Prepare status area to support multiple trays.

ash/system/status_area_widget_delegate.cc

Index: ash/system/status_area_widget_delegate.cc
diff --git a/ash/system/status_area_widget_delegate.cc b/ash/system/status_area_widget_delegate.cc
index a2cdab4bd88cc7165600b96d68886727991d9c94..44f3adb162b1b6c1d7726e989d847eb1600516b3 100644
--- a/ash/system/status_area_widget_delegate.cc
+++ b/ash/system/status_area_widget_delegate.cc
@@ -15,6 +15,7 @@
 #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 {
@@ -27,8 +28,8 @@ 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() {
@@ -72,11 +73,49 @@ bool StatusAreaWidgetDelegate::CanActivate() const {
 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