ash/app_list/views/contents_view.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 "ash/app_list/views/contents_view.h"

#include <algorithm>
#include <vector>

#include "ash/app_list/app_list_view_delegate.h"
#include "ash/app_list/views/app_list_folder_view.h"
#include "ash/app_list/views/app_list_main_view.h"
#include "ash/app_list/views/app_list_view.h"
#include "ash/app_list/views/apps_container_view.h"
#include "ash/app_list/views/apps_grid_view.h"
#include "ash/app_list/views/assistant/assistant_page_view.h"
#include "ash/app_list/views/expand_arrow_view.h"
#include "ash/app_list/views/horizontal_page_container.h"
#include "ash/app_list/views/search_box_view.h"
#include "ash/app_list/views/search_result_answer_card_view.h"
#include "ash/app_list/views/search_result_list_view.h"
#include "ash/app_list/views/search_result_page_view.h"
#include "ash/app_list/views/search_result_tile_item_list_view.h"
#include "ash/keyboard/ui/keyboard_ui_controller.h"
#include "ash/public/cpp/app_list/app_list_config.h"
#include "ash/public/cpp/app_list/app_list_features.h"
#include "ash/public/cpp/app_list/app_list_switches.h"
#include "base/logging.h"
#include "base/numerics/ranges.h"
#include "ui/compositor/layer_animation_observer.h"
#include "ui/compositor/scoped_layer_animation_settings.h"
#include "ui/display/display.h"
#include "ui/display/screen.h"
#include "ui/events/event.h"
#include "ui/views/accessibility/view_accessibility.h"
#include "ui/views/view_model.h"
#include "ui/views/widget/widget.h"

namespace ash {

namespace {

// The range of app list transition progress in which the expand arrow'
// opacity changes from 0 to 1.
constexpr float kExpandArrowOpacityStartProgress = 0.61;
constexpr float kExpandArrowOpacityEndProgress = 1;
constexpr int kSearchBarMinWidth = 440;

bool ShouldShowDenseLayout(int height,
                           ash::AppListViewState target_view_state) {
  return (height < 600 &&
          (app_list_features::IsScalableAppListEnabled() ||
           target_view_state == ash::AppListViewState::kFullscreenAllApps ||
           target_view_state == ash::AppListViewState::kFullscreenSearch));
}

// Notifies assistive technology that all schedules animations have completed on
// this view and that a location change event has occurred. This should be used
// for notifying a11y to update view locations after transformation animations.
// This object will delete itself after running OnImplicitAnimationsCompleted.
class AccessibilityAnimationObserver : public ui::ImplicitAnimationObserver {
 public:
  explicit AccessibilityAnimationObserver(views::View* view) : view_(view) {}
  ~AccessibilityAnimationObserver() override = default;

  // ui::ImplicitAnimationObserver:
  void OnImplicitAnimationsCompleted() override {
    view_->NotifyAccessibilityEvent(ax::mojom::Event::kLocationChanged, true);
    delete this;
  }

 private:
  views::View* const view_;

  DISALLOW_COPY_AND_ASSIGN(AccessibilityAnimationObserver);
};

}  // namespace

ContentsView::ContentsView(AppListView* app_list_view)
    : app_list_view_(app_list_view) {
  pagination_model_.SetTransitionDurations(
      AppListConfig::instance().page_transition_duration(),
      AppListConfig::instance().overscroll_page_transition_duration());
  pagination_model_.AddObserver(this);
}

ContentsView::~ContentsView() {
  pagination_model_.RemoveObserver(this);
}

void ContentsView::Init(AppListModel* model) {
  DCHECK(model);
  model_ = model;

  AppListViewDelegate* view_delegate = GetAppListMainView()->view_delegate();

  horizontal_page_container_ = new HorizontalPageContainer(this, model);

  AddLauncherPage(horizontal_page_container_, AppListState::kStateApps);

  // Search results UI.
  search_results_page_view_ =
      new SearchResultPageView(view_delegate, view_delegate->GetSearchModel());

  // Search result containers:
  if (app_list_features::IsAnswerCardEnabled()) {
    search_result_answer_card_view_ =
        new SearchResultAnswerCardView(view_delegate);
    search_results_page_view_->AddSearchResultContainerView(
        search_result_answer_card_view_);
  }

  expand_arrow_view_ =
      AddChildView(std::make_unique<ExpandArrowView>(this, app_list_view_));

  search_result_tile_item_list_view_ = new SearchResultTileItemListView(
      search_results_page_view_, GetSearchBoxView()->search_box(),
      view_delegate);
  search_results_page_view_->AddSearchResultContainerView(
      search_result_tile_item_list_view_);

  search_result_list_view_ =
      new SearchResultListView(GetAppListMainView(), view_delegate);
  search_results_page_view_->AddSearchResultContainerView(
      search_result_list_view_);

  AddLauncherPage(search_results_page_view_, AppListState::kStateSearchResults);

  if (app_list_features::IsAssistantLauncherUIEnabled()) {
    assistant_page_view_ =
        new AssistantPageView(view_delegate->GetAssistantViewDelegate(), this);
    assistant_page_view_->SetVisible(false);
    AddLauncherPage(assistant_page_view_,
                    AppListState::kStateEmbeddedAssistant);
  }

  int initial_page_index = GetPageIndexForState(AppListState::kStateApps);
  DCHECK_GE(initial_page_index, 0);

  page_before_search_ = initial_page_index;
  page_before_assistant_ = initial_page_index;
  // Must only call SetTotalPages once all the launcher pages have been added
  // (as it will trigger a SelectedPageChanged call).
  pagination_model_.SetTotalPages(app_list_pages_.size());

