()->insertCatalogue("exampleextension");
             return new ExampleExtension(configFile, KPanelExtension::Normal,
                           KPanelExtension::About | KPanelExtension::Help | KPanelExtension::Preferences,
                           parent, "exampleextension");
         }
     }

Note: Don't change the factory function signature or the panel will fail to load your extension.

enum Type { Normal = 0, Stretch } | ### Type

enum Action { About = 1, Help = 2, Preferences = 4, ReportBug =8 } | ### Action

enum Position { Left = 0, Right, Top, Bottom } | ### Position

KPanelExtension (const QString& configFile, Type t = Normal, int actions = 0, QWidget *parent = 0, const char *name = 0) | ### KPanelExtension

Construct a KPanelExtension just like any other widget.

Parameters:

configFile | The configFile handed over in the factory function.
Type | The extension type().
actions | Standard RMB menu actions supported by the extension (see action() ).
parent | The pointer to the parent widget handed over in the factory function.
name | A Qt object name for your extension.

~KPanelExtension () | ### ~KPanelExtension

Destructor.

QSize sizeHint (Position , QSize maxsize) | ### sizeHint

[const virtual]

Retrieve a prefered size for a given Position.

Every extension should reimplement this function.

Depending on the panel position the extensions can choose a prefered size for that location in the Window Manager Dock. Please note that the size can not be larger than the maxsize given by the handler.

Reimplemented from QFrame.

KConfig* config () | ### config

[const]

Always use this KConfig object to save/load your extensions configuration.

For unique extensions this config object will write to a config file called <extensionname>rc in the users local KDE directory.

For normal extensions this config object will write to a instance specific config file called <extensionname><instanceid>rc in the users local KDE directory.

Type type () | ### type

[const]

Returns: Type indicating the extensions type. Type

int actions () | ### actions

[const]

Returns: int indicating the supported RMB menu actions. Action

void action ( Action a ) | ### action

[virtual]

Generic action dispatcher. Called when the user selects an item from the extensions RMB menu.

Reimplement this function to handle actions.

For About, Help and Preferences, use the convenience handlers ref about(), help(), preferences()

Position preferedPosition () | ### preferedPosition

[const virtual]

Reimplement this function to set a prefered dock position for your extension. The extension manager will try to place new instances of this extension according to this setting.

Returns: Position

void updateLayout () | ### updateLayout

[signal]

Emit this signal to make the panel relayout all extensions in the dock, when you want to change the extensions size. The panel is going to relayout all extensions based on their prefered size.

void slotSetPosition (Position p) | ### slotSetPosition

[slot]

Don't reimplement, this is used internally

void about () | ### about

[protected virtual]

Is called when the user selects "About" from the extensions RMB menu. Reimplement this function to launch a about dialog.

Note that this is called only when your extension supports the About action. See Action and KPanelExtension().

void help () | ### help

[protected virtual]

Is called when the user selects "Help" from the extensions RMB menu. Reimplement this function to launch a manual or help page.

Note that this is called only when your extension supports the Help action. See Action and KPanelExtension().

void preferences () | ### preferences

[protected virtual]

Is called when the user selects "Preferences" from the extensions RMB menu. Reimplement this function to launch a preferences dialog or kcontrol module.

Note that this is called only when your extension supports the preferences action. See Action and KPanelExtension().

Position position () | ### position

[protected const]

Returns: the extension's position. (left, right, top, bottom)

Orientation orientation () | ### orientation

[protected]

Returns: the extensions orientation. (horizontal or vertical)

void positionChange ( Position ) | ### positionChange

[protected virtual]

The position changed to `position`. Reimplement this change handler in order to adjust the look of your extension.

- Author: Matthias Elter <elter@kde.org>
- Generated: root@sparc.ports.openbsd.org on Wed May 2 09:37:45 2001, using kdoc 2.0a53.