Add the button style for combobox

ui/views/controls/combobox/combobox.cc

Index: ui/views/controls/combobox/combobox.cc
diff --git a/ui/views/controls/combobox/combobox.cc b/ui/views/controls/combobox/combobox.cc
index 2600b174f07d27d2e9f3f8511ca71049270a444c..21dcf3e0c8952ec4f8bbcd5250c0a53911d30cfd 100644
--- a/ui/views/controls/combobox/combobox.cc
+++ b/ui/views/controls/combobox/combobox.cc
@@ -12,9 +12,12 @@
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/events/event.h"
 #include "ui/events/keycodes/keyboard_codes.h"
+#include "ui/gfx/animation/slide_animation.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/image/image.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/views/color_constants.h"
+#include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/combobox/combobox_listener.h"
 #include "ui/views/controls/focusable_border.h"
 #include "ui/views/controls/menu/menu_runner.h"
@@ -22,6 +25,7 @@
 #include "ui/views/controls/prefix_selector.h"
 #include "ui/views/ime/input_method.h"
 #include "ui/views/mouse_constants.h"
+#include "ui/views/painter.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
@@ -39,6 +43,8 @@ const int kMinComboboxWidth = 25;
 // Size of the combobox arrow margins
 const int kDisclosureArrowLeftPadding = 7;
 const int kDisclosureArrowRightPadding = 7;
+const int kDisclosureArrowButtonLeftPadding = 11;
+const int kDisclosureArrowButtonRightPadding = 12;
 
 // Define the id of the first item in the menu (since it needs to be > 0)
 const int kFirstMenuItemId = 1000;
@@ -48,6 +54,22 @@ const SkColor kInvalidTextColor = SK_ColorWHITE;
 // Used to indicate that no item is currently selected by the user.
 const int kNoSelection = -1;
 
+const int kBodyButtonImages[] = IMAGE_GRID(IDR_COMBOBOX_BUTTON);
+const int kHoveredBodyButtonImages[] = IMAGE_GRID2(IDR_COMBOBOX_BUTTON, H);
+const int kPressedBodyButtonImages[] = IMAGE_GRID2(IDR_COMBOBOX_BUTTON, P);
+
+#define MENU_IMAGE_GRID(x) { \
+    x ## _MENU_TOP, x ## _MENU_CENTER, x ## _MENU_BOTTOM, }
+#define MENU_IMAGE_GRID2(x, y) { \
+    x ## _MENU_TOP_ ## y, x ## _MENU_CENTER_ ## y, x ## _MENU_BOTTOM_ ## y, }
+
+const int kMenuButtonImages[] = MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON);
+const int kHoveredMenuButtonImages[] = MENU_IMAGE_GRID2(IDR_COMBOBOX_BUTTON, H);
+const int kPressedMenuButtonImages[] = MENU_IMAGE_GRID2(IDR_COMBOBOX_BUTTON, P);
+
+#undef MENU_IMAGE_GRID
+#undef MENU_IMAGE_GRID2
+
 // The background to use for invalid comboboxes.
 class InvalidBackground : public Background {
  public:
@@ -81,6 +103,132 @@ int GetAdjacentIndex(ui::ComboboxModel* model, int increment, int index) {
   return kNoSelection;
 }
 
