Adds scroll buttons to side tabs so that you can get to all the tabs.

chrome/browser/ui/views/tabs/side_tab_strip.cc

Index: chrome/browser/ui/views/tabs/side_tab_strip.cc
diff --git a/chrome/browser/ui/views/tabs/side_tab_strip.cc b/chrome/browser/ui/views/tabs/side_tab_strip.cc
index 4e1ae21f4e81a6464847c94faf1bdb2b9795194a..1c6fa8703041826eace9e1a9e4b7faf33ab7e670 100644
--- a/chrome/browser/ui/views/tabs/side_tab_strip.cc
+++ b/chrome/browser/ui/views/tabs/side_tab_strip.cc
@@ -14,16 +14,24 @@
 #include "ui/gfx/canvas.h"
 #include "views/background.h"
 #include "views/controls/button/image_button.h"
+#include "views/controls/button/text_button.h"
 
 namespace {
+
 const int kVerticalTabSpacing = 2;
 const int kTabStripWidth = 140;
 const SkColor kBackgroundColor = SkColorSetARGB(255, 209, 220, 248);
 const SkColor kSeparatorColor = SkColorSetARGB(255, 151, 159, 179);
 
+// Height of the scroll buttons.
+const int kScrollButtonHeight = 20;
+
 // Height of the separator.
 const int kSeparatorHeight = 1;
 
+// Padding between tabs and scroll button.
+const int kScrollButtonVerticalPadding = 2;
+
 // The new tab button is rendered using a SideTab.
 class SideTabNewTabButton : public SideTab {
  public:
@@ -61,6 +69,49 @@ void SideTabNewTabButton::OnMouseReleased(const views::MouseEvent& event) {
     controller_->CreateNewTab();
 }
 
+// Button class used for the scroll buttons.
+class ScrollButton : public views::TextButton {
+ public:
+  enum Type {
+    UP,
+    DOWN
+  };
+
+  explicit ScrollButton(views::ButtonListener* listener, Type type);
+
+ protected:
+  // views::View overrides.
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+
+ private:
+  const Type type_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScrollButton);
+};
+
+ScrollButton::ScrollButton(views::ButtonListener* listener,
+                           Type type)
+    : views::TextButton(listener, std::wstring()),
+      type_(type) {
+}
+
+void ScrollButton::OnPaint(gfx::Canvas* canvas) {
+  TextButton::OnPaint(canvas);
+
+  // Draw the arrow.
+  SkColor arrow_color = IsEnabled() ? SK_ColorBLACK : SK_ColorGRAY;
+  int arrow_height = 5;
+  int x = width() / 2;
+  int y = (height() - arrow_height) / 2;
+  int delta_y = 1;
+  if (type_ == DOWN) {
+    delta_y = -1;
+    y += arrow_height;
+  }
+  for (int i = 0; i < arrow_height; ++i, --x, y += delta_y)
+    canvas->FillRectInt(arrow_color, x, y, (i * 2) + 1, 1);
+}
+
 }  // namespace
 
 // static
@@ -72,13 +123,21 @@ const int SideTabStrip::kTabStripInset = 3;
 SideTabStrip::SideTabStrip(TabStripController* controller)
     : BaseTabStrip(controller, BaseTabStrip::VERTICAL_TAB_STRIP),
       newtab_button_(new SideTabNewTabButton(controller)),
-      separator_(new views::View()) {
+      scroll_up_button_(NULL),
+      scroll_down_button_(NULL),
+      separator_(new views::View()),
+      first_tab_y_offset_(0),
+      ideal_height_(0) {
   SetID(VIEW_ID_TAB_STRIP);
   set_background(views::Background::CreateSolidBackground(kBackgroundColor));
   AddChildView(newtab_button_);
   separator_->set_background(
       views::Background::CreateSolidBackground(kSeparatorColor));
   AddChildView(separator_);
+  scroll_up_button_ = new ScrollButton(this, ScrollButton::UP);
+  AddChildView(scroll_up_button_);
+  scroll_down_button_ = new ScrollButton(this, ScrollButton::DOWN);
+  AddChildView(scroll_down_button_);
 }
 
