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
14static 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)
26static 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).
39static 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).
60template <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.
71static 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 (NULL == 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.
86static 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.
109static void test_underflow(skiatest::Reporter* reporter) {
110    SkPoint pt = { 1.0e-37f, 1.0e-37f };
111    SkPoint copy = pt;
112
113    REPORTER_ASSERT(reporter, 0 == SkPoint::Normalize(&pt));
114    REPORTER_ASSERT(reporter, pt == copy);  // pt is unchanged
115
116    REPORTER_ASSERT(reporter, !pt.setLength(SK_Scalar1));
117    REPORTER_ASSERT(reporter, pt == copy);  // pt is unchanged
118}
119
120DEF_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
140DEF_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