Views: factor out Combobox background and const-ify style

ui/views/controls/combobox/combobox.cc

 // Copyright (c) 2012 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 "ui/views/controls/combobox/combobox.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 36 matching lines @@
 namespace {
 
 // Menu border widths
 const int kMenuBorderWidthLeft = 1;
 const int kMenuBorderWidthTop = 1;
 const int kMenuBorderWidthRight = 1;
 
 // Limit how small a combobox can be.
 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;
 
 // 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_GRID(IDR_COMBOBOX_BUTTON_H);
 const int kPressedBodyButtonImages[] = IMAGE_GRID(IDR_COMBOBOX_BUTTON_P);
 const int kFocusedBodyButtonImages[] = IMAGE_GRID(IDR_COMBOBOX_BUTTON_F);
 const int kFocusedHoveredBodyButtonImages[] =
     IMAGE_GRID(IDR_COMBOBOX_BUTTON_F_H);
 const int kFocusedPressedBodyButtonImages[] =
     IMAGE_GRID(IDR_COMBOBOX_BUTTON_F_P);
 
 #define MENU_IMAGE_GRID(x) { \
     x ## _MENU_TOP, x ## _MENU_CENTER, x ## _MENU_BOTTOM, }
 
 const int kMenuButtonImages[] = MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON);
 const int kHoveredMenuButtonImages[] = MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON_H);
 const int kPressedMenuButtonImages[] = MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON_P);
 const int kFocusedMenuButtonImages[] = MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON_F);
 const int kFocusedHoveredMenuButtonImages[] =
     MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON_F_H);
 const int kFocusedPressedMenuButtonImages[] =
     MENU_IMAGE_GRID(IDR_COMBOBOX_BUTTON_F_P);
 
 #undef MENU_IMAGE_GRID
 
+gfx::Rect PositionArrowWithinShoulder(const gfx::Rect& shoulder_bounds,
+                                      const gfx::Size& arrow_size) {
+  int extra_left_pad = 0;
+  gfx::Rect bounds(shoulder_bounds);
+  if (shoulder_bounds.width() % 2 == 1) {

[tapted, 2016/05/17 08:10:39]

I think this is relying too much on coincidence -- if the padding needs to
change such that the delta is ever != 1 then it will need reworking. I like the
name (i.e. 
"PositionArrowWithinShoulder") and callsite, but I think it should be a member
function that checks for `style_ == STYLE_NORMAL` and centers, or reads from
kAction{Left,Right}Padding, which will need to move to an anonymous namespace.

[Elly Fong-Jones, 2016/05/17 14:00:55]

I knew I was being too cute with this :) I changed it to explicitly position for
action style.

+    extra_left_pad = 1;
+    bounds.Inset(0, 0, 1, 0);
+  }
+  bounds.ClampToCenteredSize(arrow_size);
+  bounds.Offset(extra_left_pad, 0);
+  return bounds;
+}
+
 // The transparent button which holds a button state but is not rendered.
 class TransparentButton : public CustomButton {
  public:
   TransparentButton(ButtonListener* listener)
       : CustomButton(listener) {
     SetAnimationDuration(LabelButton::kHoverAnimationDurationMs);
     SetFocusBehavior(FocusBehavior::NEVER);
   }
   ~TransparentButton() override {}
 
@@ skipping 234 matching lines @@
 
   Combobox* owner_;           // Weak. Owns this.
   ui::ComboboxModel* model_;  // Weak.
 
   DISALLOW_COPY_AND_ASSIGN(ComboboxMenuModelAdapter);
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 // Combobox, public:
 
-Combobox::Combobox(ui::ComboboxModel* model)
+Combobox::Combobox(ui::ComboboxModel* model, Style style)
     : model_(model),
-      style_(STYLE_NORMAL),
+      style_(style),
       listener_(NULL),
       selected_index_(model_->GetDefaultIndex()),
       invalid_(false),
       menu_model_adapter_(new ComboboxMenuModelAdapter(this, model)),
       text_button_(new TransparentButton(this)),
       arrow_button_(new TransparentButton(this)),
       weak_ptr_factory_(this) {
+  if (style_ == STYLE_ACTION)
+    selected_index_ = 0;
+
   ModelChanged();
 #if defined(OS_MACOSX)
   SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY);
 #else
   SetFocusBehavior(FocusBehavior::ALWAYS);
 #endif
 
   UpdateBorder();
+  arrow_image_ = PlatformStyle::CreateComboboxArrow(enabled(), style);
   // set_background() takes ownership but takes a raw pointer.
-  std::unique_ptr<Background> b = PlatformStyle::CreateComboboxBackground();
+  std::unique_ptr<Background> b =
+      PlatformStyle::CreateComboboxBackground(GetShoulderWidth());
   set_background(b.release());
 
