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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #ifndef NS_SMILKEYSPLINE_H_
       8             : #define NS_SMILKEYSPLINE_H_
       9             : 
      10             : #include "mozilla/ArrayUtils.h"
      11             : #include "mozilla/PodOperations.h"
      12             : 
      13             : /**
      14             :  * Utility class to provide scaling defined in a keySplines element.
      15             :  */
      16             : class nsSMILKeySpline
      17             : {
      18             : public:
      19           4 :   nsSMILKeySpline() { /* caller must call Init later */ }
      20             : 
      21             :   /**
      22             :    * Creates a new key spline control point description.
      23             :    *
      24             :    * aX1, etc. are the x1, y1, x2, y2 cubic Bezier control points as defined by
      25             :    * SMILANIM 3.2.3. They must each be in the range 0.0 <= x <= 1.0
      26             :    */
      27           0 :   nsSMILKeySpline(double aX1, double aY1,
      28             :                   double aX2, double aY2)
      29           0 :   {
      30           0 :     Init(aX1, aY1, aX2, aY2);
      31           0 :   }
      32             : 
      33           4 :   double X1() const { return mX1; }
      34           4 :   double Y1() const { return mY1; }
      35           0 :   double X2() const { return mX2; }
      36           0 :   double Y2() const { return mY2; }
      37             : 
      38             :   void Init(double aX1, double aY1,
      39             :             double aX2, double aY2);
      40             : 
      41             :   /**
      42             :    * Gets the output (y) value for an input (x).
      43             :    *
      44             :    * @param aX  The input x value. A floating-point number between 0 and
      45             :    *            1 (inclusive).
      46             :    */
      47             :   double GetSplineValue(double aX) const;
      48             : 
      49             :   void GetSplineDerivativeValues(double aX, double& aDX, double& aDY) const;
      50             : 
      51          14 :   bool operator==(const nsSMILKeySpline& aOther) const {
      52          28 :     return mX1 == aOther.mX1 &&
      53          28 :            mY1 == aOther.mY1 &&
      54          42 :            mX2 == aOther.mX2 &&
      55          28 :            mY2 == aOther.mY2;
      56             :   }
      57             :   bool operator!=(const nsSMILKeySpline& aOther) const {
      58             :     return !(*this == aOther);
      59             :   }
      60           0 :   int32_t Compare(const nsSMILKeySpline& aRhs) const {
      61           0 :     if (mX1 != aRhs.mX1) return mX1 < aRhs.mX1 ? -1 : 1;
      62           0 :     if (mY1 != aRhs.mY1) return mY1 < aRhs.mY1 ? -1 : 1;
      63           0 :     if (mX2 != aRhs.mX2) return mX2 < aRhs.mX2 ? -1 : 1;
      64           0 :     if (mY2 != aRhs.mY2) return mY2 < aRhs.mY2 ? -1 : 1;
      65           0 :     return 0;
      66             :   }
      67             : 
      68             : private:
      69             :   void
      70             :   CalcSampleValues();
      71             : 
      72             :   /**
      73             :    * Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
      74             :    */
      75             :   static double
      76             :   CalcBezier(double aT, double aA1, double aA2);
      77             : 
      78             :   /**
      79             :    * Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
      80             :    */
      81             :   static double
      82             :   GetSlope(double aT, double aA1, double aA2);
      83             : 
      84             :   double
      85             :   GetTForX(double aX) const;
      86             : 
      87             :   double
      88             :   NewtonRaphsonIterate(double aX, double aGuessT) const;
      89             : 
      90             :   double
      91             :   BinarySubdivide(double aX, double aA, double aB) const;
      92             : 
      93             :   static double
      94          53 :   A(double aA1, double aA2)
      95             :   {
      96          53 :     return 1.0 - 3.0 * aA2 + 3.0 * aA1;
      97             :   }
      98             : 
      99             :   static double
     100          53 :   B(double aA1, double aA2)
     101             :   {
     102          53 :     return 3.0 * aA2 - 6.0 * aA1;
     103             :   }
     104             : 
     105             :   static double
     106          53 :   C(double aA1)
     107             :   {
     108          53 :     return 3.0 * aA1;
     109             :   }
     110             : 
     111             :   double               mX1;
     112             :   double               mY1;
     113             :   double               mX2;
     114             :   double               mY2;
     115             : 
     116             :   enum { kSplineTableSize = 11 };
     117             :   double               mSampleValues[kSplineTableSize];
     118             : 
     119             :   static const double  kSampleStepSize;
     120             : };
     121             : 
     122             : #endif // NS_SMILKEYSPLINE_H_