+// Returns the image resource ids of an array for the body button.
+//
+// TODO(hajimehoshi): This function should return the images for the 'disabled'
+// status. (crbug/270052)
+//
+// TODO(hajimehoshi): Currently, |focused| is ignored. This should return the
+// images for the 'focused' status. (crbug/270052)
+const int* GetBodyButtonImageIds(bool focused, Button::ButtonState state) {
+  switch (state) {
+    case Button::STATE_DISABLED:
+      return kBodyButtonImages;
+    case Button::STATE_NORMAL:
+      return kBodyButtonImages;
+    case Button::STATE_HOVERED:
+      return kHoveredBodyButtonImages;
+    case Button::STATE_PRESSED:
+      return kPressedBodyButtonImages;
+    default:
+      NOTREACHED();
+  }
+  return NULL;
+}
+
+// Returns the image resource ids of an array for the menu button.
+const int* GetMenuButtonImageIds(bool focused, Button::ButtonState state) {
+  switch (state) {
+    case Button::STATE_DISABLED:
+      return kMenuButtonImages;
+    case Button::STATE_NORMAL:
+      return kMenuButtonImages;
+    case Button::STATE_HOVERED:
+      return kHoveredMenuButtonImages;
+    case Button::STATE_PRESSED:
+      return kPressedMenuButtonImages;
+    default:
+      NOTREACHED();
+  }
+  return NULL;
+}
+
+// Returns the images for the buttons.
+std::vector<const gfx::ImageSkia*> GetButtonImages(bool menu,
+                                                   bool focused,
+                                                   Button::ButtonState state) {
+  const int* ids;
+  size_t num_ids;
+  if (!menu) {
+    ids = GetBodyButtonImageIds(focused, state);
+    num_ids = 9;
+  } else {
+    ids = GetMenuButtonImageIds(focused, state);
+    num_ids = 3;
+  }
+  std::vector<const gfx::ImageSkia*> images;
+  images.reserve(num_ids);
+  ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
+  for (size_t i = 0; i < num_ids; i++) {
+    int id = ids[i];
+    images.push_back(rb.GetImageSkiaNamed(id));
+  }
+  return images;
+}
+
+// Paints three images in a row at the given location.
+void PaintTandemImages(gfx::Canvas* canvas,
+                       const gfx::ImageSkia& top_image,
+                       const gfx::ImageSkia& center_image,
+                       const gfx::ImageSkia& bottom_image,
+                       int x, int y, int width, int height) {
+  canvas->DrawImageInt(top_image,
+                       0, 0, top_image.width(), top_image.height(),
+                       x, y, width, top_image.height(), false);
+  y += top_image.height();
+  int center_height = height - top_image.height() - bottom_image.height();
+  canvas->DrawImageInt(center_image,
+                       0, 0, center_image.width(), center_image.height(),
+                       x, y, width, center_height, false);
+  y += center_height;
+  canvas->DrawImageInt(bottom_image,
+                       0, 0, bottom_image.width(), bottom_image.height(),
+                       x, y, width, bottom_image.height(), false);
+}
+
+// Paints the text button.
+void PaintTextButton(
+    gfx::Canvas* canvas,
+    const std::vector<const gfx::ImageSkia*>& text_button_images,
+    int width, int height) {
+  int current_x = 0;
+  int current_width = text_button_images[0]->width();
+  PaintTandemImages(canvas,
+                    *text_button_images[0],
+                    *text_button_images[3],
+                    *text_button_images[6],
+                    current_x, 0, current_width, height);
+
+  current_x += current_width;
+  current_width = width - text_button_images[0]->width() -
+      text_button_images[2]->width();
+  PaintTandemImages(canvas,
+                    *text_button_images[1],
+                    *text_button_images[4],
+                    *text_button_images[7],
+                    current_x, 0, current_width, height);
+
+  current_x += current_width;
+  current_width = text_button_images[2]->width();
+  PaintTandemImages(canvas,
+                    *text_button_images[2],
+                    *text_button_images[5],
+                    *text_button_images[8],
+                    current_x, 0, current_width, height);
+}
+
+// Paints the arrow button.
+void PaintArrowButton(
+    gfx::Canvas* canvas,
+    const std::vector<const gfx::ImageSkia*>& arrow_button_images,
+    int x, int height) {
+  PaintTandemImages(canvas,
+                    *arrow_button_images[0],
+                    *arrow_button_images[1],
+                    *arrow_button_images[2],
+                    x, 0, arrow_button_images[0]->width(), height);
+}
+
 }  // namespace
 
 // static
@@ -91,17 +239,46 @@ const char Combobox::kViewClassName[] = "views/Combobox";
 
 Combobox::Combobox(ui::ComboboxModel* model)
     : model_(model),
+      style_(STYLE_NORMAL),
       listener_(NULL),
       selected_index_(model_->GetDefaultIndex()),
       invalid_(false),
       text_border_(new FocusableBorder()),
       disclosure_arrow_(ui::ResourceBundle::GetSharedInstance().GetImageNamed(
           IDR_MENU_DROPARROW).ToImageSkia()),
-      dropdown_open_(false) {
+      dropdown_open_(false),
+      drag_started_(false),
+      text_button_state_(Button::STATE_NORMAL),
+      arrow_button_state_(Button::STATE_NORMAL) {
   model_->AddObserver(this);
   UpdateFromModel();
   set_focusable(true);
   set_border(text_border_);
+
+  // Initialize the button images.
+  Button::ButtonState button_states[] = {
+    Button::STATE_DISABLED,
+    Button::STATE_NORMAL,
+    Button::STATE_HOVERED,
+    Button::STATE_PRESSED,
+  };
+  for (int focused = 0; focused < 2; focused++) {
+    for (size_t state_index = 0; state_index < arraysize(button_states);
+         state_index++) {
+      Button::ButtonState state = button_states[state_index];
+      body_button_images_[focused][state] =
+          GetButtonImages(false, focused, state);
+      menu_button_images_[focused][state] =
+          GetButtonImages(true, focused, state);
+    }
+  }
+
+  text_button_hover_animation_.reset(new gfx::SlideAnimation(this));
+  text_button_hover_animation_->SetSlideDuration(
+      CustomButton::kHoverFadeDurationMs);
+  arrow_button_hover_animation_.reset(new gfx::SlideAnimation(this));
+  arrow_button_hover_animation_->SetSlideDuration(
+      CustomButton::kHoverFadeDurationMs);
 }
 
