1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkMathPriv.h"
#include "SkPointPriv.h"
#include "SkScalar.h"
#include "Test.h"
/*
Duplicates lots of code from gpu/src/GrPathUtils.cpp
It'd be nice not to do so, but that code's set up currently to only have
a single implementation.
*/
// Sk uses 6, Gr (implicitly) used 10, both apparently arbitrarily.
#define MAX_COEFF_SHIFT 6
static const uint32_t MAX_POINTS_PER_CURVE = 1 << MAX_COEFF_SHIFT;
// max + 0.5 min has error [0.0, 0.12]
// max + 0.375 min has error [-.03, 0.07]
// 0.96043387 max + 0.397824735 min has error [-.06, +.05]
// For determining the maximum possible number of points to use in
// drawing a quadratic, we want to err on the high side.
static inline int cheap_distance(SkScalar dx, SkScalar dy) {
int idx = SkAbs32(SkScalarRoundToInt(dx));
int idy = SkAbs32(SkScalarRoundToInt(dy));
if (idx > idy) {
idx += idy >> 1;
} else {
idx = idy + (idx >> 1);
}
return idx;
}
static inline int estimate_distance(const SkPoint points[]) {
return cheap_distance(points[1].fX * 2 - points[2].fX - points[0].fX,
points[1].fY * 2 - points[2].fY - points[0].fY);
}
static inline SkScalar compute_distance(const SkPoint points[]) {
return SkPointPriv::DistanceToLineSegmentBetween(points[1], points[0], points[2]);
}
static inline uint32_t estimate_pointCount(int distance) {
// Includes -2 bias because this estimator runs 4x high?
int shift = 30 - SkCLZ(distance);
// Clamp to zero if above subtraction went negative.
shift &= ~(shift>>31);
if (shift > MAX_COEFF_SHIFT) {
shift = MAX_COEFF_SHIFT;
}
return 1 << shift;
}
static inline uint32_t compute_pointCount(SkScalar d, SkScalar tol) {
if (d < tol) {
return 1;
} else {
int temp = SkScalarCeilToInt(SkScalarSqrt(d / tol));
uint32_t count = SkMin32(SkNextPow2(temp), MAX_POINTS_PER_CURVE);
return count;
}
}
static uint32_t quadraticPointCount_EE(const SkPoint points[]) {
int distance = estimate_distance(points);
return estimate_pointCount(distance);
}
static uint32_t quadraticPointCount_EC(const SkPoint points[], SkScalar tol) {
int distance = estimate_distance(points);
return compute_pointCount(SkIntToScalar(distance), tol);
}
static uint32_t quadraticPointCount_CE(const SkPoint points[]) {
SkScalar distance = compute_distance(points);
return estimate_pointCount(SkScalarRoundToInt(distance));
}
static uint32_t quadraticPointCount_CC(const SkPoint points[], SkScalar tol) {
SkScalar distance = compute_distance(points);
return compute_pointCount(distance, tol);
}
// Curve from samplecode/SampleSlides.cpp
static const int gXY[] = {
4, 0, 0, -4, 8, -4, 12, 0, 8, 4, 0, 4
};
static const int gSawtooth[] = {
0, 0, 10, 10, 20, 20, 30, 10, 40, 0, 50, -10, 60, -20, 70, -10, 80, 0
};
static const int gOvalish[] = {
0, 0, 5, 15, 20, 20, 35, 15, 40, 0
};
static const int gSharpSawtooth[] = {
0, 0, 1, 10, 2, 0, 3, -10, 4, 0
};
// Curve crosses back over itself around 0,10
static const int gRibbon[] = {
-4, 0, 4, 20, 0, 25, -4, 20, 4, 0
};
static bool one_d_pe(const int* array, const unsigned int count,
skiatest::Reporter* reporter) {
SkPoint path [3];
path[1] = SkPoint::Make(SkIntToScalar(array[0]), SkIntToScalar(array[1]));
path[2] = SkPoint::Make(SkIntToScalar(array[2]), SkIntToScalar(array[3]));
int numErrors = 0;
for (unsigned i = 4; i < count; i += 2) {
path[0] = path[1];
path[1] = path[2];
path[2] = SkPoint::Make(SkIntToScalar(array[i]),
SkIntToScalar(array[i+1]));
uint32_t computedCount =
quadraticPointCount_CC(path, SkIntToScalar(1));
uint32_t estimatedCount =
quadraticPointCount_EE(path);
if (false) { // avoid bit rot, suppress warning
computedCount =
quadraticPointCount_EC(path, SkIntToScalar(1));
estimatedCount =
quadraticPointCount_CE(path);
}
// Allow estimated to be high by a factor of two, but no less than
// the computed value.
bool isAccurate = (estimatedCount >= computedCount) &&
(estimatedCount <= 2 * computedCount);
if (!isAccurate) {
ERRORF(reporter, "Curve from %.2f %.2f through %.2f %.2f to "
"%.2f %.2f computes %d, estimates %d\n",
path[0].fX, path[0].fY, path[1].fX, path[1].fY,
path[2].fX, path[2].fY, computedCount, estimatedCount);
numErrors++;
}
}
return (numErrors == 0);
}
static void TestQuadPointCount(skiatest::Reporter* reporter) {
one_d_pe(gXY, SK_ARRAY_COUNT(gXY), reporter);
one_d_pe(gSawtooth, SK_ARRAY_COUNT(gSawtooth), reporter);
one_d_pe(gOvalish, SK_ARRAY_COUNT(gOvalish), reporter);
one_d_pe(gSharpSawtooth, SK_ARRAY_COUNT(gSharpSawtooth), reporter);
one_d_pe(gRibbon, SK_ARRAY_COUNT(gRibbon), reporter);
}
DEF_TEST(PathCoverage, reporter) {
TestQuadPointCount(reporter);
}
|
