Prepare status area to support multiple trays.

ash/system/status_area_widget_delegate.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 "ash/system/status_area_widget_delegate.h"
 
 #include "ash/ash_export.h"
 #include "ash/focus_cycler.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "base/utf_string_conversions.h"
 #include "grit/ui_resources_standard.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/accessible_pane_view.h"
+#include "ui/views/layout/grid_layout.h"
 #include "ui/views/widget/widget.h"
 
 namespace {
 
 int kTraySpacing = 10;
 
 }  // namespace
 
 namespace ash {
 namespace internal {
 
 StatusAreaWidgetDelegate::StatusAreaWidgetDelegate()
-    : focus_cycler_for_testing_(NULL) {
-  SetLayout(views::BoxLayout::kHorizontal);
+    : focus_cycler_for_testing_(NULL),
+      alignment_(SHELF_ALIGNMENT_BOTTOM) {
 }
 
 StatusAreaWidgetDelegate::~StatusAreaWidgetDelegate() {
 }
 
 void StatusAreaWidgetDelegate::SetFocusCyclerForTesting(
     const FocusCycler* focus_cycler) {
   focus_cycler_for_testing_ = focus_cycler;
 }
 
@@ skipping 23 matching lines @@
   // We don't want mouse clicks to activate us, but we need to allow
   // activation when the user is using the keyboard (FocusCycler).
   const FocusCycler* focus_cycler = focus_cycler_for_testing_ ?
       focus_cycler_for_testing_ : Shell::GetInstance()->focus_cycler();
   return focus_cycler->widget_activating() == GetWidget();
 }
 
 void StatusAreaWidgetDelegate::DeleteDelegate() {
 }
 
-void StatusAreaWidgetDelegate::SetLayout(
-    views::BoxLayout::Orientation orientation) {
-  SetLayoutManager(new views::BoxLayout(orientation, 0, 0, kTraySpacing));
+void StatusAreaWidgetDelegate::AddTray(views::View* tray) {
+  SetLayoutManager(NULL);  // Reset layout manager before adding a child.
+  AddChildView(tray);
+  // Set the layout manager with the new list of children.
+  UpdateLayout();
+}
+
+void StatusAreaWidgetDelegate::UpdateLayout() {
+  // Use a grid layout so that the trays can be centered in each cell, and
+  // so that the widget gets laid out correctly when tray sizes change.

[sadrul, 2012/06/12 15:13:39]

I am not entirely sure we need grid-layout for this. (SystemTray resizes when
items change size/visibility, and it doesn't use this)

[stevenjb, 2012/06/12 16:46:50]

I started with BoxLayout. The problem is that then any spacing or alignment has
to be done by each child (i.e. tray), whereas with GridLayout we can specify
padding columns to define the spacing between trays and can center each child
vertically.

+  views::GridLayout* layout = new views::GridLayout(this);
+  SetLayoutManager(layout);
+
+  views::ColumnSet* columns = layout->AddColumnSet(0);
+  if (alignment_ == SHELF_ALIGNMENT_BOTTOM) {
+    for (int c = 0; c < child_count(); ++c) {
+      if (c != 0)
+        columns->AddPaddingColumn(0, kTraySpacing);
+      columns->AddColumn(views::GridLayout::CENTER, views::GridLayout::CENTER,
+                         0, /* resize percent */
+                         views::GridLayout::USE_PREF, 0, 0);
+    }
+    layout->StartRow(0, 0);
+    for (int c = 0; c < child_count(); ++c)
+      layout->AddView(child_at(c));
+  } else {
+    columns->AddColumn(views::GridLayout::CENTER, views::GridLayout::CENTER,
+                       0, /* resize percent */
+                       views::GridLayout::USE_PREF, 0, 0);
+    for (int c = 0; c < child_count(); ++c) {
+      if (c != 0)
+        layout->AddPaddingRow(0, kTraySpacing);
+      layout->StartRow(0, 0);
+      layout->AddView(child_at(c));
+    }
+  }
   Layout();
 }
 
+void StatusAreaWidgetDelegate::ChildPreferredSizeChanged(View* child) {
+  // Need to re-layout the parent window when trays or items are added/removed.
+  parent()->GetWidget()->GetRootView()->Layout();
+}
+
 }  // namespace internal
 }  // namespace ash