diff -r 000000000000 -r 6474c204b198 dom/smil/nsSMILKeySpline.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/smil/nsSMILKeySpline.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NS_SMILKEYSPLINE_H_
+#define NS_SMILKEYSPLINE_H_
+
+/**
+ * Utility class to provide scaling defined in a keySplines element.
+ */
+class nsSMILKeySpline
+{
+public:
+  nsSMILKeySpline() { /* caller must call Init later */ }
+
+  /**
+   * Creates a new key spline control point description.
+   *
+   * aX1, etc. are the x1, y1, x2, y2 cubic Bezier control points as defined by
+   * SMILANIM 3.2.3. They must each be in the range 0.0 <= x <= 1.0
+   */
+  nsSMILKeySpline(double aX1, double aY1,
+                  double aX2, double aY2)
+  {
+    Init(aX1, aY1, aX2, aY2);
+  }
+
+  double X1() const { return mX1; }
+  double Y1() const { return mY1; }
+  double X2() const { return mX2; }
+  double Y2() const { return mY2; }
+
+  void Init(double aX1, double aY1,
+            double aX2, double aY2);
+
+  /**
+   * Gets the output (y) value for an input (x).
+   *
+   * @param aX  The input x value. A floating-point number between 0 and
+   *            1 (inclusive).
+   */
+  double GetSplineValue(double aX) const;
+
+  void GetSplineDerivativeValues(double aX, double& aDX, double& aDY) const;
+
+private:
+  void
+  CalcSampleValues();
+
+  /**
+   * Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
+   */
+  static double
+  CalcBezier(double aT, double aA1, double aA2);
+
+  /**
+   * Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
+   */
+  static double
+  GetSlope(double aT, double aA1, double aA2);
+
+  double
+  GetTForX(double aX) const;
+
+  double
+  NewtonRaphsonIterate(double aX, double aGuessT) const;
+
+  double
+  BinarySubdivide(double aX, double aA, double aB) const;
+
+  static double
+  A(double aA1, double aA2)
+  {
+    return 1.0 - 3.0 * aA2 + 3.0 * aA1;
+  }
+
+  static double
+  B(double aA1, double aA2)
+  {
+    return 3.0 * aA2 - 6.0 * aA1;
+  }
+
+  static double
+  C(double aA1)
+  {
+    return 3.0 * aA1;
+  }
+
+  double               mX1;
+  double               mY1;
+  double               mX2;
+  double               mY2;
+
+  enum { kSplineTableSize = 11 };
+  double               mSampleValues[kSplineTableSize];
+
+  static const double  kSampleStepSize;
+};
+
+#endif // NS_SMILKEYSPLINE_H_