Reland "overivew: Animate blur when there are no maximized windows."

This is a reland of fc2d77d5

TBR=oshima@chromium.org

Original change's description:
> overivew: Animate blur when there are no maximized windows.
>
> See bug(s) for spec. This CL adds an animated blur on wallpaper when entering/existing
> overview when no maximized/fullscreen windows.
>
> Bug: 823533, 812004
> Change-Id: Icf8bdababedaaefe869f62768aacf7abcb3643d2
> Reviewed-on: https://chromium-review.googlesource.com/979167
> Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
> Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
> Commit-Queue: Sammie Quon <sammiequon@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#549780}

Bug: 823533, 812004
Change-Id: I3aa8ded00f07209108f144bddfa401a35d90ff2d
Reviewed-on: https://chromium-review.googlesource.com/1007742Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550422}

ash/wm/overview/window_grid.cc

@@ -83,10 +83,6 @@ constexpr float kOldShieldOpacity = 0.7f;
 // form the shield widgets color.
 constexpr SkColor kShieldBaseColor = SkColorSetARGB(179, 0, 0, 0);
 
-// Amount of blur to apply on the wallpaper when we enter or exit overview mode.
-constexpr float kWallpaperBlurSigma = 10.f;
-constexpr float kWallpaperClearBlurSigma = 0.f;
-
 // In the conceptual overview table, the window margin is the space reserved
 // around the window within the cell. This margin does not overlap so the
 // closest distance between adjacent windows will be twice this amount.
@@ -241,13 +237,6 @@ WindowGrid::WindowGrid(aura::Window* root_window,
     window_list_.push_back(
         std::make_unique<WindowSelectorItem>(window, window_selector_, this));
   }
-
-  if (IsNewOverviewUi() &&
-      Shell::Get()->wallpaper_controller()->IsBlurEnabled()) {
-    RootWindowController::ForWindow(root_window_)
-        ->wallpaper_widget_controller()
-        ->SetWallpaperBlur(kWallpaperBlurSigma);
-  }
 }
 
 WindowGrid::~WindowGrid() = default;
@@ -280,13 +269,6 @@ void WindowGrid::Shutdown() {
         std::move(observer));
     shield_widget->SetOpacity(0.f);
   }
-
-  if (IsNewOverviewUi() &&
-      Shell::Get()->wallpaper_controller()->IsBlurEnabled()) {
-    RootWindowController::ForWindow(root_window_)
-        ->wallpaper_widget_controller()
-        ->SetWallpaperBlur(kWallpaperClearBlurSigma);
-  }
 }
 
 void WindowGrid::PrepareForOverview() {

ash/wm/overview/window_selector.cc

@@ -651,6 +651,35 @@ bool WindowSelector::IsShuttingDown() const {
   return Shell::Get()->window_selector_controller()->is_shutting_down();
 }
 
+bool WindowSelector::ShouldAnimateWallpaper(aura::Window* root_window) {
+  // Find the grid associated with |root_window|.
+  WindowGrid* grid = nullptr;
+  for (const auto& window_grid : grid_list_) {
+    if (window_grid->root_window() == root_window) {
+      grid = window_grid.get();
+      break;
+    }
+  }
+
+  if (!grid)
+    return false;
+
+  // It is possible we leave overview mode to enter split view mode with both
+  // windows snapped. Do not animate the wallpaper in this case.
+  if (Shell::Get()->split_view_controller()->state() ==
+      SplitViewController::BOTH_SNAPPED) {
+    return false;
+  }
+
+  // If one of the windows covers the workspace, we do not need to animate.
+  for (const auto& selector_item : grid->window_list()) {
+    if (CanCoverAvailableWorkspace(selector_item->GetWindow()))
+      return false;
+  }
+
+  return true;
+}
+
 bool WindowSelector::HandleKeyEvent(views::Textfield* sender,
                                     const ui::KeyEvent& key_event) {
   // Do not do anything with the events if none of the window grids have windows

ash/wm/overview/window_selector.h

@@ -129,6 +129,11 @@ class ASH_EXPORT WindowSelector : public display::DisplayObserver,
   // If we are in middle of ending overview mode.
   bool IsShuttingDown() const;
 
