chrome/browser/views/tabs/tab_strip.cc

// Copyright (c) 2006-2008 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 "chrome/browser/views/tabs/tab_strip.h"

#include "base/gfx/size.h"
#include "chrome/app/theme/theme_resources.h"
#include "chrome/browser/profile.h"
#include "chrome/browser/tab_contents/tab_contents.h"
#include "chrome/browser/tabs/tab_strip_model.h"
#include "chrome/browser/user_metrics.h"
#include "chrome/browser/view_ids.h"
#include "chrome/browser/views/tabs/dragged_tab_controller.h"
#include "chrome/browser/views/tabs/tab.h"
#include "chrome/browser/tab_contents/web_contents.h"
#include "chrome/common/drag_drop_types.h"
#include "chrome/common/gfx/chrome_canvas.h"
#include "chrome/common/gfx/path.h"
#include "chrome/common/l10n_util.h"
#include "chrome/common/os_exchange_data.h"
#include "chrome/common/pref_names.h"
#include "chrome/common/resource_bundle.h"
#include "chrome/common/slide_animation.h"
#include "chrome/common/stl_util-inl.h"
#include "chrome/common/win_util.h"
#include "chrome/views/image_view.h"
#include "chrome/views/painter.h"

#include "generated_resources.h"

#undef min
#undef max

using views::DropTargetEvent;

static const int kDefaultAnimationDurationMs = 100;
static const int kResizeLayoutAnimationDurationMs = 166;
static const int kReorderAnimationDurationMs = 166;

static const int kNewTabButtonHOffset = -5;
static const int kNewTabButtonVOffset = 5;
static const int kResizeTabsTimeMs = 300;
static const int kSuspendAnimationsTimeMs = 200;
static const int kTabHOffset = -16;
static const int kTabStripAnimationVSlop = 40;

// Size of the drop indicator.
static int drop_indicator_width;
static int drop_indicator_height;

static inline int Round(double x) {
  // Why oh why is this not in a standard header?
  return static_cast<int>(floor(x + 0.5));
}

///////////////////////////////////////////////////////////////////////////////
// NewTabButton
//
//  A subclass of button that hit-tests to the shape of the new tab button.

class NewTabButton : public views::Button {
 public:
  NewTabButton() {}
  virtual ~NewTabButton() {}

 protected:
  // Overridden from views::View:
  virtual bool HasHitTestMask() const {
    return true;
  }
  virtual void GetHitTestMask(gfx::Path* path) const {
    DCHECK(path);

    SkScalar h = SkIntToScalar(height());
    SkScalar w = SkIntToScalar(width());

    // These values are defined by the shape of the new tab bitmap. Should that
    // bitmap ever change, these values will need to be updated. They're so
    // custom it's not really worth defining constants for.
    path->moveTo(0, 1);
    path->lineTo(w - 7, 1);
    path->lineTo(w - 4, 4);
    path->lineTo(w, 16);
    path->lineTo(w - 1, 17);
    path->lineTo(7, 17);
    path->lineTo(4, 13);
    path->lineTo(0, 1);
    path->close();
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(NewTabButton);
};

///////////////////////////////////////////////////////////////////////////////
//
// TabAnimation
//
//  A base class for all TabStrip animations.
//
class TabStrip::TabAnimation : public AnimationDelegate {
 public:
  friend class TabStrip;

  // Possible types of animation.
  enum Type {
    INSERT,
    REMOVE,
    MOVE,
    RESIZE
  };

  TabAnimation(TabStrip* tabstrip, Type type)
      : tabstrip_(tabstrip),
        animation_(this),
        start_selected_width_(0),
        start_unselected_width_(0),
        end_selected_width_(0),
        end_unselected_width_(0),
        layout_on_completion_(false),
        type_(type) {
  }
  virtual ~TabAnimation() {}

  Type type() const { return type_; }

  void Start() {
    animation_.SetSlideDuration(GetDuration());
    animation_.SetTweenType(SlideAnimation::EASE_OUT);
    if (!animation_.IsShowing()) {
      animation_.Reset();
      animation_.Show();
    }
  }

  void Stop() {
    animation_.Stop();
  }

  void set_layout_on_completion(bool layout_on_completion) {
    layout_on_completion_ = layout_on_completion;
  }

  // Retrieves the width for the Tab at the specified index if an animation is
  // active.
  static double GetCurrentTabWidth(TabStrip* tabstrip,
                                   TabStrip::TabAnimation* animation,
                                   int index) {
    double unselected, selected;
    tabstrip->GetCurrentTabWidths(&unselected, &selected);
    Tab* tab = tabstrip->GetTabAt(index);
    double tab_width = tab->IsSelected() ? selected : unselected;
    if (animation) {
      double specified_tab_width = animation->GetWidthForTab(index);
      if (specified_tab_width != -1)
        tab_width = specified_tab_width;
    }
    return tab_width;
  }

  // Overridden from AnimationDelegate:
  virtual void AnimationProgressed(const Animation* animation) {
    tabstrip_->AnimationLayout(end_unselected_width_);
  }

  virtual void AnimationEnded(const Animation* animation) {
    tabstrip_->FinishAnimation(this, layout_on_completion_);
    // This object is destroyed now, so we can't do anything else after this.
  }

  virtual void AnimationCanceled(const Animation* animation) {
    AnimationEnded(animation);
  }

 protected:
  // Returns the duration of the animation.
  virtual int GetDuration() const {
    return kDefaultAnimationDurationMs;
  }

  // Subclasses override to return the width of the Tab at the specified index
  // at the current animation frame. -1 indicates the default width should be
  // used for the Tab.
  virtual double GetWidthForTab(int index) const {
    return -1;  // Use default.
  }

  // Figure out the desired start and end widths for the specified pre- and
  // post- animation tab counts.
  void GenerateStartAndEndWidths(int start_tab_count, int end_tab_count) {
    tabstrip_->GetDesiredTabWidths(start_tab_count, &start_unselected_width_,
                                   &start_selected_width_);
    double standard_tab_width =
        static_cast<double>(TabRenderer::GetStandardSize().width());
    if (start_tab_count < end_tab_count &&
        start_unselected_width_ < standard_tab_width) {
      double minimum_tab_width =
          static_cast<double>(TabRenderer::GetMinimumUnselectedSize().width());
      start_unselected_width_ -= minimum_tab_width / start_tab_count;
    }
    tabstrip_->GenerateIdealBounds();
    tabstrip_->GetDesiredTabWidths(end_tab_count,
                                   &end_unselected_width_,
                                   &end_selected_width_);
  }

  TabStrip* tabstrip_;
  SlideAnimation animation_;

  double start_selected_width_;
  double start_unselected_width_;
  double end_selected_width_;
  double end_unselected_width_;

 private:
  // True if a complete re-layout is required upon completion of the animation.
  // Subclasses set this if they don't perform a complete layout
  // themselves and canceling the animation may leave the strip in an
  // inconsistent state.
  bool layout_on_completion_;

  const Type type_;

  DISALLOW_EVIL_CONSTRUCTORS(TabAnimation);
};

