Shrink gaps between top shortcut buttons.

- Expand/Collapse button should be in the fixed size.
- Secure minumum gap between Expand/Collapse and other buttons.
- Shring gap between other buttons when there's not enough space

Bug: 847100
Change-Id: I295126c63ed2702ca7e10906f6d4ca599485e904
Reviewed-on: https://chromium-review.googlesource.com/1078031
Commit-Queue: Tatsuhisa Yamaguchi <yamaguchi@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563122}

ash/system/tray/tray_constants.h

@@ -174,6 +174,11 @@ constexpr int kUnifiedFeaturePodItemsInRow = 3;
 constexpr int kUnifiedFeaturePodMaxItemsInCollapsed = 5;
 constexpr int kUnifiedNotificationSeparatorThickness = 1;
 
+// Gap between the buttons on the top shortcut row, other than the
+// expand/collapse button.
+constexpr int kUnifiedTopShortcutButtonDefaultSpacing = 16;
+constexpr int kUnifiedTopShortcutButtonMinSpacing = 4;
+
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRAY_CONSTANTS_H_

ash/system/unified/top_shortcuts_view.cc

@@ -39,21 +39,97 @@ UserAvatarButton::UserAvatarButton(views::ButtonListener* listener)
   AddChildView(CreateUserAvatarView(0 /* user_index */));
 }
 
+class TopShortcutButtonContainer : public views::View {
+ public:
+  TopShortcutButtonContainer();
+  ~TopShortcutButtonContainer() override;
+
+  // views::View:
+  void Layout() override;
+  gfx::Size CalculatePreferredSize() const override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TopShortcutButtonContainer);
+};
+
+// Buttons are equally spaced by the default value, but the gap will be
+// narrowed evenly when the parent view is not large enough.
+void TopShortcutButtonContainer::Layout() {
+  gfx::Rect child_area(GetContentsBounds());
+
+  int total_horizontal_size = 0;
+  int num_visible = 0;
+  for (int i = 0; i < child_count(); i++) {
+    const views::View* child = child_at(i);
+    if (!child->visible())
+      continue;
+    int child_horizontal_size = child->GetPreferredSize().width();
+    if (child_horizontal_size == 0)
+      continue;
+    total_horizontal_size += child_horizontal_size;
+    num_visible++;
+  }
+  int spacing = std::max(kUnifiedTopShortcutButtonMinSpacing,
+                         std::min(kUnifiedTopShortcutButtonDefaultSpacing,
+                                  (child_area.width() - total_horizontal_size) /
+                                      (num_visible - 1)));
+
+  int horizontal_position = child_area.x();
+  for (int i = 0; i < child_count(); i++) {
+    views::View* child = child_at(i);
+    if (!child->visible())
+      continue;
+    gfx::Rect bounds(child_area);
+    bounds.set_x(horizontal_position);
+    bounds.set_width(child->GetPreferredSize().width());
+    child->SetBoundsRect(bounds);
+    horizontal_position += child->GetPreferredSize().width() + spacing;
+  }
+}
+
+gfx::Size TopShortcutButtonContainer::CalculatePreferredSize() const {
+  int total_horizontal_size = 0;
+  int max_height = 0;
+  int num_visible = 0;
+  for (int i = 0; i < child_count(); i++) {
+    const views::View* child = child_at(i);
+    if (!child->visible())
+      continue;
+    int child_horizontal_size = child->GetPreferredSize().width();
+    if (child_horizontal_size == 0)
+      continue;
+    total_horizontal_size += child_horizontal_size;
+    num_visible++;
+    max_height = std::max(child->GetPreferredSize().height(), max_height);
+  }
+  int width =
+      (num_visible == 0)
+          ? 0
+          : total_horizontal_size +
+                (num_visible - 1) * kUnifiedTopShortcutButtonDefaultSpacing;
+  return gfx::Size(width, max_height);
+}
+
+TopShortcutButtonContainer::~TopShortcutButtonContainer() = default;
+
+TopShortcutButtonContainer::TopShortcutButtonContainer() = default;
+
 }  // namespace
 
 TopShortcutsView::TopShortcutsView(UnifiedSystemTrayController* controller)
-    : controller_(controller) {
+    : controller_(controller), container_(new TopShortcutButtonContainer()) {
   DCHECK(controller_);
 
   auto* layout = SetLayoutManager(std::make_unique<views::BoxLayout>(
       views::BoxLayout::kHorizontal, kUnifiedTopShortcutPadding,
       kUnifiedTopShortcutSpacing));
   layout->set_cross_axis_alignment(views::BoxLayout::CROSS_AXIS_ALIGNMENT_END);
+  AddChildView(container_);
 
   if (Shell::Get()->session_controller()->login_status() !=
       LoginStatus::NOT_LOGGED_IN) {
     user_avatar_button_ = new UserAvatarButton(this);
-    AddChildView(user_avatar_button_);
+    container_->AddChildView(user_avatar_button_);
   }
 
   // Show the buttons in this row as disabled if the user is at the login
@@ -62,30 +138,28 @@ TopShortcutsView::TopShortcutsView(UnifiedSystemTrayController* controller)
   const bool can_show_web_ui = TrayPopupUtils::CanOpenWebUISettings();
 
   sign_out_button_ = new SignOutButton(this);
-  AddChildView(sign_out_button_);
+  container_->AddChildView(sign_out_button_);
 
   lock_button_ = new TopShortcutButton(this, kSystemMenuLockIcon,
                                        IDS_ASH_STATUS_TRAY_LOCK);
   lock_button_->SetEnabled(can_show_web_ui &&
                            Shell::Get()->session_controller()->CanLockScreen());
-  AddChildView(lock_button_);
+  container_->AddChildView(lock_button_);
 
   settings_button_ = new TopShortcutButton(this, kSystemMenuSettingsIcon,
                                            IDS_ASH_STATUS_TRAY_SETTINGS);
   settings_button_->SetEnabled(can_show_web_ui);
-  AddChildView(settings_button_);
+  container_->AddChildView(settings_button_);
 
   bool reboot = Shell::Get()->shutdown_controller()->reboot_on_shutdown();
   power_button_ = new TopShortcutButton(
       this, kSystemMenuPowerIcon,
       reboot ? IDS_ASH_STATUS_TRAY_REBOOT : IDS_ASH_STATUS_TRAY_SHUTDOWN);
-  AddChildView(power_button_);
+  container_->AddChildView(power_button_);
 
-  // |collapse_button_| should be right-aligned, so we need spacing between
-  // other buttons and |collapse_button_|.
-  views::View* spacing = new views::View;
-  AddChildView(spacing);
-  layout->SetFlexForView(spacing, 1);
+  // |collapse_button_| should be right-aligned, so we make the buttons
+  // container flex occupying all remaining space.
+  layout->SetFlexForView(container_, 1);
 
   collapse_button_ = new CollapseButton(this);
   AddChildView(collapse_button_);

ash/system/unified/top_shortcuts_view.h

@@ -38,6 +38,7 @@ class ASH_EXPORT TopShortcutsView : public views::View,
   // Owned by views hierarchy.
   views::Button* user_avatar_button_ = nullptr;
   SignOutButton* sign_out_button_ = nullptr;
+  views::View* const container_;
   TopShortcutButton* lock_button_ = nullptr;
   TopShortcutButton* settings_button_ = nullptr;
   TopShortcutButton* power_button_ = nullptr;