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
208
209
210
211
212
213
214
215
216
217
218
|
<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 299559 $ -->
<refentry xml:id="cairocontext.arc" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>CairoContext::arc</refname>
<refname>cairo_arc</refname>
<refpurpose>Adds a circular arc</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<para>Object oriented style (method):</para>
<methodsynopsis>
<modifier>public</modifier> <type>void</type><methodname>CairoContext::arc</methodname>
<methodparam><type>float</type><parameter>x</parameter></methodparam>
<methodparam><type>float</type><parameter>y</parameter></methodparam>
<methodparam><type>float</type><parameter>radius</parameter></methodparam>
<methodparam><type>float</type><parameter>angle1</parameter></methodparam>
<methodparam><type>float</type><parameter>angle2</parameter></methodparam>
</methodsynopsis>
<para>Procedural style:</para>
<methodsynopsis>
<type>void</type><methodname>cairo_arc</methodname>
<methodparam><type>CairoContext</type><parameter>context</parameter></methodparam>
<methodparam><type>float</type><parameter>x</parameter></methodparam>
<methodparam><type>float</type><parameter>y</parameter></methodparam>
<methodparam><type>float</type><parameter>radius</parameter></methodparam>
<methodparam><type>float</type><parameter>angle1</parameter></methodparam>
<methodparam><type>float</type><parameter>angle2</parameter></methodparam>
</methodsynopsis>
<para>
Adds a circular arc of the given radius to the current path.
The arc is centered at (<parameter>x</parameter>, <parameter>y</parameter>), begins at
<parameter>angle1</parameter> and proceeds in the direction of increasing angles to end at
<parameter>angle2</parameter>.
If <parameter>angle2</parameter> is less than <parameter>angle1</parameter> it will be
progressively increased by 2*M_PI until it is greater than <parameter>angle1</parameter>.
If there is a current point, an initial line segment will be added to the path to connect the
current point to the beginning of the arc. If this initial line is undesired,
it can be avoided by calling <methodname>CairoContext::newSubPath</methodname> or procedural
<function>cairo_new_sub_path</function> before calling <methodname>CairoContext::arc</methodname>
or <function>cairo_arc</function>.
Angles are measured in radians. An angle of 0.0 is in the direction of the positive X axis
(in user space). An angle of M_PI/2.0 radians (90 degrees) is in the direction of the positive
Y axis (in user space). Angles increase in the direction from the positive X axis toward the
positive Y axis. So with the default transformation matrix, angles increase in a clockwise direction.
(To convert from degrees to radians, use degrees * (M_PI / 180.).)
This function gives the arc in the direction of increasing angles; see
<methodname>CairoContext::arcNegative</methodname> or <function>cairo_arc_negative</function>
to get the arc in the direction of decreasing angles.
<!--
The arc is circular in user space. To achieve an elliptical arc, you can scale the current
transformation matrix by different amounts in the X and Y directions.
For example, to draw an ellipse in the box given by x, y, width, height:
-->
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>context</parameter></term>
<listitem>
<para>
A valid CairoContext object
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>x</parameter></term>
<listitem>
<para>
x position
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>y</parameter></term>
<listitem>
<para>
y position
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>radius</parameter></term>
<listitem>
<para>
Radius of the arc
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>angle1</parameter></term>
<listitem>
<para>
start angle
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>angle2</parameter></term>
<listitem>
<para>
end angle
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
&return.void;
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Object oriented style</title>
<programlisting role="php">
<![CDATA[
<?php
$s = new CairoImageSurface(CairoFormat::ARGB32, 100, 100);
$c = new CairoContext($s);
$c->setSourceRgb(0, 0, 0);
$c->paint();
$c->setLineWidth(1);
$c->setSourceRgb(1, 1, 1);
for ($r = 50; $r > 0; $r -= 10) {
$c->arc(50, 50, $r, 0, 2 * M_PI);
$c->stroke();
$c->fill();
}
$s->writeToPng(dirname(__FILE__) . '/CairoContext__arc.png');
?>
]]>
</programlisting>
</example>
</para>
<para>
<example>
<title>Procedural style</title>
<programlisting role="php">
<![CDATA[
<?php
$s = cairo_image_surface_create(CAIRO_SURFACE_TYPE_IMAGE, 100, 100);
$c = cairo_create($s);
cairo_set_source_rgb($c, 0, 0, 0);
cairo_paint($c);
cairo_set_source_rgb($c, 1, 1, 1);
cairo_set_line_width($c, 1);
for ($r = 50; $r > 0; $r -= 10) {
cairo_arc($c, 50, 50, $r, 0, 2 * M_PI);
cairo_stroke($c);
cairo_fill($c);
}
cairo_surface_write_to_png($s, dirname(__FILE__) . '/cairo_arc.png');
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><methodname>CairoContext::arcNegative</methodname></member>
</simplelist>
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