///////////////////////////////////////////////////////////////////////////////

// Handles insertion of a Tab at |index|.
class InsertTabAnimation : public TabStrip::TabAnimation {
 public:
  explicit InsertTabAnimation(TabStrip* tabstrip, int index)
      : TabAnimation(tabstrip, INSERT),
        index_(index) {
    int tab_count = tabstrip->GetTabCount();
    GenerateStartAndEndWidths(tab_count - 1, tab_count);
  }
  virtual ~InsertTabAnimation() {}

 protected:
  // Overridden from TabStrip::TabAnimation:
  virtual double GetWidthForTab(int index) const {
    if (index == index_) {
      bool is_selected = tabstrip_->model()->selected_index() == index;
      double target_width =
          is_selected ? end_unselected_width_ : end_selected_width_;
      double start_width = is_selected ? Tab::GetMinimumSelectedSize().width() :
          Tab::GetMinimumUnselectedSize().width();
      double delta = target_width - start_width;
      if (delta > 0)
        return start_width + (delta * animation_.GetCurrentValue());
      return start_width;
    }
    if (tabstrip_->GetTabAt(index)->IsSelected()) {
      double delta = end_selected_width_ - start_selected_width_;
      return start_selected_width_ + (delta * animation_.GetCurrentValue());
    }
    double delta = end_unselected_width_ - start_unselected_width_;
    return start_unselected_width_ + (delta * animation_.GetCurrentValue());
  }

 private:
  int index_;

  DISALLOW_EVIL_CONSTRUCTORS(InsertTabAnimation);
};

///////////////////////////////////////////////////////////////////////////////

// Handles removal of a Tab from |index|
class RemoveTabAnimation : public TabStrip::TabAnimation {
 public:
  RemoveTabAnimation(TabStrip* tabstrip, int index, TabContents* contents)
      : TabAnimation(tabstrip, REMOVE),
        index_(index) {
    int tab_count = tabstrip->GetTabCount();
    GenerateStartAndEndWidths(tab_count, tab_count - 1);
  }

  // Returns the index of the tab being removed.
  int index() const { return index_; }

  virtual ~RemoveTabAnimation() {
  }

 protected:
  // Overridden from TabStrip::TabAnimation:
  virtual double GetWidthForTab(int index) const {
    Tab* tab = tabstrip_->GetTabAt(index);
    if (index == index_) {
      // The tab(s) being removed are gradually shrunken depending on the state
      // of the animation.
      // Removed animated Tabs are never selected.
      double start_width = start_unselected_width_;
      // Make sure target_width is at least abs(kTabHOffset), otherwise if
      // less than kTabHOffset during layout tabs get negatively offset.
      double target_width =
          std::max(abs(kTabHOffset),
                   Tab::GetMinimumUnselectedSize().width() + kTabHOffset);
      double delta = start_width - target_width;
      return start_width - (delta * animation_.GetCurrentValue());
    }
    if (tabstrip_->available_width_for_tabs_ != -1 &&
        index_ != tabstrip_->GetTabCount() - 1) {
      return TabStrip::TabAnimation::GetWidthForTab(index);
    }
    // All other tabs are sized according to the start/end widths specified at
    // the start of the animation.
    if (tab->IsSelected()) {
      double delta = end_selected_width_ - start_selected_width_;
      return start_selected_width_ + (delta * animation_.GetCurrentValue());
    }
    double delta = end_unselected_width_ - start_unselected_width_;
    return start_unselected_width_ + (delta * animation_.GetCurrentValue());
  }

  virtual void AnimationEnded(const Animation* animation) {
    RemoveTabAt(index_);
    HighlightCloseButton();
    TabStrip::TabAnimation::AnimationEnded(animation);
  }

 private:
  // Cleans up the Tab from the TabStrip at the specified |index| once its
  // animated removal is complete.
  void RemoveTabAt(int index) const {
    // Save a pointer to the Tab before we remove the TabData, we'll need this
    // later.
    Tab* removed = tabstrip_->tab_data_.at(index).tab;

    // Remove the Tab from the TabStrip's list...
    tabstrip_->tab_data_.erase(tabstrip_->tab_data_.begin() + index);

    // If the TabContents being detached was removed as a result of a drag
    // gesture from its corresponding Tab, we don't want to remove the Tab from
    // the child list, because if we do so it'll stop receiving events and the
    // drag will stall. So we only remove if a drag isn't active, or the Tab
    // was for some other TabContents.
    if (!tabstrip_->IsDragSessionActive() ||
        !tabstrip_->drag_controller_->IsDragSourceTab(removed)) {
      tabstrip_->RemoveChildView(removed);
      delete removed;
    }
  }

  // When the animation completes, we send the Container a message to simulate
  // a mouse moved event at the current mouse position. This tickles the Tab
  // the mouse is currently over to show the "hot" state of the close button.
  void HighlightCloseButton() {
    if (tabstrip_->available_width_for_tabs_ == -1 ||
        tabstrip_->IsDragSessionActive()) {
      // This function is not required (and indeed may crash!) for removes
      // spawned by non-mouse closes and drag-detaches.
      return;
    }

    POINT pt;
    GetCursorPos(&pt);
    views::Widget* widget = tabstrip_->GetWidget();
    RECT wr;
    GetWindowRect(widget->GetHWND(), &wr);
    pt.x -= wr.left;
    pt.y -= wr.top;

    // Return to message loop - otherwise we may disrupt some operation that's
    // in progress.
    PostMessage(widget->GetHWND(), WM_MOUSEMOVE, 0, MAKELPARAM(pt.x, pt.y));
  }

  int index_;

  DISALLOW_EVIL_CONSTRUCTORS(RemoveTabAnimation);
};

///////////////////////////////////////////////////////////////////////////////

// Handles the movement of a Tab from one position to another.
class MoveTabAnimation : public TabStrip::TabAnimation {
 public:
  MoveTabAnimation(TabStrip* tabstrip, int tab_a_index, int tab_b_index)
      : TabAnimation(tabstrip, MOVE),
        start_tab_a_bounds_(tabstrip_->GetIdealBounds(tab_b_index)),
        start_tab_b_bounds_(tabstrip_->GetIdealBounds(tab_a_index)) {
    tab_a_ = tabstrip_->GetTabAt(tab_a_index);
    tab_b_ = tabstrip_->GetTabAt(tab_b_index);

    // Since we don't do a full TabStrip re-layout, we need to force a full
    // layout upon completion since we're not guaranteed to be in a good state
    // if for example the animation is canceled.
    set_layout_on_completion(true);
  }
  virtual ~MoveTabAnimation() {}

  // Overridden from AnimationDelegate:
  virtual void AnimationProgressed(const Animation* animation) {
    // Position Tab A
    double distance = start_tab_b_bounds_.x() - start_tab_a_bounds_.x();
    double delta = distance * animation_.GetCurrentValue();
    double new_x = start_tab_a_bounds_.x() + delta;
    tab_a_->SetBounds(Round(new_x), tab_a_->y(), tab_a_->width(),
                      tab_a_->height());

