#include <IBaseVisitor.h>

Inheritance diagram for IBaseVisitor:

Public Member Functions
virtual bool16	InitVisitor (IDataBase theDB, IBaseHandler theHandler, bool16 bFinishChildren=kFalse)=0

virtual IBaseHandler *	GetHandler (void) const =0

virtual bool16	GetFinishChildren (void) const =0

virtual bool16	VisitChildren (IVisitorHelper *pVisitable)=0

virtual bool16	VisitSpread (IVisitorHelper *pVisitable)=0

virtual bool16	VisitSpreadLayer (IVisitorHelper *pVisitable)=0

virtual bool16	VisitInlineItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitSplineItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitMultiColumnFrameItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitFrameItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitGroupItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitGuideItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitPage (IVisitorHelper *pVisitable)=0

virtual bool16	VisitImageItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitHTMLItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitEPSTextItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitEPSItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitPICTItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitWMFItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitPDFItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitTOPItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitOwnedItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitWaxAnchoredElementItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitParcelItem (IVisitorHelper *pVisitable)=0

virtual bool16	VisitUnknownItem (IVisitorHelper *pVisitable)=0

Public Member Functions inherited from IPMUnknown
virtual IPMUnknown *	QueryInterface (PMIID interfaceID) const =0

virtual void	AddRef () const =0

virtual void	Release () const =0

Detailed Description

An interface class used in conjunction with IBaseHandler and IVisitorHelper, IBaseVisitor

accomplishes a traversal (or visitation) of an arbitrary structure of connected

nodes -- typically (but not limited to) pageitems on a spread. As the visitor traverses the

structure, it uses each node's IVisitorHelper::Accept() routine to invoke the appropriate method

in the IBaseHandler to accomplish whatever task is required. A depth-first traversal of the node

structure is performed in the visitation scheme.

Using a separate handler is an extension of the visitor design pattern presented

in Gamma, et al, and allows the visitor scheme to be problem-independent. That is, a generic

visitor scheme for traversal can be married with any number of handler bosses, each doing a

specific task or solving a particular problem during the traversal. An example of the use

of the visitor/handler scheme in InDesign is hit-testing.

NOTE: Third-party-created pageitems that are not derived from built-in InDesign page item bosses must contain

an IVisitorHelper interface on the page item boss in order for hit-testing to be supported for the item.

Also, since VisitXXX routines aren't defined for these pageitems in IBaseVisitor,

these should be provided by custom implementations that are added-in to the kBaseVisitorBoss.

InDesign's visitor capability can be extended to support new types of nodes by creating an interface,

say IMyNodeVisitor, and adding it in to kBaseVisitorBoss. It would contain a VisitMyNode routine, as

follows:

<pre>

bool16 MyNodeVisitorImpl::VisitMyNode(IVisitorHelper* pVisitable)

{

bool16 bDone = kFalse;

Get the current handler by asking the base visitor InterfacePtr<IBaseVisitor> baseVisitor(this, UseDefaultIID()); if (baseVisitor) { InterfacePtr<IBaseHandler> theHandler(baseVisitor->GetHandler(), IID_IBASEHANDLER); if (theHandler) { Invoke the handler's HandleMyNode, which is added-in to the handler boss InterfacePtr<IMyNodeHandler> myHandler(theHandler, UseDefaultIID()); if (myHandler) bDone = myHandler->HandleMyNode(pVisitable, this); } } return bDone; }

A custom IMyNodeVisitor may implement an alternative child traversal scheme by providing its own version of VisitChildren. The built-in IBaseVisitor::VisitChildren() implementation is as follows:


    bool16 BaseVisitorImpl::VisitChildren(IVisitorHelper* pVisitable) 

    {

        bool16 bDone = kFalse;

fTheHandler and fFinishChildren were cached when InitVisitor was called

        if (pVisitable) 

        {

            int32 childCount = pVisitable->CollectChildren(fTheHandler);

            for (int32 i = childCount-1; i >= 0 && (fFinishChildren || !bDone); i--) 

            {

                InterfacePtr<IVisitorHelper> aChild(pVisitable->QueryChild(i));

                if (aChild) 

                {

                    bDone |= aChild->Accept(this);

                }

            }

        }

        return bDone;

    }

See Also: IBaseHandler; IVisitorHelper

Member Function Documentation

virtual bool16 IBaseVisitor::GetFinishChildren ( void ) const

pure virtual

Get the bFinishChildren flag

Returns: bool16 provided as bFinishChildren in InitVisitor

virtual IBaseHandler* IBaseVisitor::GetHandler ( void ) const

pure virtual

Get the handler used in this visitation

Returns: IBaseHandler pointer for handler provided in InitVisitor

virtual bool16 IBaseVisitor::InitVisitor	(	IDataBase *	theDB,
		IBaseHandler *	theHandler,
		bool16	bFinishChildren = `kFalse`
	)

pure virtual

Initialize the visitor with the database, the handler to use for acting on each node visited, and a flag dictating whether all children of a node should be visited if one returns kTrue.

Parameters

theDB	IN IDataBase pointer for database being traversed
theHandler	IN IBaseHandler pointer for handler to use for node actions
bFinishChildren	IN kFalse if VisitChildren should return immediately after a child returns kTrue from visitation, kTrue if all children should be visited regardless of return value

virtual bool16 IBaseVisitor::VisitChildren ( IVisitorHelper * pVisitable )

pure virtual

Visit the children of the node referenced by pVisitable. The base class implementation knows how to use IHierarchy to traverse nodes.

Parameters