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
|
/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1999-2000 Raph Levien
*
* 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; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* Apply a dash style to a vector path. */
#include "config.h"
#include "art_vpath_dash.h"
#include <math.h>
#include <stdlib.h>
#include "art_misc.h"
#include "art_vpath.h"
/* Return the length of the largest subpath within vpath */
static int
art_vpath_dash_max_subpath (const ArtVpath *vpath)
{
int max_subpath;
int i;
int start;
max_subpath = 0;
start = 0;
for (i = 0; vpath[i].code != ART_END; i++)
{
if (vpath[i].code == ART_MOVETO || vpath[i].code == ART_MOVETO_OPEN)
{
if (i - start > max_subpath)
max_subpath = i - start;
start = i;
}
}
if (i - start > max_subpath)
max_subpath = i - start;
return max_subpath;
}
/**
* art_vpath_dash: Add dash style to vpath.
* @vpath: Original vpath.
* @dash: Dash style.
*
* Creates a new vpath that is the result of applying dash style @dash
* to @vpath.
*
* This implementation has two known flaws:
*
* First, it adds a spurious break at the beginning of the vpath. The
* only way I see to resolve this flaw is to run the state forward one
* dash break at the beginning, and fix up by looping back to the
* first dash break at the end. This is doable but of course adds some
* complexity.
*
* Second, it does not suppress output points that are within epsilon
* of each other.
*
* Return value: Newly created vpath.
**/
ArtVpath *
art_vpath_dash (const ArtVpath *vpath, const ArtVpathDash *dash)
{
int max_subpath;
double *dists;
ArtVpath *result;
int n_result, n_result_max;
int start, end;
int i;
double total_dist;
/* state while traversing dasharray - offset is offset of current dash
value, toggle is 0 for "off" and 1 for "on", and phase is the distance
in, >= 0, < dash->dash[offset]. */
int offset, toggle;
double phase;
/* initial values */
int offset_init, toggle_init;
double phase_init;
max_subpath = art_vpath_dash_max_subpath (vpath);
dists = art_new (double, max_subpath);
n_result = 0;
n_result_max = 16;
result = art_new (ArtVpath, n_result_max);
/* determine initial values of dash state */
toggle_init = 1;
offset_init = 0;
phase_init = dash->offset;
while (phase_init >= dash->dash[offset_init])
{
toggle_init = !toggle_init;
phase_init -= dash->dash[offset_init];
offset_init++;
if (offset_init == dash->n_dash)
offset_init = 0;
}
for (start = 0; vpath[start].code != ART_END; start = end)
{
for (end = start + 1; vpath[end].code == ART_LINETO; end++);
/* subpath is [start..end) */
total_dist = 0;
for (i = start; i < end - 1; i++)
{
double dx, dy;
dx = vpath[i + 1].x - vpath[i].x;
dy = vpath[i + 1].y - vpath[i].y;
dists[i - start] = sqrt (dx * dx + dy * dy);
total_dist += dists[i - start];
}
if (total_dist <= dash->dash[offset_init] - phase_init)
{
/* subpath fits entirely within first dash */
if (toggle_init)
{
for (i = start; i < end; i++)
art_vpath_add_point (&result, &n_result, &n_result_max,
vpath[i].code, vpath[i].x, vpath[i].y);
}
}
else
{
/* subpath is composed of at least one dash - thus all
generated pieces are open */
double dist;
phase = phase_init;
offset = offset_init;
toggle = toggle_init;
dist = 0;
i = start;
if (toggle)
art_vpath_add_point (&result, &n_result, &n_result_max,
ART_MOVETO_OPEN, vpath[i].x, vpath[i].y);
while (i != end - 1)
{
if (dists[i - start] - dist > dash->dash[offset] - phase)
{
/* dash boundary is next */
double a;
double x, y;
dist += dash->dash[offset] - phase;
a = dist / dists[i - start];
x = vpath[i].x + a * (vpath[i + 1].x - vpath[i].x);
y = vpath[i].y + a * (vpath[i + 1].y - vpath[i].y);
art_vpath_add_point (&result, &n_result, &n_result_max,
toggle ? ART_LINETO : ART_MOVETO_OPEN,
x, y);
/* advance to next dash */
toggle = !toggle;
phase = 0;
offset++;
if (offset == dash->n_dash)
offset = 0;
}
else
{
/* end of line in vpath is next */
phase += dists[i - start] - dist;
i++;
dist = 0;
if (toggle)
art_vpath_add_point (&result, &n_result, &n_result_max,
ART_LINETO, vpath[i].x, vpath[i].y);
}
}
}
}
art_vpath_add_point (&result, &n_result, &n_result_max,
ART_END, 0, 0);
art_free (dists);
return result;
}
|
