SkMatrix22.cpp 1.1 KB

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  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. #include "include/core/SkMatrix.h"
  8. #include "include/core/SkPoint.h"
  9. #include "include/core/SkScalar.h"
  10. #include "src/utils/SkMatrix22.h"
  11. void SkComputeGivensRotation(const SkVector& h, SkMatrix* G) {
  12. const SkScalar& a = h.fX;
  13. const SkScalar& b = h.fY;
  14. SkScalar c, s;
  15. if (0 == b) {
  16. c = SkScalarCopySign(SK_Scalar1, a);
  17. s = 0;
  18. //r = SkScalarAbs(a);
  19. } else if (0 == a) {
  20. c = 0;
  21. s = -SkScalarCopySign(SK_Scalar1, b);
  22. //r = SkScalarAbs(b);
  23. } else if (SkScalarAbs(b) > SkScalarAbs(a)) {
  24. SkScalar t = a / b;
  25. SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), b);
  26. s = -SK_Scalar1 / u;
  27. c = -s * t;
  28. //r = b * u;
  29. } else {
  30. SkScalar t = b / a;
  31. SkScalar u = SkScalarCopySign(SkScalarSqrt(SK_Scalar1 + t*t), a);
  32. c = SK_Scalar1 / u;
  33. s = -c * t;
  34. //r = a * u;
  35. }
  36. G->setSinCos(s, c);
  37. }