  // Page 0 is selected by SetTotalPages and needs to be 'hidden' when selecting
  // the initial page.
  app_list_pages_[GetActivePageIndex()]->OnWillBeHidden();

  pagination_model_.SelectPage(initial_page_index, false);

  // Update suggestion chips after valid page is selected to prevent the update
  // from being ignored.
  GetAppsContainerView()->UpdateSuggestionChips();

  ActivePageChanged();

  // Hide the search results initially.
  ShowSearchResults(false);
}

void ContentsView::ResetForShow() {
  target_page_for_last_view_state_update_ = base::nullopt;
  GetAppsContainerView()->ResetForShowApps();
  // SearchBoxView::ResetForShow() before SetActiveState(). It clears the search
  // query internally, which can show the search results page through
  // QueryChanged(). Since it wants to reset to kStateApps, first reset the
  // search box and then set its active state to kStateApps.
  GetSearchBoxView()->ResetForShow();
  // Make sure the default visibilities of the pages. This should be done before
  // SetActiveState() since it checks the visibility of the pages.
  horizontal_page_container_->SetVisible(true);
  search_results_page_view_->SetVisible(false);
  // SearchBoxView::UpdateOpacity() may change search result page opacity during
  // drag - make sure that opacity value is reset to 1.0f.
  search_results_page_view_->layer()->SetOpacity(1.0f);
  if (assistant_page_view_)
    assistant_page_view_->SetVisible(false);
  SetActiveState(AppListState::kStateApps, /*animate=*/false);
  // In side shelf, the opacity of the contents is not animated so set it to the
  // final state. In tablet mode, opacity of the elements is controlled by the
  // HomeLauncherGestureHandler which expects these elements to be opaque.
  // Otherwise the contents animate from 0 to 1 so set the initial opacity to 0.
  if (app_list_view_->is_side_shelf() || app_list_view_->is_tablet_mode()) {
    AnimateToViewState(AppListViewState::kFullscreenAllApps, base::TimeDelta());
  } else if (last_target_view_state_.has_value() &&
             *last_target_view_state_ != AppListViewState::kClosed) {
    AnimateToViewState(AppListViewState::kClosed, base::TimeDelta());
  }
}

void ContentsView::CancelDrag() {
  if (GetAppsContainerView()->apps_grid_view()->has_dragged_view())
    GetAppsContainerView()->apps_grid_view()->EndDrag(true);
  if (GetAppsContainerView()
          ->app_list_folder_view()
          ->items_grid_view()
          ->has_dragged_view()) {
    GetAppsContainerView()->app_list_folder_view()->items_grid_view()->EndDrag(
        true);
  }
}

void ContentsView::SetDragAndDropHostOfCurrentAppList(
    ApplicationDragAndDropHost* drag_and_drop_host) {
  GetAppsContainerView()->SetDragAndDropHostOfCurrentAppList(
      drag_and_drop_host);
}

void ContentsView::OnAppListViewTargetStateChanged(
    AppListViewState target_state) {
  target_view_state_ = target_state;
  if (target_state == AppListViewState::kClosed) {
    CancelDrag();
    expand_arrow_view_->MaybeEnableHintingAnimation(false);
    return;
  }
  UpdateExpandArrowBehavior(target_state);
}

void ContentsView::SetActiveState(AppListState state) {
  SetActiveState(state, !AppListView::ShortAnimationsForTesting());
}

void ContentsView::SetActiveState(AppListState state, bool animate) {
  if (IsStateActive(state))
    return;

  // The primary way to set the state to search or Assistant results should be
  // via |ShowSearchResults| or |ShowEmbeddedAssistantUI|.
  DCHECK(state != AppListState::kStateSearchResults &&
         state != AppListState::kStateEmbeddedAssistant);

  const int page_index = GetPageIndexForState(state);
  page_before_search_ = page_index;
  page_before_assistant_ = page_index;
  SetActiveStateInternal(page_index, animate);
}

int ContentsView::GetActivePageIndex() const {
  // The active page is changed at the beginning of an animation, not the end.
  return pagination_model_.SelectedTargetPage();
}

AppListState ContentsView::GetActiveState() const {
  return GetStateForPageIndex(GetActivePageIndex());
}

bool ContentsView::IsStateActive(AppListState state) const {
  int active_page_index = GetActivePageIndex();
  return active_page_index >= 0 &&
         GetPageIndexForState(state) == active_page_index;
}

int ContentsView::GetPageIndexForState(AppListState state) const {
  // Find the index of the view corresponding to the given state.
  std::map<AppListState, int>::const_iterator it = state_to_view_.find(state);
  if (it == state_to_view_.end())
    return -1;

  return it->second;
}

AppListState ContentsView::GetStateForPageIndex(int index) const {
  std::map<int, AppListState>::const_iterator it = view_to_state_.find(index);
  if (it == view_to_state_.end())
    return AppListState::kInvalidState;

  return it->second;
}

int ContentsView::NumLauncherPages() const {
  return pagination_model_.total_pages();
}