+  // Checks if the grid associated with a given |root_window| needs to have the
+  // wallpaper animated. Returns false if one of the grids windows covers the
+  // the entire workspace, true otherwise.
+  bool ShouldAnimateWallpaper(aura::Window* root_window);
+
   WindowSelectorDelegate* delegate() { return delegate_; }
 
   bool restoring_minimized_windows() const {

ash/wm/overview/window_selector_controller.cc

@@ -7,8 +7,11 @@
 #include <vector>
 
 #include "ash/public/cpp/window_properties.h"
+#include "ash/root_window_controller.h"
 #include "ash/session/session_controller.h"
 #include "ash/shell.h"
+#include "ash/wallpaper/wallpaper_controller.h"
+#include "ash/wallpaper/wallpaper_widget_controller.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/overview_utils.h"
 #include "ash/wm/overview/window_grid.h"
@@ -21,12 +24,19 @@
 #include "ash/wm/window_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
+#include "ui/gfx/animation/animation_delegate.h"
+#include "ui/gfx/animation/slide_animation.h"
 #include "ui/wm/core/window_util.h"
 
 namespace ash {
 
 namespace {
 
+// Amount of blur to apply on the wallpaper when we enter or exit overview mode.
+constexpr double kWallpaperBlurSigma = 10.f;
+constexpr double kWallpaperClearBlurSigma = 0.f;
+constexpr int kBlurSlideDurationMs = 250;
+
 // Returns true if |window| should be hidden when entering overview.
 bool ShouldHideWindowInOverview(const aura::Window* window) {
   return !window->GetProperty(ash::kShowInOverviewKey);
@@ -55,11 +65,137 @@ bool ShouldExcludeWindowFromOverview(const aura::Window* window) {
   return false;
 }
 
+bool IsBlurEnabled() {
+  return IsNewOverviewUi() &&
+         Shell::Get()->wallpaper_controller()->IsBlurEnabled();
+}
+
 }  // namespace
 