    // Position Tab B
    distance = start_tab_a_bounds_.x() - start_tab_b_bounds_.x();
    delta = distance * animation_.GetCurrentValue();
    new_x = start_tab_b_bounds_.x() + delta;
    tab_b_->SetBounds(Round(new_x), tab_b_->y(), tab_b_->width(),
                      tab_b_->height());

    tabstrip_->SchedulePaint();
  }

 protected:
  // Overridden from TabStrip::TabAnimation:
  virtual int GetDuration() const { return kReorderAnimationDurationMs; }

 private:
  // The two tabs being exchanged.
  Tab* tab_a_;
  Tab* tab_b_;

  // ...and their bounds.
  gfx::Rect start_tab_a_bounds_;
  gfx::Rect start_tab_b_bounds_;

  DISALLOW_EVIL_CONSTRUCTORS(MoveTabAnimation);
};

///////////////////////////////////////////////////////////////////////////////

// Handles the animated resize layout of the entire TabStrip from one width
// to another.
class ResizeLayoutAnimation : public TabStrip::TabAnimation {
 public:
  explicit ResizeLayoutAnimation(TabStrip* tabstrip)
      : TabAnimation(tabstrip, RESIZE) {
    int tab_count = tabstrip->GetTabCount();
    GenerateStartAndEndWidths(tab_count, tab_count);
    InitStartState();
  }
  virtual ~ResizeLayoutAnimation() {
  }

  // Overridden from AnimationDelegate:
  virtual void AnimationEnded(const Animation* animation) {
    tabstrip_->resize_layout_scheduled_ = false;
    TabStrip::TabAnimation::AnimationEnded(animation);
  }

 protected:
  // Overridden from TabStrip::TabAnimation:
  virtual int GetDuration() const {
    return kResizeLayoutAnimationDurationMs;
  }

  virtual double GetWidthForTab(int index) const {
    if (tabstrip_->GetTabAt(index)->IsSelected()) {
      double delta = end_selected_width_ - start_selected_width_;
      return start_selected_width_ + (delta * animation_.GetCurrentValue());
    }
    double delta = end_unselected_width_ - start_unselected_width_;
    return start_unselected_width_ + (delta * animation_.GetCurrentValue());
  }

 private:
  // We need to start from the current widths of the Tabs as they were last
  // laid out, _not_ the last known good state, which is what'll be done if we
  // don't measure the Tab sizes here and just go with the default TabAnimation
  // behavior...
  void InitStartState() {
    for (int i = 0; i < tabstrip_->GetTabCount(); ++i) {
      Tab* current_tab = tabstrip_->GetTabAt(i);
      if (current_tab->IsSelected()) {
        start_selected_width_ = current_tab->width();
      } else {
        start_unselected_width_ = current_tab->width();
      }
    }
  }

  DISALLOW_EVIL_CONSTRUCTORS(ResizeLayoutAnimation);
};

///////////////////////////////////////////////////////////////////////////////
// TabStrip, public:

TabStrip::TabStrip(TabStripModel* model)
    : model_(model),
      resize_layout_factory_(this),
      added_as_message_loop_observer_(false),
      resize_layout_scheduled_(false),
      current_unselected_width_(Tab::GetStandardSize().width()),
      current_selected_width_(Tab::GetStandardSize().width()),
      available_width_for_tabs_(-1) {
  Init();
}

TabStrip::~TabStrip() {
  // TODO(beng): (1031854) Restore this line once XPFrame/VistaFrame are dead.
  //model_->RemoveObserver(this);

  // TODO(beng): remove this if it doesn't work to fix the TabSelectedAt bug.
  drag_controller_.reset(NULL);

  // Make sure we unhook ourselves as a message loop observer so that we don't
  // crash in the case where the user closes the window after closing a tab
  // but before moving the mouse.
  RemoveMessageLoopObserver();
}

int TabStrip::GetPreferredHeight() {
  return GetPreferredSize().height();
}

bool TabStrip::HasAvailableDragActions() const {
  return model_->delegate()->GetDragActions() != 0;
}

bool TabStrip::CanProcessInputEvents() const {
  return IsAnimating() == NULL;
}

bool TabStrip::PointIsWithinWindowCaption(const gfx::Point& point) {
  views::View* v = GetViewForPoint(point);

  // If there is no control at this location, claim the hit was in the title
  // bar to get a move action.
  if (v == this)
    return true;

  // If the point is within the bounds of a Tab, the point can be considered
  // part of the caption if there are no available drag operations for the Tab.
  if (v->GetClassName() == Tab::kTabClassName && !HasAvailableDragActions())
    return true;

  // Check to see if the point is within the non-button parts of the new tab
  // button. The button has a non-rectangular shape, so if it's not in the
  // visual portions of the button we treat it as a click to the caption.
  gfx::Point point_in_newtab_coords(point);
  View::ConvertPointToView(this, newtab_button_, &point_in_newtab_coords);
  if (newtab_button_->bounds().Contains(point) &&
      !newtab_button_->HitTest(point_in_newtab_coords)) {
    return true;
  }

  // All other regions, including the new Tab button, should be considered part
  // of the containing Window's client area so that regular events can be
  // processed for them.
  return false;
}

bool TabStrip::IsCompatibleWith(TabStrip* other) {
  return model_->profile() == other->model()->profile();
}

bool TabStrip::IsAnimating() const {
  return active_animation_.get() != NULL;
}

void TabStrip::DestroyDragController() {
  if (IsDragSessionActive())
    drag_controller_.reset(NULL);
}

void TabStrip::DestroyDraggedSourceTab(Tab* tab) {
  // We could be running an animation that references this Tab.
  if (active_animation_.get())
    active_animation_->Stop();
  // Make sure we leave the tab_data_ vector in a consistent state, otherwise
  // we'll be pointing to tabs that have been deleted and removed from the
  // child view list.
  std::vector<TabData>::iterator it = tab_data_.begin();
  for (; it != tab_data_.end(); ++it) {
    if (it->tab == tab) {
      if (!model_->closing_all())
        NOTREACHED() << "Leaving in an inconsistent state!";
      tab_data_.erase(it);
      break;
    }
  }
  tab->GetParent()->RemoveChildView(tab);
  delete tab;
  // Force a layout here, because if we've just quickly drag detached a Tab,
  // the stopping of the active animation above may have left the TabStrip in a
  // bad (visual) state.
  Layout();
}

gfx::Rect TabStrip::GetIdealBounds(int index) {
  DCHECK(index >= 0 && index < GetTabCount());
  return tab_data_.at(index).ideal_bounds;
}

void TabStrip::UpdateLoadingAnimations() {
  for (int i = 0, index = 0; i < GetTabCount(); ++i, ++index) {
    Tab* current_tab = GetTabAt(i);
    if (current_tab->closing()) {
      --index;
    } else {
      TabContents* contents = model_->GetTabContentsAt(index);
      if (!contents || !contents->is_loading()) {
        current_tab->ValidateLoadingAnimation(Tab::ANIMATION_NONE);
      } else if (contents->waiting_for_response()) {
        current_tab->ValidateLoadingAnimation(Tab::ANIMATION_WAITING);
      } else {
        current_tab->ValidateLoadingAnimation(Tab::ANIMATION_LOADING);
      }
    }
  }
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, views::View overrides:

void TabStrip::PaintChildren(ChromeCanvas* canvas) {
  // Paint the tabs in reverse order, so they stack to the left.
  Tab* selected_tab = NULL;
  for (int i = GetTabCount() - 1; i >= 0; --i) {
    Tab* tab = GetTabAt(i);
    // We must ask the _Tab's_ model, not ourselves, because in some situations
    // the model will be different to this object, e.g. when a Tab is being
    // removed after its TabContents has been destroyed.
    if (!tab->IsSelected()) {
      tab->ProcessPaint(canvas);
    } else {
      selected_tab = tab;
    }
  }

  if (win_util::ShouldUseVistaFrame()) {
    // Make sure unselected tabs are somewhat transparent.
    SkPaint paint;
    paint.setColor(SkColorSetARGB(200, 255, 255, 255));
    paint.setPorterDuffXfermode(SkPorterDuff::kDstIn_Mode);
    paint.setStyle(SkPaint::kFill_Style);
    canvas->FillRectInt(
        0, 0, width(),
        height() - 2,  // Visible region that overlaps the toolbar.
        paint);
  }

  // Paint the selected tab last, so it overlaps all the others.
  if (selected_tab)
    selected_tab->ProcessPaint(canvas);

  // Paint the New Tab button.
  newtab_button_->ProcessPaint(canvas);
}

// Overridden to support automation. See automation_proxy_uitest.cc.
views::View* TabStrip::GetViewByID(int view_id) const {
  if (GetTabCount() > 0) {
    if (view_id == VIEW_ID_TAB_LAST) {
      return GetTabAt(GetTabCount() - 1);
    } else if ((view_id >= VIEW_ID_TAB_0) && (view_id < VIEW_ID_TAB_LAST)) {
      int index = view_id - VIEW_ID_TAB_0;
      if (index >= 0 && index < GetTabCount()) {
        return GetTabAt(index);
      } else {
        return NULL;
      }
    }
  }

  return View::GetViewByID(view_id);
}

void TabStrip::Layout() {
  // Called from:
  // - window resize
  // - animation completion
  if (active_animation_.get())
    active_animation_->Stop();
  GenerateIdealBounds();
  int tab_count = GetTabCount();
  int tab_right = 0;
  for (int i = 0; i < tab_count; ++i) {
    const gfx::Rect& bounds = tab_data_.at(i).ideal_bounds;
    GetTabAt(i)->SetBounds(bounds.x(), bounds.y(), bounds.width(),
                           bounds.height());
    tab_right = bounds.right() + kTabHOffset;
  }
  LayoutNewTabButton(static_cast<double>(tab_right), current_unselected_width_);
  SchedulePaint();
}

gfx::Size TabStrip::GetPreferredSize() {
  return gfx::Size(0, Tab::GetMinimumUnselectedSize().height());
}

void TabStrip::OnDragEntered(const DropTargetEvent& event) {
  UpdateDropIndex(event);
}

int TabStrip::OnDragUpdated(const DropTargetEvent& event) {
  UpdateDropIndex(event);
  return GetDropEffect(event);
}

void TabStrip::OnDragExited() {
  SetDropIndex(-1, false);
}

int TabStrip::OnPerformDrop(const DropTargetEvent& event) {
  if (!drop_info_.get())
    return DragDropTypes::DRAG_NONE;

  const int drop_index = drop_info_->drop_index;
  const bool drop_before = drop_info_->drop_before;

  // Hide the drop indicator.
  SetDropIndex(-1, false);

  GURL url;
  std::wstring title;
  if (!event.GetData().GetURLAndTitle(&url, &title) || !url.is_valid())
    return DragDropTypes::DRAG_NONE;

  if (drop_before) {
    UserMetrics::RecordAction(L"Tab_DropURLBetweenTabs", model_->profile());

    // Insert a new tab.
    TabContents* contents =
        model_->delegate()->CreateTabContentsForURL(
            url, GURL(), model_->profile(), PageTransition::TYPED, false,
            NULL);
    model_->AddTabContents(contents, drop_index, PageTransition::GENERATED,
                           true);
  } else {
    UserMetrics::RecordAction(L"Tab_DropURLOnTab", model_->profile());

    model_->GetTabContentsAt(drop_index)->controller()->
        LoadURL(url, GURL(), PageTransition::GENERATED);
    model_->SelectTabContentsAt(drop_index, true);
  }

  return GetDropEffect(event);
}

bool TabStrip::GetAccessibleRole(VARIANT* role) {
  DCHECK(role);

  role->vt = VT_I4;
  role->lVal = ROLE_SYSTEM_GROUPING;
  return true;
}

bool TabStrip::GetAccessibleName(std::wstring* name) {
  if (!accessible_name_.empty()) {
    (*name).assign(accessible_name_);
    return true;
  }
  return false;
}

void TabStrip::SetAccessibleName(const std::wstring& name) {
  accessible_name_.assign(name);
}

views::View* TabStrip::GetViewForPoint(const gfx::Point& point) {
  return GetViewForPoint(point, false);
}

views::View* TabStrip::GetViewForPoint(const gfx::Point& point,
                                       bool can_create_floating) {
  // Return any view that isn't a Tab or this TabStrip immediately. We don't
  // want to interfere.
  views::View* v = View::GetViewForPoint(point, can_create_floating);
  if (v && v != this && v->GetClassName() != Tab::kTabClassName)
    return v;

  // The display order doesn't necessarily match the child list order, so we
  // walk the display list hit-testing Tabs. Since the selected tab always
  // renders on top of adjacent tabs, it needs to be hit-tested before any
  // left-adjacent Tab, so we look ahead for it as we walk.
  int tab_count = GetTabCount();
  for (int i = 0; i < tab_count; ++i) {
    Tab* next_tab = i < (tab_count - 1) ? GetTabAt(i + 1) : NULL;
    if (next_tab && next_tab->IsSelected() && IsPointInTab(next_tab, point))
      return next_tab;
    Tab* tab = GetTabAt(i);
    if (IsPointInTab(tab, point))
      return tab;
  }

  // No need to do any floating view stuff, we don't use them in the TabStrip.
  return this;
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, TabStripModelObserver implementation:

void TabStrip::TabInsertedAt(TabContents* contents,
                             int index,
                             bool foreground) {
  DCHECK(contents);
  DCHECK(index == TabStripModel::kNoTab || model_->ContainsIndex(index));

  if (active_animation_.get())
    active_animation_->Stop();

  bool contains_tab = false;
  Tab* tab = NULL;
  // First see if this Tab is one that was dragged out of this TabStrip and is
  // now being dragged back in. In this case, the DraggedTabController actually
  // has the Tab already constructed and we can just insert it into our list
  // again.
  if (IsDragSessionActive()) {
    tab = drag_controller_->GetDragSourceTabForContents(contents);
    if (tab) {
      // If the Tab was detached, it would have been animated closed but not
      // removed, so we need to reset this property.
      tab->set_closing(false);
      tab->ValidateLoadingAnimation(TabRenderer::ANIMATION_NONE);
      tab->SetVisible(true);
    }