AppsContainerView* ContentsView::GetAppsContainerView() {
  return horizontal_page_container_->apps_container_view();
}

gfx::Size ContentsView::AdjustSearchBoxSizeToFitMargins(
    const gfx::Size& preferred_size) const {
  if (!app_list_features::IsScalableAppListEnabled())
    return preferred_size;
  const int padded_width =
      GetContentsBounds().width() -
      2 * app_list_view_->GetAppListConfig().GetIdealHorizontalMargin(
              GetContentsBounds());
  return gfx::Size(base::ClampToRange(padded_width, kSearchBarMinWidth,
                                      preferred_size.width()),
                   preferred_size.height());
}

void ContentsView::SetActiveStateInternal(int page_index, bool animate) {
  if (!GetPageView(page_index)->GetVisible())
    return;

  app_list_pages_[GetActivePageIndex()]->OnWillBeHidden();

  // Start animating to the new page.
  const bool should_animate = animate && !set_active_state_without_animation_;
  // There's a chance of selecting page during the transition animation. To
  // reschedule the new animation from the beginning, |pagination_model_| needs
  // to finish the ongoing animation here.
  if (should_animate && pagination_model_.has_transition() &&
      pagination_model_.transition().target_page != page_index) {
    pagination_model_.FinishAnimation();
    // If the pending animation was animating from the current target page, the
    // target page might have got hidden as the animation was finished. Make
    // sure the page is reshown in that case.
    GetPageView(page_index)->SetVisible(true);
  }
  pagination_model_.SelectPage(page_index, should_animate);
  ActivePageChanged();

  if (!should_animate)
    Layout();
}

void ContentsView::ActivePageChanged() {
  AppListState state = AppListState::kInvalidState;

  std::map<int, AppListState>::const_iterator it =
      view_to_state_.find(GetActivePageIndex());
  if (it != view_to_state_.end())
    state = it->second;

  app_list_pages_[GetActivePageIndex()]->OnWillBeShown();

  GetAppListMainView()->model()->SetState(state);
  UpdateSearchBoxVisibility(state);
}

void ContentsView::ShowSearchResults(bool show) {
  int search_page = GetPageIndexForState(AppListState::kStateSearchResults);
  DCHECK_GE(search_page, 0);

  // Hide or Show results
  GetPageView(search_page)->SetVisible(show);

  page_before_assistant_ = show ? search_page : page_before_search_;
  SetActiveStateInternal(show ? search_page : page_before_search_,
                         !AppListView::ShortAnimationsForTesting());
}

bool ContentsView::IsShowingSearchResults() const {
  return IsStateActive(AppListState::kStateSearchResults);
}

void ContentsView::ShowEmbeddedAssistantUI(bool show) {
  expand_arrow_view_->SetVisible(!show);

  const int assistant_page =
      GetPageIndexForState(AppListState::kStateEmbeddedAssistant);
  DCHECK_GE(assistant_page, 0);

  // Hide or Show results.
  auto* page_view = GetPageView(assistant_page);
  page_view->SetVisible(show);
  if (show) {
    page_view->RequestFocus();
    // RequestFocus() might cause ResetForShow() method through
    // AppListView::OnHomeLauncherGainingFocusWithoutAnimation() and it can hide
    // |page_view|. Thus |page_view|'s visibility should be set again. See
    // b/140831868.
    page_view->SetVisible(show);
  }

  const int search_results_page =
      GetPageIndexForState(AppListState::kStateSearchResults);
  DCHECK_GE(search_results_page, 0);
  GetPageView(page_before_assistant_)->SetVisible(!show);

  // No animation when transiting from/to |search_results_page| and in test.
  const bool animate = !AppListView::ShortAnimationsForTesting() &&
                       page_before_assistant_ != search_results_page;
  const int current_page = pagination_model_.selected_page();
  SetActiveStateInternal(show ? assistant_page : page_before_assistant_,
                         animate);
  // Sometimes the page stays in |assistant_page|, but the preferred bounds
  // might change meanwhile.
  if (show && current_page == assistant_page) {
    page_view->UpdatePageBoundsForState(
        AppListState::kStateEmbeddedAssistant, GetContentsBounds(),
        GetSearchBoxBounds(AppListState::kStateEmbeddedAssistant));
  }
  // If |page_before_assistant_| is kStateApps, we need to set app_list_view to
  // kPeeking and layout the suggestion chips.
  if (!show && page_before_assistant_ ==
                   GetPageIndexForState(AppListState::kStateApps)) {
    GetSearchBoxView()->ClearSearch();
    GetSearchBoxView()->SetSearchBoxActive(false, ui::ET_UNKNOWN);
    GetAppsContainerView()->Layout();
  }
}

bool ContentsView::IsShowingEmbeddedAssistantUI() const {
  return IsStateActive(AppListState::kStateEmbeddedAssistant);
}

void ContentsView::FocusEmbeddedAssistantPage() {
  const int assistant_page =
      GetPageIndexForState(AppListState::kStateEmbeddedAssistant);
  DCHECK_GE(assistant_page, 0);
  auto* page_view = GetPageView(assistant_page);
  page_view->RequestFocus();
  page_view->SetVisible(true);
}

void ContentsView::InitializeSearchBoxAnimation(AppListState current_state,
                                                AppListState target_state) {
  SearchBoxView* search_box = GetSearchBoxView();
  if (!search_box->GetWidget())
    return;

  search_box->UpdateLayout(
      1.f, current_state, GetSearchBoxSize(current_state).height(),
      target_state, GetSearchBoxSize(target_state).height());
  search_box->UpdateBackground(1.f, current_state, target_state);

  gfx::Rect target_bounds = GetSearchBoxBounds(target_state);
  target_bounds = search_box->GetViewBoundsForSearchBoxContentsBounds(
      ConvertRectToWidgetWithoutTransform(target_bounds));

