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
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
/*
* This file is part of the WebKit open source project.
*
* Copyright (C) 2006, 2007 Eric Seidel (eric@webkit.org)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "config.h"
#include "PathTraversalState.h"
#include "Path.h"
#include <math.h>
namespace WebCore {
static const float kPathSegmentLengthTolerance = 0.00001f;
static inline FloatPoint midPoint(const FloatPoint& first, const FloatPoint& second)
{
return FloatPoint((first.x() + second.x()) / 2.0f, (first.y() + second.y()) / 2.0f);
}
static inline float distanceLine(const FloatPoint& start, const FloatPoint& end)
{
return sqrtf((end.x() - start.x()) * (end.x() - start.x()) + (end.y() - start.y()) * (end.y() - start.y()));
}
struct QuadraticBezier {
QuadraticBezier() { }
QuadraticBezier(const FloatPoint& s, const FloatPoint& c, const FloatPoint& e)
: start(s)
, control(c)
, end(e)
{
}
float approximateDistance() const
{
return distanceLine(start, control) + distanceLine(control, end);
}
void split(QuadraticBezier& left, QuadraticBezier& right) const
{
left.control = midPoint(start, control);
right.control = midPoint(control, end);
FloatPoint leftControlToRightControl = midPoint(left.control, right.control);
left.end = leftControlToRightControl;
right.start = leftControlToRightControl;
left.start = start;
right.end = end;
}
FloatPoint start;
FloatPoint control;
FloatPoint end;
};
struct CubicBezier {
CubicBezier() { }
CubicBezier(const FloatPoint& s, const FloatPoint& c1, const FloatPoint& c2, const FloatPoint& e)
: start(s)
, control1(c1)
, control2(c2)
, end(e)
{
}
float approximateDistance() const
{
return distanceLine(start, control1) + distanceLine(control1, control2) + distanceLine(control2, end);
}
void split(CubicBezier& left, CubicBezier& right) const
{
FloatPoint startToControl1 = midPoint(control1, control2);
left.start = start;
left.control1 = midPoint(start, control1);
left.control2 = midPoint(left.control1, startToControl1);
right.control2 = midPoint(control2, end);
right.control1 = midPoint(right.control2, startToControl1);
right.end = end;
FloatPoint leftControl2ToRightControl1 = midPoint(left.control2, right.control1);
left.end = leftControl2ToRightControl1;
right.start = leftControl2ToRightControl1;
}
FloatPoint start;
FloatPoint control1;
FloatPoint control2;
FloatPoint end;
};
// FIXME: This function is possibly very slow due to the ifs required for proper path measuring
// A simple speed-up would be to use an additional boolean template parameter to control whether
// to use the "fast" version of this function with no PathTraversalState updating, vs. the slow
// version which does update the PathTraversalState. We'll have to shark it to see if that's necessary.
// Another check which is possible up-front (to send us down the fast path) would be to check if
// approximateDistance() + current total distance > desired distance
template<class CurveType>
static float curveLength(PathTraversalState& traversalState, CurveType curve)
{
Vector<CurveType> curveStack;
curveStack.append(curve);
float totalLength = 0.0f;
do {
float length = curve.approximateDistance();
if ((length - distanceLine(curve.start, curve.end)) > kPathSegmentLengthTolerance) {
CurveType left, right;
curve.split(left, right);
curve = left;
curveStack.append(right);
} else {
totalLength += length;
if (traversalState.m_action == PathTraversalState::TraversalPointAtLength
|| traversalState.m_action == PathTraversalState::TraversalNormalAngleAtLength) {
traversalState.m_previous = curve.start;
traversalState.m_current = curve.end;
if (traversalState.m_totalLength + totalLength > traversalState.m_desiredLength)
return totalLength;
}
curve = curveStack.last();
curveStack.removeLast();
}
} while (!curveStack.isEmpty());
return totalLength;
}
PathTraversalState::PathTraversalState(PathTraversalAction action)
: m_action(action)
, m_success(false)
, m_totalLength(0.0f)
, m_segmentIndex(0)
, m_desiredLength(0.0f)
, m_normalAngle(0.0f)
{
}
float PathTraversalState::closeSubpath()
{
float distance = distanceLine(m_current, m_start);
m_current = m_control1 = m_control2 = m_start;
return distance;
}
float PathTraversalState::moveTo(const FloatPoint& point)
{
m_current = m_start = m_control1 = m_control2 = point;
return 0.0f;
}
float PathTraversalState::lineTo(const FloatPoint& point)
{
float distance = distanceLine(m_current, point);
m_current = m_control1 = m_control2 = point;
return distance;
}
float PathTraversalState::quadraticBezierTo(const FloatPoint& newControl, const FloatPoint& newEnd)
{
float distance = curveLength<QuadraticBezier>(*this, QuadraticBezier(m_current, newControl, newEnd));
m_control1 = newControl;
m_control2 = newEnd;
if (m_action != TraversalPointAtLength && m_action != TraversalNormalAngleAtLength)
m_current = newEnd;
return distance;
}
float PathTraversalState::cubicBezierTo(const FloatPoint& newControl1, const FloatPoint& newControl2, const FloatPoint& newEnd)
{
float distance = curveLength<CubicBezier>(*this, CubicBezier(m_current, newControl1, newControl2, newEnd));
m_control1 = newEnd;
m_control2 = newControl2;
if (m_action != TraversalPointAtLength && m_action != TraversalNormalAngleAtLength)
m_current = newEnd;
return distance;
}
}
|