    // See if we're already in the list. We don't want to add ourselves twice.
    std::vector<TabData>::const_iterator iter = tab_data_.begin();
    for (; iter != tab_data_.end() && !contains_tab; ++iter) {
      if (iter->tab == tab)
        contains_tab = true;
    }
  }

  // Otherwise we need to make a new Tab.
  if (!tab)
    tab = new Tab(this);

  // Only insert if we're not already in the list.
  if (!contains_tab) {
    if (index == TabStripModel::kNoTab) {
      TabData d = { tab, gfx::Rect() };
      tab_data_.push_back(d);
      tab->UpdateData(contents);
    } else {
      TabData d = { tab, gfx::Rect() };
      tab_data_.insert(tab_data_.begin() + index, d);
      tab->UpdateData(contents);
    }
  }

  // We only add the tab to the child list if it's not already - an invisible
  // tab maintained by the DraggedTabController will already be parented.
  if (!tab->GetParent())
    AddChildView(tab);

  // Don't animate the first tab, it looks weird, and don't animate anything
  // if the containing window isn't visible yet.
  if (GetTabCount() > 1 && GetWidget() &&
      IsWindowVisible(GetWidget()->GetHWND())) {
    StartInsertTabAnimation(index);
  } else {
    Layout();
  }
}

void TabStrip::TabDetachedAt(TabContents* contents, int index) {
  if (CanUpdateDisplay()) {
    GenerateIdealBounds();
    StartRemoveTabAnimation(index, contents);
    // Have to do this _after_ calling StartRemoveTabAnimation, so that any
    // previous remove is completed fully and index is valid in sync with the
    // model index.
    GetTabAt(index)->set_closing(true);
  }
}

void TabStrip::TabSelectedAt(TabContents* old_contents,
                             TabContents* new_contents,
                             int index,
                             bool user_gesture) {
  DCHECK(index >= 0 && index < GetTabCount());
  if (CanUpdateDisplay()) {
    // We have "tiny tabs" if the tabs are so tiny that the unselected ones are
    // a different size to the selected ones.
    bool tiny_tabs = current_unselected_width_ != current_selected_width_;
    if (!IsAnimating() && (!resize_layout_scheduled_ || tiny_tabs)) {
      Layout();
    } else {
      SchedulePaint();
    }
  }
}

void TabStrip::TabMoved(TabContents* contents, int from_index, int to_index) {
  Tab* tab = GetTabAt(from_index);
  Tab* other_tab = GetTabAt(to_index);
  tab_data_.erase(tab_data_.begin() + from_index);
  TabData data = {tab, gfx::Rect()};
  tab_data_.insert(tab_data_.begin() + to_index, data);
  GenerateIdealBounds();
  StartMoveTabAnimation(from_index, to_index);
}

void TabStrip::TabChangedAt(TabContents* contents, int index) {
  // Index is in terms of the model. Need to make sure we adjust that index in
  // case we have an animation going.
  Tab* tab = GetTabAtAdjustForAnimation(index);
  tab->UpdateData(contents);
  tab->UpdateFromModel();
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, Tab::Delegate implementation:

bool TabStrip::IsTabSelected(const Tab* tab) const {
  if (tab->closing())
    return false;

  int tab_count = GetTabCount();
  for (int i = 0, index = 0; i < tab_count; ++i, ++index) {
    Tab* current_tab = GetTabAt(i);
    if (current_tab->closing())
      --index;
    if (current_tab == tab)
      return index == model_->selected_index();
  }
  return false;
}

void TabStrip::SelectTab(Tab* tab) {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    model_->SelectTabContentsAt(index, true);
}

void TabStrip::CloseTab(Tab* tab) {
  int tab_index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(tab_index)) {
    TabContents* contents = model_->GetTabContentsAt(tab_index);
    if (contents)
      UserMetrics::RecordAction(L"CloseTab_Mouse", contents->profile());
    Tab* last_tab = GetTabAt(GetTabCount() - 1);
    // Limit the width available to the TabStrip for laying out Tabs, so that
    // Tabs are not resized until a later time (when the mouse pointer leaves
    // the TabStrip).
    available_width_for_tabs_ = GetAvailableWidthForTabs(last_tab);
    resize_layout_scheduled_ = true;
    AddMessageLoopObserver();
    model_->CloseTabContentsAt(tab_index);
  }
}

bool TabStrip::IsCommandEnabledForTab(
    TabStripModel::ContextMenuCommand command_id, const Tab* tab) const {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    return model_->IsContextMenuCommandEnabled(index, command_id);
  return false;
}

void TabStrip::ExecuteCommandForTab(
    TabStripModel::ContextMenuCommand command_id, Tab* tab) {
  int index = GetIndexOfTab(tab);
  if (model_->ContainsIndex(index))
    model_->ExecuteContextMenuCommand(index, command_id);
}

void TabStrip::StartHighlightTabsForCommand(
    TabStripModel::ContextMenuCommand command_id, Tab* tab) {
  if (command_id == TabStripModel::CommandCloseTabsOpenedBy) {
    int index = GetIndexOfTab(tab);
    if (model_->ContainsIndex(index)) {
      std::vector<int> indices = model_->GetIndexesOpenedBy(index);
      std::vector<int>::const_iterator iter = indices.begin();
      for (; iter != indices.end(); ++iter) {
        int current_index = *iter;
        DCHECK(current_index >= 0 && current_index < GetTabCount());
        Tab* current_tab = GetTabAt(current_index);
        current_tab->StartPulse();
      }
    }
  } else if (command_id == TabStripModel::CommandCloseTabsToRight) {
    int index = GetIndexOfTab(tab);
    if (model_->ContainsIndex(index)) {
      for (int i = index + 1; i < GetTabCount(); ++i) {
        Tab* current_tab = GetTabAt(i);
        current_tab->StartPulse();
      }
    }
  } else if (command_id == TabStripModel::CommandCloseOtherTabs) {
    for (int i = 0; i < GetTabCount(); ++i) {
      Tab* current_tab = GetTabAt(i);
      if (current_tab != tab)
        current_tab->StartPulse();
    }
  }
}

void TabStrip::StopHighlightTabsForCommand(
    TabStripModel::ContextMenuCommand command_id, Tab* tab) {
  if (command_id == TabStripModel::CommandCloseTabsOpenedBy ||
      command_id == TabStripModel::CommandCloseTabsToRight ||
      command_id == TabStripModel::CommandCloseOtherTabs) {
    // Just tell all Tabs to stop pulsing - it's safe.
    StopAllHighlighting();
  }
}

void TabStrip::StopAllHighlighting() {
  for (int i = 0; i < GetTabCount(); ++i)
    GetTabAt(i)->StopPulse();
}

void TabStrip::MaybeStartDrag(Tab* tab, const views::MouseEvent& event) {
  // Don't accidentally start any drag operations during animations if the
  // mouse is down... during an animation tabs are being resized automatically,
  // so the View system can misinterpret this easily if the mouse is down that
  // the user is dragging.
  if (IsAnimating() || tab->closing() || !HasAvailableDragActions())
    return;
  drag_controller_.reset(new DraggedTabController(tab, this));
  drag_controller_->CaptureDragInfo(gfx::Point(event.x(), event.y()));
}