 Combobox::~Combobox() {
@@ -114,6 +291,22 @@ const gfx::Font& Combobox::GetFont() {
   return rb.GetFont(ui::ResourceBundle::BaseFont);
 }
 
+void Combobox::SetStyle(Style style) {
+  if (style_ == style)
+    return;
+
+  style_ = style;
+  switch (style) {
+    case STYLE_NORMAL:
+      text_border_->ResetInsets();
+      break;
+    case STYLE_BUTTONS:
+      text_border_->SetInsets(8, 13, 8, 13);
+      break;
+  }
+  PreferredSizeChanged();
+}
+
 void Combobox::ModelChanged() {
   selected_index_ = std::min(0, model_->GetItemCount());
   UpdateFromModel();
@@ -201,9 +394,8 @@ gfx::Size Combobox::GetPreferredSize() {
   // the minimum width for the dropdown list.
   gfx::Insets insets = GetInsets();
   int total_width = std::max(kMinComboboxWidth, content_size_.width()) +
-      insets.width() + kDisclosureArrowLeftPadding +
-      disclosure_arrow_->width() + kDisclosureArrowRightPadding;
-
+      insets.width() + GetDisclosureArrowLeftPadding() +
+      disclosure_arrow_->width() + GetDisclosureArrowRightPadding();
   return gfx::Size(total_width, content_size_.height() + insets.height());
 }
 
@@ -225,17 +417,64 @@ bool Combobox::OnMousePressed(const ui::MouseEvent& mouse_event) {
   const base::TimeDelta delta = base::Time::Now() - closed_time_;
   if (mouse_event.IsLeftMouseButton() &&
       (delta.InMilliseconds() > kMinimumMsBetweenButtonClicks)) {
-    UpdateFromModel();
-    ShowDropDownMenu(ui::MENU_SOURCE_MOUSE);
+    if (InArrowButton(mouse_event.location())) {
+      UpdateFromModel();
+      ShowDropDownMenu(ui::MENU_SOURCE_MOUSE);
+    } else if (InTextButton(mouse_event.location())) {
+      SetButtonStates(Button::STATE_PRESSED, Button::STATE_NORMAL);
+    }
   }
-
   return true;
 }
 
 bool Combobox::OnMouseDragged(const ui::MouseEvent& mouse_event) {
+  if (!drag_started_) {
+    drag_started_ = true;
+    drag_start_point_ = mouse_event.location();
+  }
+  bool on_text = InTextButton(mouse_event.location()) &&
+      InTextButton(drag_start_point_);
+  bool on_arrow = InArrowButton(mouse_event.location()) &&
+      InArrowButton(drag_start_point_);
+  SetButtonStates(on_text ? Button::STATE_PRESSED : Button::STATE_NORMAL,
+                  on_arrow ? Button::STATE_PRESSED : Button::STATE_NORMAL);
   return true;
 }
 
