251 lines
10 KiB
C++
251 lines
10 KiB
C++
/*
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* Copyright 2008 by Rob Scheepmaker <r.scheepmaker@student.utwente.nl>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*/
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#ifndef PLASMA_EXTENDER_H
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#define PLASMA_EXTENDER_H
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#include <QtGui/QGraphicsWidget>
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#include "plasma/framesvg.h"
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#include "plasma/plasma_export.h"
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namespace Plasma
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{
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class ExtenderPrivate;
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class ExtenderItem;
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class Applet;
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/**
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* @class Extender plasma/extender.h <Plasma/Extender>
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*
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* @short Extends applets to allow detachable parts
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*
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* An Extender is a widget that visually extends the normal contents of an applet with
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* additional dynamic widgets called ExtenderItems. These ExtenderItems can be
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* detached by the user and dropped either on another Extender or on the canvas directly.
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*
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* This widget allows using ExtenderItems in your applet. Extender takes care of the presentation
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* of a collection of ExtenderItems and keeps track of ExtenderItems that originate in it.
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*
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* The default Extender implementation displays extender items in a vertical layout with
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* spacers that appear when dropping an ExtenderItem over it.
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*
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* If you wish to have a different presentation of extender items, you can choose to subclass
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* Extender and reimplement the extenderItem* events and, optionally, the saveState function.
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*
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* To use an Extender in you applet, you'll have to instantiate one. A call to extender() in your
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* applet will create an extender on your applet if you haven't got one already. Every applet can
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* contain only one extender. Think of it as a decorator that adds some functionality to applets
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* that require it. Never instantiate an Extender before init() in your applet. This won't work
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* correctly since a scene is required when an Extender is instantiated.
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*
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* As soon as an Extender is instantiated, ExtenderItems contained previously in this Extender are
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* restored using the initExtenderItem function from the applet the items originally came from. For
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* more information on how this works and how to use ExtenderItems in general, see the ExtenderItem
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* API documentation.
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*/
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class PLASMA_EXPORT Extender : public QGraphicsWidget
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{
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Q_OBJECT
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Q_PROPERTY(QString emptyExtenderMessage READ emptyExtenderMessage WRITE setEmptyExtenderMessage)
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public:
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/**
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* Description on how to render the extender's items.
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*/
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enum Appearance {
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NoBorders = 0, /**< Draws no borders on the extender's items. When placed in an applet
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on the desktop, use this setting and use the standard margins of
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the applet containing this extender. */
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BottomUpStacked = 1, /**< Draws no borders on the topmost extenderitem, but draws the
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left, top and right border on subsequent items. When margins
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of the containing dialog are set to 0, except for the top
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margin, this leads to the 'stacked' look, recommended for
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extenders of applet's contained in a panel at the bottom of
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the screen. */
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TopDownStacked = 2 /**< Draws no borders on the bottom extenderitem, but draws the
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left, bottom and right border on subsequent items. When margins
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of the containing dialog are set to 0, except for the bottom
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margin, this leads to the 'stacked' look, recommended for
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extenders of applet's contained in a panel at the top of
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the screen. */
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};
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/**
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* Creates an extender. Note that extender expects applet to have a config(), and needs a
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* scene because of that. So you should only instantiate an extender in init() or later, not
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* in an applet's constructor.
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* The constructor also takes care of restoring ExtenderItems that were contained in this
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* extender before, so ExtenderItems are persistent between sessions.
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* @param applet The applet this extender is part of. Null is not allowed here.
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*/
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explicit Extender(Applet *applet);
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~Extender();
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/**
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* @param message The text to be shown whenever the applet's extender is empty.
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* Defaults to i18n'ed "no items".
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*/
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void setEmptyExtenderMessage(const QString &message);
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/**
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* @return The text to be shown whenever the applet's layout is empty.
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*/
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QString emptyExtenderMessage() const;
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/**
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* @returns a list of all extender items (attached AND detached) where the source applet is
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* this applet.
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*/
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QList<ExtenderItem*> items() const;
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/**
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* @returns a list of all attached extender items.
