Extract colors from wallpaper and dynamically update login screen overlay

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

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_USERS_WALLPAPER_WALLPAPER_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_USERS_WALLPAPER_WALLPAPER_MANAGER_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "ash/public/interfaces/wallpaper.mojom.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/weak_ptr.h"
 #include "base/scoped_observer.h"
 #include "chrome/browser/chromeos/customization/customization_wallpaper_downloader.h"
 #include "chrome/browser/chromeos/settings/cros_settings.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_image/user_image.h"
 #include "components/user_manager/user_manager.h"
+#include "components/wallpaper/wallpaper_color_calculator.h"
+#include "components/wallpaper/wallpaper_color_calculator_observer.h"
 #include "components/wallpaper/wallpaper_layout.h"
 #include "components/wallpaper/wallpaper_manager_base.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "ui/aura/window_observer.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/wm/public/activation_change_observer.h"
 #include "ui/wm/public/activation_client.h"
 
 namespace chromeos {
 
 class WallpaperManager
     : public wallpaper::WallpaperManagerBase,
       public ash::mojom::WallpaperPicker,
       public content::NotificationObserver,
       public user_manager::UserManager::UserSessionStateObserver,
       public wm::ActivationChangeObserver,
-      public aura::WindowObserver {
+      public aura::WindowObserver,
+      public wallpaper::WallpaperColorCalculatorObserver {
  public:
   class PendingWallpaper;
 
   ~WallpaperManager() override;
 
   // Creates an instance of Wallpaper Manager. If there is no instance, create
   // one. Otherwise, returns the existing instance.
   static void Initialize();
 
   // Gets pointer to singleton WallpaperManager instance.
   static WallpaperManager* Get();
 
   // Deletes the existing instance of WallpaperManager. Allows the
   // WallpaperManager to remove any observers it has registered.
   static void Shutdown();
 
   // Returns if the image is in the pending list. |image_id| can be obtained
   // from gfx::ImageSkia by using WallpaperResizer::GetImageId().
   bool IsPendingWallpaper(uint32_t image_id);
 
+  // Calculates a prominent color based on the wallpaper image and notifies
+  // |observers_| of the value. An existing calculation in progress (if any)
+  // will be destroyed first.
+  void CalculateProminentColor(const gfx::ImageSkia& image);
+
+  SkColor prominent_color() const { return prominent_color_; }
+
   // wallpaper::WallpaperManagerBase:
   WallpaperResolution GetAppropriateResolution() override;
   void AddObservers() override;
   void EnsureLoggedInUserWallpaperLoaded() override;
   void InitializeWallpaper() override;
   void RemoveUserWallpaperInfo(const AccountId& account_id) override;
   void OnPolicyFetched(const std::string& policy,
                        const AccountId& account_id,
                        std::unique_ptr<std::string> data) override;
   void SetCustomWallpaper(const AccountId& account_id,
@@ skipping 35 matching lines @@
   void UserChangedChildStatus(user_manager::User* user) override;
 
   // wm::ActivationChangeObserver:
   void OnWindowActivated(ActivationReason reason,
                          aura::Window* gained_active,
                          aura::Window* lost_active) override;
 
   // aura::WindowObserver:
   void OnWindowDestroying(aura::Window* window) override;
 
+  // wallpaper::WallpaperColorCalculatorObserver:
+  void OnColorCalculationComplete() override;
+
  private:
   friend class TestApi;
   friend class WallpaperManagerBrowserTest;
   friend class WallpaperManagerBrowserTestDefaultWallpaper;
   friend class WallpaperManagerPolicyTest;
 
   WallpaperManager();
 
   // Returns modifiable PendingWallpaper.
   // Returns pending_inactive_ or creates new PendingWallpaper if necessary.
@@ skipping 26 matching lines @@
   // device wallpaper policy setting.
   void OnCheckDeviceWallpaperMatchHash(const AccountId& account_id,
                                        const std::string& url,
                                        const std::string& hash,
                                        bool match);
   // This is called when the device wallpaper is decoded successfully.
   void OnDeviceWallpaperDecoded(
       const AccountId& account_id,
       std::unique_ptr<user_manager::UserImage> user_image);
 
+  // Sets |prominent_color_| and notifies the observers if there is a change.
+  void SetProminentColor(SkColor color);
+
   // wallpaper::WallpaperManagerBase:
   void InitializeRegisteredDeviceWallpaper() override;
   bool GetUserWallpaperInfo(const AccountId& account_id,
                             wallpaper::WallpaperInfo* info) const override;
   // Returns true if the device wallpaper should be set for the account.
   bool ShouldSetDeviceWallpaper(const AccountId& account_id,
                                 std::string* url,
                                 std::string* hash) override;
   base::FilePath GetDeviceWallpaperDir() override;
   base::FilePath GetDeviceWallpaperFilePath() override;
@@ skipping 59 matching lines @@
   // All pending will be finally deleted on destroy.
   typedef std::vector<scoped_refptr<PendingWallpaper>> PendingList;
   PendingList loading_;
 
   content::NotificationRegistrar registrar_;
 
   ScopedObserver<wm::ActivationClient, wm::ActivationChangeObserver>
       activation_client_observer_;
   ScopedObserver<aura::Window, aura::WindowObserver> window_observer_;
 
+  // The prominent color extracted from the current wallpaper.
+  // SK_ColorTRANSPARENT is used if color extraction fails.

[jdufault, 2017/06/12 21:37:28]

Use base::Optional<>. Try to avoid using magic values for failure state, better
to encode it into the type system.

[Wenzhao (Colin) Zang, 2017/06/12 23:40:34]

Done.

+  SkColor prominent_color_;
+
+  std::unique_ptr<wallpaper::WallpaperColorCalculator> color_calculator_;
+
   base::WeakPtrFactory<WallpaperManager> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(WallpaperManager);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USERS_WALLPAPER_WALLPAPER_MANAGER_H_