+void Combobox::OnMouseReleased(const ui::MouseEvent& mouse_event) {
+  bool on_text = InTextButton(mouse_event.location());
+  bool on_arrow = InArrowButton(mouse_event.location());
+  SetButtonStates(on_text ? Button::STATE_HOVERED : Button::STATE_NORMAL,
+                  on_arrow ? Button::STATE_HOVERED : Button::STATE_NORMAL);
+  if (mouse_event.IsOnlyLeftMouseButton() &&
+      InTextButton(mouse_event.location())) {
+    HandleClickEvent();
+  }
+}
+
+void Combobox::OnMouseCaptureLost() {
+  drag_started_ = false;
+  SetButtonStates(Button::STATE_NORMAL, Button::STATE_NORMAL);
+}
+
+void Combobox::OnMouseEntered(const ui::MouseEvent& mouse_event) {
+  bool on_text = InTextButton(mouse_event.location());
+  bool on_arrow = InArrowButton(mouse_event.location());
+  SetButtonStates(on_text ? Button::STATE_HOVERED : Button::STATE_NORMAL,
+                  on_arrow ? Button::STATE_HOVERED : Button::STATE_NORMAL);
+}
+
+void Combobox::OnMouseExited(const ui::MouseEvent& mouse_event) {
+  SetButtonStates(Button::STATE_NORMAL, Button::STATE_NORMAL);
+}
+
+void Combobox::OnMouseMoved(const ui::MouseEvent& mouse_event) {
+  bool on_text = InTextButton(mouse_event.location());
+  bool on_arrow = InArrowButton(mouse_event.location());
+  SetButtonStates(on_text ? Button::STATE_HOVERED : Button::STATE_NORMAL,
+                  on_arrow ? Button::STATE_HOVERED : Button::STATE_NORMAL);
+}
+
 bool Combobox::OnKeyPressed(const ui::KeyEvent& e) {
   // TODO(oshima): handle IME.
   DCHECK_EQ(e.type(), ui::ET_KEY_PRESSED);
@@ -280,6 +519,19 @@ bool Combobox::OnKeyPressed(const ui::KeyEvent& e) {
       new_index = GetAdjacentIndex(model(), -1, selected_index_);
       break;
 
+    // Click the button only when the button style mode.
+    case ui::VKEY_SPACE:
+      SetButtonStates(Button::STATE_PRESSED, Button::STATE_NORMAL);
+      // When pressing space, the click event will be raised after the key is
+      // released.
+      break;
+
+    // Click the button only when the button style mode.
+    case ui::VKEY_RETURN:
+      SetButtonStates(Button::STATE_NORMAL, Button::STATE_NORMAL);
+      HandleClickEvent();
+      break;
+
     default:
       return false;
   }
@@ -297,13 +549,25 @@ bool Combobox::OnKeyPressed(const ui::KeyEvent& e) {
 }
 
 bool Combobox::OnKeyReleased(const ui::KeyEvent& e) {
-  return false;  // crbug.com/127520
+  if (style_ != STYLE_BUTTONS)
+    return false;  // crbug.com/127520
+
+  if (e.key_code() == ui::VKEY_SPACE) {
+    SetButtonStates(Button::STATE_NORMAL, Button::STATE_NORMAL);
+    HandleClickEvent();
+  }
+  return false;
 }
 
 void Combobox::OnGestureEvent(ui::GestureEvent* gesture) {
   if (gesture->type() == ui::ET_GESTURE_TAP) {
-    UpdateFromModel();
-    ShowDropDownMenu(ui::MENU_SOURCE_TOUCH);
+    if (InArrowButton(gesture->location())) {
+      UpdateFromModel();
+      ShowDropDownMenu(ui::MENU_SOURCE_TOUCH);
+    } else if (InTextButton(gesture->location())) {
+      SetButtonStates(Button::STATE_PRESSED, Button::STATE_NORMAL);
+      HandleClickEvent();
+    }
     gesture->StopPropagation();
     return;
   }
@@ -311,9 +575,19 @@ void Combobox::OnGestureEvent(ui::GestureEvent* gesture) {
 }
 
 void Combobox::OnPaint(gfx::Canvas* canvas) {
-  OnPaintBackground(canvas);
-  PaintText(canvas);
-  OnPaintBorder(canvas);
+  switch (style_) {
+    case STYLE_NORMAL: {
+      OnPaintBackground(canvas);
+      PaintText(canvas);
+      OnPaintBorder(canvas);
+      break;
+    }
+    case STYLE_BUTTONS: {
+      PaintButtons(canvas);
+      PaintText(canvas);
+      break;
+    }
+  }
 }
 
 void Combobox::OnFocus() {
@@ -341,6 +615,10 @@ void Combobox::OnModelChanged() {
   ModelChanged();
 }
 
+void Combobox::AnimationProgressed(const gfx::Animation* animation) {
+  SchedulePaint();
+}
+
 void Combobox::UpdateFromModel() {
   int max_width = 0;
   const gfx::Font& font = Combobox::GetFont();
@@ -392,8 +670,8 @@ void Combobox::PaintText(gfx::Canvas* canvas) {
     selected_index_ = 0;
   string16 text = model()->GetItemAt(selected_index_);
 
