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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkMatrix22_DEFINED
#define SkMatrix22_DEFINED
#include "SkPoint.h"
class SkMatrix;
/** Find the Givens matrix G, which is the rotational matrix
* that rotates the vector h to the positive hoizontal axis.
* G * h = [hypot(h), 0]
*
* This is equivalent to
*
* SkScalar r = h.length();
* SkScalar r_inv = r ? SkScalarInvert(r) : 0;
* h.scale(r_inv);
* G->setSinCos(-h.fY, h.fX);
*
* but has better numerical stability by using (partial) hypot,
* and saves a multiply by not computing r.
*/
void SkComputeGivensRotation(const SkVector& h, SkMatrix* G);
#endif
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