Experimental app list: Added a current page indicator to the launcher.

ui/app_list/views/contents_switcher_view.cc

Index: ui/app_list/views/contents_switcher_view.cc
diff --git a/ui/app_list/views/contents_switcher_view.cc b/ui/app_list/views/contents_switcher_view.cc
index 95669439fdb2f06df7d6ed6533d0e8d832cb101b..d755b59c4ee60e8f894bbf517eb61a78d8759682 100644
--- a/ui/app_list/views/contents_switcher_view.cc
+++ b/ui/app_list/views/contents_switcher_view.cc
@@ -6,17 +6,35 @@
 
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/views/contents_view.h"
+#include "ui/views/background.h"
 #include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/layout/box_layout.h"
+#include "ui/views/layout/fill_layout.h"
 
 namespace app_list {
 
 namespace {
 
-const int kPreferredHeight = 32;
+const int kPageIndicatorHeight = 1;
+const int kButtonImageSize = 32;
+const int kPreferredHeight = kButtonImageSize + kPageIndicatorHeight;
 const int kButtonSpacing = 4;
 
+class ContentsPageIndicatorView : public views::View {
+ public:
+  ContentsPageIndicatorView() {};
+  virtual ~ContentsPageIndicatorView() {};
+
+  // Overridden from views::View:
+  virtual gfx::Size GetPreferredSize() const OVERRIDE {
+    return gfx::Size(0, kPageIndicatorHeight);
+  };
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContentsPageIndicatorView);
+};
+
 }  // namespace
 
 ContentsSwitcherView::ContentsSwitcherView(ContentsView* contents_view)
@@ -31,13 +49,40 @@ ContentsSwitcherView::~ContentsSwitcherView() {}
 
 void ContentsSwitcherView::AddSwitcherButton(int resource_id, int page_index) {
   views::ImageButton* button = new views::ImageButton(this);
+  button->SetPreferredSize(gfx::Size(kButtonImageSize, kButtonImageSize));

[Matt Giuca, 2014/07/09 07:01:20]

What does setting this do? (Why is it needed now and not before?)

[calamity, 2014/07/09 08:02:54]

It should have been there before. It has no effect on the current app list. It's
for semantic layout correctness. It tells the ImageButton what size to be when
it has no image set. We can remove this if you really want.

   if (resource_id) {
     button->SetImage(
         views::CustomButton::STATE_NORMAL,
         ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id));
   }
   button->set_tag(page_index);
-  buttons_->AddChildView(button);
+
+  // Add an indicator for the current launcher page.
+  app_list::ContentsPageIndicatorView* indicator =
+      new app_list::ContentsPageIndicatorView();
+  indicator->set_background(
+      views::Background::CreateSolidBackground(app_list::kPagerSelectedColor));
+  indicator->SetVisible(false);
+  page_active_indicators_.push_back(indicator);
+
+  // A container view that will consume space when its child is not visible.
+  // TODO(calamity): Remove this once BoxLayout supports space-consuming
+  // invisible views.
+  views::View* indicator_container = new views::View();
+  indicator_container->SetLayoutManager(new views::FillLayout());
+  indicator_container->AddChildView(indicator);
+
+  // View containing the indicator view and image button.
+  views::View* button_container = new views::View();
+  views::BoxLayout* layout_manager =
+      new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0);
+  layout_manager->set_main_axis_alignment(
+      views::BoxLayout::MAIN_AXIS_ALIGNMENT_CENTER);
+  button_container->SetLayoutManager(layout_manager);
+  button_container->AddChildView(indicator_container);
+  button_container->AddChildView(button);
+
+  buttons_->AddChildView(button_container);
 }
 
 gfx::Size ContentsSwitcherView::GetPreferredSize() const {
@@ -61,4 +106,14 @@ void ContentsSwitcherView::ButtonPressed(views::Button* sender,
   contents_view_->SetActivePage(sender->tag());
 }
 
+void ContentsSwitcherView::SelectedPageChanged(int old_selected,
+                                               int new_selected) {
+  int num_indicators = static_cast<int>(page_active_indicators_.size());
+  if (old_selected >= 0 && old_selected < num_indicators)
+    page_active_indicators_[old_selected]->SetVisible(false);
+
+  if (new_selected >= 0 && new_selected < num_indicators)
+    page_active_indicators_[new_selected]->SetVisible(true);
+}
+
 }  // namespace app_list