-  int disclosure_arrow_offset = width() - disclosure_arrow_->width()
-      - kDisclosureArrowLeftPadding - kDisclosureArrowRightPadding;
+  int disclosure_arrow_offset = width() - disclosure_arrow_->width() -
+      GetDisclosureArrowLeftPadding() - GetDisclosureArrowRightPadding();
 
   const gfx::Font& font = Combobox::GetFont();
   int text_width = font.GetStringWidth(text);
@@ -404,7 +682,8 @@ void Combobox::PaintText(gfx::Canvas* canvas) {
   AdjustBoundsForRTLUI(&text_bounds);
   canvas->DrawStringInt(text, font, text_color, text_bounds);
 
-  gfx::Rect arrow_bounds(disclosure_arrow_offset + kDisclosureArrowLeftPadding,
+  int arrow_x = disclosure_arrow_offset + GetDisclosureArrowLeftPadding();
+  gfx::Rect arrow_bounds(arrow_x,
                          height() / 2 - disclosure_arrow_->height() / 2,
                          disclosure_arrow_->width(),
                          disclosure_arrow_->height());
@@ -420,6 +699,59 @@ void Combobox::PaintText(gfx::Canvas* canvas) {
   canvas->Restore();
 }
 
+void Combobox::PaintButtons(gfx::Canvas* canvas) {
+  canvas->Save();
+  if (base::i18n::IsRTL()) {
+    canvas->Translate(gfx::Vector2d(width(), 0));
+    canvas->Scale(-1, 1);
+  }
+
+  bool focused = HasFocus() && IsAccessibilityFocusable();
+  const std::vector<const gfx::ImageSkia*>& text_button_images =
+      body_button_images_[focused][text_button_state_ == Button::STATE_HOVERED ?
+                                   Button::STATE_NORMAL : text_button_state_];
+  const std::vector<const gfx::ImageSkia*>& arrow_button_images =
+      menu_button_images_[focused][
+          arrow_button_state_ == Button::STATE_HOVERED ?
+          Button::STATE_NORMAL : arrow_button_state_];
+
+  int text_button_width = width() - arrow_button_images[0]->width();
+  int text_button_hover_alpha =
+      static_cast<int>(text_button_hover_animation_->GetCurrentValue() * 255);
+  if (text_button_hover_alpha < 255) {
+    canvas->SaveLayerAlpha(255 - text_button_hover_alpha);
+    PaintTextButton(canvas, text_button_images, text_button_width, height());
+    canvas->Restore();
+  }
+  if (0 < text_button_hover_alpha) {
+    canvas->SaveLayerAlpha(text_button_hover_alpha);
+    const std::vector<const gfx::ImageSkia*>& text_button_hovered_images =
+        body_button_images_[focused][Button::STATE_HOVERED];
+    PaintTextButton(canvas, text_button_hovered_images,
+                    text_button_width, height());
+    canvas->Restore();
+  }
+
+  int arrow_button_x = text_button_width;
+  int arrow_button_hover_alpha =
+      static_cast<int>(arrow_button_hover_animation_->GetCurrentValue() * 255);
+  if (arrow_button_hover_alpha < 255) {
+    canvas->SaveLayerAlpha(255 - arrow_button_hover_alpha);
+    PaintArrowButton(canvas, arrow_button_images, arrow_button_x, height());
+    canvas->Restore();
+  }
+  if (0 < arrow_button_hover_alpha) {
+    canvas->SaveLayerAlpha(arrow_button_hover_alpha);
+    const std::vector<const gfx::ImageSkia*>& arrow_button_hovered_images =
+        menu_button_images_[focused][Button::STATE_HOVERED];
+    PaintArrowButton(canvas, arrow_button_hovered_images,
+                     arrow_button_x, height());
+    canvas->Restore();
+  }
+
+  canvas->Restore();
+}
+
 void Combobox::ShowDropDownMenu(ui::MenuSourceType source_type) {
   if (!dropdown_list_menu_runner_.get())
     UpdateFromModel();
@@ -427,8 +759,8 @@ void Combobox::ShowDropDownMenu(ui::MenuSourceType source_type) {
   // Extend the menu to the width of the combobox.
   MenuItemView* menu = dropdown_list_menu_runner_->GetMenu();
   SubmenuView* submenu = menu->CreateSubmenu();
-  submenu->set_minimum_preferred_width(size().width() -
-                                (kMenuBorderWidthLeft + kMenuBorderWidthRight));
+  submenu->set_minimum_preferred_width(
+      size().width() - (kMenuBorderWidthLeft + kMenuBorderWidthRight));
 
   gfx::Rect lb = GetLocalBounds();
   gfx::Point menu_position(lb.origin());
@@ -441,15 +773,19 @@ void Combobox::ShowDropDownMenu(ui::MenuSourceType source_type) {
 