  // The search box animation is conducted as transform animation. Initially
  // search box changes its bounds to the target bounds but sets the transform
  // to be original bounds. Note that this transform shouldn't be animated
  // through ui::LayerAnimator since intermediate transformed bounds might not
  // match with other animation and that could look janky.
  search_box->GetWidget()->SetBounds(target_bounds);

  UpdateSearchBoxAnimation(0.0f, current_state, target_state);
}

void ContentsView::UpdateSearchBoxAnimation(double progress,
                                            AppListState current_state,
                                            AppListState target_state) {
  SearchBoxView* search_box = GetSearchBoxView();
  if (!search_box->GetWidget())
    return;

  gfx::Rect previous_bounds = GetSearchBoxBounds(current_state);
  previous_bounds = search_box->GetViewBoundsForSearchBoxContentsBounds(
      ConvertRectToWidgetWithoutTransform(previous_bounds));
  gfx::Rect target_bounds = GetSearchBoxBounds(target_state);
  target_bounds = search_box->GetViewBoundsForSearchBoxContentsBounds(
      ConvertRectToWidgetWithoutTransform(target_bounds));

  gfx::Rect current_bounds =
      gfx::Tween::RectValueBetween(progress, previous_bounds, target_bounds);
  gfx::Transform transform;

  if (current_bounds != target_bounds) {
    transform.Translate(current_bounds.origin() - target_bounds.origin());
    transform.Scale(
        static_cast<float>(current_bounds.width()) / target_bounds.width(),
        static_cast<float>(current_bounds.height()) / target_bounds.height());
  }
  search_box->GetWidget()->GetLayer()->SetTransform(transform);
}

void ContentsView::UpdateExpandArrowOpacity(AppListState target_state,
                                            bool animate) {
  float expand_arrow_target_opacity = 0.0f;
  if (target_state == AppListState::kStateApps) {
    expand_arrow_target_opacity = 1.0f;
  } else if (target_state == AppListState::kStateSearchResults ||
             target_state == AppListState::kStateEmbeddedAssistant) {
    expand_arrow_target_opacity = 0.0f;
  } else {
    // not updated.
    return;
  }

  std::unique_ptr<ui::ScopedLayerAnimationSettings> settings;
  if (animate)
    settings = CreateTransitionAnimationSettings(expand_arrow_view_->layer());
  expand_arrow_view_->layer()->SetOpacity(expand_arrow_target_opacity);
}

void ContentsView::UpdateExpandArrowBehavior(AppListViewState target_state) {
  const bool expand_arrow_enabled = target_state == AppListViewState::kPeeking;
  // The expand arrow is only focusable and has InkDropMode on in peeking
  // state.
  expand_arrow_view_->SetFocusBehavior(
      expand_arrow_enabled ? FocusBehavior::ALWAYS : FocusBehavior::NEVER);
  expand_arrow_view_->SetInkDropMode(
      expand_arrow_enabled ? views::InkDropHostView::InkDropMode::ON
                           : views::InkDropHostView::InkDropMode::OFF);

  // Allow ChromeVox to focus the expand arrow only when peeking launcher.
  expand_arrow_view_->GetViewAccessibility().OverrideIsIgnored(
      !expand_arrow_enabled);
  expand_arrow_view_->GetViewAccessibility().NotifyAccessibilityEvent(
      ax::mojom::Event::kTreeChanged);

  expand_arrow_view_->MaybeEnableHintingAnimation(expand_arrow_enabled);
}

void ContentsView::UpdateSearchBoxVisibility(AppListState current_state) {
  auto* search_box_widget = GetSearchBoxView()->GetWidget();
  if (search_box_widget) {
    // Hide search box widget in order to click on the embedded Assistant UI.
    const bool show_search_box =
        current_state != AppListState::kStateEmbeddedAssistant;
    show_search_box ? search_box_widget->Show() : search_box_widget->Hide();
  }
}

PaginationModel* ContentsView::GetAppsPaginationModel() {
  return GetAppsContainerView()->apps_grid_view()->pagination_model();
}

void ContentsView::ShowFolderContent(AppListFolderItem* item) {
  GetAppsContainerView()->ShowActiveFolder(item);
}

AppListPage* ContentsView::GetPageView(int index) const {
  DCHECK_GT(static_cast<int>(app_list_pages_.size()), index);
  return app_list_pages_[index];
}

SearchBoxView* ContentsView::GetSearchBoxView() const {
  return GetAppListMainView()->search_box_view();
}

