ui/views/layout/box_layout.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
   6 #define UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/compiler_specific.h"
  10 #include "ui/gfx/insets.h"
  11 #include "ui/views/layout/layout_manager.h"
  12
  13 namespace gfx {
  14 class Rect;
  15 class Size;
  16 }
  17
  18 namespace views {
  19
  20 class View;
  21
  22 // A Layout manager that arranges child views vertically or horizontally in a
  23 // side-by-side fashion with spacing around and between the child views. The
  24 // child views are always sized according to their preferred size. If the
  25 // host's bounds provide insufficient space, child views will be clamped.
  26 // Excess space will not be distributed.
  27 class VIEWS_EXPORT BoxLayout : public LayoutManager {
  28  public:
  29   enum Orientation {
  30     kHorizontal,
  31     kVertical,
  32   };
  33
  34   // This specifies where along the main axis the children should be laid out.
  35   // e.g. a horizontal layout of MAIN_AXIS_ALIGNMENT_END will result in the
  36   // child views being right-aligned.
  37   enum MainAxisAlignment {
  38     MAIN_AXIS_ALIGNMENT_START,
  39     MAIN_AXIS_ALIGNMENT_CENTER,
  40     MAIN_AXIS_ALIGNMENT_END,
  41
  42     // This distributes extra space among the child views. This increases the
  43     // size of child views along the main axis rather than the space between
  44     // them.
  45     MAIN_AXIS_ALIGNMENT_FILL,
  46     // TODO(calamity): Add MAIN_AXIS_ALIGNMENT_JUSTIFY which spreads blank space
  47     // in-between the child views.
  48   };
  49
  50   // TODO(calamity): Add CrossAxisAlignment property to allow cross axis
  51   // alignment.
  52
  53   // Use |inside_border_horizontal_spacing| and
  54   // |inside_border_vertical_spacing| to add additional space between the child
  55   // view area and the host view border. |between_child_spacing| controls the
  56   // space in between child views.
  57   BoxLayout(Orientation orientation,
  58             int inside_border_horizontal_spacing,
  59             int inside_border_vertical_spacing,
  60             int between_child_spacing);
  61   virtual ~BoxLayout();
  62
  63   void set_main_axis_alignment(MainAxisAlignment main_axis_alignment) {
  64     main_axis_alignment_ = main_axis_alignment;
  65   }
  66
  67   // Overridden from views::LayoutManager:
  68   virtual void Layout(View* host) OVERRIDE;
  69   virtual gfx::Size GetPreferredSize(const View* host) const OVERRIDE;
  70   virtual int GetPreferredHeightForWidth(const View* host,
  71                                          int width) const OVERRIDE;
  72
  73  private:
  74   // Returns the size and position along the main axis of |child_area|.
  75   int MainAxisSize(const gfx::Rect& child_area) const;
  76   int MainAxisPosition(const gfx::Rect& child_area) const;
  77
  78   // Sets the size and position along the main axis of |child_area|.
  79   void SetMainAxisSize(int size, gfx::Rect* child_area) const;
  80   void SetMainAxisPosition(int position, gfx::Rect* child_area) const;
  81
  82   // The preferred size for the dialog given the width of the child area.
  83   gfx::Size GetPreferredSizeForChildWidth(const View* host,
  84                                           int child_area_width) const;
  85
  86   // The amount of space the layout requires in addition to any space for the
  87   // child views.
  88   gfx::Size NonChildSize(const View* host) const;
  89
  90   const Orientation orientation_;
  91
  92   // Spacing between child views and host view border.
  93   gfx::Insets inside_border_insets_;
  94
  95   // Spacing to put in between child views.
  96   const int between_child_spacing_;
  97
  98   // The alignment of children in the main axis. This is
  99   // MAIN_AXIS_ALIGNMENT_START by default.
 100   MainAxisAlignment main_axis_alignment_;
 101
 102   DISALLOW_IMPLICIT_CONSTRUCTORS(BoxLayout);
 103 };
 104
 105 } // namespace views
 106
 107 #endif  // UI_VIEWS_LAYOUT_BOX_LAYOUT_H_