   View::ConvertPointToScreen(this, &menu_position);
   if (menu_position.x() < 0)
-      menu_position.set_x(0);
+    menu_position.set_x(0);
 
   gfx::Rect bounds(menu_position, lb.size());
 
   dropdown_open_ = true;
+  Button::ButtonState original_arrow_button_state = arrow_button_state_;
+  SetButtonStates(Button::STATE_NORMAL, Button::STATE_PRESSED);
   if (dropdown_list_menu_runner_->RunMenuAt(GetWidget(), NULL, bounds,
           MenuItemView::TOPLEFT, source_type, MenuRunner::COMBOBOX) ==
-      MenuRunner::MENU_DELETED)
+      MenuRunner::MENU_DELETED) {
     return;
+  }
+  SetButtonStates(Button::STATE_NORMAL, original_arrow_button_state);
   dropdown_open_ = false;
   closed_time_ = base::Time::Now();
 
@@ -474,4 +810,88 @@ int Combobox::MenuCommandToIndex(int menu_command_id) const {
   return index;
 }
 
+int Combobox::GetDisclosureArrowLeftPadding() const {
+  switch (style_) {
+    case STYLE_NORMAL:
+      return kDisclosureArrowLeftPadding;
+    case STYLE_BUTTONS:
+      return kDisclosureArrowButtonLeftPadding;
+  }
+  NOTREACHED();
+  return 0;
+}
+
+int Combobox::GetDisclosureArrowRightPadding() const {
+  switch (style_) {
+    case STYLE_NORMAL:
+      return kDisclosureArrowRightPadding;
+    case STYLE_BUTTONS:
+      return kDisclosureArrowButtonRightPadding;
+  }
+  NOTREACHED();
+  return 0;
+}
+
+void Combobox::HandleClickEvent() {
+  if (style_ != STYLE_BUTTONS)
+    return;
+
+  if (listener_)
+    listener_->OnTextButtonClicked(this);
+}
+
+void Combobox::SetButtonStates(Button::ButtonState text_button_state,
+                               Button::ButtonState arrow_button_state) {
+  if (style_ != STYLE_BUTTONS)
+    return;
+
+  AnimateStateTransition(text_button_hover_animation_.get(),
+                         text_button_state_, text_button_state);
+  AnimateStateTransition(arrow_button_hover_animation_.get(),
+                         arrow_button_state_, arrow_button_state);
+
+  text_button_state_ = text_button_state;
+  arrow_button_state_ = arrow_button_state;
+  SchedulePaint();
+}
+
+void Combobox::AnimateStateTransition(gfx::SlideAnimation* animation,
+                                      Button::ButtonState from,
+                                      Button::ButtonState to) {
+  if (from == Button::STATE_NORMAL && to == Button::STATE_HOVERED)
+    animation->Show();
+  else if (from == Button::STATE_HOVERED && to == Button::STATE_NORMAL)
+    animation->Hide();
+  else if (from != to)
+    animation->Reset(to == Button::STATE_HOVERED ? 1.0 : 0.0);
+}
+
+bool Combobox::InTextButton(const gfx::Point& point) {
+  if (!HitTestPoint(point))
+    return false;
+
+  if (style_ != STYLE_BUTTONS)
+    return false;
+
+  int x = point.x();
+  const gfx::ImageSkia* menu_button_image =
+      menu_button_images_[false][Button::STATE_NORMAL][0];
+  return x < width() - menu_button_image->width();
+}
+
+bool Combobox::InArrowButton(const gfx::Point& point) {
+  if (!HitTestPoint(point))
+    return false;
+
+  // When |style_| is not the button style, whole of this control functions as a
+  // disclosure arrow button.
+  if (style_ != STYLE_BUTTONS)
+    return true;
+
+  int x = point.x();
+  const gfx::ImageSkia* menu_button_image =
+      menu_button_images_[false][Button::STATE_NORMAL][0];
+  return width() - menu_button_image->width() <= x && x < width();
+}
+
 }  // namespace views