AppListMainView* ContentsView::GetAppListMainView() const {
  return app_list_view_->app_list_main_view();
}

int ContentsView::AddLauncherPage(AppListPage* view) {
  view->set_contents_view(this);
  AddChildView(view);
  app_list_pages_.push_back(view);
  return app_list_pages_.size() - 1;
}

int ContentsView::AddLauncherPage(AppListPage* view, AppListState state) {
  int page_index = AddLauncherPage(view);
  bool success =
      state_to_view_.insert(std::make_pair(state, page_index)).second;
  success = success &&
            view_to_state_.insert(std::make_pair(page_index, state)).second;

  // There shouldn't be duplicates in either map.
  DCHECK(success);
  return page_index;
}

gfx::Rect ContentsView::GetSearchBoxBounds(AppListState state) const {
  if (app_list_view_->is_in_drag()) {
    return GetSearchBoxExpectedBoundsForProgress(
        state, app_list_view_->GetAppListTransitionProgress(
                   state == AppListState::kStateSearchResults
                       ? AppListView::kProgressFlagSearchResults
                       : AppListView::kProgressFlagNone));
  }
  return GetSearchBoxBoundsForViewState(state, target_view_state());
}

gfx::Size ContentsView::GetSearchBoxSize(AppListState state) const {
  AppListPage* page = GetPageView(GetPageIndexForState(state));
  gfx::Size size_preferred_by_page = page->GetPreferredSearchBoxSize();
  if (!size_preferred_by_page.IsEmpty())
    return AdjustSearchBoxSizeToFitMargins(size_preferred_by_page);

  gfx::Size preferred_size = GetSearchBoxView()->GetPreferredSize();

  // Reduce the search box size in fullscreen view state when the work area
  // height is less than 600 dip - the goal is to increase the amount of space
  // available to the apps grid.
  if (ShouldShowDenseLayout(GetContentsBounds().height(), target_view_state_)) {
    preferred_size.set_height(
        AppListConfig::instance().search_box_height_for_dense_layout());
  } else {
    preferred_size.set_height(AppListConfig::instance().search_box_height());
  }

  return AdjustSearchBoxSizeToFitMargins(preferred_size);
}

gfx::Rect ContentsView::GetSearchBoxBoundsForViewState(
    AppListState state,
    AppListViewState view_state) const {
  gfx::Size size = GetSearchBoxSize(state);
  return gfx::Rect(gfx::Point((width() - size.width()) / 2,
                              GetSearchBoxTopForViewState(state, view_state)),
                   size);
}

gfx::Rect ContentsView::GetSearchBoxExpectedBoundsForProgress(
    AppListState state,
    float progress) const {
  AppListViewState baseline_state = state == AppListState::kStateSearchResults
                                        ? AppListViewState::kHalf
                                        : AppListViewState::kPeeking;
  gfx::Rect bounds = GetSearchBoxBoundsForViewState(state, baseline_state);

  if (progress <= 1) {
    bounds.set_y(gfx::Tween::IntValueBetween(progress, 0, bounds.y()));
  } else {
    const int fullscreen_y = GetSearchBoxTopForViewState(
        state, AppListViewState::kFullscreenAllApps);
    bounds.set_y(
        gfx::Tween::IntValueBetween(progress - 1, bounds.y(), fullscreen_y));
  }
  return bounds;
}

bool ContentsView::Back() {
  // If the virtual keyboard is visible, dismiss the keyboard and return early
  auto* const keyboard_controller = keyboard::KeyboardUIController::Get();
  if (keyboard_controller->IsKeyboardVisible()) {
    keyboard_controller->HideKeyboardByUser();
    return true;
  }

  AppListState state = view_to_state_[GetActivePageIndex()];
  switch (state) {
    case AppListState::kStateApps: {
      PaginationModel* pagination_model =
          GetAppsContainerView()->apps_grid_view()->pagination_model();
      if (GetAppsContainerView()->IsInFolderView()) {
        GetAppsContainerView()->app_list_folder_view()->CloseFolderPage();
      } else if (app_list_view_->is_tablet_mode() &&
                 pagination_model->total_pages() > 0 &&
                 pagination_model->selected_page() > 0) {
        pagination_model->SelectPage(
            0, !app_list_view_->ShortAnimationsForTesting());
      } else {
        // Close the app list when Back() is called from the apps page.
        return false;
      }
      break;
    }
    case AppListState::kStateSearchResults:
      GetSearchBoxView()->ClearSearchAndDeactivateSearchBox();
      ShowSearchResults(false);
      for (auto& observer : search_box_observers_)
        observer.OnSearchBoxClearAndDeactivated();
      break;
    case AppListState::kStateEmbeddedAssistant:
      ShowEmbeddedAssistantUI(false);
      break;
    case AppListState::kStateStart_DEPRECATED:
    case AppListState::kInvalidState:
      NOTREACHED();
      break;
  }
  return true;
}

void ContentsView::Layout() {
  const gfx::Rect rect = GetContentsBounds();
  if (rect.IsEmpty())
    return;

  // Layout expand arrow.
  gfx::Rect arrow_rect(GetContentsBounds());
  const gfx::Size arrow_size(expand_arrow_view_->GetPreferredSize());
  arrow_rect.set_height(arrow_size.height());
  arrow_rect.ClampToCenteredSize(arrow_size);
  expand_arrow_view_->SetBoundsRect(arrow_rect);
  expand_arrow_view_->SchedulePaint();

  if (pagination_model_.has_transition())
    return;

