Inside Macintosh: Cyberdog Programmer's Kit / Part 2 - Programming in Cyberdog

Chapter 3 - Adding Cyberdog Features to an OpenDoc Part

Modifying Your Part's Class Definition

To add Cyberdog features to your OpenDoc part class, you need to modify several methods and define new methods and fields. The button part example assumes that you are modifying the SamplePart class. This example shows only the steps necessary to modify the class to support Cyberdog items, the Cyberdog menus, and the Cyberdog Preferences command. Listing 3-1 shows the definitions of the methods and fields that you must either add or modify.

Listing 3-1 The CybTxtBtn class definition

class CybTxtBtn {
public:
   // Modified to initialize Cyberdog-related fields
   CybTxtBtn();
   virtual ~CybTxtBtn();
   
   // Modified to create a Cyberdog item
   void        InitPart(Environment* ev, ODStorageUnit* storageUnit,
                      ODPart* partWrapper);

   // Modified to allow drag and drop of Cyberdog items or text
   ODDragResultDragEnter(Environment* ev, 
                      ODDragItemIterator* dragInfo, 
                      ODFacet* facet, ODPoint* where);
   ODDropResultDrop  (Environment* ev, 
                      ODDragItemIterator* dragInfo, 
                      ODFacet* facet, ODPoint* where);

   // Modified to remove the Cyberdog service menu object
   void  ReleaseAll(Environment* ev);

   // Added to handle menus
   void CreateMenus(Environment* ev);
   void CheckMenus(Environment *ev, ODFrame* frame);
   ...
protected:
   // Added to initialize Cyberdog
   void  Initialize(Environment* ev, ODStorageUnit* storageUnit);

   // Modified to handle reading and writing of Cyberdog items
   void  InternalizeContent( Environment* ev, 
                        ODStorageUnit* storageUnit);
   void  ExternalizeContent( Environment* ev, 
                        ODStorageUnit* storageUnit,
                        ODDraftKey key, ODFrame* scopeFrame);

   // Modified to open a Cyberdog item
   ODBooleanHandleMouseEvent(Environment* ev, ODEventData* event,
                         ODFacet* facet, ODEventInfo* eventInfo);

   // Modified to handle Cyberdog menus and the Preferences command
   ODBooleanHandleMenuEvent(Environment* ev, ODEventData* event,
                        ODFrame* frame);
   void  PartActivated(Environment* ev, ODFrame* frame);
   void  FocusLost(Environment* ev,ODTypeToken focus, 
                   ODFrame* ownerFrame);
   void  AdjustMenus (Environment* ev, ODFrame* frame);

   ...
private:
   // Added or modified to support Cyberdog
   CyberItem* fCyberItem;        // Reference to Cyberdog item
   CyberServiceMenu* fCyberServiceMenu;// Reference to the Cyberdog
                                 // service menu object
   ODMenuBar* fMenuBar;          // Reference to the menu bar
   ...
}

The constructor, destructor, and Initialize and ReleaseAll methods handle initialization and release or deletion of the Cyberdog objects used in this example. They are described in "Initializing and Releasing Cyberdog Objects" (page 94).

The InitPart method handles creating the initial Cyberdog item associated with the button part. The InternalizeContent and ExternalizeContent methods read and write Cyberdog items to and from a storage unit. They are described in "Reading and Writing Cyberdog Items" (page 98).

The DragEnter and Drop methods are responsible for handling drag and drop of text or Cyberdog items on the button part. They are described in "Supporting Drag and Drop of Cyberdog Items" (page 101). The HandleMouseEvent opens the Cyberdog item when the user clicks in the part. It is described in "Opening a Cyberdog Item" (page 100).

The CreateMenus, CheckMenus, HandleMenuEvent, PartActivated, FocusLost, and AdjustMenus methods handle manipulation of Cyberdog service menus. The HandleMenuEvent method also initiates the display of the "Cyberdog Preferences" dialog box. For information about setting up Cyberdog menus, see "Displaying Cyberdog Menus" (page 105). For information about implementing the Cyberdog Preferences command, see "Implementing the Cyberdog Preferences Command" (page 109).

The fCyberItem field holds a reference to the current Cyberdog item associated with the part. The fCyberServiceMenu field holds a reference to the Cyberdog service menu object. The fMenuBar field refers to the part's menu bar. Initially, these fields are set to kODNULL.