chrome/browser/chromeos/login/screens/base_screen.h

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