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*/
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QList<ExtenderItem*> attachedItems() const;
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/**
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* @returns a list of all detached extender items.
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*/
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QList<ExtenderItem*> detachedItems() const;
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/**
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* This function can be used for easily determining if a certain item is already displayed
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* in a extender item somewhere, so your applet doesn't duplicate this item. Say the applet
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* displays 'jobs', from an engine which add's a source for every job. In sourceAdded you
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* could do something like:
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* if (!item(source)) {
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* //add an extender item monitoring this source.
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* }
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*/
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ExtenderItem *item(const QString &name) const;
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/**
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* Use this function to instruct the extender on how to render it's items. Usually you will
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* want to call this function in your applet's constraintsEvent, allthough this is already
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* done for you when using PopupApplet at base class for your applet. Defaults to NoBorders.
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*/
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void setAppearance(Appearance appearance);
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/**
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* @return the current way of rendering extender items that is used.
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*/
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Appearance appearance() const;
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protected:
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/**
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* Get's called after an item has been added to this extender. The bookkeeping has already
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* been done when this function get's called. The only thing left to do is put it somewhere
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* appropriate. The default implementation adds the extenderItem to the appropriate place in
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* a QGraphicsLinearLayout.
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* @param item The item that has just been added.
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* @param pos The location the item has been dropped in local coordinates.
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*/
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virtual void itemAddedEvent(ExtenderItem *item, const QPointF &pos);
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/**
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* Get's called after an item has been removed from this extender. All bookkeeping has
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* already been done when this function get's called.
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* @param item The item that has just been removed.
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*/
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virtual void itemRemovedEvent(ExtenderItem *item);
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/**
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* Get's called when an ExtenderItem that get's dragged enters this extender. Default
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* implementation does nothing.
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*/
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virtual void itemHoverEnterEvent(ExtenderItem *item);
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/**
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* Gets called when an ExtenderItem is hovering over this extender. Implement this function
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* to give some visual feedback about what will happen when the mouse button is released at
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* that position. The default implementation shows a spacer at the appropriate location in
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* the layout.
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* @param item The item that's hovering over this extender. Most useful for obtaining the
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* size of the spacer.
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* @param pos The location the item is hovering.
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*/
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virtual void itemHoverMoveEvent(ExtenderItem *item, const QPointF &pos);
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/**
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* Get's called when an ExtenderItem that was previously hovering over this extender moves
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* away from this extender. The default implementation removes any spacer from the layout.
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*/
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virtual void itemHoverLeaveEvent(ExtenderItem *item);
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/**
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* This function get's called for every extender when plasma exits. Implement this function
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* to store the current state of this extender (position in a layout for example), so this
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* can be restored when applet starts again. The default implementation stores the y
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* coordinate of every extender item in the config field extenderItemPos.
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*/
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virtual void saveState();
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/**
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* This function get's called on every item to determine which background border's to
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* render.
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* @param item the item for which it's position or extender has changed.
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* @return the borders that have to be enabled on it's background.
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*/
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virtual FrameSvg::EnabledBorders enabledBordersForItem(ExtenderItem *item) const;
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/**
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* Reimplemented from QGraphicsWidget
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*/
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QVariant itemChange(GraphicsItemChange change, const QVariant &value);
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/**
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* Reimplemented from QGraphicsWidget
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*/
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void resizeEvent(QGraphicsSceneResizeEvent *event);
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Q_SIGNALS:
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/**
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* Fires when an extender item is added to this extender.
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*/
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void itemAttached(Plasma::ExtenderItem *);
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/**
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* Fires when an extender item is removed from this extender.
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*/
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void itemDetached(Plasma::ExtenderItem *);
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/**
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* Fires when an extender's preferred size changes.
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*/
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void geometryChanged();
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private:
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ExtenderPrivate *const d;
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friend class ExtenderPrivate;
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friend class ExtenderItem;
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friend class ExtenderItemPrivate;
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//dialog needs access to the extender's applet location.
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friend class DialogPrivate;
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//applet should be able to call saveState();
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friend class Applet;
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};
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} // Plasma namespace
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#endif //PLASMA_EXTENDER_H
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