src/libs/alm/RowColumnManager.h

   1 /*
   2  * Copyright 2011, Haiku, Inc. All rights reserved.
   3  * Copyright 2011, Clemens Zeidler <haiku@clemens-zeidler.de>
   4  * Distributed under the terms of the MIT License.
   5  */
   6 #ifndef ROW_COLUMN_MANAGER_H
   7 #define ROW_COLUMN_MANAGER_H
   8
   9
  10 #include "Area.h"
  11 #include "Column.h"
  12 #include "LinearSpec.h"
  13 #include "Row.h"
  14 #include "Tab.h"
  15
  16
  17 namespace BPrivate {
  18         class SharedSolver;
  19 };
  20
  21
  22 namespace BALM {
  23
  24
  25 /*! The RowColumnManager groups areas with same vertical or horizontal tabs
  26         into column and rows. For each row and column, a preferred size is
  27         calculated from the areas in the row or column. This preferred size is used
  28         to create a preferred size soft-constraint.
  29         Having only one constraint for each row and column avoids the so called
  30         spring effect. That is each area with a preferred size constraint is pulling
  31         or pressing torwards its preferred size. For example, a row with three areas
  32         pushes stronger than a row with two areas. Assuming that all areas have the
  33         same preferred size, the three-area row gets a different size than the
  34         two-area row. However, one would expect that both rows have the same height.
  35         The row and column approach of the RowColumnManager solves this problem.
  36
  37 */
  38 class RowColumnManager {
  39 public:
  40                                                                 RowColumnManager(LinearSpec* spec);
  41                                                                 ~RowColumnManager();
  42
  43                         void                            AddArea(Area* area);
  44                         void                            RemoveArea(Area* area);
  45
  46                         void                            UpdateConstraints();
  47                         void                            TabsChanged(Area* area);
  48 private:
  49                         friend class BPrivate::SharedSolver;
  50                         Row*                            _FindRowFor(Area* area);
  51                         Column*                         _FindColumnFor(Area* area);
  52
  53                         double                          _PreferredHeight(Row* row,
  54                                                                         double& weight);
  55                         double                          _PreferredWidth(Column* column,
  56                                                                         double& weight);
  57
  58                         void                            _UpdateConstraints(Row* row);
  59                         void                            _UpdateConstraints(Column* column);
  60
  61                         BObjectList<Row>        fRows;
  62                         BObjectList<Column>     fColumns;
  63
  64                         LinearSpec*                     fLinearSpec;
  65 };
  66
  67
  68 } // namespace BALM
  69
  70
  71 #endif // ROW_COLUMN_MANAGER_H
  72