/*
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* Copyright 2014 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "SkMatrix.h"
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#include "SkMatrix22.h"
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#include "SkPoint.h"
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#include "SkScalar.h"
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void SkComputeGivensRotation(const SkVector& h, SkMatrix* G) {
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const SkScalar& a = h.fX;
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const SkScalar& b = h.fY;
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SkScalar c, s;
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if (0 == b) {
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c = SkScalarCopySign(SK_Scalar1, a);
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s = 0;
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//r = SkScalarAbs(a);
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} else if (0 == a) {
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c = 0;
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s = -SkScalarCopySign(SK_Scalar1, b);
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//r = SkScalarAbs(b);
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} else if (SkScalarAbs(b) > SkScalarAbs(a)) {
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SkScalar t = a / b;
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SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), b);
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s = -SK_Scalar1 / u;
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c = -s * t;
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//r = b * u;
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} else {
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SkScalar t = b / a;
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SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), a);
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c = SK_Scalar1 / u;
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s = -c * t;
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//r = a * u;
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}
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G->setSinCos(s, c);
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}
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