fitcurve.h

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// $Id: fitcurve.h 751 2006-03-31 15:43:49Z alex $
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 */
// Header file for the functions


#ifndef INC_FITCURVE
#define INC_FITCURVE

#include <math.h>

/********************************************************************************************

>   class FitPoint

    Author:     Rik_Heywood (Xara Group Ltd) <camelotdev@xara.com>
    Created:    02/03/94
    Purpose:    This class is really a vector class that is used by the curve fitting
                functions. It is also used as a coordinate class in the curve fitting
                functions, but these are really regarded as vectors from the origin.
                It has the following public member variables :-
                MonoOn double x;        - The X coord of the vector MonoOff
                MonoOn double y;        - The Y Coord of the vecotr MonoOff

********************************************************************************************/

class FitPoint : public CC_CLASS_MEMDUMP
{
    // Give my name in memory dumps
    CC_DECLARE_MEMDUMP(FitPoint);

public:
    // Construction
    FitPoint() {}
    FitPoint(double cx, double cy) { x=cx; y=cy;}
    FitPoint(DocCoord coord) { x=coord.x; y=coord.y; }
    FitPoint(const FitPoint& Other) {x=Other.x; y=Other.y;}

    // destruction
    ~FitPoint() {}

    // operator =
    void operator = (const FitPoint& Other) { x=Other.x; y=Other.y; }
    void operator = (const DocCoord& Other) { x=Other.x; y=Other.y; }

    // Length Functions
    FitPoint SetLength( double NewLen );

    // Addition/Subtraction operators
    friend FitPoint operator + (const FitPoint& Point1, const FitPoint& Point2);
    friend FitPoint operator - (const FitPoint& Point1, const FitPoint& Point2);

    // Unary minus
    FitPoint operator - ();

    // Scale
    FitPoint operator * ( double Factor );

    // General geometry functions
    double SquaredLength()  { return (x*x + y*y); }
    double Length()         { return sqrt(x*x + y*y); }
    double Dot(const FitPoint& Other)   { return (Other.x*x + Other.y*y); }

    // Debug functions
    void Dump();

public:
    double x;
    double y;
};





/********************************************************************************************

>   class CurveFitObject : public CC_CLASS_MEMDUMP

    Author:     Rik_Heywood (Xara Group Ltd) <camelotdev@xara.com>
    Created:    22/9/94
    Purpose:    Fits bezier curves to a serious of coordinates. Call the constructor,
                Initialise and finally FitCurve to fit a bezier curve to the coords.
    SeeAlso:    FitPoint

********************************************************************************************/

class CurveFitObject : public CC_CLASS_MEMDUMP
{
    // Give my name in memory dumps
    CC_DECLARE_MEMDUMP(CurveFitObject);

public:
    // Constructor that makes a note of things we will need to fit the curve
    CurveFitObject(Path* LongPath, double Error);
    ~CurveFitObject();

    // Strip useful points out of the path and puts them in the array
    BOOL Initialise(Path* CopyPath, INT32 NumPoints);

    // Fit the curve
    void FitCurve();

// Private member functions to help out the above functions
private:
    // The heart of the curve fitting code
    void FitCubic( INT32 FirstPoint, INT32 LastPoint, FitPoint Tangent1, FitPoint Tangent2,
                   BOOL IsStartCusp = TRUE, BOOL IsEndCusp = TRUE);

    // The function that does the actual maths
    void GenerateBezier( INT32 FirstPoint, INT32 LastPoint, FitPoint Tangent1, FitPoint Tangent2, FitPoint* Bezier );

    // Functions to determine how close a fit we have
    FitPoint BezierPoint( FitPoint* Bez, double u );
    double   CalcMaxError( INT32 FirstPoint, INT32 LastPoint, FitPoint* Bezier, INT32* SplitPoint );

    // Functions to find the tangents to the curve at various points
    FitPoint LeftTangent(INT32 Start);
    FitPoint RightTangent(INT32 End);
    FitPoint CentreTangent(INT32 Centre);

    // Functions to evaluate various components of the bezier function
    double Bezier0(double u) { double t=1.0-u; return (t*t*t); }
    double Bezier1(double u) { double t=1.0-u; return (3*u*t*t); }
    double Bezier2(double u) { double t=1.0-u; return (3*u*u*t); }
    double Bezier3(double u) { return (u*u*u); }

    // Functions to put curve elements into the path
    void InsertBezier( FitPoint* Bezier, BOOL, BOOL);
    void InsertLine( const DocCoord& Start, const DocCoord& End, FitPoint Tangent1, FitPoint Tangent2, BOOL, BOOL);
    void InsertStraightLine(const DocCoord& End);

// Member vars
private:
    // Pointers to the actual path object to get and store the points in and an array to
    // hold the coords that we will use in the smoothing process
    Path*       LongPath;
    DocCoord*   PathArray;
    INT32*      LineArray;

    // An array that holds the distance of each point from the start of the path
    INT32*      Distances;

    // The accuracy of the required fit. The larger this number, the smoother the fit.
    // Values of about 27,000,000 give smooth curves in millipoints at 100% zoom factor
    double      Error;

    // count of the total number of coordinates
    INT32       TotalCoords;
    INT32           TotalStraightLines;
};

/********************************************************************************************

>   class FitCurveNoChangeGeometry : public CC_CLASS_MEMDUMP

    Author:     David_McClarnon (Xara Group Ltd) <camelotdev@xara.com>
    Created:    12/1/2000
    Purpose:    This class uses the fit curve functionality to reduce the number of points
                in a path, whereas keeping the geometry as close to the original as possible

********************************************************************************************/
class FitCurveNoChangeGeometry : public CC_CLASS_MEMDUMP
{
    // Give my name in memory dumps
    CC_DECLARE_MEMDUMP(CurveFitObject);
public:
    static void SmoothPath(Path * pPath, double Error);
private:
    static void SmoothPathNoChangeGeometry(Path * pPath, double Error);
    static void EliminateColinearPointsFromPath(Path * pPath);
} ;

#endif

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