Add Flex to views::BoxLayout.

ui/views/layout/box_layout.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
 #define UI_VIEWS_LAYOUT_BOX_LAYOUT_H_
 
+#include <map>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/gfx/insets.h"
 #include "ui/views/layout/layout_manager.h"
 
 namespace gfx {
 class Rect;
 class Size;
 }
 
@@ skipping 13 matching lines @@
     kVertical,
   };
 
   // This specifies where along the main axis the children should be laid out.
   // e.g. a horizontal layout of MAIN_AXIS_ALIGNMENT_END will result in the
   // child views being right-aligned.
   enum MainAxisAlignment {
     MAIN_AXIS_ALIGNMENT_START,
     MAIN_AXIS_ALIGNMENT_CENTER,
     MAIN_AXIS_ALIGNMENT_END,
-
-    // This distributes extra space among the child views. This increases the
-    // size of child views along the main axis rather than the space between
-    // them.
-    MAIN_AXIS_ALIGNMENT_FILL,
     // TODO(calamity): Add MAIN_AXIS_ALIGNMENT_JUSTIFY which spreads blank space
     // in-between the child views.
   };
 
   // This specifies where along the cross axis the children should be laid out.
   // e.g. a horizontal layout of CROSS_AXIS_ALIGNMENT_END will result in the
   // child views being bottom-aligned.
   enum CrossAxisAlignment {
     // This causes the child view to stretch to fit the host in the cross axis.
     CROSS_AXIS_ALIGNMENT_STRETCH,
@@ skipping 17 matching lines @@
   }
 
   void set_cross_axis_alignment(CrossAxisAlignment cross_axis_alignment) {
     cross_axis_alignment_ = cross_axis_alignment;
   }
 
   void set_inside_border_insets(const gfx::Insets& insets) {
     inside_border_insets_ = insets;
   }
 
+  // Sets the flex weight for the view at |index|. Using the preferred size as
+  // the basis, free space along the main axis is distributed to views in the
+  // ratio of their flex weights. Similarly, if the views will overflow the
+  // parent, space is subtracted in these ratios.
+  //
+  // A flex of 0 means this view is not resized. Flex values must not be
+  // negative.
+  // Flex weights are set for the index and will not rearrange when the host's
+  // views do.
+  void SetFlexForViewAt(int index, int flex);

[sky, 2014/07/18 15:54:00]

Using indices like this is fragile and I suspect prone to unexpected conditions
(eg you set this for a view but a view and a new view gets inserted before the
view). I think this would make more sense to be View based.

[calamity, 2014/07/22 05:35:15]

Done.

+
+  // Clears the flex for the view at |index|, causing it to use the default
+  // flex.
+  void ClearFlexForViewAt(int index);
+
+  // Sets the flex for views to use when none is specified.
+  void SetDefaultFlex(int default_flex);
+
   // Overridden from views::LayoutManager:
   virtual void Layout(View* host) OVERRIDE;
   virtual gfx::Size GetPreferredSize(const View* host) const OVERRIDE;
   virtual int GetPreferredHeightForWidth(const View* host,
                                          int width) const OVERRIDE;
 
  private:
+  // Returns the flex for the specified index.
+  int GetFlexForViewAt(int index);

[sky, 2014/07/18 15:54:00]

const

[calamity, 2014/07/22 05:35:14]

Done.

+
   // Returns the size and position along the main axis of |rect|.
   int MainAxisSize(const gfx::Rect& rect) const;
   int MainAxisPosition(const gfx::Rect& rect) const;
 
   // Sets the size and position along the main axis of |rect|.
   void SetMainAxisSize(int size, gfx::Rect* rect) const;
   void SetMainAxisPosition(int position, gfx::Rect* rect) const;
 
   // Returns the size and position along the cross axis of |rect|.
   int CrossAxisSize(const gfx::Rect& rect) const;
@@ skipping 27 matching lines @@
   const int between_child_spacing_;
 
   // The alignment of children in the main axis. This is
   // MAIN_AXIS_ALIGNMENT_START by default.
   MainAxisAlignment main_axis_alignment_;
 
   // The alignment of children in the cross axis. This is
   // CROSS_AXIS_ALIGNMENT_STRETCH by default.
   CrossAxisAlignment cross_axis_alignment_;
 
+  // A map of view indexes to flex weights.
+  std::map<int, int> flex_map_;
+
+  // The flex weight for views if none is set. Defaults to 0.
+  int default_flex_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(BoxLayout);
 };
 
 } // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_BOX_LAYOUT_H_