  // The bounds calculations will potentially be mid-transition (depending on
  // the state of the PaginationModel).
  int current_page = std::max(0, pagination_model_.selected_page());
  AppListState current_state = GetStateForPageIndex(current_page);
  const gfx::Rect search_box_bounds = GetSearchBoxBounds(current_state);

  // Update app list pages.
  for (AppListPage* page : app_list_pages_) {
    page->UpdatePageBoundsForState(current_state, rect, search_box_bounds);
    page->UpdateOpacityForState(current_state);
  }

  UpdateExpandArrowOpacity(current_state, false);

  // Update the searchbox bounds.
  auto* search_box = GetSearchBoxView();
  // Convert search box bounds to the search box widget's coordinate system.
  const gfx::Rect search_box_widget_bounds =
      search_box->GetViewBoundsForSearchBoxContentsBounds(
          ConvertRectToWidgetWithoutTransform(search_box_bounds));
  search_box->GetWidget()->SetBounds(search_box_widget_bounds);
  search_box->UpdateLayout(1.f, current_state, search_box_bounds.height(),
                           current_state, search_box_bounds.height());
  search_box->UpdateBackground(1.f, current_state, current_state);
  // Reset the transform which can be set through animation.
  search_box->GetWidget()->GetLayer()->SetTransform(gfx::Transform());
}

const char* ContentsView::GetClassName() const {
  return "ContentsView";
}

void ContentsView::TotalPagesChanged(int previous_page_count,
                                     int new_page_count) {}

void ContentsView::SelectedPageChanged(int old_selected, int new_selected) {
  if (old_selected >= 0)
    app_list_pages_[old_selected]->OnHidden();

  if (new_selected >= 0)
    app_list_pages_[new_selected]->OnShown();
}

void ContentsView::TransitionStarted() {
  const int current_page = pagination_model_.selected_page();
  const int target_page = pagination_model_.transition().target_page;

  const AppListState current_state = GetStateForPageIndex(current_page);
  const AppListState target_state = GetStateForPageIndex(target_page);
  for (AppListPage* page : app_list_pages_)
    page->OnAnimationStarted(current_state, target_state);

  InitializeSearchBoxAnimation(current_state, target_state);
  UpdateExpandArrowOpacity(target_state, true);
}

void ContentsView::TransitionChanged() {
  const int current_page = pagination_model_.selected_page();
  const int target_page = pagination_model_.transition().target_page;

  const AppListState current_state = GetStateForPageIndex(current_page);
  const AppListState target_state = GetStateForPageIndex(target_page);
  const double progress = pagination_model_.transition().progress;
  for (AppListPage* page : app_list_pages_) {
    if (!page->GetVisible() ||
        !ShouldLayoutPage(page, current_state, target_state)) {
      continue;
    }
    page->OnAnimationUpdated(progress, current_state, target_state);
  }

  // Update search box's transform gradually. See the comment in
  // InitiateSearchBoxAnimation for why it's not animated through
  // ui::LayerAnimator.
  UpdateSearchBoxAnimation(progress, current_state, target_state);
}

views::View* ContentsView::GetSelectedView() const {
  return app_list_pages_[GetActivePageIndex()]->GetSelectedView();
}

void ContentsView::UpdateYPositionAndOpacity() {
  const int current_page = pagination_model_.has_transition()
                               ? pagination_model_.transition().target_page
                               : pagination_model_.selected_page();
  const AppListState current_state = GetStateForPageIndex(current_page);
  float progress = 0.0f;
  if (app_list_view_->is_in_drag()) {
    progress = app_list_view_->GetAppListTransitionProgress(
        current_state == AppListState::kStateSearchResults
            ? AppListView::kProgressFlagSearchResults
            : AppListView::kProgressFlagNone);
  } else {
    progress = AppListView::GetTransitionProgressForState(target_view_state());
  }

  const bool restore_opacity = !app_list_view_->is_in_drag() &&
                               target_view_state() != AppListViewState::kClosed;
  if (current_state != AppListState::kStateApps) {
    expand_arrow_view_->layer()->SetOpacity(0.0f);
  } else if (restore_opacity) {
    expand_arrow_view_->layer()->SetOpacity(1.0f);
  } else {
    // Changes the opacity of expand arrow between 0 and 1 when app list
    // transition progress changes between |kExpandArrowOpacityStartProgress|
    // and |kExpandArrowOpacityEndProgress|.
    expand_arrow_view_->layer()->SetOpacity(
        std::min(std::max((progress - kExpandArrowOpacityStartProgress) /
                              (kExpandArrowOpacityEndProgress -
                               kExpandArrowOpacityStartProgress),
                          0.f),
                 1.0f));
  }

  expand_arrow_view_->SchedulePaint();

  SearchBoxView* search_box = GetSearchBoxView();
  const gfx::Rect search_box_bounds = GetSearchBoxBounds(current_state);
  const gfx::Rect search_rect =
      search_box->GetViewBoundsForSearchBoxContentsBounds(
          ConvertRectToWidgetWithoutTransform(search_box_bounds));
  search_box->GetWidget()->SetBounds(search_rect);

  for (AppListPage* page : app_list_pages_) {
    page->UpdatePageBoundsForState(current_state, GetContentsBounds(),
                                   search_box_bounds);
  }

