CrOS Shelf: Skip layout of tray containers and hotseat when not needed

Also calculate the new hotseat state as part of calculating new target
bounds instead of passing it in.

Bug: 1042911, 1040177
Change-Id: Ie3471df435ba9ce49130e528811c17da0e249b0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025428
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736118}

ash/shelf/hotseat_widget.cc

@@ -335,7 +335,7 @@ void HotseatWidget::OnTabletModeChanged() {
   delegate_view_->OnTabletModeChanged();
 }
 
-float HotseatWidget::CalculateOpacity() {
+float HotseatWidget::CalculateOpacity() const {
   const float target_opacity =
       GetShelfView()->shelf()->shelf_layout_manager()->GetOpacity();
   return (state() == HotseatState::kExtended) ? 1.0f  // fully opaque
@@ -348,6 +348,9 @@ void HotseatWidget::SetOpaqueBackground(
 }
 
 void HotseatWidget::UpdateLayout(bool animate) {
+  const LayoutInputs new_layout_inputs = GetLayoutInputs();
+  if (layout_inputs_.has_value() && *layout_inputs_ == new_layout_inputs)
+    return;
   ui::Layer* layer = GetNativeView()->layer();
   ui::ScopedLayerAnimationSettings animation_setter(layer->GetAnimator());
   animation_setter.SetTransitionDuration(
@@ -357,9 +360,9 @@ void HotseatWidget::UpdateLayout(bool animate) {
   animation_setter.SetPreemptionStrategy(
       ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
 
-  layer->SetOpacity(CalculateOpacity());
-  SetBounds(
-      GetShelfView()->shelf()->shelf_layout_manager()->GetHotseatBounds());
+  layer->SetOpacity(new_layout_inputs.opacity);
+  SetBounds(new_layout_inputs.bounds);
+  layout_inputs_ = new_layout_inputs;
 }
 
 gfx::Size HotseatWidget::GetOpaqueBackgroundSize() const {
@@ -411,4 +414,9 @@ void HotseatWidget::SetState(HotseatState state) {
   }
 }
 
+HotseatWidget::LayoutInputs HotseatWidget::GetLayoutInputs() const {
+  return {GetShelfView()->shelf()->shelf_layout_manager()->GetHotseatBounds(),
+          CalculateOpacity()};
+}
+
 }  // namespace ash

ash/shelf/hotseat_widget.h

@@ -8,6 +8,7 @@
 #include "ash/ash_export.h"
 #include "ash/public/cpp/shelf_config.h"
 #include "ash/public/cpp/shelf_types.h"
+#include "base/optional.h"
 #include "ui/views/widget/widget.h"
 
 namespace aura {
@@ -58,7 +59,7 @@ class ASH_EXPORT HotseatWidget : public views::Widget,
   void OnTabletModeChanged();
 
   // Returns the target opacity (between 0 and 1) given current conditions.
-  float CalculateOpacity();
+  float CalculateOpacity() const;
 
   // Sets the bounds of the opaque background which functions as the hotseat
   // background.
@@ -99,6 +100,23 @@ class ASH_EXPORT HotseatWidget : public views::Widget,
  private:
   class DelegateView;
 
+  struct LayoutInputs {
+    gfx::Rect bounds;
+    float opacity = 0.0f;
+
+    bool operator==(const LayoutInputs& other) const {
+      return bounds == other.bounds && opacity == other.opacity;
+    }
+  };
+
+  // Collects the inputs for layout.
+  LayoutInputs GetLayoutInputs() const;
+
+  // The set of inputs that impact this widget's layout. The assumption is that
+  // this widget needs a relayout if, and only if, one or more of these has
+  // changed.
+  base::Optional<LayoutInputs> layout_inputs_;
+
   HotseatState state_ = HotseatState::kShown;
 
   // View containing the shelf items within an active user session. Owned by

ash/shelf/shelf_layout_manager.cc

@@ -489,7 +489,7 @@ void ShelfLayoutManager::LayoutShelf(bool animate) {
   if (in_shutdown_)
     return;
 
-  CalculateTargetBoundsAndUpdateWorkArea(hotseat_state());
+  CalculateTargetBoundsAndUpdateWorkArea();
   UpdateBoundsAndOpacity(animate);
 
