/*  -*- c++ -*-

  kwidgetlister.h

  This file is part of libkdepim
  Copyright (c) 2001 Marc Mutz <mutz@kde.org>

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License,
  version 2, as published by the Free Software Foundation.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

  In addition, as a special exception, the copyright holders give
  permission to link the code of this library with any edition of
  the Qt library by Trolltech AS, Norway (or with modified versions
  of Qt that use the same license as Qt), and distribute linked
  combinations including the two.  You must obey the GNU General
  Public License in all respects for all of the code used other than
  Qt.  If you modify this file, you may extend this exception to
  your version of the file, but you are not obligated to do so.  If
  you do not wish to do so, delete this exception statement from
  your version.
*/

#ifndef KDEPIM_KWIDGETLISTER_H
#define KDEPIM_KWIDGETLISTER_H

#include <QWidget>

class QPushButton;
class QVBoxLayout;
class KHBox;

/**
  @short Widget that manages a list of other widgets (incl. 'more', 'fewer' and 'clear' buttons).

  Simple widget that nonetheless does a lot of the dirty work for
  the filter edit widgets (KMSearchPatternEdit and
  KMFilterActionEdit). It provides a growable and shrinkable area
  where widget may be displayed in rows. Widgets can be added by
  hitting the provided 'More' button, removed by the 'Fewer' button
  and cleared (e.g. reset, if an derived class implements that and
  removed for all but @ref mMinWidgets).

  To use this widget, derive from it with the template changed to
  the type of widgets this class should list. Then reimplement @ref
  addWidgetAtEnd, @ref removeLastWidget, calling the original
  implementation as necessary. Instantiate an object of the class and
  put it in your dialog.

  @author Marc Mutz <Marc@Mutz.com>
  @see KMSearchPatternEdit::WidgetLister KMFilterActionEdit::WidgetLister

*/

class KWidgetLister : public QWidget
{
  Q_OBJECT
  public:
    explicit KWidgetLister( int minWidgets=1, int maxWidgets=8,
                            QWidget *parent=0, const char *name=0 );
    virtual ~KWidgetLister();

  protected Q_SLOTS:
    /** Called whenever the user clicks on the 'more' button.
        Reimplementations should call this method, because this
        implementation does all the dirty work with adding the widgets
        to the layout (through @ref addWidgetAtEnd) and enabling/disabling
        the control buttons. */
    virtual void slotMore();

    /** Called whenever the user clicks on the 'fewer' button.
        Reimplementations should call this method, because this
        implementation does all the dirty work with removing the widgets
        from the layout (through @ref removeLastWidget) and
        enabling/disabling the control buttons. */
    virtual void slotFewer();

    /** Called whenever the user clicks on the 'clear' button.
        Reimplementations should call this method, because this
        implementation does all the dirty work with removing all but
        @ref mMinWidgets widgets from the layout and enabling/disabling
        the control buttons. */
    virtual void slotClear();

  protected:
    /** Adds a single widget. Doesn't care if there are already @ref
        mMaxWidgets on screen and whether it should enable/disable any
        controls. It simply does what it is asked to do.  You want to
        reimplement this method if you want to initialize the widget
        when showing it on screen. Make sure you call this
        implementaion, though, since you cannot put the widget on screen
        from derived classes (@p mLayout is private).
        Make sure the parent of the QWidget to add is this KWidgetLister. */
    virtual void addWidgetAtEnd( QWidget *w=0 );

    /** Removes a single (always the last) widget. Doesn't care if there
        are still only @ref mMinWidgets left on screen and whether it
        should enable/disable any controls. It simply does what it is
        asked to do. You want to reimplement this method if you want to
        save the widget's state before removing it from screen. Make
        sure you call this implementaion, though, since you should not
        remove the widget from screen from derived classes. */
    virtual void removeLastWidget();

    /** Called to clear a given widget. The default implementation does
        nothing. */
    virtual void clearWidget( QWidget *w );

    /** Because QT 2.x does not support signals/slots in template
        classes, we are forced to emulate this by forcing the
        implementers of subclasses of KWidgetLister to reimplement this
        function which replaces the "@p new @p T" call. */
    virtual QWidget *createWidget( QWidget *parent );

    /** Sets the number of widgets on scrren to exactly @p aNum. Doesn't
        check if @p aNum is inside the range @p
        [mMinWidgets,mMaxWidgets]. */
    virtual void setNumberOfShownWidgetsTo( int aNum );

    /** The list of widgets. Note that this list is set to auto-delete,
        meaning that widgets that are removed from the screen by either
        @ref slotFewer or @ref slotClear will be destroyed! */
    QList<QWidget*> mWidgetList;

    /** The minimum number of widgets that are to stay on screen. */
    int mMinWidgets;

    /** The maximum number of widgets that are to be shown on screen. */
    int mMaxWidgets;

  Q_SIGNALS:
    /** This signal is emitted whenever a widget was added */
    void widgetAdded();
    /** This signal is emitted whenever a widget was added */
    void widgetAdded(QWidget *);
    /** This signal is emitted whenever a widget was removed */
    void widgetRemoved();
    /** This signal is emitted whenever the clear button is clicked */
    void clearWidgets();

  private:
    void enableControls();

    QPushButton *mBtnMore, *mBtnFewer, *mBtnClear;
    QVBoxLayout *mLayout;
    KHBox       *mButtonBox;
};

#endif /* _KWIDGETLISTER_H_ */
