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

  Program:   Visualization Toolkit
  Module:    vtkImageSource.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$
  Thanks:    Thanks to C. Charles Law who developed this class.

Copyright (c) 1993-1995 Ken Martin, Will Schroeder, Bill Lorensen.

This software is copyrighted by Ken Martin, Will Schroeder and Bill Lorensen.
The following terms apply to all files associated with the software unless
explicitly disclaimed in individual files. This copyright specifically does
not apply to the related textbook "The Visualization Toolkit" ISBN
013199837-4 published by Prentice Hall which is covered by its own copyright.

The authors hereby grant permission to use, copy, and distribute this
software and its documentation for any purpose, provided that existing
copyright notices are retained in all copies and that this notice is included
verbatim in any distributions. Additionally, the authors grant permission to
modify this software and its documentation for any purpose, provided that
such modifications are not distributed without the explicit consent of the
authors and that existing copyright notices are retained in all copies. Some
of the algorithms implemented by this software are patented, observe all
applicable patent law.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF,
EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN
"AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.


=========================================================================*/
// .NAME vtkImageSource - Source of data for the imaging pipeline
// .SECTION Description
// vtkImageSource is the superclass for all imaging sources and filters.
// The method Update(), called by the cache, is the major interface
// to the source.

// .SECTION See Also
// vtkImageCache vtkImageFilter


#ifndef __vtkImageSource_h
#define __vtkImageSource_h

#include "vtkImageData.h"
#include "vtkProcessObject.h"

class vtkImageCache;

class VTK_EXPORT vtkImageSource : public vtkProcessObject
{
public:
  vtkImageSource();
  ~vtkImageSource();
  const char *GetClassName() {return "vtkImageSource";};
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // This method sets the value of the cache's ReleaseDataFlag.  When this flag
  // is set, the cache releases its data after every generate.  When a default
  // cache is created, this flag is automatically set.
  virtual void SetReleaseDataFlag(int value);
  vtkBooleanMacro(ReleaseDataFlag, int);

  // Description:
  // This method gets the value of the caches ReleaseDataFlag.
  int  GetReleaseDataFlag();

  // Description:
  // This method can be used to intercept a generate call made to a cache.
  // It allows a source to generate a larger region than was originally 
  // specified.  The default method does not alter the specified region extent.
  virtual void InterceptCacheUpdate();

  // Description:
  // This method is called by the cache.
  virtual void InternalUpdate(vtkImageData *data);

  // Description:
  // This method can be called directly.
  // It simply forwards the update to the cache.
  virtual void Update();

  // Description:
  // This method updates the cache with the whole image extent.
  virtual void UpdateWholeExtent();

  // Description:
  // This method updates the instance variables "WholeExtent", "Spacing",
  // "Origin", "Bounds" etc.  It needs to be separate from "Update" because
  // the image information may be needed to compute the required UpdateExtent
  // of the input (see "vtkImageFilter").
  virtual void UpdateImageInformation() = 0;

  // Description:
  // Returns the maximum MTime of this source and every object affecting
  // this source's output. 
  virtual unsigned long GetPipelineMTime();

  // Description:
  // Returns an object which will generate data for Regions.
  vtkImageCache *GetOutput();

  // Description:
  // Use this method to specify a cache object for the filter.  
  // If a cache has been set previously, it is deleted, and caches
  // are not reference counted yet.  BE CAREFUL.
  // The Source of the Cache is set as a side action.
  virtual void SetCache(vtkImageCache *cache);

  // Description:
  // Returns the cache object of the source.  If one does not exist, a default
  // is created.
  vtkImageCache *GetCache();
  
  // Description:
  // Subclasses can override this method to do custom streaming and
  // splitting for multiprocessing.
  virtual int SplitExtent(int splitExt[6], int startExt[6], 
			  int num, int total);

  // Description:
  // This UnRegister method detects the small reference counting loop:
  // ImageSource <-> ImageCache, and destructs anyway.
  void UnRegister(vtkObject *o);
  
protected:
  vtkImageCache *Output;

  virtual void Execute(vtkImageData *data); 
  virtual void CheckCache();
};


#endif


