/*
 * Copyright 2011, Haiku, Inc. All rights reserved.
 * Copyright 2011, Clemens Zeidler <haiku@clemens-zeidler.de>
 * Distributed under the terms of the MIT License.
 */
#ifndef ROW_COLUMN_MANAGER_H
#define ROW_COLUMN_MANAGER_H


#include "Area.h"
#include "Column.h"
#include "LinearSpec.h"
#include "Row.h"
#include "Tab.h"


namespace BPrivate {
        class SharedSolver;
};


namespace BALM {


/*! The RowColumnManager groups areas with same vertical or horizontal tabs
        into column and rows. For each row and column, a preferred size is
        calculated from the areas in the row or column. This preferred size is used
        to create a preferred size soft-constraint.
        Having only one constraint for each row and column avoids the so called
        spring effect. That is each area with a preferred size constraint is pulling
        or pressing torwards its preferred size. For example, a row with three areas
        pushes stronger than a row with two areas. Assuming that all areas have the
        same preferred size, the three-area row gets a different size than the
        two-area row. However, one would expect that both rows have the same height.
        The row and column approach of the RowColumnManager solves this problem.

*/
class RowColumnManager {
public:
                                                                RowColumnManager(LinearSpec* spec);
                                                                ~RowColumnManager();

                        void                            AddArea(Area* area);
                        void                            RemoveArea(Area* area);

                        void                            UpdateConstraints();
                        void                            TabsChanged(Area* area);
private:
                        friend class BPrivate::SharedSolver;
                        Row*                            _FindRowFor(Area* area);
                        Column*                         _FindColumnFor(Area* area);

                        double                          _PreferredHeight(Row* row,
                                                                        double& weight);
                        double                          _PreferredWidth(Column* column,
                                                                        double& weight);

                        void                            _UpdateConstraints(Row* row);
                        void                            _UpdateConstraints(Column* column);

                        BObjectList<Row>        fRows;
                        BObjectList<Column>     fColumns;

                        LinearSpec*                     fLinearSpec;
};


} // namespace BALM


#endif // ROW_COLUMN_MANAGER_H