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2.3.4.1 Part Kind and Part Category

   Different parts in a document hold data of a different purpose and 
   different format, understandable to different part editors.  OpenDoc must 
   be able to associate a part editor only with data that the editor can 
   properly manipulate, in order to avoid file corruption and to have 
   meaningful drawing and editing.  Therefore these two part properties, part 
   kind and part category, have to be assigned for each part. 


    Part kind OpenDoc uses the concept of part kind, a typing scheme similar 
             to file type, to determine which part editor is to be associated 
             with a given part in a document.  A part kind refers to the data 
             format of a part's contents. 

   Part category A component category refers to a set of part kinds.  A 
             category describes the type of data contained in a part, such as 
             styled text.  For example, the category styled text includes the 
             kinds. 

   The list of categories is maintained by CI Labs, a consortium that 
   coordinates cross-platform OpenDoc development; Styled Text and Video are 
   two examples of part categories.  If SurfWriter is a MacWrite-like text 
   editor, its part kind might be SurfWriter Text and would be in the styled 
   text category.  The SurfWriter editor would most likely allow translation 
   from other part kinds in the same category. 

   View type Your part editor needs to assign the default view type for its 
   embedded parts, which determines how each part is initially displayed, as 
   an icon or in a frame. 

   °   The icon for a part can be not only the standard 32-by-32 and 16-by-16 
       pixel sizes, but also a thumbnail icon (64-by-64 pixels).  The 
       thumbnail shows a miniature representation (a poster page) of the 
       part's contents to help users identify the part. 

   °   A part can be displayed with its contents in a bounded area called a 
       frame (see "Frames and Facets" in topic 2.3.2.1), which allows editing 
       in place (rather than requiring the part to be opened into a separate 
       window).  Frames are usually, but not necessarily, rectangular.  A 
       part's content may be displayed in more than one frame at a time and 
       may have multiple representations; for example, a tabular part may be 
       seen as a chart in one frame and as a text table in another. 


   In the finder, documents are displayed only as 32-by-32 or 16-by-16 pixel 
   icons in the initial OpenDoc release; eventually thumbnail icons and 
   frames will also be supported at the finder level. 


 


                                              



 
   Figure 14. Frame View for Parts Layout Editing 

   Users can change the view type with the Part Info command in the Edit menu 
   (and possibly with accelerator commands, such as View as Icon, that are 
   provided by the part editor).  In Figure 14, frame view is desirable 
   because it allows the user to see the graphic laid out in the document and 
   to edit it in place.  An icon view might be preferable for, say, a 
   spreadsheet part that gives supporting data on a subject covered broadly 
   in the text.  Any frame may be reduced to an icon at any time, or any icon 
   opened into a frame, without affecting the view type of any other part; 
   however, the containing part may reflow content when an embedded part's 
   view type is changed. 

   Except that a part may be edited only when its content is viewed in a 
   frame, icons and frames are functionally equivalent.  Operations such as 
   drag and drop that may be applied to one may be applied to the other. 
   Whether viewed as icons or in frames, embedded parts can be opened into 
   separate windows if desired (although they're still embedded parts and not 
   documents). 

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