michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef NS_SMILKEYSPLINE_H_
michael@0: #define NS_SMILKEYSPLINE_H_
michael@0: 
michael@0: /**
michael@0:  * Utility class to provide scaling defined in a keySplines element.
michael@0:  */
michael@0: class nsSMILKeySpline
michael@0: {
michael@0: public:
michael@0:   nsSMILKeySpline() { /* caller must call Init later */ }
michael@0: 
michael@0:   /**
michael@0:    * Creates a new key spline control point description.
michael@0:    *
michael@0:    * aX1, etc. are the x1, y1, x2, y2 cubic Bezier control points as defined by
michael@0:    * SMILANIM 3.2.3. They must each be in the range 0.0 <= x <= 1.0
michael@0:    */
michael@0:   nsSMILKeySpline(double aX1, double aY1,
michael@0:                   double aX2, double aY2)
michael@0:   {
michael@0:     Init(aX1, aY1, aX2, aY2);
michael@0:   }
michael@0: 
michael@0:   double X1() const { return mX1; }
michael@0:   double Y1() const { return mY1; }
michael@0:   double X2() const { return mX2; }
michael@0:   double Y2() const { return mY2; }
michael@0: 
michael@0:   void Init(double aX1, double aY1,
michael@0:             double aX2, double aY2);
michael@0: 
michael@0:   /**
michael@0:    * Gets the output (y) value for an input (x).
michael@0:    *
michael@0:    * @param aX  The input x value. A floating-point number between 0 and
michael@0:    *            1 (inclusive).
michael@0:    */
michael@0:   double GetSplineValue(double aX) const;
michael@0: 
michael@0:   void GetSplineDerivativeValues(double aX, double& aDX, double& aDY) const;
michael@0: 
michael@0: private:
michael@0:   void
michael@0:   CalcSampleValues();
michael@0: 
michael@0:   /**
michael@0:    * Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
michael@0:    */
michael@0:   static double
michael@0:   CalcBezier(double aT, double aA1, double aA2);
michael@0: 
michael@0:   /**
michael@0:    * Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
michael@0:    */
michael@0:   static double
michael@0:   GetSlope(double aT, double aA1, double aA2);
michael@0: 
michael@0:   double
michael@0:   GetTForX(double aX) const;
michael@0: 
michael@0:   double
michael@0:   NewtonRaphsonIterate(double aX, double aGuessT) const;
michael@0: 
michael@0:   double
michael@0:   BinarySubdivide(double aX, double aA, double aB) const;
michael@0: 
michael@0:   static double
michael@0:   A(double aA1, double aA2)
michael@0:   {
michael@0:     return 1.0 - 3.0 * aA2 + 3.0 * aA1;
michael@0:   }
michael@0: 
michael@0:   static double
michael@0:   B(double aA1, double aA2)
michael@0:   {
michael@0:     return 3.0 * aA2 - 6.0 * aA1;
michael@0:   }
michael@0: 
michael@0:   static double
michael@0:   C(double aA1)
michael@0:   {
michael@0:     return 3.0 * aA1;
michael@0:   }
michael@0: 
michael@0:   double               mX1;
michael@0:   double               mY1;
michael@0:   double               mX2;
michael@0:   double               mY2;
michael@0: 
michael@0:   enum { kSplineTableSize = 11 };
michael@0:   double               mSampleValues[kSplineTableSize];
michael@0: 
michael@0:   static const double  kSampleStepSize;
michael@0: };
michael@0: 
michael@0: #endif // NS_SMILKEYSPLINE_H_