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/***************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (directui@nokia.com)
**
** This file is part of libmeegotouch.
**
** If you have questions regarding the use of this file, please contact
** Nokia at directui@nokia.com.
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License version 2.1 as published by the Free Software Foundation
** and appearing in the file LICENSE.LGPL included in the packaging
** of this file.
**
****************************************************************************/
#ifndef MABSTRACTSCROLLER_H
#define MABSTRACTSCROLLER_H
#include <QObject>
class QGraphicsWidget;
class QPoint;
class QRect;
//! \internal
/*! \brief Interface for extending widget scrolling support in MScrollChain
*
* Through this interface, once registered, the MScrollChain queries how
* much a widget can scroll, actually scroll it, and restore any scrolling.
*/
class MAbstractScroller : public QObject
{
Q_OBJECT
public:
MAbstractScroller();
virtual ~MAbstractScroller();
/*! \brief Queries how much widget can scroll given the origin and target areas.
*
* The scroller should not make assumptions about its own position since some
* parent widget might have already planned scrolling.
*
* Current limitation: If scrolling amount of the particular widget is restricted,
* and this method is called more than once, subsequent queries might promise too
* much and exceed the scrolling range of the widget.
* This method could be replaced by getters for viewport area and scrollable range,
* and then MScrollChain would do the math, keeping track of scrolling position.
*
* \param widget The scrollable widget in question.
* \param targetRect Target rectangle of the area of interest, in local widget coordinates.
* \param originPoint Current position (top left) of the area to be moved to targetRect, in local widget coordinates.
*/
virtual QPoint queryScrollingAmount(const QGraphicsWidget *widget,
const QRect &targetRect,
const QPoint &originPoint) = 0;
//! \brief Scrolls the contents of given \a widget by the amount of \a contentsOffset.
virtual void applyScrolling(QGraphicsWidget *widget, const QPoint &contentsOffset) = 0;
//! \brief Restores the widget to its original state (Optional)
virtual void restoreScrolling(QGraphicsWidget *widget);
//! \brief Helper method for moving a small rectangle inside a larger area.
static void moveRectInsideArea(const QRect &area, QRect &rect);
};
//! \internal_end
#endif // MABSTRACTSCROLLER_H
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