void TabStrip::ContinueDrag(const views::MouseEvent& event) {
  // We can get called even if |MaybeStartDrag| wasn't called in the event of
  // a TabStrip animation when the mouse button is down. In this case we should
  // _not_ continue the drag because it can lead to weird bugs.
  if (drag_controller_.get())
    drag_controller_->Drag();
}

bool TabStrip::EndDrag(bool canceled) {
  return drag_controller_.get() ? drag_controller_->EndDrag(canceled) : false;
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, views::BaseButton::ButtonListener implementation:

void TabStrip::ButtonPressed(views::BaseButton* sender) {
  if (sender == newtab_button_)
    model_->AddBlankTab(true);
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, MessageLoop::Observer implementation:

void TabStrip::WillProcessMessage(const MSG& msg) {
}

void TabStrip::DidProcessMessage(const MSG& msg) {
  // We spy on three different Windows messages here to see if the mouse has
  // moved out of the bounds of the tabstrip, which we use as our cue to kick
  // of the resize animation. The messages are:
  //
  // WM_MOUSEMOVE:
  //   For when the mouse moves from the tabstrip over into the rest of the
  //   browser UI, i.e. within the bounds of the same windows HWND.
  // WM_MOUSELEAVE:
  //   For when the mouse moves very rapidly from a tab closed in the middle of
  //   the tabstrip (_not_ the end) out of the bounds of the browser's HWND and
  //   over some other HWND.
  // WM_NCMOUSELEAVE:
  //   For when the mouse moves very rapidly from the end of the tabstrip (when
  //   the last tab is closed and the mouse is left floating over the title
  //   bar). Because the empty area of the tabstrip at the end of the title bar
  //   is registered by the ChromeFrame as part of the "caption" area of the
  //   window (the frame's OnNCHitTest method returns HTCAPTION for this
  //   region), the frame's HWND receives a WM_MOUSEMOVE message immediately,
  //   because as far as it is concerned the mouse has _left_ the client area
  //   of the window (and is now over the non-client area). To be notified
  //   again when the mouse leaves the _non-client_ area, we use the
  //   WM_NCMOUSELEAVE message, which causes us to re-evaluate the cursor
  //   position and correctly resize the tabstrip.
  //
  switch (msg.message) {
    case WM_MOUSEMOVE:
    case WM_MOUSELEAVE:
    case WM_NCMOUSELEAVE:
      if (!IsCursorInTabStripZone()) {
        // Mouse moved outside the tab slop zone, start a timer to do a resize
        // layout after a short while...
        if (resize_layout_factory_.empty()) {
          MessageLoop::current()->PostDelayedTask(FROM_HERE,
              resize_layout_factory_.NewRunnableMethod(
                  &TabStrip::ResizeLayoutTabs),
              kResizeTabsTimeMs);
        }
      } else {
        // Mouse moved quickly out of the tab strip and then into it again, so
        // cancel the timer so that the strip doesn't move when the mouse moves
        // back over it.
        resize_layout_factory_.RevokeAll();
      }
      break;
  }
}

///////////////////////////////////////////////////////////////////////////////
// TabStrip, private:

void TabStrip::Init() {
  model_->AddObserver(this);
  newtab_button_ = new NewTabButton;
  newtab_button_->SetListener(this, TabStripModel::kNoTab);
  ResourceBundle& rb = ResourceBundle::GetSharedInstance();
  SkBitmap* bitmap;

  bitmap = rb.GetBitmapNamed(IDR_NEWTAB_BUTTON);
  newtab_button_->SetImage(views::Button::BS_NORMAL, bitmap);
  newtab_button_->SetImage(views::Button::BS_PUSHED,
                           rb.GetBitmapNamed(IDR_NEWTAB_BUTTON_P));
  newtab_button_->SetImage(views::Button::BS_HOT,
                           rb.GetBitmapNamed(IDR_NEWTAB_BUTTON_H));

  newtab_button_size_.SetSize(bitmap->width(), bitmap->height());
  actual_newtab_button_size_ = newtab_button_size_;

  newtab_button_->SetAccessibleName(l10n_util::GetString(IDS_ACCNAME_NEWTAB));
  AddChildView(newtab_button_);

  if (drop_indicator_width == 0) {
    // Direction doesn't matter, both images are the same size.
    SkBitmap* drop_image = GetDropArrowImage(true);
    drop_indicator_width = drop_image->width();
    drop_indicator_height = drop_image->height();
  }
}

Tab* TabStrip::GetTabAt(int index) const {
  DCHECK(index >= 0 && index < GetTabCount());
  return tab_data_.at(index).tab;
}

Tab* TabStrip::GetTabAtAdjustForAnimation(int index) const {
  if (active_animation_.get() &&
      active_animation_->type() == TabAnimation::REMOVE &&
      index >=
      static_cast<RemoveTabAnimation*>(active_animation_.get())->index()) {
    index++;
  }
  return GetTabAt(index);
}

int TabStrip::GetTabCount() const {
  return static_cast<int>(tab_data_.size());
}

void TabStrip::GetCurrentTabWidths(double* unselected_width,
                                   double* selected_width) const {
  *unselected_width = current_unselected_width_;
  *selected_width = current_selected_width_;
}

void TabStrip::GetDesiredTabWidths(int tab_count,
                                   double* unselected_width,
                                   double* selected_width) const {
  const double min_unselected_width = Tab::GetMinimumUnselectedSize().width();
  const double min_selected_width = Tab::GetMinimumSelectedSize().width();
  if (tab_count == 0) {
    // Return immediately to avoid divide-by-zero below.
    *unselected_width = min_unselected_width;
    *selected_width = min_selected_width;
    return;
  }

  // Determine how much space we can actually allocate to tabs.
  int available_width;
  if (available_width_for_tabs_ < 0) {
    available_width = width();
    available_width -= (kNewTabButtonHOffset + newtab_button_size_.width());
  } else {
    // Interesting corner case: if |available_width_for_tabs_| > the result
    // of the calculation in the conditional arm above, the strip is in
    // overflow.  We can either use the specified width or the true available
    // width here; the first preserves the consistent "leave the last tab under
    // the user's mouse so they can close many tabs" behavior at the cost of
    // prolonging the glitchy appearance of the overflow state, while the second
    // gets us out of overflow as soon as possible but forces the user to move
    // their mouse for a few tabs' worth of closing.  We choose visual
    // imperfection over behavioral imperfection and select the first option.
    available_width = available_width_for_tabs_;
  }

  // Calculate the desired tab widths by dividing the available space into equal
  // portions.  Don't let tabs get larger than the "standard width" or smaller
  // than the minimum width for each type, respectively.
  const int total_offset = kTabHOffset * (tab_count - 1);
  const double desired_tab_width = std::min((static_cast<double>(
      available_width - total_offset) / static_cast<double>(tab_count)),
      static_cast<double>(Tab::GetStandardSize().width()));
  *unselected_width = std::max(desired_tab_width, min_unselected_width);
  *selected_width = std::max(desired_tab_width, min_selected_width);

