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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
      6 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
      7 
      8 #include <string>
      9 
     10 #include "base/basictypes.h"
     11 
     12 namespace base {
     13 class DictionaryValue;
     14 }
     15 
     16 namespace chromeos {
     17 
     18 class ScreenContext;
     19 
     20 // Base class for the all OOBE/login/before-session screens.
     21 // Screens are identified by ID, screen and it's JS counterpart must have same
     22 // id.
     23 // Most of the screens will be re-created for each appearance with Initialize()
     24 // method called just once. However if initialization is too expensive, screen
     25 // can override result of IsPermanent() method, and do clean-up upon subsequent
     26 // Initialize() method calls.
     27 class BaseScreen {
     28  public:
     29   BaseScreen();
     30   virtual ~BaseScreen();
     31 
     32   // ---- Old implementation ----
     33 
     34   virtual void PrepareToShow() = 0;
     35 
     36   // Makes wizard screen visible.
     37   virtual void Show() = 0;
     38 
     39   // Makes wizard screen invisible.
     40   virtual void Hide() = 0;
     41 
     42   // Returns the screen name.
     43   virtual std::string GetName() const = 0;
     44 
     45   // ---- New Implementation ----
     46 
     47   // Called to perform initialization of the screen. UI is guaranteed to exist
     48   // at this point. Screen can alter context, resulting context will be passed
     49   // to JS. This method will be called once per instance of the Screen object,
     50   // unless |IsPermanent()| returns |true|.
     51   virtual void Initialize(ScreenContext* context);
     52 
     53   // Called when screen appears.
     54   virtual void OnShow();
     55   // Called when screen disappears, either because it finished it's work, or
     56   // because some other screen pops up.
     57   virtual void OnHide();
     58 
     59   // Called when we navigate from screen so that we will never return to it.
     60   // This is a last chance to call JS counterpart, this object will be deleted
     61   // soon.
     62   virtual void OnClose();
     63 
     64   // Indicates whether status area should be displayed while this screen is
     65   // displayed.
     66   virtual bool IsStatusAreaDisplayed();
     67 
     68   // If this method returns |true|, screen will not be deleted once we leave it.
     69   // However, Initialize() might be called several times in this case.
     70   virtual bool IsPermanent();
     71 
     72   // Returns the identifier of the screen.
     73   virtual std::string GetID() const;
     74 
     75  protected:
     76   // Screen can call this method to notify framework that it have finished
     77   // it's work with |outcome|.
     78   void Finish(const std::string& outcome);
     79 
     80   // Called when button with |button_id| was pressed. Notification
     81   // about this event comes from the JS counterpart.
     82   virtual void OnButtonPressed(const std::string& button_id);
     83 
     84   // Called when context for the currenct screen was
     85   // changed. Notification about this event comes from the JS
     86   // counterpart.
     87   virtual void OnContextChanged(const base::DictionaryValue* diff);
     88 
     89  private:
     90   friend class ScreenManager;
     91   void SetContext(ScreenContext* context);
     92 
     93   DISALLOW_COPY_AND_ASSIGN(BaseScreen);
     94 };
     95 
     96 }  // namespace chromeos
     97 
     98 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
     99