  // If in drag, reset the transforms that might have been set in
  // AnimateToViewState().
  if (app_list_view_->is_in_drag()) {
    search_box->layer()->SetTransform(gfx::Transform());
    expand_arrow_view_->layer()->SetTransform(gfx::Transform());
    for (AppListPage* page : app_list_pages_)
      page->layer()->SetTransform(gfx::Transform());
  }

  if (app_list_features::IsScalableAppListEnabled() ||
      current_state == AppListState::kStateApps) {
    // Layout the apps container at the position where it would be with apps
    // page active with the current app list height - use apps state app list
    // progress to aciheve that.
    const float apps_container_progress =
        app_list_view_->is_in_drag()
            ? app_list_view_->GetAppListTransitionProgress(
                  AppListView::kProgressFlagNone)
            : progress;
    GetAppsContainerView()->UpdateYPositionAndOpacity(apps_container_progress,
                                                      restore_opacity);
  }

  target_page_for_last_view_state_update_ = current_state;
}

void ContentsView::AnimateToViewState(AppListViewState target_view_state,
                                      const base::TimeDelta& duration) {
  const AppListState target_page =
      GetStateForPageIndex(pagination_model_.has_transition()
                               ? pagination_model_.transition().target_page
                               : pagination_model_.selected_page());

  // Animates layer's opacity.
  // |layer| - The layer to animate.
  // |target_opacity| - The target layer opacity.
  // |half_duration| - Whether the animation duration should be half of the
  //     overall view state transition. Used during transition to closed state
  //     to speed up the search box and contenst view animation so the don't
  //     show under the shelf.
  auto animate_opacity = [](base::TimeDelta duration, views::View* view,
                            bool target_visibility) {
    ui::Layer* const layer = view->layer();
    ui::ScopedLayerAnimationSettings animation(layer->GetAnimator());
    animation.SetTransitionDuration(duration / (target_visibility ? 1 : 2));
    animation.SetTweenType(gfx::Tween::EASE_IN);
    animation.SetPreemptionStrategy(
        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
    layer->SetOpacity(target_visibility ? 1.0f : 0.0f);
  };

  // Fade in or out the contents view, the search box.
  const bool closing = target_view_state == AppListViewState::kClosed;
  animate_opacity(duration, GetSearchBoxView(), !closing /*target_visibility*/);

  // Fade in or out the expand arrow.
  const bool target_arrow_visibility =
      target_page == AppListState::kStateApps && !closing;
  animate_opacity(duration, expand_arrow_view_, target_arrow_visibility);

  // Animates layer's vertical position (using transform animation).
  // |layer| - The layer to transform.
  // |y_offset| - The initial vertical offset - the layer's vertical offset will
  //              be animated to 0.
  auto animate_transform = [](base::TimeDelta duration, float y_offset,
                              views::View* view) {
    ui::Layer* layer = view->layer();
    gfx::Transform transform;
    transform.Translate(0, y_offset);
    layer->SetTransform(transform);

    auto settings = std::make_unique<ui::ScopedLayerAnimationSettings>(
        layer->GetAnimator());
    settings->SetTweenType(gfx::Tween::EASE_OUT);
    settings->SetTransitionDuration(duration);
    settings->SetPreemptionStrategy(
        ui::LayerAnimator::IMMEDIATELY_SET_NEW_TARGET);
    // Observer will delete itself after animation completes.
    settings->AddObserver(new AccessibilityAnimationObserver(view));

    layer->SetTransform(gfx::Transform());
  };

  // Animate the app list contents to the target state. The transform is
  // performed by setting the target view bounds (for search box and the app
  // list pages), applying a transform that positions the views into their
  // current states, and finally setting up transform animation to the identity
  // transform (to move the layers into their target bounds).
  // Note that pages are positioned relative to the search box view, and the
  // vertical offset from the search box remains constant through out the
  // animation, so it's sufficient to calculate the target search box view
  // offset and apply the transform to the whole contents view.
  const gfx::Rect target_search_box_bounds =
      GetSearchBoxBoundsForViewState(target_page, target_view_state);

  SearchBoxView* search_box = GetSearchBoxView();
  const gfx::Rect target_search_box_widget_bounds =
      search_box->GetViewBoundsForSearchBoxContentsBounds(
          ConvertRectToWidgetWithoutTransform(target_search_box_bounds));
  search_box->GetWidget()->SetBounds(target_search_box_widget_bounds);

  // Even though the target bounds are calculated for the target page, use the
  // last page for which app list view state was updated - in case page
  // transition is in progress, the total search box position change can be
  // described as composite of:
  // 1.  Change in contents view padding due to app list view state change.
  // 2.  Change in contents view padding due to page change.
  // Only the first part is expected to be handled by this animation, and this
  // uses the last used page as reference.
  // The second change will be handled by the page transition animation.
  const AppListState selected_page =
      target_page_for_last_view_state_update_.value_or(
          GetStateForPageIndex(pagination_model_.selected_page()));
  const int progress_baseline_flag =
      selected_page == AppListState::kStateSearchResults
          ? AppListView::kProgressFlagSearchResults
          : AppListView::kProgressFlagNone;
  const float progress = app_list_view_->GetAppListTransitionProgress(
      AppListView::kProgressFlagWithTransform | progress_baseline_flag);
  const gfx::Rect current_search_box_bounds =
      GetSearchBoxExpectedBoundsForProgress(selected_page, progress);

  const int y_offset =
      current_search_box_bounds.y() -
      GetSearchBoxBoundsForViewState(selected_page, target_view_state).y();