   // Update insets in ShelfWindowTargeter when shelf bounds change.
@@ -1031,7 +1031,7 @@ void ShelfLayoutManager::OnSessionStateChanged(
   if (was_locked != state_.IsScreenLocked())
     UpdateShelfVisibilityAfterLoginUIChange();
 
-  CalculateTargetBoundsAndUpdateWorkArea(hotseat_state());
+  CalculateTargetBoundsAndUpdateWorkArea();
   UpdateBoundsAndOpacity(true /* animate */);
   UpdateVisibilityState();
 }
@@ -1055,7 +1055,7 @@ void ShelfLayoutManager::OnDisplayMetricsChanged(
     return;
 
   // Update |user_work_area_bounds_| for the new display arrangement.
-  CalculateTargetBoundsAndUpdateWorkArea(hotseat_state());
+  CalculateTargetBoundsAndUpdateWorkArea();
 }
 
 void ShelfLayoutManager::OnLocaleChanged() {
@@ -1167,7 +1167,7 @@ void ShelfLayoutManager::ResumeWorkAreaUpdate() {
 
   UpdateVisibilityState();
 
-  CalculateTargetBoundsAndUpdateWorkArea(hotseat_state());
+  CalculateTargetBoundsAndUpdateWorkArea();
   UpdateBoundsAndOpacity(/*animate=*/true);
   MaybeUpdateShelfBackground(AnimationChangeType::ANIMATE);
 }
@@ -1175,7 +1175,6 @@ void ShelfLayoutManager::ResumeWorkAreaUpdate() {
 void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
   if (suspend_visibility_update_)
     return;
-
   State state;
   const HotseatState previous_hotseat_state = hotseat_state();
   state.visibility_state = visibility_state;
@@ -1183,7 +1182,8 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
   state.window_state =
       GetShelfWorkspaceWindowState(shelf_widget_->GetNativeWindow());
   HotseatState new_hotseat_state =
-      CalculateHotseatState(state.visibility_state, state.auto_hide_state);
+      CalculateHotseatState(visibility_state, state.auto_hide_state);
+
   // Preserve the log in screen states.
   state.session_state = state_.session_state;
   state.pre_lock_screen_animation_active =
@@ -1234,7 +1234,7 @@ void ShelfLayoutManager::SetState(ShelfVisibilityState visibility_state) {
   if (!delay_background_change)
     MaybeUpdateShelfBackground(change_type);
 
-  CalculateTargetBoundsAndUpdateWorkArea(new_hotseat_state);
+  CalculateTargetBoundsAndUpdateWorkArea();
   UpdateBoundsAndOpacity(true /* animate */);
 
   // OnAutoHideStateChanged Should be emitted when:
@@ -1427,7 +1427,7 @@ void ShelfLayoutManager::SetDimmed(bool dimmed) {
     return;
 
   dimmed_for_inactivity_ = dimmed;
-  CalculateTargetBoundsAndUpdateWorkArea(hotseat_state());
+  CalculateTargetBoundsAndUpdateWorkArea();
 
   AnimateOpacity(shelf_widget_->navigation_widget(), target_bounds_.opacity,
                  kDimAnimationDuration, gfx::Tween::LINEAR);
@@ -1727,8 +1727,9 @@ void ShelfLayoutManager::CalculateTargetBounds(
   }
 }
 
-void ShelfLayoutManager::CalculateTargetBoundsAndUpdateWorkArea(
-    HotseatState hotseat_target_state) {
+void ShelfLayoutManager::CalculateTargetBoundsAndUpdateWorkArea() {
+  HotseatState hotseat_target_state =
+      CalculateHotseatState(visibility_state(), auto_hide_state());
   CalculateTargetBounds(state_, hotseat_target_state);
   gfx::Rect shelf_bounds_for_workarea_calculation = target_bounds_.shelf_bounds;
   // When the hotseat is enabled, only use the in-app shelf bounds when

ash/shelf/shelf_layout_manager.h

@@ -408,10 +408,9 @@ class ASH_EXPORT ShelfLayoutManager
   void CalculateTargetBounds(const State& state,
                              HotseatState hotseat_target_state);
 
