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..03f0d6383651df6ef50ea00fff88e8f306b6c668 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));
   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 +106,40 @@ void ContentsSwitcherView::ButtonPressed(views::Button* sender,
   contents_view_->SetActivePage(sender->tag());
 }
 
+void ContentsSwitcherView::TotalPagesChanged() {
+}
+
+void ContentsSwitcherView::SelectedPageChanged(int old_selected,
+                                               int new_selected) {
+  // Makes the indicator visible when it is first drawn and when the
+  // selected page is changed.
+  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);
+}
+
+void ContentsSwitcherView::TransitionStarted() {
+}
+
+void ContentsSwitcherView::TransitionChanged() {
+  // Change the indicator at the beginning of the transition animation.
+  const PaginationModel& pm = contents_view_->pagination_model();
+  int old_selected = pm.selected_page();
+  int new_selected = pm.transition().target_page;
+  if (pm.IsRevertingCurrentTransition()) {
+    old_selected = pm.transition().target_page;
+    new_selected = pm.selected_page();
+  }
+  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