components/renderer_context_menu/render_view_context_menu_observer.h

   1 // Copyright 2014 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 COMPONENTS_RENDERER_CONTEXT_MENU_RENDER_VIEW_CONTEXT_MENU_OBSERVER_H_
   6 #define COMPONENTS_RENDERER_CONTEXT_MENU_RENDER_VIEW_CONTEXT_MENU_OBSERVER_H_
   7
   8 namespace content {
   9 struct ContextMenuParams;
  10 }
  11
  12 // The interface used for implementing context-menu items. The following
  13 // instruction describe how to implement a context-menu item with this
  14 // interface.
  15 //
  16 // 1. Add command IDs for the context-menu items to 'chrome_command_ids.h'.
  17 //
  18 //   #define IDC_MY_COMMAND 99999
  19 //
  20 // 2. Add strings for the context-menu items to 'generated_sources.grd'.
  21 //
  22 //   <message name="IDS_MY_COMMAND" desc="...">
  23 //     My command
  24 //   </message>
  25 //
  26 // 3. Create a class that implements this interface. (It is a good idea to use
  27 // the RenderViewContextMenuProxy interface to avoid accessing the
  28 // RenderViewContextMenu class directly.)
  29 //
  30 //  class MyMenuObserver : public RenderViewContextMenuObserver {
  31 //   public:
  32 //    MyMenuObserver(RenderViewContextMenuProxy* p);
  33 //    ~MyMenuObserver();
  34 //
  35 //    virtual void InitMenu(const content::ContextMenuParams& params) override;
  36 //    virtual bool IsCommandIdSupported(int command_id) override;
  37 //    virtual bool IsCommandIdEnabled(int command_id) override;
  38 //    virtual void ExecuteCommand(int command_id) override;
  39 //
  40 //   private:
  41 //    RenderViewContextMenuProxy* proxy_;
  42 //  }
  43 //
  44 //  void MyMenuObserver::InitMenu(const content::ContextMenuParams& params) {
  45 //    proxy_->AddMenuItem(IDC_MY_COMMAND,...);
  46 //  }
  47 //
  48 //  bool MyMenuObserver::IsCommandIdSupported(int command_id) {
  49 //    return command_id == IDC_MY_COMMAND;
  50 //  }
  51 //
  52 //  bool MyMenuObserver::IsCommandIdEnabled(int command_id) {
  53 //    DCHECK(command_id == IDC_MY_COMMAND);
  54 //    return true;
  55 //  }
  56 //
  57 //  void MyMenuObserver::ExecuteCommand(int command_id) {
  58 //    DCHECK(command_id == IDC_MY_COMMAND);
  59 //  }
  60 //
  61 // 4. Add this observer class to the RenderViewContextMenu class. (It is good
  62 // to use scoped_ptr<> so Chrome can create its instances only when it needs.)
  63 //
  64 //  class RenderViewContextMenu {
  65 //    ...
  66 //   private:
  67 //    scoped_ptr<MyMenuObserver> my_menu_observer_;
  68 //  };
  69 //
  70 // 5. Create its instance in InitMenu() and add it to the observer list of the
  71 // RenderViewContextMenu class.
  72 //
  73 //  void RenderViewContextMenu::InitMenu() {
  74 //    ...
  75 //    my_menu_observer_.reset(new MyMenuObserver(this));
  76 //    observers_.AddObserver(my_menu_observer_.get());
  77 //  }
  78 //
  79 //
  80 class RenderViewContextMenuObserver {
  81  public:
  82   virtual ~RenderViewContextMenuObserver() {}
  83
  84   // Called when the RenderViewContextMenu class initializes a context menu. We
  85   // usually call RenderViewContextMenuProxy::AddMenuItem() to add menu items
  86   // in this function.
  87   virtual void InitMenu(const content::ContextMenuParams& params) {}
  88
  89   // Called when the RenderViewContextMenu class asks whether an observer
  90   // listens for the specified command ID. If this function returns true, the
  91   // RenderViewContextMenu class calls IsCommandIdEnabled() or ExecuteCommand().
  92   virtual bool IsCommandIdSupported(int command_id);
  93
  94   // Called when the RenderViewContextMenu class sets the initial status of the
  95   // specified context-menu item. If we need to enable or disable a context-menu
  96   // item while showing, use RenderViewContextMenuProxy::UpdateMenuItem().
  97   virtual bool IsCommandIdChecked(int command_id);
  98   virtual bool IsCommandIdEnabled(int command_id);
  99
 100   // Called when a user selects the specified context-menu item.
 101   virtual void ExecuteCommand(int command_id) {}
 102
 103   // Called when a user closes the context menu without selecting any items.
 104   virtual void OnMenuCancel() {}
 105 };
 106
 107 #endif  // COMPONENTS_RENDERER_CONTEXT_MENU_RENDER_VIEW_CONTEXT_MENU_OBSERVER_H_