-  // Calculates the target bounds using |state_|, |hotseat_target_state|, and
-  // updates the |user_work_area_bounds_|.
-  void CalculateTargetBoundsAndUpdateWorkArea(
-      HotseatState hotseat_target_state);
+  // Calculates the target bounds using |state_| and updates the
+  // |user_work_area_bounds_|.
+  void CalculateTargetBoundsAndUpdateWorkArea();
 
   // Updates the target bounds if a gesture-drag is in progress. This is only
   // used by |CalculateTargetBounds()|.

ash/system/tray/tray_container.cc

@@ -68,8 +68,17 @@ const char* TrayContainer::GetClassName() const {
   return "TrayContainer";
 }
 
+TrayContainer::LayoutInputs TrayContainer::GetLayoutInputs() const {
+  return {shelf_->IsHorizontalAlignment(),
+          ShelfConfig::Get()->status_area_hit_region_padding(),
+          GetAnchorBoundsInScreen(), main_axis_margin_, cross_axis_margin_};
+}
+
 void TrayContainer::UpdateLayout() {
-  const bool is_horizontal = shelf_->IsHorizontalAlignment();
+  const LayoutInputs new_layout_inputs = GetLayoutInputs();
+  if (layout_inputs_.has_value() && *layout_inputs_ == new_layout_inputs)
+    return;
+  const bool is_horizontal = new_layout_inputs.shelf_alignment_is_horizontal;
 
   // Adjust the size of status tray dark background by adding additional
   // empty border.
@@ -79,13 +88,12 @@ void TrayContainer::UpdateLayout() {
 
   gfx::Insets insets(
       is_horizontal
-          ? gfx::Insets(0, ShelfConfig::Get()->status_area_hit_region_padding())
-          : gfx::Insets(ShelfConfig::Get()->status_area_hit_region_padding(),
-                        0));
+          ? gfx::Insets(0, new_layout_inputs.status_area_hit_region_padding)
+          : gfx::Insets(new_layout_inputs.status_area_hit_region_padding, 0));
   SetBorder(views::CreateEmptyBorder(insets));
 
-  int horizontal_margin = main_axis_margin_;
-  int vertical_margin = cross_axis_margin_;
+  int horizontal_margin = new_layout_inputs.main_axis_margin;
+  int vertical_margin = new_layout_inputs.cross_axis_margin;
   if (!is_horizontal)
     std::swap(horizontal_margin, vertical_margin);
 
@@ -96,6 +104,7 @@ void TrayContainer::UpdateLayout() {
   views::View::SetLayoutManager(std::move(layout));
 
   PreferredSizeChanged();
+  layout_inputs_ = new_layout_inputs;
 }
 
 }  // namespace ash

ash/system/tray/tray_container.h

@@ -6,6 +6,7 @@
 #define ASH_SYSTEM_TRAY_TRAY_CONTAINER_H_
 
 #include "base/macros.h"
+#include "base/optional.h"
 #include "ui/views/view.h"
 
 namespace ash {
@@ -32,8 +33,34 @@ class TrayContainer : public views::View {
   const char* GetClassName() const override;
 
  private:
+  struct LayoutInputs {
+    bool shelf_alignment_is_horizontal = true;
+    int status_area_hit_region_padding = 0;
+    gfx::Rect anchor_bounds_in_screen;
+    int main_axis_margin = 0;
+    int cross_axis_margin = 0;
+
+    bool operator==(const LayoutInputs& other) const {
+      return shelf_alignment_is_horizontal ==
+                 other.shelf_alignment_is_horizontal &&
+             status_area_hit_region_padding ==
+                 other.status_area_hit_region_padding &&
+             anchor_bounds_in_screen == other.anchor_bounds_in_screen &&
+             main_axis_margin == other.main_axis_margin &&
+             cross_axis_margin == other.cross_axis_margin;
+    }
+  };
+
+  // Collects the inputs for layout.
+  LayoutInputs GetLayoutInputs() const;
+
   void UpdateLayout();
 
+  // The set of inputs that impact this widget's layout. The assumption is that
+  // this widget needs a relayout if, and only if, one or more of these has
+  // changed.
+  base::Optional<LayoutInputs> layout_inputs_;
+
   Shelf* const shelf_;
 
   int main_axis_margin_ = 0;