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