  // When there are multiple tabs, we'll have one selected and some unselected
  // tabs.  If the desired width was between the minimum sizes of these types,
  // try to shrink the tabs with the smaller minimum.  For example, if we have
  // a strip of width 10 with 4 tabs, the desired width per tab will be 2.5.  If
  // selected tabs have a minimum width of 4 and unselected tabs have a minimum
  // width of 1, the above code would set *unselected_width = 2.5,
  // *selected_width = 4, which results in a total width of 11.5.  Instead, we
  // want to set *unselected_width = 2, *selected_width = 4, for a total width
  // of 10.
  if (tab_count > 1) {
    if ((min_unselected_width < min_selected_width) &&
        (desired_tab_width < min_selected_width)) {
      // Unselected width = (total width - selected width) / (num_tabs - 1)
      *unselected_width = std::max(static_cast<double>(
          available_width - total_offset - min_selected_width) /
          static_cast<double>(tab_count - 1), min_unselected_width);
    } else if ((min_unselected_width > min_selected_width) &&
               (desired_tab_width < min_unselected_width)) {
      // Selected width = (total width - (unselected width * (num_tabs - 1)))
      *selected_width = std::max(available_width - total_offset -
          (min_unselected_width * (tab_count - 1)), min_selected_width);
    }
  }
}

void TabStrip::ResizeLayoutTabs() {
  resize_layout_factory_.RevokeAll();

  // It is critically important that this is unhooked here, otherwise we will
  // keep spying on messages forever.
  RemoveMessageLoopObserver();

  available_width_for_tabs_ = -1;
  double unselected, selected;
  GetDesiredTabWidths(GetTabCount(), &unselected, &selected);
  Tab* first_tab = GetTabAt(0);
  int w = Round(first_tab->IsSelected() ? selected : selected);

  // We only want to run the animation if we're not already at the desired
  // size.
  if (abs(first_tab->width() - w) > 1)
    StartResizeLayoutAnimation();
}

bool TabStrip::IsCursorInTabStripZone() {
  gfx::Rect bounds = GetLocalBounds(true);
  gfx::Point tabstrip_topleft(bounds.origin());
  View::ConvertPointToScreen(this, &tabstrip_topleft);
  bounds.set_origin(tabstrip_topleft);
  bounds.set_height(bounds.height() + kTabStripAnimationVSlop);

  CPoint cursor_point;
  GetCursorPos(&cursor_point);

  return bounds.Contains(cursor_point.x, cursor_point.y);
}

void TabStrip::AddMessageLoopObserver() {
  if (!added_as_message_loop_observer_) {
    MessageLoopForUI::current()->AddObserver(this);
    added_as_message_loop_observer_ = true;
  }
}

void TabStrip::RemoveMessageLoopObserver() {
  if (added_as_message_loop_observer_) {
    MessageLoopForUI::current()->RemoveObserver(this);
    added_as_message_loop_observer_ = false;
  }
}

gfx::Rect TabStrip::GetDropBounds(int drop_index,
                                  bool drop_before,
                                  bool* is_beneath) {
  DCHECK(drop_index != -1);
  int center_x;
  if (drop_index < GetTabCount()) {
    Tab* tab = GetTabAt(drop_index);
    if (drop_before)
      center_x = tab->x() - (kTabHOffset / 2);
    else
      center_x = tab->x() + (tab->width() / 2);
  } else {
    Tab* last_tab = GetTabAt(drop_index - 1);
    center_x = last_tab->x() + last_tab->width() + (kTabHOffset / 2);
  }

  // Mirror the center point if necessary.
  center_x = MirroredXCoordinateInsideView(center_x);

  // Determine the screen bounds.
  gfx::Point drop_loc(center_x - drop_indicator_width / 2,
                      -drop_indicator_height);
  ConvertPointToScreen(this, &drop_loc);
  gfx::Rect drop_bounds(drop_loc.x(), drop_loc.y(), drop_indicator_width,
                        drop_indicator_height);

  // If the rect doesn't fit on the monitor, push the arrow to the bottom.
  gfx::Rect monitor_bounds = win_util::GetMonitorBoundsForRect(drop_bounds);
  *is_beneath = (monitor_bounds.IsEmpty() ||
                 !monitor_bounds.Contains(drop_bounds));
  if (*is_beneath)
    drop_bounds.Offset(0, drop_bounds.height() + height());

  return drop_bounds;
}

void TabStrip::UpdateDropIndex(const DropTargetEvent& event) {
  // If the UI layout is right-to-left, we need to mirror the mouse
  // coordinates since we calculate the drop index based on the
  // original (and therefore non-mirrored) positions of the tabs.
  const int x = MirroredXCoordinateInsideView(event.x());
  for (int i = 0; i < GetTabCount(); ++i) {
    Tab* tab = GetTabAt(i);
    const int tab_max_x = tab->x() + tab->width();
    const int hot_width = tab->width() / 3;
    if (x < tab_max_x) {
      if (x < tab->x() + hot_width)
        SetDropIndex(i, true);
      else if (x >= tab_max_x - hot_width)
        SetDropIndex(i + 1, true);
      else
        SetDropIndex(i, false);
      return;
    }
  }

  // The drop isn't over a tab, add it to the end.
  SetDropIndex(GetTabCount(), true);
}

void TabStrip::SetDropIndex(int index, bool drop_before) {
  if (index == -1) {
    if (drop_info_.get())
      drop_info_.reset(NULL);
    return;
  }

  if (drop_info_.get() && drop_info_->drop_index == index &&
      drop_info_->drop_before == drop_before) {
    return;
  }

  bool is_beneath;
  gfx::Rect drop_bounds = GetDropBounds(index, drop_before, &is_beneath);

  if (!drop_info_.get()) {
    drop_info_.reset(new DropInfo(index, drop_before, !is_beneath));
  } else {
    drop_info_->drop_index = index;
    drop_info_->drop_before = drop_before;
    if (is_beneath == drop_info_->point_down) {
      drop_info_->point_down = !is_beneath;
      drop_info_->arrow_view->SetImage(
          GetDropArrowImage(drop_info_->point_down));
    }
  }

  // Reposition the window. Need to show it too as the window is initially
  // hidden.

  drop_info_->arrow_window->SetWindowPos(
      HWND_TOPMOST, drop_bounds.x(), drop_bounds.y(), drop_bounds.width(),
      drop_bounds.height(), SWP_NOACTIVATE | SWP_SHOWWINDOW);
}

int TabStrip::GetDropEffect(const views::DropTargetEvent& event) {
  const int source_ops = event.GetSourceOperations();
  if (source_ops & DragDropTypes::DRAG_COPY)
    return DragDropTypes::DRAG_COPY;
  if (source_ops & DragDropTypes::DRAG_LINK)
    return DragDropTypes::DRAG_LINK;
  return DragDropTypes::DRAG_MOVE;
}