 SideTabStrip::~SideTabStrip() {
@@ -118,6 +177,9 @@ void SideTabStrip::RemoveTabAt(int model_index) {
 
 void SideTabStrip::SelectTabAt(int old_model_index, int new_model_index) {
   GetBaseTabAtModelIndex(new_model_index)->SchedulePaint();
+
+  if (controller()->IsActiveTab(new_model_index))
+    MakeTabVisible(ModelIndexToTabIndex(new_model_index));
 }
 
 void SideTabStrip::TabTitleChangedNotLoading(int model_index) {
@@ -132,6 +194,12 @@ void SideTabStrip::PaintChildren(gfx::Canvas* canvas) {
   // them last.
   std::vector<BaseTab*> dragging_tabs;
 
+  // Make sure nothing draws on top of the scroll buttons.
+  canvas->Save();
+  canvas->ClipRectInt(kTabStripInset, kTabStripInset,
+                      width() - kTabStripInset - kTabStripInset,
+                      GetMaxTabY() - kTabStripInset);
+
   // Paint the new tab and separator first so that any tabs animating appear on
   // top.
   separator_->Paint(canvas);
@@ -147,6 +215,74 @@ void SideTabStrip::PaintChildren(gfx::Canvas* canvas) {
 
   for (size_t i = 0; i < dragging_tabs.size(); ++i)
     dragging_tabs[i]->Paint(canvas);
+
+  canvas->Restore();
+
+  scroll_down_button_->Paint(canvas);
+  scroll_up_button_->Paint(canvas);
+}
+
+views::View* SideTabStrip::GetEventHandlerForPoint(const gfx::Point& point) {
+  // Check the scroll buttons first as they visually appear on top of everything
+  // else.
+  if (scroll_down_button_->IsVisible()) {
+    gfx::Point local_point(point);
+    View::ConvertPointToView(this, scroll_down_button_, &local_point);
+    if (scroll_down_button_->HitTest(local_point))
+      return scroll_down_button_->GetEventHandlerForPoint(local_point);
+  }
+
+  if (scroll_up_button_->IsVisible()) {
+    gfx::Point local_point(point);
+    View::ConvertPointToView(this, scroll_up_button_, &local_point);
+    if (scroll_up_button_->HitTest(local_point))
+      return scroll_up_button_->GetEventHandlerForPoint(local_point);
+  }
+  return views::View::GetEventHandlerForPoint(point);
+}
+
+void SideTabStrip::ButtonPressed(views::Button* sender,
+                                 const views::Event& event) {
+  int max_offset = GetMaxOffset();
+  if (max_offset == 0) {
+    // All the tabs fit, no need to scroll.
+    return;
+  }
+
+  // Determine the index of the first visible tab.
+  int initial_y = kTabStripInset;
+  int first_vis_index = -1;
+  for (int i = 0; i < tab_count(); ++i) {
+    if (ideal_bounds(i).bottom() > initial_y) {
+      first_vis_index = i;
+      break;
+    }
+  }
+  if (first_vis_index == -1)
+    return;
+
+  int delta = 0;
+  if (sender == scroll_up_button_) {
+    delta = initial_y - ideal_bounds(first_vis_index).y();
+    if (delta <= 0) {
+      if (first_vis_index == 0) {
+        delta = -first_tab_y_offset_;
+      } else {
+        delta = initial_y - ideal_bounds(first_vis_index - 1).y();
+        DCHECK_NE(0, delta);  // Not fatal, but indicates we aren't scrolling.
+      }
+    }
+  } else {
+    DCHECK_EQ(sender, scroll_down_button_);
+    if (ideal_bounds(first_vis_index).y() > initial_y) {
+      delta = initial_y - ideal_bounds(first_vis_index).y();
+    } else if (first_vis_index + 1 == tab_count()) {
+      delta = -first_tab_y_offset_;
+    } else {
+      delta = initial_y - ideal_bounds(first_vis_index + 1).y();
+    }
+  }
+  SetFirstTabYOffset(first_tab_y_offset_ + delta);
 }
 
 BaseTab* SideTabStrip::CreateTab() {
@@ -162,7 +298,7 @@ void SideTabStrip::GenerateIdealBounds() {
   gfx::Rect layout_rect = GetContentsBounds();
   layout_rect.Inset(kTabStripInset, kTabStripInset);
 
