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.

[sashab, 2014/07/01 06:52:04]

Is this TODO still needed? This can be emulated with all child views having a
flex of 1.

[calamity, 2014/07/01 08:19:44]

This TODO outlines spreading the blank space to the spaces between the views
rather than among the 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,
     CROSS_AXIS_ALIGNMENT_START,
     CROSS_AXIS_ALIGNMENT_CENTER,
@@ skipping 15 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;
   }
 
+  void set_default_flex(int flex) { default_flex_ = flex; }

[sashab, 2014/07/01 06:52:04]

Is there a reason these methods use underscores and the other methods use camel
case?

[calamity, 2014/07/01 08:19:44]

Setting a property verbatim can be inlined and unix_cased. Anything else is
CamelCased and in the .cc.

+
+  // Sets the flex weight for the view at |index|. This uses the preferred main
+  // axis size as a basis and then distributes any free space along the main
+  // axis to the views in the ratio of the flex weights. If the views will
+  // overflow the parent in the main axis, this subtracts space from the views
+  // in the ratio of the flex weights.
+  void SetFlexForViewAt(int index, int flex);

[sashab, 2014/07/01 06:52:04]

Can flex be negative? Maybe add 'The flex cannot be negative' and add a
DCHECK().

I also think you can make this comment a bit clearer:
Sets the flex weight for the view at |index|. 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.

[calamity, 2014/07/01 08:19:44]

Done.

+
+  // Clears the flex for the view at |index|, causing it to use the default
+  // flex.
+  void ClearFlexForViewAt(int index);
+
   // 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.

[sashab, 2014/07/01 06:52:04]

Nit: 'Returns the flex *for the view*...'

[calamity, 2014/07/01 08:19:44]

I think this is disingenuous as it implies the flex weight is linked to the
view. Also updated comment above to reflect that this is not the case.

+  int GetFlexForViewAt(int index);
+
   // 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.

[sashab, 2014/07/01 06:52:04]

Add to this comment 'Defaults to 0.'

[calamity, 2014/07/01 08:19:44]

Done.

+  int default_flex_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(BoxLayout);
 };
 
 } // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_BOX_LAYOUT_H_