191 lines
7.7 KiB
C++
191 lines
7.7 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 program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This program 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 *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the *
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* Free Software Foundation, Inc., *
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* 51 Franklin Street, Fifth Floor, 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/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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* 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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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
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WRITE setEmptyExtenderMessage)
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public:
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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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* @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 emptyExtenderMessage 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 allready 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 (!extenderItem(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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protected:
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/**
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* Get's called after an item has been added to this extender. The bookkeeping has allready
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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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* allready 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 usefull 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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* @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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//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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