components/webui_generator/view_model.h

   1 // Copyright 2015 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_UI_WEBUI_WUG_VIEW_MODEL_H_
   6 #define CHROME_BROWSER_UI_WEBUI_WUG_VIEW_MODEL_H_
   7
   8 #include <vector>
   9
  10 #include "base/macros.h"
  11 #include "components/login/screens/screen_context.h"
  12 #include "components/webui_generator/export.h"
  13
  14 namespace base {
  15 class DictionaryValue;
  16 }
  17
  18 namespace webui_generator {
  19
  20 using Context = login::ScreenContext;
  21 class View;
  22
  23 // Base class for view-model. Usually View is responsible for creating and
  24 // initializing instances of this class.
  25 class WUG_EXPORT ViewModel {
  26  public:
  27   ViewModel();
  28   virtual ~ViewModel();
  29
  30   void SetView(View* view);
  31
  32   // Called by view to notify that children are ready.
  33   void OnChildrenReady();
  34
  35   // Called by view when it became bound (meaning that all changes in context
  36   // will be reflected in view right after they are made).
  37   virtual void OnViewBound() = 0;
  38
  39   // Notifies view-model about context changes happended on view side.
  40   // View-model corrects its copy of context according to changes in |diff|.
  41   void UpdateContext(const base::DictionaryValue& diff);
  42
  43   // Notifies view-model about |event| sent from view.
  44   virtual void OnEvent(const std::string& event);
  45
  46  protected:
  47   // Scoped context editor, which automatically commits all pending
  48   // context changes on destruction.
  49   class ContextEditor {
  50    public:
  51     using KeyType = ::login::ScreenContext::KeyType;
  52     using String16List = ::login::String16List;
  53     using StringList = ::login::StringList;
  54
  55     explicit ContextEditor(ViewModel& screen);
  56     ~ContextEditor();
  57
  58     const ContextEditor& SetBoolean(const KeyType& key, bool value) const;
  59     const ContextEditor& SetInteger(const KeyType& key, int value) const;
  60     const ContextEditor& SetDouble(const KeyType& key, double value) const;
  61     const ContextEditor& SetString(const KeyType& key,
  62                                    const std::string& value) const;
  63     const ContextEditor& SetString(const KeyType& key,
  64                                    const base::string16& value) const;
  65     const ContextEditor& SetStringList(const KeyType& key,
  66                                        const StringList& value) const;
  67     const ContextEditor& SetString16List(const KeyType& key,
  68                                          const String16List& value) const;
  69
  70    private:
  71     ViewModel& view_model_;
  72     Context& context_;
  73   };
  74
  75   // This method is called in a time appropriate for initialization. At this
  76   // point it is allowed to make changes in the context, but it is not allowed
  77   // to access child view-models.
  78   virtual void Initialize() = 0;
  79
  80   // This method is called when all children are ready.
  81   virtual void OnAfterChildrenReady() = 0;
  82
  83   // This method is called after context was changed on view side.
  84   // |chanaged_keys| contains a list of keys of changed fields.
  85   virtual void OnContextChanged(const std::vector<std::string>& changed_keys) {}
  86
  87   Context& context() { return context_; }
  88   const Context& context() const { return context_; }
  89
  90   View* view() const { return view_; }
  91
  92   // Returns scoped context editor. The editor or it's copies should not outlive
  93   // current BaseScreen instance.
  94   ContextEditor GetContextEditor();
  95
  96   // Notifies view about changes made in context.
  97   void CommitContextChanges();
  98
  99  private:
 100   Context context_;
 101   View* view_;
 102
 103   DISALLOW_COPY_AND_ASSIGN(ViewModel);
 104 };
 105
 106 }  // namespace webui_generator
 107
 108 #endif  // CHROME_BROWSER_UI_WEBUI_WUG_VIEW_MODEL_H_