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TMessagesProj/jni/rlottie/src/vector/vinterpolator.h

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+/* 
+ * Copyright (c) 2018 Samsung Electronics Co., Ltd. All rights reserved.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef VINTERPOLATOR_H
+#define VINTERPOLATOR_H
+
+#include "vpoint.h"
+
+V_BEGIN_NAMESPACE
+
+class VInterpolator {
+public:
+    VInterpolator()
+    { /* caller must call Init later */
+    }
+
+    VInterpolator(float aX1, float aY1, float aX2, float aY2)
+    {
+        init(aX1, aY1, aX2, aY2);
+    }
+
+    VInterpolator(VPointF pt1, VPointF pt2)
+    {
+        init(pt1.x(), pt1.y(), pt2.x(), pt2.y());
+    }
+
+    void init(float aX1, float aY1, float aX2, float aY2);
+
+    float value(float aX) const;
+
+    void GetSplineDerivativeValues(float aX, float& aDX, float& aDY) const;
+
+private:
+    void CalcSampleValues();
+
+    /**
+     * Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
+     */
+    static float CalcBezier(float aT, float aA1, float aA2);
+
+    /**
+     * Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
+     */
+    static float GetSlope(float aT, float aA1, float aA2);
+
+    float GetTForX(float aX) const;
+
+    float NewtonRaphsonIterate(float aX, float aGuessT) const;
+
+    float BinarySubdivide(float aX, float aA, float aB) const;
+
+    static float A(float aA1, float aA2) { return 1.0 - 3.0 * aA2 + 3.0 * aA1; }
+
+    static float B(float aA1, float aA2) { return 3.0 * aA2 - 6.0 * aA1; }
+
+    static float C(float aA1) { return 3.0 * aA1; }
+
+    float mX1;
+    float mY1;
+    float mX2;
+    float mY2;
+    enum { kSplineTableSize = 11 };
+    float              mSampleValues[kSplineTableSize];
+    static const float kSampleStepSize;
+};
+
+V_END_NAMESPACE
+
+#endif  // VINTERPOLATOR_H