   // Initialize the button images.
   Button::ButtonState button_states[] = {
     Button::STATE_DISABLED,
     Button::STATE_NORMAL,
     Button::STATE_HOVERED,
     Button::STATE_PRESSED,
   };
   for (int i = 0; i < 2; i++) {
@@ skipping 21 matching lines @@
     DCHECK(selector_.get() != GetInputMethod()->GetTextInputClient());
   }
 }
 
 // static
 const gfx::FontList& Combobox::GetFontList() {
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   return rb.GetFontListWithDelta(ui::kLabelFontSizeDelta);
 }
 
-void Combobox::SetStyle(Style style) {
-  if (style_ == style)
-    return;
-
-  style_ = style;
-  if (style_ == STYLE_ACTION)
-    selected_index_ = 0;
-
-  UpdateBorder();
-  content_size_ = GetContentSize();
-  PreferredSizeChanged();
-}
-
 void Combobox::ModelChanged() {
   // If the selection is no longer valid (or the model is empty), restore the
   // default index.
   if (selected_index_ >= model_->GetItemCount() ||
       model_->GetItemCount() == 0 ||
       model_->IsItemSeparatorAt(selected_index_)) {
     selected_index_ = model_->GetDefaultIndex();
   }
 
   content_size_ = GetContentSize();
@@ skipping 28 matching lines @@
 void Combobox::SetInvalid(bool invalid) {
   if (invalid == invalid_)
     return;
 
   invalid_ = invalid;
 
   UpdateBorder();
   SchedulePaint();
 }
 
-int Combobox::GetArrowButtonWidth() const {
-  return GetDisclosureArrowLeftPadding() +
-         ArrowSize().width() +
-         GetDisclosureArrowRightPadding();
-}
-
 void Combobox::Layout() {
   PrefixDelegate::Layout();
 
   gfx::Insets insets = GetInsets();
   int text_button_width = 0;
   int arrow_button_width = 0;
 
   switch (style_) {
     case STYLE_NORMAL: {
       arrow_button_width = width();
       break;
     }
     case STYLE_ACTION: {
-      arrow_button_width = GetDisclosureArrowLeftPadding() +
-          ArrowSize().width() +
-          GetDisclosureArrowRightPadding();
+      arrow_button_width = GetShoulderWidth();
       text_button_width = width() - arrow_button_width;
       break;
     }
   }
 
   int arrow_button_x = std::max(0, text_button_width);
   text_button_->SetBounds(0, 0, std::max(0, text_button_width), height());
   arrow_button_->SetBounds(arrow_button_x, 0, arrow_button_width, height());
 }
 
+void Combobox::OnEnabledChanged() {
+  PrefixDelegate::OnEnabledChanged();
+  arrow_image_ = PlatformStyle::CreateComboboxArrow(enabled(), style_);
+}
+
 int Combobox::GetRowCount() {
   return model()->GetItemCount();
 }
 
 int Combobox::GetSelectedRow() {
   return selected_index_;
 }
 
 void Combobox::SetSelectedRow(int row) {
   int prev_index = selected_index_;
@@ skipping 12 matching lines @@
 
 gfx::Size Combobox::GetPreferredSize() const {
   // The preferred size will drive the local bounds which in turn is used to set
   // the minimum width for the dropdown list.
   gfx::Insets insets = GetInsets();
   insets += gfx::Insets(Textfield::kTextPadding,
                         Textfield::kTextPadding,
                         Textfield::kTextPadding,
                         Textfield::kTextPadding);
   int total_width = std::max(kMinComboboxWidth, content_size_.width()) +
-                    insets.width() + GetDisclosureArrowLeftPadding() +
-                    ArrowSize().width() + GetDisclosureArrowRightPadding();
+                    insets.width() + GetShoulderWidth();
   return gfx::Size(total_width, content_size_.height() + insets.height());
 }
 
 const char* Combobox::GetClassName() const {
   return kViewClassName;
 }
 
 bool Combobox::SkipDefaultKeyEventProcessing(const ui::KeyEvent& e) {
   // Escape should close the drop down list when it is active, not host UI.
   if (e.key_code() != ui::VKEY_ESCAPE ||
@@ skipping 187 matching lines @@
       enabled() ? ui::NativeTheme::kColorId_LabelEnabledColor :
                   ui::NativeTheme::kColorId_LabelDisabledColor);
 