  // For search box, animate the search_box view layer instead of the widget
  // layer to avoid conflict with pagination model transitions (which update the
  // search box widget layer transform as the transition progresses).
  animate_transform(duration, y_offset, search_box);

  // Update app list page bounds to their target values. This assumes that
  // potential in-progress pagination transition does not directly animate page
  // bounds.
  for (AppListPage* page : app_list_pages_) {
    page->UpdatePageBoundsForState(target_page, GetContentsBounds(),
                                   target_search_box_bounds);
    if (page != horizontal_page_container_) {
      animate_opacity(duration, page, closing ? 0.0f : 1.0f);
      animate_transform(duration, y_offset, page);
    } else {
      GetAppsContainerView()->AnimateOpacity(
          progress, target_view_state,
          base::BindRepeating(animate_opacity, duration));
      GetAppsContainerView()->AnimateYPosition(
          target_view_state,
          base::BindRepeating(animate_transform, duration, y_offset));
    }
  }

  last_target_view_state_ = target_view_state;
  target_page_for_last_view_state_update_ = target_page;

  // Schedule expand arrow repaint to ensure the view picks up the new target
  // state.
  expand_arrow_view()->SchedulePaint();
  animate_transform(
      duration,
      expand_arrow_view()->CalculateOffsetFromCurrentAppListProgress(progress),
      expand_arrow_view());
}

void ContentsView::SetExpandArrowViewVisibility(bool show) {
  if (expand_arrow_view_->GetVisible() == show)
    return;

  expand_arrow_view_->SetVisible(show);
}

std::unique_ptr<ui::ScopedLayerAnimationSettings>
ContentsView::CreateTransitionAnimationSettings(ui::Layer* layer) const {
  DCHECK(pagination_model_.has_transition());
  auto settings =
      std::make_unique<ui::ScopedLayerAnimationSettings>(layer->GetAnimator());
  settings->SetTweenType(gfx::Tween::FAST_OUT_SLOW_IN);
  settings->SetTransitionDuration(
      pagination_model_.GetTransitionAnimationSlideDuration());
  return settings;
}

void ContentsView::NotifySearchBoxBoundsUpdated() {
  for (auto& observer : search_box_observers_)
    observer.OnSearchBoxBoundsUpdated();
}

void ContentsView::AddSearchBoxUpdateObserver(
    SearchBoxUpdateObserver* observer) {
  search_box_observers_.AddObserver(observer);
}

void ContentsView::RemoveSearchBoxUpdateObserver(
    SearchBoxUpdateObserver* observer) {
  search_box_observers_.RemoveObserver(observer);
}

bool ContentsView::ShouldLayoutPage(AppListPage* page,
                                    AppListState current_state,
                                    AppListState target_state) const {
  if ((page == horizontal_page_container_ &&
       app_list_features::IsScalableAppListEnabled()) ||
      page == search_results_page_view_) {
    return ((current_state == AppListState::kStateSearchResults &&
             target_state == AppListState::kStateApps) ||
            (current_state == AppListState::kStateApps &&
             target_state == AppListState::kStateSearchResults));
  }

  if (page == horizontal_page_container_) {
    return (current_state == AppListState::kStateSearchResults &&
            target_state == AppListState::kStateApps);
  }

  if (page == assistant_page_view_) {
    return current_state == AppListState::kStateEmbeddedAssistant ||
           target_state == AppListState::kStateEmbeddedAssistant;
  }

  return false;
}

gfx::Rect ContentsView::ConvertRectToWidgetWithoutTransform(
    const gfx::Rect& rect) {
  gfx::Rect widget_rect = rect;
  for (const views::View* v = this; v; v = v->parent()) {
    widget_rect.Offset(v->GetMirroredPosition().OffsetFromOrigin());
  }
  return widget_rect;
}

int ContentsView::GetSearchBoxTopForViewState(
    AppListState state,
    AppListViewState view_state) const {
  AppListPage* page = GetPageView(GetPageIndexForState(state));
  base::Optional<int> value_for_page = page->GetSearchBoxTop(view_state);
  if (value_for_page.has_value())
    return value_for_page.value();

  switch (view_state) {
    case AppListViewState::kClosed:
      return AppListConfig::instance().search_box_closed_top_padding();
    case AppListViewState::kFullscreenAllApps:
    case AppListViewState::kFullscreenSearch:
      if (app_list_features::IsScalableAppListEnabled()) {
        return horizontal_page_container_->apps_container_view()
            ->CalculateMarginsForAvailableBounds(
                GetContentsBounds(), GetSearchBoxSize(AppListState::kStateApps),
                true /*for_full_container_bounds*/)
            .top();
      }
      return AppListConfig::instance().search_box_fullscreen_top_padding();
    case AppListViewState::kPeeking:
    case AppListViewState::kHalf:
      return AppListConfig::instance().search_box_peeking_top_padding();
  }

  NOTREACHED();
  return AppListConfig::instance().search_box_fullscreen_top_padding();
}

}  // namespace ash