/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkSource.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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=========================================================================*/
// .NAME vtkSource - abstract class specifies interface for visualization network source
// .SECTION Description
// vtkSource is an abstract object that specifies behavior and interface
// of source objects. Source objects are objects that begin visualization
// pipeline. Sources include readers (read data from file or communications
// port) and procedural sources (generate data programmatically). vtkSource 
// objects are also objects that generate output data. In this sense
// vtkSource is used as a superclass to vtkFilter.
//
// Concrete subclasses of vtkSource must define Update() and Execute() 
// methods. The public method Update() invokes network execution and will
// bring the network up-to-date. The protected Execute() method actually
// does the work of data creation/generation. The difference between the two
// methods is that Update() implements input consistency checks and modified
// time comparisons and then invokes the Execute() which is an implementation 
// of a particular algorithm.
//
// An important feature of subclasses of vtkSource is that it is possible 
// to control the memory-management model (i.e., retain output versus delete
// output data). If enabled the ReleaseDataFlag enables the deletion of the
// output data once the downstream process object finishes processing the
// data (please see text).

// .SECTION See Also
// vtkProcessObject vtkDataSetReader vtkFilter vtkPolyDataSource 
// vtkStructuredGridSource vtkStructuredPointsSource vtkUnstructuredGridSource

#ifndef __vtkSource_h
#define __vtkSource_h

#include "vtkProcessObject.h"
#include "vtkDataObject.h"

class VTK_EXPORT vtkSource : public vtkProcessObject
{
public:
  static vtkSource *New();

  vtkTypeMacro(vtkSource,vtkProcessObject);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Bring object up-to-date before execution. Update() checks modified
  // time against last execution time, and re-executes object if necessary.
  virtual void Update();

  // Description:
  // Like update, but make sure the update extent is the whole extent in
  // the output.
  virtual void UpdateWholeExtent();

  // Description:
  // Updates any global information about the data 
  // (like spacing for images)
  virtual void UpdateInformation();

  // Description:
  virtual void PropagateUpdateExtent(vtkDataObject *output);

  // Description:
  virtual void TriggerAsynchronousUpdate();

  // Description:
  virtual void UpdateData(vtkDataObject *output);

  // Description:
  // Propagate the computation of the size of the pipeline. The first
  // size is the size of the pipeline after this source has finished
  // executing (and potentially freeing some input data). The second
  // size is the size of the specified output. The third size is the
  // maximum pipeline size encountered so far during this propagation.
  // All sizes are in kilobytes.
  void ComputeEstimatedPipelineMemorySize( vtkDataObject *output,
					   unsigned long size[3] );

  // Description:
  // The estimated size of the specified output after execution of
  // this source is stored in the first size entry. The second size
  // is the sum of all estimated output memory. The size of all inputs
  // is given to help this filter in the estimation.
  // All sizes are in kilobytes.
  virtual void ComputeEstimatedOutputMemorySize( vtkDataObject *output,
						 unsigned long *inputSize,
						 unsigned long size[2] );

  // Description:
  // Give the source a chance to say that it will produce more output
  // than it was asked to produce. For example, FFT always produces the
  // whole thing, and many imaging filters must produce the output in
  // whole slices (whole extent in two dimensions). By default we do not
  // modify the output update extent.
  virtual void EnlargeOutputUpdateExtents(vtkDataObject *vtkNotUsed(output)){};
  
  // Description:
  // What is the input update extent that is required to produce the
  // desired output? By default, the whole input is always required but
  // this is overridden in many subclasses. 
  virtual void ComputeInputUpdateExtents( vtkDataObject *output );

  // Description:
  // Turn on/off flag to control whether this object's data is released
  // after being used by a source.
  virtual void SetReleaseDataFlag(int);
  virtual int GetReleaseDataFlag();
  vtkBooleanMacro(ReleaseDataFlag,int);

  // Description:
  // Handle the source/data loop.
  void UnRegister(vtkObject *o);
  
  // Description:
  // Test to see if this object is in a reference counting loop.
  virtual int InRegisterLoop(vtkObject *);

  // Description:
  // Return an array with all the inputs of this process object.
  // This is useful for tracing back in the pipeline to contruct
  // graphs etc.
  vtkDataObject **GetOutputs();
  vtkGetMacro(NumberOfOutputs,int);
    
protected:
  vtkSource();
  ~vtkSource();
  vtkSource(const vtkSource&) {};
  void operator=(const vtkSource&) {};

  virtual void Execute();

  // By default, UpdateInformation calls this method to copy information
  // unmodified from the input to the output.
  virtual void ExecuteInformation();

  // Called to allocate the input array.  Copies old inputs.
  void SetNumberOfOutputs(int num);

  // method used internally for getting an output.
  vtkDataObject *GetOutput(int idx);

  // protected methods for setting inputs.
  virtual void SetNthOutput(int num, vtkDataObject *output);
  virtual void AddOutput(vtkDataObject *output);
  virtual void RemoveOutput(vtkDataObject *output);

  
  
  vtkDataObject **Outputs;     // An Array of the outputs to the filter
  int NumberOfOutputs;
  int Updating;
  // Time when ExecuteInformation was last called.
  vtkTimeStamp InformationTime;
};

#endif



