text: 
  /*
   * Copyright 2011 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  // Unit tests for src/core/SkPoint.cpp and its header
  
  #include "SkPoint.h"
  #include "SkRect.h"
  #include "Test.h"
  
  static void test_casts(skiatest::Reporter* reporter) {
      SkPoint p = { 0, 0 };
      SkRect  r = { 0, 0, 0, 0 };
  
      const SkScalar* pPtr = SkTCast<const SkScalar*>(&p);
      const SkScalar* rPtr = SkTCast<const SkScalar*>(&r);
  
      REPORTER_ASSERT(reporter, p.asScalars() == pPtr);
      REPORTER_ASSERT(reporter, r.asScalars() == rPtr);
  }
  
  // Tests SkPoint::Normalize() for this (x,y)
  static void test_Normalize(skiatest::Reporter* reporter,
                             SkScalar x, SkScalar y) {
      SkPoint point;
      point.set(x, y);
      SkScalar oldLength = point.length();
      SkScalar returned = SkPoint::Normalize(&point);
      SkScalar newLength = point.length();
      REPORTER_ASSERT(reporter, SkScalarNearlyEqual(returned, oldLength));
      REPORTER_ASSERT(reporter, SkScalarNearlyEqual(newLength, SK_Scalar1));
  }
  
  // Tests that SkPoint::length() and SkPoint::Length() both return
  // approximately expectedLength for this (x,y).
  static void test_length(skiatest::Reporter* reporter, SkScalar x, SkScalar y,
                          SkScalar expectedLength) {
      SkPoint point;
      point.set(x, y);
      SkScalar s1 = point.length();
      SkScalar s2 = SkPoint::Length(x, y);
      //The following should be exactly the same, but need not be.
      //See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323
      REPORTER_ASSERT(reporter, SkScalarNearlyEqual(s1, s2));
      REPORTER_ASSERT(reporter, SkScalarNearlyEqual(s1, expectedLength));
  
      test_Normalize(reporter, x, y);
  }
  
  // Ugh. Windows compiler can dive into other .cpp files, and sometimes
  // notices that I will generate an overflow... which is exactly the point
  // of this test!
  //
  // To avoid this warning, I need to convince the compiler that I might not
  // use that big value, hence this hacky helper function: reporter is
  // ALWAYS non-null. (shhhhhh, don't tell the compiler that).
  template <typename T> T get_value(skiatest::Reporter* reporter, T value) {
      return reporter ? value : 0;
  }
  
  // On linux gcc, 32bit, we are seeing the compiler propagate up the value
  // of SkPoint::length() as a double (which we use sometimes to avoid overflow
  // during the computation), even though the signature says float (SkScalar).
  //
  // force_as_float is meant to capture our latest technique (horrible as
  // it is) to force the value to be a float, so we can test whether it was
  // finite or not.
  static float force_as_float(skiatest::Reporter* reporter, float value) {
      uint32_t storage;
      memcpy(&storage, &value, 4);
      // even the pair of memcpy calls are not sufficient, since those seem to
      // be no-op'd, so we add a runtime tests (just like get_value) to force
      // the compiler to give us an actual float.
      if (NULL == reporter) {
          storage = ~storage;
      }
      memcpy(&value, &storage, 4);
      return value;
  }
  
  // test that we handle very large values correctly. i.e. that we can
  // successfully normalize something whose mag overflows a float.
  static void test_overflow(skiatest::Reporter* reporter) {
      SkScalar bigFloat = get_value(reporter, 3.4e38f);
      SkPoint pt = { bigFloat, bigFloat };
  
      SkScalar length = pt.length();
      length = force_as_float(reporter, length);
  
      // expect this to be non-finite, but dump the results if not.
      if (SkScalarIsFinite(length)) {
          SkDebugf("length(%g, %g) == %g\n", pt.fX, pt.fY, length);
          REPORTER_ASSERT(reporter, !SkScalarIsFinite(length));
      }
  
      // this should succeed, even though we can't represent length
      REPORTER_ASSERT(reporter, pt.setLength(SK_Scalar1));
  
      // now that pt is normalized, we check its length
      length = pt.length();
      REPORTER_ASSERT(reporter, SkScalarNearlyEqual(length, SK_Scalar1));
  }
  
  // test that we handle very small values correctly. i.e. that we can
  // report failure if we try to normalize them.
  static void test_underflow(skiatest::Reporter* reporter) {
      SkPoint pt = { 1.0e-37f, 1.0e-37f };
      SkPoint copy = pt;
  
      REPORTER_ASSERT(reporter, 0 == SkPoint::Normalize(&pt));
      REPORTER_ASSERT(reporter, pt == copy);  // pt is unchanged
  
      REPORTER_ASSERT(reporter, !pt.setLength(SK_Scalar1));
      REPORTER_ASSERT(reporter, pt == copy);  // pt is unchanged
  }
  
  #include "TestClassDef.h"
  DEF_TEST(Point, reporter) {
      test_casts(reporter);
  
      static const struct {
          SkScalar fX;
          SkScalar fY;
          SkScalar fLength;
      } gRec[] = {
          { SkIntToScalar(3), SkIntToScalar(4), SkIntToScalar(5) },
          { 0.6f, 0.8f, SK_Scalar1 },
      };
  
      for (size_t i = 0; i < SK_ARRAY_COUNT(gRec); ++i) {
          test_length(reporter, gRec[i].fX, gRec[i].fY, gRec[i].fLength);
      }
  
      test_underflow(reporter);
      test_overflow(reporter);
  }
  
  DEF_TEST(Point_setLengthFast, reporter) {
      // Scale a (1,1) point to a bunch of different lengths,
      // making sure the slow and fast paths are within 0.1%.
      const float tests[] = { 1.0f, 0.0f, 1.0e-37f, 3.4e38f, 42.0f, 0.00012f };
  
      const SkPoint kOne = {1.0f, 1.0f};
      for (unsigned i = 0; i < SK_ARRAY_COUNT(tests); i++) {
          SkPoint slow = kOne, fast = kOne;
  
          slow.setLength(tests[i]);
          fast.setLengthFast(tests[i]);
  
          if (slow.length() < FLT_MIN && fast.length() < FLT_MIN) continue;
  
          SkScalar ratio = slow.length() / fast.length();
          REPORTER_ASSERT(reporter, ratio > 0.999f);
          REPORTER_ASSERT(reporter, ratio < 1.001f);
      }
  }
  