-  int y = layout_rect.y();
+  int y = layout_rect.y() + first_tab_y_offset_;
   bool last_was_mini = true;
   bool has_non_closing_tab = false;
   separator_bounds_.SetRect(0, -kSeparatorHeight, width(), kSeparatorHeight);
@@ -196,7 +332,14 @@ void SideTabStrip::GenerateIdealBounds() {
     newtab_button_bounds_ =
         gfx::Rect(layout_rect.x(), y, layout_rect.width(),
                   newtab_button_->GetPreferredSize().height());
+    y += newtab_button_->GetPreferredSize().height();
   }
+
+  ideal_height_ = y - layout_rect.y() - first_tab_y_offset_;
+
+  scroll_up_button_->SetEnabled(first_tab_y_offset_ != 0);
+  scroll_down_button_->SetEnabled(GetMaxOffset() != 0 &&
+                                  first_tab_y_offset_ != GetMaxOffset());
 }
 
 void SideTabStrip::StartInsertTabAnimation(int model_index) {
@@ -232,10 +375,13 @@ void SideTabStrip::AnimateToIdealBounds() {
 
 void SideTabStrip::DoLayout() {
   BaseTabStrip::DoLayout();
-
   newtab_button_->SetBoundsRect(newtab_button_bounds_);
-
   separator_->SetBoundsRect(separator_bounds_);
+  int scroll_button_y = height() - kScrollButtonHeight;
+  scroll_up_button_->SetBounds(0, scroll_button_y, width() / 2,
+                               kScrollButtonHeight);
+  scroll_down_button_->SetBounds(width() / 2, scroll_button_y, width() / 2,
+                                 kScrollButtonHeight);
 }
 
 void SideTabStrip::LayoutDraggedTabsAt(const std::vector<BaseTab*>& tabs,
@@ -271,3 +417,55 @@ void SideTabStrip::CalculateBoundsForDraggedTabs(
 int SideTabStrip::GetSizeNeededForTabs(const std::vector<BaseTab*>& tabs) {
   return static_cast<int>(tabs.size()) * SideTab::GetPreferredHeight();
 }
+
+void SideTabStrip::OnBoundsChanged(const gfx::Rect& previous_bounds) {
+  // When our height changes we may be able to show more.
+  first_tab_y_offset_ = std::max(GetMaxOffset(),
+                                 std::min(0, first_tab_y_offset_));
+  for (int i = 0; i < controller()->GetCount(); ++i) {
+    if (controller()->IsActiveTab(i)) {
+      MakeTabVisible(ModelIndexToTabIndex(i));
+      break;
+    }
+  }
+}
+
+void SideTabStrip::SetFirstTabYOffset(int new_offset) {
+  int max_offset = GetMaxOffset();
+  if (max_offset == 0) {
+    // All the tabs fit, no need to scroll.
+    return;
+  }
+  new_offset = std::max(max_offset, std::min(0, new_offset));
+  if (new_offset == first_tab_y_offset_)
+    return;
+
+  StopAnimating(false);
+  first_tab_y_offset_ = new_offset;
+  GenerateIdealBounds();
+  DoLayout();
+
+}
+
+int SideTabStrip::GetMaxOffset() const {
+  int available_height = GetMaxTabY() - kTabStripInset;
+  return std::min(0, available_height - ideal_height_);
+}
+
+int SideTabStrip::GetMaxTabY() const {
+  return height() - kTabStripInset - kScrollButtonVerticalPadding -
+      kScrollButtonHeight;
+}
+
+void SideTabStrip::MakeTabVisible(int tab_index) {
+  if (height() == 0)
+    return;
+
+  if (ideal_bounds(tab_index).y() < kTabStripInset) {
+    SetFirstTabYOffset(first_tab_y_offset_ - ideal_bounds(tab_index).y() +
+                       kTabStripInset);
+  } else if (ideal_bounds(tab_index).bottom() > GetMaxTabY()) {
+    SetFirstTabYOffset(GetMaxTabY() - (ideal_bounds(tab_index).bottom() -
+                                       first_tab_y_offset_));
+  }
+}