Add main axis alignment for BoxLayout.

ui/views/layout/box_layout.cc

 // 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.
 
 #include "ui/views/layout/box_layout.h"
 
 #include "ui/gfx/rect.h"
 #include "ui/views/view.h"
 
 namespace views {
 
 BoxLayout::BoxLayout(BoxLayout::Orientation orientation,
                      int inside_border_horizontal_spacing,
                      int inside_border_vertical_spacing,
                      int between_child_spacing)
     : orientation_(orientation),
       inside_border_insets_(inside_border_vertical_spacing,
                             inside_border_horizontal_spacing,
                             inside_border_vertical_spacing,
                             inside_border_horizontal_spacing),
       between_child_spacing_(between_child_spacing),
-      spread_blank_space_(false) {
+      spread_blank_space_(false),
+      box_pack_(BOX_PACK_START) {
 }
 
 BoxLayout::~BoxLayout() {
 }
 
 void BoxLayout::Layout(View* host) {
   gfx::Rect child_area(host->GetLocalBounds());
   child_area.Inset(host->GetInsets());
   child_area.Inset(inside_border_insets_);
-  int x = child_area.x();
-  int y = child_area.y();
 
   int padding = 0;
-  if (spread_blank_space_) {
+  if (box_pack_ != BOX_PACK_START || spread_blank_space_) {
     int total = 0;
     int visible = 0;
     for (int i = 0; i < host->child_count(); ++i) {
       View* child = host->child_at(i);
       if (!child->visible())
         continue;
       if (orientation_ == kHorizontal) {
         total += child->GetPreferredSize().width() + between_child_spacing_;
       } else {
         total += child->GetHeightForWidth(child_area.width()) +
             between_child_spacing_;
       }
       ++visible;
     }
 
     if (visible) {
       total -= between_child_spacing_;
-      if (orientation_ == kHorizontal)
-        padding = (child_area.width() - total) / visible;
-      else
-        padding = (child_area.height() - total) / visible;
+      if (spread_blank_space_) {
+        if (orientation_ == kHorizontal)
+          padding = (child_area.width() - total) / visible;

[benwells, 2014/05/13 02:48:05]

I think this code would be easier to follow at a glance if you added three a few
private functions:

int BoxLayout::MainAxisSize(child)
int BoxLayout::MainAxisPosition(child)
void BoxLayout::SetMainAxisSize(child, size)
void BoxLayout::SetMainAxisPosition(child, position)

[calamity, 2014/05/13 04:29:29]

Done.

+        else
+          padding = (child_area.height() - total) / visible;
 
-      if (padding < 0)
-        padding = 0;
+        if (padding < 0)
+          padding = 0;
+      } else {
+        if (box_pack_ == BOX_PACK_CENTER) {
+          if (orientation_ == kHorizontal) {
+            child_area.set_x(child_area.x() + (child_area.width() - total) / 2);
+            child_area.set_width(total);
+          } else {
+            child_area.set_y(child_area.y() +
+                             (child_area.height() - total) / 2);
+            child_area.set_height(total);
+          }
+        } else if (box_pack_ == BOX_PACK_END) {
+          if (orientation_ == kHorizontal) {
+            child_area.set_x(child_area.x() + child_area.width() - total);
+            child_area.set_width(total);
+          } else {
+            child_area.set_y(child_area.y() + child_area.height() - total);
+            child_area.set_height(total);
+          }
+        }
+      }
     }
   }
 
+  int x = child_area.x();
+  int y = child_area.y();
   for (int i = 0; i < host->child_count(); ++i) {
     View* child = host->child_at(i);
     if (child->visible()) {
       gfx::Rect bounds(x, y, child_area.width(), child_area.height());
       if (orientation_ == kHorizontal) {
         bounds.set_width(child->GetPreferredSize().width() + padding);
         if (bounds.width() > 0)
           x += bounds.width() + between_child_spacing_;
       } else {
         bounds.set_height(child->GetHeightForWidth(bounds.width()) + padding);
@@ skipping 73 matching lines @@
                    child_area_bounds.height() + non_child_size.height());
 }
 
 gfx::Size BoxLayout::NonChildSize(View* host) {
   gfx::Insets insets(host->GetInsets());
   return gfx::Size(insets.width() + inside_border_insets_.width(),
                    insets.height() + inside_border_insets_.height());
 }
 
 } // namespace views