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

  Program:   Visualization Toolkit
  Module:    vtkPiecewiseFunction.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

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

/**
 * @class   vtkPiecewiseFunction
 * @brief   Defines a 1D piecewise function.
 *
 *
 * Defines a piecewise function mapping. This mapping allows the addition
 * of control points, and allows the user to control the function between
 * the control points. A piecewise hermite curve is used between control
 * points, based on the sharpness and midpoint parameters. A sharpness of
 * 0 yields a piecewise linear function and a sharpness of 1 yields a
 * piecewise constant function. The midpoint is the normalized distance
 * between control points at which the curve reaches the median Y value.
 * The midpoint and sharpness values specified when adding a node are used
 * to control the transition to the next node (the last node's values are
 * ignored) Outside the range of nodes, the values are 0 if Clamping is off,
 * or the nearest node point if Clamping is on. Using the legacy methods for
 * adding points  (which do not have Sharpness and Midpoint parameters)
 * will default to Midpoint = 0.5 (halfway between the control points) and
 * Sharpness = 0.0 (linear).
*/

#ifndef vtkPiecewiseFunction_h
#define vtkPiecewiseFunction_h

#include "vtkCommonDataModelModule.h" // For export macro
#include "vtkDataObject.h"

class vtkPiecewiseFunctionInternals;

class VTKCOMMONDATAMODEL_EXPORT vtkPiecewiseFunction : public vtkDataObject
{
public:
  static vtkPiecewiseFunction *New();
  vtkTypeMacro(vtkPiecewiseFunction,vtkDataObject);
  void PrintSelf(ostream& os, vtkIndent indent) VTK_OVERRIDE;

  void DeepCopy( vtkDataObject *f ) VTK_OVERRIDE;
  void ShallowCopy( vtkDataObject *f ) VTK_OVERRIDE;

  /**
   * Return what type of dataset this is.
   */
  int GetDataObjectType() VTK_OVERRIDE {return VTK_PIECEWISE_FUNCTION;};

  /**
   * Get the number of points used to specify the function
   */
  int  GetSize();

  //@{
  /**
   * Add/Remove points to/from the function. If a duplicate point is added
   * then the function value is changed at that location.
   * Return the index of the point (0 based), or -1 on error.
   */
  int AddPoint( double x, double y );
  int AddPoint( double x, double y, double midpoint, double sharpness );
  int RemovePoint( double x );
  //@}

  /**
   * Removes all points from the function.
   */
  void RemoveAllPoints();

  /**
   * Add a line segment to the function. All points defined between the
   * two points specified are removed from the function. This is a legacy
   * method that does not allow the specification of the sharpness and
   * midpoint values for the two nodes.
   */
  void AddSegment( double x1, double y1, double x2, double y2 );

  /**
   * Returns the value of the function at the specified location using
   * the specified interpolation.
   */
  double GetValue( double x );

  //@{
  /**
   * For the node specified by index, set/get the
   * location (X), value (Y), midpoint, and sharpness
   * values at the node. Returns -1 if the index is
   * out of range, returns 1 otherwise.
   */
  int GetNodeValue( int index, double val[4] );
  int SetNodeValue( int index, double val[4] );
  //@}

  //@{
  /**
   * Returns a pointer to the data stored in the table.
   * Fills from a pointer to data stored in a similar table. These are
   * legacy methods which will be maintained for compatibility - however,
   * note that the vtkPiecewiseFunction no longer stores the nodes
   * in a double array internally.
   */
  double *GetDataPointer();
  void FillFromDataPointer(int, double*);
  //@}

  //@{
  /**
   * Returns the min and max node locations of the function.
   */
  vtkGetVector2Macro( Range, double );
  //@}

  /**
   * Remove all points out of the new range, and make sure there is a point
   * at each end of that range.
   * Return 1 on success, 0 otherwise.
   */
  int AdjustRange(double range[2]);

  //@{
  /**
   * Fills in an array of function values evaluated at regular intervals.
   * Parameter "stride" is used to step through the output "table".
   */
  void GetTable( double x1, double x2, int size, float *table, int stride=1 );
  void GetTable( double x1, double x2, int size, double *table, int stride=1 );
  //@}

  /**
   * Constructs a piecewise function from a table.  Function range is
   * is set to [x1, x2], function size is set to size, and function points
   * are regularly spaced between x1 and x2.  Parameter "stride" is
   * is step through the input table.
   */
  void BuildFunctionFromTable( double x1, double x2, int size,
                               double *table, int stride=1 );

  //@{
  /**
   * When zero range clamping is Off, GetValue() returns 0.0 when a
   * value is requested outside of the points specified.
   * When zero range clamping is On, GetValue() returns the value at
   * the value at the lowest point for a request below all points
   * specified and returns the value at the highest point for a request
   * above all points specified. On is the default.
   */
  vtkSetMacro( Clamping, int );
  vtkGetMacro( Clamping, int );
  vtkBooleanMacro( Clamping, int );
  //@}

  /**
   * Return the type of function:
   * Function Types:
   * 0 : Constant        (No change in slope between end points)
   * 1 : NonDecreasing   (Always increasing or zero slope)
   * 2 : NonIncreasing   (Always decreasing or zero slope)
   * 3 : Varied          (Contains both decreasing and increasing slopes)
   */
  const char  *GetType();

  /**
   * Returns the first point location which precedes a non-zero segment of the
   * function. Note that the value at this point may be zero.
   */
  double GetFirstNonZeroValue();

  /**
   * Clears out the current function. A newly created vtkPiecewiseFunction
   * is alreay initialized, so there is no need to call this method which
   * in turn simply calls RemoveAllPoints()
   */
  void Initialize() VTK_OVERRIDE;

  //@{
  /**
   * Retrieve an instance of this class from an information object.
   */
  static vtkPiecewiseFunction* GetData(vtkInformation* info);
  static vtkPiecewiseFunction* GetData(vtkInformationVector* v, int i=0);
  //@}

  //@{
  /**
   * Toggle whether to allow duplicate scalar values in the piecewise
   * function (off by default).
   */
  vtkSetMacro(AllowDuplicateScalars, int);
  vtkGetMacro(AllowDuplicateScalars, int);
  vtkBooleanMacro(AllowDuplicateScalars, int);
  //@}

  /**
   * Estimates the minimum size of a table such that it would correctly sample this function.
   * The returned value should be passed as parameter 'n' when calling GetTable().
   */
  int EstimateMinNumberOfSamples(double const & x1, double const & x2);

protected:
  vtkPiecewiseFunction();
  ~vtkPiecewiseFunction() VTK_OVERRIDE;

  // Internal method to sort the vector and update the
  // Range whenever a node is added, edited or removed.
  // It always calls Modified().
  void SortAndUpdateRange();
  // Returns true if the range has been updated and Modified() has been called
  bool UpdateRange();

  /**
   * Traverses the nodes to find the minimum distance. Assumes nodes are sorted.
   */
  double FindMinimumXDistance();

  // The internal STL structures
  vtkPiecewiseFunctionInternals *Internal;

  // Determines the function value outside of defined points
  // Zero = always return 0.0 outside of defined points
  // One  = clamp to the lowest value below defined points and
  //        highest value above defined points
  int   Clamping;

  // Array of points ((X,Y) pairs)
  double *Function;

  // Min and max range of function point locations
  double Range[2];

  int AllowDuplicateScalars;

private:
  vtkPiecewiseFunction(const vtkPiecewiseFunction&) VTK_DELETE_FUNCTION;
  void operator=(const vtkPiecewiseFunction&) VTK_DELETE_FUNCTION;
};

#endif


