base_screen.h revision 116680a4aac90f2aa7413d9095a592090648e557 
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
12namespace base {
13class DictionaryValue;
14}
15
16namespace chromeos {
17
18class 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.
27class 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