1/*
2 * Copyright 2014 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkMatrix.h"
9#include "SkMatrix22.h"
10#include "SkPoint.h"
11#include "SkScalar.h"
12
13void SkComputeGivensRotation(const SkVector& h, SkMatrix* G) {
14    const SkScalar& a = h.fX;
15    const SkScalar& b = h.fY;
16    SkScalar c, s;
17    if (0 == b) {
18        c = SkScalarCopySign(SK_Scalar1, a);
19        s = 0;
20        //r = SkScalarAbs(a);
21    } else if (0 == a) {
22        c = 0;
23        s = -SkScalarCopySign(SK_Scalar1, b);
24        //r = SkScalarAbs(b);
25    } else if (SkScalarAbs(b) > SkScalarAbs(a)) {
26        SkScalar t = a / b;
27        SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), b);
28        s = -SK_Scalar1 / u;
29        c = -s * t;
30        //r = b * u;
31    } else {
32        SkScalar t = b / a;
33        SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), a);
34        c = SK_Scalar1 / u;
35        s = -c * t;
36        //r = a * u;
37    }
38
39    G->setSinCos(s, c);
40}
41