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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 DOM_SMIL_SMILKEYSPLINE_H_
+#define DOM_SMIL_SMILKEYSPLINE_H_
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/PodOperations.h"
+
+namespace mozilla {
+
+/**
+ * Utility class to provide scaling defined in a keySplines element.
+ */
+class SMILKeySpline {
+ public:
+ constexpr SMILKeySpline() : mX1(0), mY1(0), mX2(0), mY2(0) {
+ /* 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
+ */
+ SMILKeySpline(double aX1, double aY1, double aX2, double aY2)
+ : mX1(0), mY1(0), mX2(0), mY2(0) {
+ 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;
+
+ bool operator==(const SMILKeySpline& aOther) const {
+ return mX1 == aOther.mX1 && mY1 == aOther.mY1 && mX2 == aOther.mX2 &&
+ mY2 == aOther.mY2;
+ }
+ bool operator!=(const SMILKeySpline& aOther) const {
+ return !(*this == aOther);
+ }
+ int32_t Compare(const SMILKeySpline& aRhs) const {
+ if (mX1 != aRhs.mX1) return mX1 < aRhs.mX1 ? -1 : 1;
+ if (mY1 != aRhs.mY1) return mY1 < aRhs.mY1 ? -1 : 1;
+ if (mX2 != aRhs.mX2) return mX2 < aRhs.mX2 ? -1 : 1;
+ if (mY2 != aRhs.mY2) return mY2 < aRhs.mY2 ? -1 : 1;
+ return 0;
+ }
+
+ 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;
+};
+
+} // namespace mozilla
+
+#endif // DOM_SMIL_SMILKEYSPLINE_H_