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 "SkPoint.h"
10#include "SkRect.h"
11#include "Test.h"
12
13static 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, p.asScalars() == pPtr);
21    REPORTER_ASSERT(reporter, r.asScalars() == rPtr);
22}
23
24// Tests SkPoint::Normalize() for this (x,y)
25static 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).
38static 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).
59template <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.
70static 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.
85static 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.
108static 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
119DEF_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
139DEF_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        fast.setLengthFast(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