Extract colors from wallpaper and dynamically update login screen overlay

chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.cc

 // Copyright 2014 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 "chrome/browser/chromeos/login/users/wallpaper/wallpaper_manager.h"
 
 #include <utility>
 
 #include "ash/ash_constants.h"
 #include "ash/public/cpp/shelf_types.h"
@@ skipping 186 matching lines @@
 void SetKnownUserWallpaperFilesId(
     const AccountId& account_id,
     const wallpaper::WallpaperFilesId& wallpaper_files_id) {
   user_manager::known_user::SetStringPref(account_id, kWallpaperFilesId,
                                           wallpaper_files_id.id());
 }
 
 // A helper to set the wallpaper image for Classic Ash and Mash.
 void SetWallpaper(const gfx::ImageSkia& image,
                   wallpaper::WallpaperLayout layout) {
+  WallpaperManager::Get()->CalculateProminentColor(image);
   if (ash_util::IsRunningInMash()) {
     // In mash, connect to the WallpaperController interface via mojo.
     service_manager::Connector* connector =
         content::ServiceManagerConnection::GetForProcess()->GetConnector();
     if (!connector)
       return;
 
     ash::mojom::WallpaperControllerPtr wallpaper_controller;
     connector->BindInterface(ash::mojom::kServiceName, &wallpaper_controller);
     // TODO(crbug.com/655875): Optimize ash wallpaper transport; avoid sending
@@ skipping 171 matching lines @@
   base::Time started_load_at_;
 
   DISALLOW_COPY_AND_ASSIGN(PendingWallpaper);
 };
 
 // WallpaperManager, public: ---------------------------------------------------
 
 WallpaperManager::~WallpaperManager() {
   show_user_name_on_signin_subscription_.reset();
   device_wallpaper_image_subscription_.reset();
   user_manager::UserManager::Get()->RemoveSessionStateObserver(this);

[xdai1, 2017/06/14 18:23:40]

Please also remove itself as an observer of WallpaperColorCalculator in
Wallpaper destructor

[Wenzhao (Colin) Zang, 2017/06/15 18:14:40]

Done.

   weak_factory_.InvalidateWeakPtrs();
 }
 
 // static
 void WallpaperManager::Initialize() {
   CHECK(!wallpaper_manager);
   wallpaper_manager = new WallpaperManager();
 }
 
 // static
@@ skipping 11 matching lines @@
 
 bool WallpaperManager::IsPendingWallpaper(uint32_t image_id) {
   for (size_t i = 0; i < loading_.size(); ++i) {
     if (loading_[i]->GetImageId() == image_id) {
       return true;
     }
   }
   return false;
 }
 
+void WallpaperManager::CalculateProminentColor(const gfx::ImageSkia& image) {
+  // Cancel in-flight color calculations, if any.
+  if (color_calculator_) {
+    color_calculator_->RemoveObserver(this);
+    color_calculator_.reset();
+  }
+
+  color_calculator_ = base::MakeUnique<wallpaper::WallpaperColorCalculator>(
+      image, color_utils::LumaRange::DARK, color_utils::SaturationRange::MUTED,
+      task_runner_);
+  color_calculator_->AddObserver(this);
+  if (!color_calculator_->StartCalculation()) {
+    if (!prominent_color_.has_value())
+      return;
+    prominent_color_.reset();
+    for (auto& observer : observers_)
+      observer.OnWallpaperColorsChanged();
+  }
+}
+
 WallpaperManager::WallpaperResolution
 WallpaperManager::GetAppropriateResolution() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   gfx::Size size = ash::WallpaperController::GetMaxDisplaySizeInNative();
   return (size.width() > wallpaper::kSmallWallpaperMaxWidth ||
           size.height() > wallpaper::kSmallWallpaperMaxHeight)
              ? WALLPAPER_RESOLUTION_LARGE
              : WALLPAPER_RESOLUTION_SMALL;
 }
 
@@ skipping 464 matching lines @@
     window_observer_.Add(gained_active);
   }
 }
 
 void WallpaperManager::OnWindowDestroying(aura::Window* window) {
   window_observer_.Remove(window);
   chromeos::WallpaperWindowStateManager::RestoreWindows(
       user_manager::UserManager::Get()->GetActiveUser()->username_hash());
 }
 
+void WallpaperManager::OnColorCalculationComplete() {
+  SkColor color = color_calculator_->prominent_color();
+  color_calculator_.reset();
+  if (prominent_color_ == color)
+    return;
+  prominent_color_ = color;
+
+  for (auto& observer : observers_)
+    observer.OnWallpaperColorsChanged();
+}
+
 // WallpaperManager, private: --------------------------------------------------
 
 WallpaperManager::WallpaperManager()
     : binding_(this),
       pending_inactive_(nullptr),
       activation_client_observer_(this),
       window_observer_(this),
       weak_factory_(this) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   wallpaper::WallpaperManagerBase::SetPathIds(
@@ skipping 521 matching lines @@
 
   UMA_HISTOGRAM_ENUMERATION(
       "Ash.Wallpaper.Apps",
       wallpaper_manager_util::ShouldUseAndroidWallpapersApp(profile)
           ? WALLPAPERS_APP_ANDROID
           : WALLPAPERS_PICKER_APP_CHROMEOS,
       WALLPAPERS_APPS_NUM);
 }
 
 }  // namespace chromeos