1
2 /*
3 * Copyright 2011 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8 // Unit tests for src/core/SkPoint.cpp and its header
9
10 #include "SkPoint.h"
11 #include "SkRect.h"
12 #include "Test.h"
13
test_casts(skiatest::Reporter * reporter)14 static void test_casts(skiatest::Reporter* reporter) {
15 SkPoint p = { 0, 0 };
16 SkRect r = { 0, 0, 0, 0 };
17
18 const SkScalar* pPtr = SkTCast<const SkScalar*>(&p);
19 const SkScalar* rPtr = SkTCast<const SkScalar*>(&r);
20
21 REPORTER_ASSERT(reporter, p.asScalars() == pPtr);
22 REPORTER_ASSERT(reporter, r.asScalars() == rPtr);
23 }
24
25 // Tests SkPoint::Normalize() for this (x,y)
test_Normalize(skiatest::Reporter * reporter,SkScalar x,SkScalar y)26 static void test_Normalize(skiatest::Reporter* reporter,
27 SkScalar x, SkScalar y) {
28 SkPoint point;
29 point.set(x, y);
30 SkScalar oldLength = point.length();
31 SkScalar returned = SkPoint::Normalize(&point);
32 SkScalar newLength = point.length();
33 REPORTER_ASSERT(reporter, SkScalarNearlyEqual(returned, oldLength));
34 REPORTER_ASSERT(reporter, SkScalarNearlyEqual(newLength, SK_Scalar1));
35 }
36
37 // Tests that SkPoint::length() and SkPoint::Length() both return
38 // approximately expectedLength for this (x,y).
test_length(skiatest::Reporter * reporter,SkScalar x,SkScalar y,SkScalar expectedLength)39 static void test_length(skiatest::Reporter* reporter, SkScalar x, SkScalar y,
40 SkScalar expectedLength) {
41 SkPoint point;
42 point.set(x, y);
43 SkScalar s1 = point.length();
44 SkScalar s2 = SkPoint::Length(x, y);
45 //The following should be exactly the same, but need not be.
46 //See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323
47 REPORTER_ASSERT(reporter, SkScalarNearlyEqual(s1, s2));
48 REPORTER_ASSERT(reporter, SkScalarNearlyEqual(s1, expectedLength));
49
50 test_Normalize(reporter, x, y);
51 }
52
53 // Ugh. Windows compiler can dive into other .cpp files, and sometimes
54 // notices that I will generate an overflow... which is exactly the point
55 // of this test!
56 //
57 // To avoid this warning, I need to convince the compiler that I might not
58 // use that big value, hence this hacky helper function: reporter is
59 // ALWAYS non-null. (shhhhhh, don't tell the compiler that).
get_value(skiatest::Reporter * reporter,T value)60 template <typename T> T get_value(skiatest::Reporter* reporter, T value) {
61 return reporter ? value : 0;
62 }
63
64 // On linux gcc, 32bit, we are seeing the compiler propagate up the value
65 // of SkPoint::length() as a double (which we use sometimes to avoid overflow
66 // during the computation), even though the signature says float (SkScalar).
67 //
68 // force_as_float is meant to capture our latest technique (horrible as
69 // it is) to force the value to be a float, so we can test whether it was
70 // finite or not.
force_as_float(skiatest::Reporter * reporter,float value)71 static float force_as_float(skiatest::Reporter* reporter, float value) {
72 uint32_t storage;
73 memcpy(&storage, &value, 4);
74 // even the pair of memcpy calls are not sufficient, since those seem to
75 // be no-op'd, so we add a runtime tests (just like get_value) to force
76 // the compiler to give us an actual float.
77 if (nullptr == reporter) {
78 storage = ~storage;
79 }
80 memcpy(&value, &storage, 4);
81 return value;
82 }
83
84 // test that we handle very large values correctly. i.e. that we can
85 // successfully normalize something whose mag overflows a float.
test_overflow(skiatest::Reporter * reporter)86 static void test_overflow(skiatest::Reporter* reporter) {
87 SkScalar bigFloat = get_value(reporter, 3.4e38f);
88 SkPoint pt = { bigFloat, bigFloat };
89
90 SkScalar length = pt.length();
91 length = force_as_float(reporter, length);
92
93 // expect this to be non-finite, but dump the results if not.
94 if (SkScalarIsFinite(length)) {
95 SkDebugf("length(%g, %g) == %g\n", pt.fX, pt.fY, length);
96 REPORTER_ASSERT(reporter, !SkScalarIsFinite(length));
97 }
98
99 // this should succeed, even though we can't represent length
100 REPORTER_ASSERT(reporter, pt.setLength(SK_Scalar1));
101
102 // now that pt is normalized, we check its length
103 length = pt.length();
104 REPORTER_ASSERT(reporter, SkScalarNearlyEqual(length, SK_Scalar1));
105 }
106
107 // test that we handle very small values correctly. i.e. that we can
108 // report failure if we try to normalize them.
test_underflow(skiatest::Reporter * reporter)109 static void test_underflow(skiatest::Reporter* reporter) {
110 SkPoint pt = { 1.0e-37f, 1.0e-37f };
111 const SkPoint empty = { 0, 0 };
112
113 REPORTER_ASSERT(reporter, 0 == SkPoint::Normalize(&pt));
114 REPORTER_ASSERT(reporter, pt == empty);
115
116 REPORTER_ASSERT(reporter, !pt.setLength(SK_Scalar1));
117 REPORTER_ASSERT(reporter, pt == empty);
118 }
119
DEF_TEST(Point,reporter)120 DEF_TEST(Point, reporter) {
121 test_casts(reporter);
122
123 static const struct {
124 SkScalar fX;
125 SkScalar fY;
126 SkScalar fLength;
127 } gRec[] = {
128 { SkIntToScalar(3), SkIntToScalar(4), SkIntToScalar(5) },
129 { 0.6f, 0.8f, SK_Scalar1 },
130 };
131
132 for (size_t i = 0; i < SK_ARRAY_COUNT(gRec); ++i) {
133 test_length(reporter, gRec[i].fX, gRec[i].fY, gRec[i].fLength);
134 }
135
136 test_underflow(reporter);
137 test_overflow(reporter);
138 }
139
DEF_TEST(Point_setLengthFast,reporter)140 DEF_TEST(Point_setLengthFast, reporter) {
141 // Scale a (1,1) point to a bunch of different lengths,
142 // making sure the slow and fast paths are within 0.1%.
143 const float tests[] = { 1.0f, 0.0f, 1.0e-37f, 3.4e38f, 42.0f, 0.00012f };
144
145 const SkPoint kOne = {1.0f, 1.0f};
146 for (unsigned i = 0; i < SK_ARRAY_COUNT(tests); i++) {
147 SkPoint slow = kOne, fast = kOne;
148
149 slow.setLength(tests[i]);
150 fast.setLengthFast(tests[i]);
151
152 if (slow.length() < FLT_MIN && fast.length() < FLT_MIN) continue;
153
154 SkScalar ratio = slow.length() / fast.length();
155 REPORTER_ASSERT(reporter, ratio > 0.999f);
156 REPORTER_ASSERT(reporter, ratio < 1.001f);
157 }
158 }
159