-WindowSelectorController::WindowSelectorController() = default;
+// Class that handles of blurring wallpaper upon entering and exiting overview
+// mode. Blurs the wallpaper automatically if the wallpaper is not visible
+// prior to entering overview mode (covered by a window), otherwise animates
+// the blur.
+class WindowSelectorController::OverviewBlurController
+    : public gfx::AnimationDelegate,
+      public aura::WindowObserver {
+ public:
+  OverviewBlurController() : animation_(this) {
+    animation_.SetSlideDuration(kBlurSlideDurationMs);
+  }
+
+  ~OverviewBlurController() override {
+    animation_.Stop();
+    for (aura::Window* root : roots_to_animate_)
+      root->RemoveObserver(this);
+  }
+
+  void Blur() {
+    state_ = WallpaperAnimationState::kAddingBlur;
+    OnBlurChange();
+  }
+
+  void Unblur() {
+    state_ = WallpaperAnimationState::kRemovingBlur;
+    OnBlurChange();
+  }
+
+ private:
+  enum class WallpaperAnimationState {
+    kAddingBlur,
+    kRemovingBlur,
+    kNormal,
+  };
+
+  // gfx::AnimationDelegate:
+  void AnimationEnded(const gfx::Animation* animation) override {
+    if (state_ == WallpaperAnimationState::kNormal)
+      return;
+
+    double value = state_ == WallpaperAnimationState::kAddingBlur
+                       ? kWallpaperBlurSigma
+                       : kWallpaperClearBlurSigma;
+    for (aura::Window* root : roots_to_animate_)
+      ApplyBlur(root, value);
+    state_ = WallpaperAnimationState::kNormal;
+  }
+
+  void AnimationProgressed(const gfx::Animation* animation) override {
+    double value = animation_.CurrentValueBetween(kWallpaperClearBlurSigma,
+                                                  kWallpaperBlurSigma);
+    for (aura::Window* root : roots_to_animate_)
+      ApplyBlur(root, value);
+  }
+
+  void AnimationCanceled(const gfx::Animation* animation) override {
+    for (aura::Window* root : roots_to_animate_)
+      ApplyBlur(root, kWallpaperClearBlurSigma);
+    state_ = WallpaperAnimationState::kNormal;
+  }
+
+  // aura::WindowObserver:
+  void OnWindowDestroying(aura::Window* window) override {
+    window->RemoveObserver(this);
+    auto it =
+        std::find(roots_to_animate_.begin(), roots_to_animate_.end(), window);
+    if (it != roots_to_animate_.end())
+      roots_to_animate_.erase(it);
+  }
+
+  void ApplyBlur(aura::Window* root, float blur_sigma) {
+    RootWindowController::ForWindow(root)
+        ->wallpaper_widget_controller()
+        ->SetWallpaperBlur(static_cast<float>(blur_sigma));
+  }
+
+  // Called when the wallpaper is to be changed. Checks to see which root
+  // windows should have their wallpaper blurs animated and fills
+  // |roots_to_animate_| accordingly. Applys blur or unblur immediately if
+  // the wallpaper does not need blur animation.
+  void OnBlurChange() {
+    bool should_blur = state_ == WallpaperAnimationState::kAddingBlur;
+    double value = should_blur ? kWallpaperBlurSigma : kWallpaperClearBlurSigma;
+    for (aura::Window* root : roots_to_animate_)
+      root->RemoveObserver(this);
+    roots_to_animate_.clear();
+
+    WindowSelector* window_selector =
+        Shell::Get()->window_selector_controller()->window_selector();
+    DCHECK(window_selector);
+    for (aura::Window* root : Shell::Get()->GetAllRootWindows()) {
+      if (!window_selector->ShouldAnimateWallpaper(root)) {
+        ApplyBlur(root, value);
+      } else {
+        root->AddObserver(this);
+        roots_to_animate_.push_back(root);
+      }
+    }
+
+    // Run the animation if one of the roots needs to be aniamted.
+    if (roots_to_animate_.empty()) {
+      state_ = WallpaperAnimationState::kNormal;
+    } else if (should_blur) {
+      animation_.Show();
+    } else {
+      animation_.Hide();
+    }
+  }
+
+  WallpaperAnimationState state_ = WallpaperAnimationState::kNormal;
+  gfx::SlideAnimation animation_;
+  // Vector which contains the root windows, if any, whose wallpaper should have
+  // blur animated after Blur or Unblur is called.
+  std::vector<aura::Window*> roots_to_animate_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverviewBlurController);
+};
+
+WindowSelectorController::WindowSelectorController()
+    : overview_blur_controller_(std::make_unique<OverviewBlurController>()) {}
 
 WindowSelectorController::~WindowSelectorController() {
+  overview_blur_controller_.reset();
+
   // Destroy widgets that may be still animating if shell shuts down soon after
   // exiting overview mode.
   for (std::unique_ptr<DelayedAnimationObserver>& animation_observer :
@@ -117,6 +253,8 @@ bool WindowSelectorController::ToggleOverview() {
     window_selector_.reset(new WindowSelector(this));
     Shell::Get()->NotifyOverviewModeStarting();
     window_selector_->Init(windows, hide_windows);
+    if (IsBlurEnabled())
+      overview_blur_controller_->Blur();
     OnSelectionStarted();
   }
   return true;
@@ -269,6 +407,9 @@ WindowSelectorController::GetWindowsListInOverviewGridsForTesting() {
 void WindowSelectorController::OnSelectionEnded() {
   if (is_shutting_down_)
     return;
+
+  if (IsBlurEnabled())
+    overview_blur_controller_->Unblur();
   is_shutting_down_ = true;
   Shell::Get()->NotifyOverviewModeEnding();
   window_selector_->Shutdown();

ash/wm/overview/window_selector_controller.h

@@ -70,6 +70,7 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
   WindowSelector* window_selector() { return window_selector_.get(); }
 
  private:
+  class OverviewBlurController;
   friend class WindowSelectorTest;
 
   // Dispatched when window selection begins.
@@ -86,6 +87,10 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
   // If we are in middle of ending overview mode.
   bool is_shutting_down_ = false;
 
+  // Handles blurring of the wallpaper when entering or exiting overview mode.
+  // Animates the blurring if necessary.
+  std::unique_ptr<OverviewBlurController> overview_blur_controller_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowSelectorController);
 };