gfx/skia/trunk/src/pathops/SkLineParameters.h@129ffea94266
gfx/skia/trunk/src/pathops/SkLineParameters.h
Sat, 03 Jan 2015 20:18:00 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Sat, 03 Jan 2015 20:18:00 +0100
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
- permissions
- -rw-r--r--
Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.
1 /*
2 * Copyright 2012 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 #include "SkPathOpsCubic.h"
8 #include "SkPathOpsLine.h"
9 #include "SkPathOpsQuad.h"
11 // Sources
12 // computer-aided design - volume 22 number 9 november 1990 pp 538 - 549
13 // online at http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf
15 // This turns a line segment into a parameterized line, of the form
16 // ax + by + c = 0
17 // When a^2 + b^2 == 1, the line is normalized.
18 // The distance to the line for (x, y) is d(x,y) = ax + by + c
19 //
20 // Note that the distances below are not necessarily normalized. To get the true
21 // distance, it's necessary to either call normalize() after xxxEndPoints(), or
22 // divide the result of xxxDistance() by sqrt(normalSquared())
24 class SkLineParameters {
25 public:
27 void cubicEndPoints(const SkDCubic& pts) {
28 int endIndex = 1;
29 cubicEndPoints(pts, 0, endIndex);
30 if (dy() != 0) {
31 return;
32 }
33 if (dx() == 0) {
34 cubicEndPoints(pts, 0, ++endIndex);
35 SkASSERT(endIndex == 2);
36 if (dy() != 0) {
37 return;
38 }
39 if (dx() == 0) {
40 cubicEndPoints(pts, 0, ++endIndex); // line
41 SkASSERT(endIndex == 3);
42 return;
43 }
44 }
45 if (dx() < 0) { // only worry about y bias when breaking cw/ccw tie
46 return;
47 }
48 // if cubic tangent is on x axis, look at next control point to break tie
49 // control point may be approximate, so it must move significantly to account for error
50 if (NotAlmostEqualUlps(pts[0].fY, pts[++endIndex].fY)) {
51 if (pts[0].fY > pts[endIndex].fY) {
52 a = DBL_EPSILON; // push it from 0 to slightly negative (y() returns -a)
53 }
54 return;
55 }
56 if (endIndex == 3) {
57 return;
58 }
59 SkASSERT(endIndex == 2);
60 if (pts[0].fY > pts[3].fY) {
61 a = DBL_EPSILON; // push it from 0 to slightly negative (y() returns -a)
62 }
63 }
65 void cubicEndPoints(const SkDCubic& pts, int s, int e) {
66 a = pts[s].fY - pts[e].fY;
67 b = pts[e].fX - pts[s].fX;
68 c = pts[s].fX * pts[e].fY - pts[e].fX * pts[s].fY;
69 }
71 double cubicPart(const SkDCubic& part) {
72 cubicEndPoints(part);
73 if (part[0] == part[1] || ((const SkDLine& ) part[0]).nearRay(part[2])) {
74 return pointDistance(part[3]);
75 }
76 return pointDistance(part[2]);
77 }
79 void lineEndPoints(const SkDLine& pts) {
80 a = pts[0].fY - pts[1].fY;
81 b = pts[1].fX - pts[0].fX;
82 c = pts[0].fX * pts[1].fY - pts[1].fX * pts[0].fY;
83 }
85 void quadEndPoints(const SkDQuad& pts) {
86 quadEndPoints(pts, 0, 1);
87 if (dy() != 0) {
88 return;
89 }
90 if (dx() == 0) {
91 quadEndPoints(pts, 0, 2);
92 return;
93 }
94 if (dx() < 0) { // only worry about y bias when breaking cw/ccw tie
95 return;
96 }
97 if (pts[0].fY > pts[2].fY) {
98 a = DBL_EPSILON;
99 }
100 }
102 void quadEndPoints(const SkDQuad& pts, int s, int e) {
103 a = pts[s].fY - pts[e].fY;
104 b = pts[e].fX - pts[s].fX;
105 c = pts[s].fX * pts[e].fY - pts[e].fX * pts[s].fY;
106 }
108 double quadPart(const SkDQuad& part) {
109 quadEndPoints(part);
110 return pointDistance(part[2]);
111 }
113 double normalSquared() const {
114 return a * a + b * b;
115 }
117 bool normalize() {
118 double normal = sqrt(normalSquared());
119 if (approximately_zero(normal)) {
120 a = b = c = 0;
121 return false;
122 }
123 double reciprocal = 1 / normal;
124 a *= reciprocal;
125 b *= reciprocal;
126 c *= reciprocal;
127 return true;
128 }
130 void cubicDistanceY(const SkDCubic& pts, SkDCubic& distance) const {
131 double oneThird = 1 / 3.0;
132 for (int index = 0; index < 4; ++index) {
133 distance[index].fX = index * oneThird;
134 distance[index].fY = a * pts[index].fX + b * pts[index].fY + c;
135 }
136 }
138 void quadDistanceY(const SkDQuad& pts, SkDQuad& distance) const {
139 double oneHalf = 1 / 2.0;
140 for (int index = 0; index < 3; ++index) {
141 distance[index].fX = index * oneHalf;
142 distance[index].fY = a * pts[index].fX + b * pts[index].fY + c;
143 }
144 }
146 double controlPtDistance(const SkDCubic& pts, int index) const {
147 SkASSERT(index == 1 || index == 2);
148 return a * pts[index].fX + b * pts[index].fY + c;
149 }
151 double controlPtDistance(const SkDQuad& pts) const {
152 return a * pts[1].fX + b * pts[1].fY + c;
153 }
155 double pointDistance(const SkDPoint& pt) const {
156 return a * pt.fX + b * pt.fY + c;
157 }
159 double dx() const {
160 return b;
161 }
163 double dy() const {
164 return -a;
165 }
167 private:
168 double a;
169 double b;
170 double c;
171 };