   DCHECK_GE(selected_index_, 0);
   DCHECK_LT(selected_index_, model()->GetItemCount());
   if (selected_index_ < 0 || selected_index_ > model()->GetItemCount())
     selected_index_ = 0;
   base::string16 text = model()->GetItemAt(selected_index_);
 
   gfx::Size arrow_size = ArrowSize();
-  int disclosure_arrow_offset = width() - arrow_size.width() -
-      GetDisclosureArrowLeftPadding() - GetDisclosureArrowRightPadding();
+  int disclosure_arrow_offset = width() - GetShoulderWidth();
 
   const gfx::FontList& font_list = Combobox::GetFontList();
   int text_width = gfx::GetStringWidth(text, font_list);
   if ((text_width + insets.width()) > disclosure_arrow_offset)
     text_width = disclosure_arrow_offset - insets.width();
 
   gfx::Rect text_bounds(x, y, text_width, text_height);
   AdjustBoundsForRTLUI(&text_bounds);
   canvas->DrawStringRect(text, font_list, text_color, text_bounds);
 
-  int arrow_x = disclosure_arrow_offset + GetDisclosureArrowLeftPadding();
-  gfx::Rect arrow_bounds(arrow_x,
-                         height() / 2 - arrow_size.height() / 2,
-                         arrow_size.width(),
-                         arrow_size.height());
+  gfx::Rect arrow_bounds(disclosure_arrow_offset, 0, GetShoulderWidth(),
+                         height());
+  arrow_bounds = PositionArrowWithinShoulder(arrow_bounds, ArrowSize());
   AdjustBoundsForRTLUI(&arrow_bounds);
 
-  gfx::ImageSkia arrow_image = PlatformStyle::CreateComboboxArrow(
-      enabled(), style_);
-  canvas->DrawImageInt(arrow_image, arrow_bounds.x(), arrow_bounds.y());
+  canvas->DrawImageInt(arrow_image_, arrow_bounds.x(), arrow_bounds.y());
 }
 
 void Combobox::PaintButtons(gfx::Canvas* canvas) {
   DCHECK(style_ == STYLE_ACTION);
 
-  gfx::ScopedCanvas scoped_canvas(canvas);
-  if (base::i18n::IsRTL()) {
-    canvas->Translate(gfx::Vector2d(width(), 0));
-    canvas->Scale(-1, 1);
-  }
+  gfx::ScopedRTLFlipCanvas scoped_canvas(canvas, bounds());
 
   bool focused = HasFocus();
   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_hover_alpha =
       text_button_->state() == Button::STATE_PRESSED ? 0 :
       static_cast<int>(static_cast<TransparentButton*>(text_button_)->
@@ skipping 87 matching lines @@
 
   // This combobox may be deleted by the listener.
   base::WeakPtr<Combobox> weak_ptr = weak_ptr_factory_.GetWeakPtr();
   if (listener_)
     listener_->OnPerformAction(this);
 
   if (weak_ptr && style_ == STYLE_ACTION)
     selected_index_ = 0;
 }
 
-int Combobox::GetDisclosureArrowLeftPadding() const {
-  switch (style_) {
-    case STYLE_NORMAL:
-      return kDisclosureArrowLeftPadding;
-    case STYLE_ACTION:
-      return kDisclosureArrowButtonLeftPadding;
-  }
-  NOTREACHED();
-  return 0;
-}
-
-int Combobox::GetDisclosureArrowRightPadding() const {
-  switch (style_) {
-    case STYLE_NORMAL:
-      return kDisclosureArrowRightPadding;
-    case STYLE_ACTION:
-      return kDisclosureArrowButtonRightPadding;
-  }
-  NOTREACHED();
-  return 0;
-}
-
 gfx::Size Combobox::ArrowSize() const {
-  return PlatformStyle::CreateComboboxArrow(enabled(), style_).size();
+  return arrow_image_.size();
 }
 
 gfx::Size Combobox::GetContentSize() const {
   const gfx::FontList& font_list = GetFontList();
 
   int width = 0;
   for (int i = 0; i < model()->GetItemCount(); ++i) {
     if (model_->IsItemSeparatorAt(i))
       continue;
 
     if (style_ != STYLE_ACTION || i == selected_index_) {
       width = std::max(
           width,
           gfx::GetStringWidth(menu_model_adapter_->GetLabelAt(i), font_list));
     }
   }
   return gfx::Size(width, font_list.GetHeight());
 }
 
 PrefixSelector* Combobox::GetPrefixSelector() {
   if (!selector_)
     selector_.reset(new PrefixSelector(this));
   return selector_.get();
 }
 
+int Combobox::GetShoulderWidth() const {
+  const int kNormalPadding = 7;
+  const int kActionLeftPadding = 12;
+  const int kActionRightPadding = 11;
+  int padding = style_ == STYLE_NORMAL ?
+                          kNormalPadding * 2 :
+                          kActionLeftPadding + kActionRightPadding;
+  return ArrowSize().width() + padding;
+}
+
 }  // namespace views