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IlvPathSteppingData Class Referenceabstract

Graphic path-related class. More...

#include <ilviews/graphics/path.h>

Inheritance diagram for IlvPathSteppingData:
IlvPathDrawingData

Public Member Functions

IlFloat getAngle () const
 Gets the angle of the current step. More...
 
IlUInt getCurPath () const
 Gets the current path. More...
 
const IlvPointgetCurPosition () const
 Gets the coordinates of a point on the current segment. More...
 
IlUInt getCurSegment () const
 Gets the current segment in the current path. More...
 
const IlvGraphicPathgetGraphicPath () const
 Gets the graphic path. More...
 
const IlvPointArraygetTransformedPaths () const
 Gets an array of transformed IlvPointArray. More...
 
const IlvTransformergetTransformer () const
 Gets the current transformer. More...
 
IlAny getUserArg () const
 Gets the user-defined value given to the constructor. More...
 
IlUInt getUserStep () const
 Gets the step used in stepping. More...
 
virtual void init (const IlvGraphicPath *gp, const IlvPointArray *transformed, const IlvTransformer *tr)
 Reinitializes the drawing data. More...
 
virtual void stepping ()
 Implements the algorithm to travel along the graphic path. More...
 

Protected Member Functions

 IlvPathSteppingData (IlUInt userStep, IlAny userArg)
 Constructor. More...
 
virtual IlBoolean acceptPath ()
 Protected Member Function. More...
 
virtual IlBoolean beginStepping ()
 Begins the travelling operation. More...
 
virtual IlBoolean doIt ()=0
 Protected Member Function. More...
 
virtual void endStepping ()
 Begins the travelling operation. More...
 

Detailed Description

Graphic path-related class.

Library: views

The IlvPathSteppingData class is an abstract class. Instances of this class are intended to be associated with an IlvGraphicPath object. Its main purpose is to travel the collection of polypoints, considered for this purpose as polylines, and to call its member function doIt periodically. How often doIt is called depends on the step of the IlvPathSteppingData.

The step is not time-based but must be considered as a distance along the path.

See also
IlvGraphicPath, IlvPathDrawingData.

Constructor & Destructor Documentation

§ IlvPathSteppingData()

IlvPathSteppingData::IlvPathSteppingData ( IlUInt  userStep,
IlAny  userArg 
)
protected

Constructor.

The constructor initializes a new IlvPathSteppingData object with a stepping distance of userStep and a user parameter of userArg.

Parameters
userStepThe stepping distance.
userArgThe user parameter.

Member Function Documentation

§ acceptPath()

virtual IlBoolean IlvPathSteppingData::acceptPath ( )
protectedvirtual

Protected Member Function.

Called by stepping before processing a new point array. If it returns IlFalse, this point array is ignored and stepping proceeds with the next one. The default implementation does nothing and returns IlTrue. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

§ beginStepping()

virtual IlBoolean IlvPathSteppingData::beginStepping ( )
protectedvirtual

Begins the travelling operation.

Called by stepping before anything else. If it returns IlFalse, stepping returns immediately without calling endStepping. The default implementation does nothing and returns IlTrue. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

§ doIt()

virtual IlBoolean IlvPathSteppingData::doIt ( )
protectedpure virtual

Protected Member Function.

Called at each step by stepping. If it returns IlFalse, stepping returns immediately without calling endStepping. This method is called by the method stepping and is meant to be redefined in subclasses.

Implemented in IlvPathDrawingData.

§ endStepping()

virtual void IlvPathSteppingData::endStepping ( )
protectedvirtual

Begins the travelling operation.

Called at each step by stepping. The default implementation does nothing. This method is called by the method stepping and is meant to be redefined in subclasses.

§ getAngle()

IlFloat IlvPathSteppingData::getAngle ( ) const

Gets the angle of the current step.

Holds the angle of the current step relative to a horizontal line. This value is not always equal to the angle of the current polyline segment. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

§ getCurPath()

IlUInt IlvPathSteppingData::getCurPath ( ) const

Gets the current path.

Holds the index of the current IlvPointArray.

§ getCurPosition()

const IlvPoint* IlvPathSteppingData::getCurPosition ( ) const

Gets the coordinates of a point on the current segment.

Holds the actual coordinates of a point on the current segment. This point is the origin of the current step.

§ getCurSegment()

IlUInt IlvPathSteppingData::getCurSegment ( ) const

Gets the current segment in the current path.

Holds the index of the current segment in the current path, that is, the index of the last IlvPoint crossed in the current IlvPointArray indicated by _curPath.

§ getGraphicPath()

const IlvGraphicPath* IlvPathSteppingData::getGraphicPath ( ) const

Gets the graphic path.

Returns the graphic path. This is set each time init is called.

Returns
The graphic path.

§ getTransformedPaths()

const IlvPointArray* IlvPathSteppingData::getTransformedPaths ( ) const

Gets an array of transformed IlvPointArray.

Returns an array of transformed IlvPointArray. The member function stepping uses this array instead of the points contained in the IlvGraphicPath (these two data items may be identical if the transformer returned by getTransformer is 0).

Returns
An array of transformed IlvPointArray.

§ getTransformer()

const IlvTransformer* IlvPathSteppingData::getTransformer ( ) const

Gets the current transformer.

Returns
The current transformer.

§ getUserArg()

IlAny IlvPathSteppingData::getUserArg ( ) const

Gets the user-defined value given to the constructor.

Returns the user-defined value given to the constructor.

Returns
The user-defined value given to the constructor.

§ getUserStep()

IlUInt IlvPathSteppingData::getUserStep ( ) const

Gets the step used in stepping.

Returns the step used in stepping.

Returns
The step used in stepping.

§ init()

virtual void IlvPathSteppingData::init ( const IlvGraphicPath gp,
const IlvPointArray transformed,
const IlvTransformer tr 
)
virtual

Reinitializes the drawing data.

Reinitializes the drawing data between subsequent calls to stepping. transformed is an array of IlvPointArray. It contains the points of the IlvGraphicPath, and the transformer tr has been applied to each of them. stepping uses this data instead of the original points of gp. If tr is 0, transformed may be equal to the internal array of the graphic path, that is, gp->getPaths().

Parameters
gpThe graphic path.
transformedThe array of transformed IlvPointArray.
trThe transformer to be applied to gp.

§ stepping()

virtual void IlvPathSteppingData::stepping ( )
virtual

Implements the algorithm to travel along the graphic path.

Implements the algorithm to travel along the graphic path and calls doIt every time a distance equal to the step is travelled. In other words, stepping approximates each polypoint of the IlvGraphicPath by a polyline whose segments all have the same length, step. For each one of these segments, stepping calls doIt.

stepping calls several virtual methods to allow subclasses to perform specific actions without rewriting the entire stepping algorithm.

  • Before doing anything else, stepping calls beginStepping. If it returns IlFalse, the method returns immediately (without calling endStepping).
  • The algorithm basically consists of two nested loops, the first one on the point arrays polyline and the second one on the points of a point array. Before starting a new point array, stepping calls acceptPath: if the return value is IlFalse, the point array is ignored and the next one is picked.
  • doIt is called at each step, as described above. If it returns IlFalse, stepping returns immediately (without calling endStepping).
  • When all the polypoints have been processed, endStepping is called.

This method is responsible for updating most of the protected fields returned by the following get methods.


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