// static
SkBitmap* TabStrip::GetDropArrowImage(bool is_down) {
  return ResourceBundle::GetSharedInstance().GetBitmapNamed(
      is_down ? IDR_TAB_DROP_DOWN : IDR_TAB_DROP_UP);
}

// TabStrip::DropInfo ----------------------------------------------------------

TabStrip::DropInfo::DropInfo(int drop_index, bool drop_before, bool point_down)
    : drop_index(drop_index),
      drop_before(drop_before),
      point_down(point_down) {
  arrow_window = new views::WidgetWin;
  arrow_window->set_window_style(WS_POPUP);
  arrow_window->set_window_ex_style(WS_EX_TOPMOST | WS_EX_NOACTIVATE |
                                    WS_EX_LAYERED | WS_EX_TRANSPARENT);

  arrow_view = new views::ImageView;
  arrow_view->SetImage(GetDropArrowImage(point_down));

  arrow_window->Init(
      NULL,
      gfx::Rect(0, 0, drop_indicator_width, drop_indicator_height),
      true);
  arrow_window->SetContentsView(arrow_view);
}

TabStrip::DropInfo::~DropInfo() {
  // Close eventually deletes the window, which deletes arrow_view too.
  arrow_window->Close();
}

///////////////////////////////////////////////////////////////////////////////

// Called from:
// - BasicLayout
// - Tab insertion/removal
// - Tab reorder
void TabStrip::GenerateIdealBounds() {
  int tab_count = GetTabCount();
  double unselected, selected;
  GetDesiredTabWidths(tab_count, &unselected, &selected);

  current_unselected_width_ = unselected;
  current_selected_width_ = selected;

  // NOTE: This currently assumes a tab's height doesn't differ based on
  // selected state or the number of tabs in the strip!
  int tab_height = Tab::GetStandardSize().height();
  double tab_x = 0;
  for (int i = 0; i < tab_count; ++i) {
    Tab* tab = GetTabAt(i);
    double tab_width = unselected;
    if (tab->IsSelected())
      tab_width = selected;
    double end_of_tab = tab_x + tab_width;
    int rounded_tab_x = Round(tab_x);
    gfx::Rect state(rounded_tab_x, 0, Round(end_of_tab) - rounded_tab_x,
                    tab_height);
    tab_data_.at(i).ideal_bounds = state;
    tab_x = end_of_tab + kTabHOffset;
  }
}

void TabStrip::LayoutNewTabButton(double last_tab_right,
                                  double unselected_width) {
  int delta = abs(Round(unselected_width) - Tab::GetStandardSize().width());
  if (delta > 1 && !resize_layout_scheduled_) {
    // We're shrinking tabs, so we need to anchor the New Tab button to the
    // right edge of the TabStrip's bounds, rather than the right edge of the
    // right-most Tab, otherwise it'll bounce when animating.
    newtab_button_->SetBounds(width() - newtab_button_size_.width(),
                              kNewTabButtonVOffset,
                              newtab_button_size_.width(),
                              newtab_button_size_.height());
  } else {
    newtab_button_->SetBounds(
        Round(last_tab_right - kTabHOffset) + kNewTabButtonHOffset,
        kNewTabButtonVOffset, newtab_button_size_.width(),
        newtab_button_size_.height());
  }
}

// Called from:
// - animation tick
void TabStrip::AnimationLayout(double unselected_width) {
  int tab_height = Tab::GetStandardSize().height();
  double tab_x = 0;
  for (int i = 0; i < GetTabCount(); ++i) {
    TabAnimation* animation = active_animation_.get();
    double tab_width = TabAnimation::GetCurrentTabWidth(this, animation, i);
    double end_of_tab = tab_x + tab_width;
    int rounded_tab_x = Round(tab_x);
    Tab* tab = GetTabAt(i);
    tab->SetBounds(rounded_tab_x, 0, Round(end_of_tab) - rounded_tab_x,
                   tab_height);
    tab_x = end_of_tab + kTabHOffset;
  }
  LayoutNewTabButton(tab_x, unselected_width);
  SchedulePaint();
}

void TabStrip::StartResizeLayoutAnimation() {
  if (active_animation_.get())
    active_animation_->Stop();
  active_animation_.reset(new ResizeLayoutAnimation(this));
  active_animation_->Start();
}

void TabStrip::StartInsertTabAnimation(int index) {
  // Don't shock users by letting all tabs move when they are focused
  // on the tab-strip. Wait for later, when they aren't looking.
  int last_tab_index = GetTabCount() - 2;
  if (last_tab_index > 0) {
    Tab* last_tab = GetTabAt(last_tab_index);
	  available_width_for_tabs_ = std::min(
		  GetAvailableWidthForTabs(last_tab) + last_tab->width(),
		  width() - (kNewTabButtonHOffset + newtab_button_size_.width()));
  } else {
    available_width_for_tabs_ = -1;
  }
  if (active_animation_.get())
    active_animation_->Stop();
  active_animation_.reset(new InsertTabAnimation(this, index));
  active_animation_->Start();
}

void TabStrip::StartRemoveTabAnimation(int index, TabContents* contents) {
  if (active_animation_.get()) {
    // Some animations (e.g. MoveTabAnimation) cause there to be a Layout when
    // they're completed (which includes canceled). Since |tab_data_| is now
    // inconsistent with TabStripModel, doing this Layout will crash now, so
    // we ask the MoveTabAnimation to skip its Layout (the state will be
    // corrected by the RemoveTabAnimation we're about to initiate).
    active_animation_->set_layout_on_completion(false);
    active_animation_->Stop();
  }
  active_animation_.reset(new RemoveTabAnimation(this, index, contents));
  active_animation_->Start();
}

void TabStrip::StartMoveTabAnimation(int from_index, int to_index) {
  if (active_animation_.get())
    active_animation_->Stop();
  active_animation_.reset(new MoveTabAnimation(this, from_index, to_index));
  active_animation_->Start();
}

bool TabStrip::CanUpdateDisplay() {
  // Don't bother laying out/painting when we're closing all tabs.
  if (model_->closing_all()) {
    // Make sure any active animation is ended, too.
    if (active_animation_.get())
      active_animation_->Stop();
    return false;
  }
  return true;
}

void TabStrip::FinishAnimation(TabStrip::TabAnimation* animation,
                               bool layout) {
  active_animation_.reset(NULL);
  if (layout)
    Layout();
}

int TabStrip::GetIndexOfTab(const Tab* tab) const {
  for (int i = 0, index = 0; i < GetTabCount(); ++i, ++index) {
    Tab* current_tab = GetTabAt(i);
    if (current_tab->closing()) {
      --index;
    } else if (current_tab == tab) {
      return index;
    }
  }
  return -1;
}

int TabStrip::GetAvailableWidthForTabs(Tab* last_tab) const {
  return last_tab->x() + last_tab->width();
}

bool TabStrip::IsPointInTab(Tab* tab,
                            const gfx::Point& point_in_tabstrip_coords) {
  gfx::Point point_in_tab_coords(point_in_tabstrip_coords);
  View::ConvertPointToView(this, tab, &point_in_tab_coords);
  return tab->HitTest(point_in_tab_coords);
}