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<title>Adds a circular arc</title>
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<h1 class="refname">CairoContext::arc</h1>
<h1 class="refname">cairo_arc</h1>
<p class="verinfo">(PECL cairo >= 0.1.0)</p><p class="refpurpose"><span class="refname">CairoContext::arc</span> -- <span class="refname">cairo_arc</span> — <span class="dc-title">Adds a circular arc</span></p>
</div>
<div class="refsect1 description" id="refsect1-cairocontext.arc-description">
<h3 class="title">Description</h3>
<p class="para">Object oriented style (method):</p>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>CairoContext::arc</strong></span>
( <span class="methodparam"><span class="type">float</span> <code class="parameter">$x</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$y</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$radius</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle1</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle2</code></span>
)</div>
<p class="para rdfs-comment">Procedural style:</p>
<div class="methodsynopsis dc-description">
<span class="type"><span class="type void">void</span></span> <span class="methodname"><strong>cairo_arc</strong></span>
( <span class="methodparam"><span class="type"><a href="class.cairocontext.html" class="type CairoContext">CairoContext</a></span> <code class="parameter">$context</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$x</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$y</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$radius</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle1</code></span>
, <span class="methodparam"><span class="type">float</span> <code class="parameter">$angle2</code></span>
)</div>
<p class="para rdfs-comment">
Adds a circular arc of the given radius to the current path.
The arc is centered at (<em><code class="parameter">x</code></em>, <em><code class="parameter">y</code></em>), begins at
<em><code class="parameter">angle1</code></em> and proceeds in the direction of increasing angles to end at
<em><code class="parameter">angle2</code></em>.
If <em><code class="parameter">angle2</code></em> is less than <em><code class="parameter">angle1</code></em> it will be
progressively increased by 2*M_PI until it is greater than <em><code class="parameter">angle1</code></em>.
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 <span class="methodname"><a href="cairocontext.newsubpath.html" class="methodname">CairoContext::newSubPath()</a></span> or procedural
<span class="function"><a href="cairocontext.newsubpath.html" class="function">cairo_new_sub_path()</a></span> before calling <span class="methodname"><strong>CairoContext::arc()</strong></span>
or <span class="function"><strong>cairo_arc()</strong></span>.
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
<span class="methodname"><a href="cairocontext.arcnegative.html" class="methodname">CairoContext::arcNegative()</a></span> or <span class="function"><a href="cairocontext.arcnegative.html" class="function">cairo_arc_negative()</a></span>
to get the arc in the direction of decreasing angles.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-cairocontext.arc-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">context</code></em></span>
<dd>
<p class="para">
A valid CairoContext object
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">x</code></em></span>
<dd>
<p class="para">
x position
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">y</code></em></span>
<dd>
<p class="para">
y position
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">radius</code></em></span>
<dd>
<p class="para">
Radius of the arc
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">angle1</code></em></span>
<dd>
<p class="para">
start angle
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">angle2</code></em></span>
<dd>
<p class="para">
end angle
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-cairocontext.arc-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
No value is returned.
</p>
</div>
<div class="refsect1 examples" id="refsect1-cairocontext.arc-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-2848">
<p><strong>Example #1 Object oriented style</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /><br />$s </span><span style="color: #007700">= new </span><span style="color: #0000BB">CairoImageSurface</span><span style="color: #007700">(</span><span style="color: #0000BB">CairoFormat</span><span style="color: #007700">::</span><span style="color: #0000BB">ARGB32</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= new </span><span style="color: #0000BB">CairoContext</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">setSourceRgb</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">paint</span><span style="color: #007700">();<br /><br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">setLineWidth</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">setSourceRgb</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br />for (</span><span style="color: #0000BB">$r </span><span style="color: #007700">= </span><span style="color: #0000BB">50</span><span style="color: #007700">; </span><span style="color: #0000BB">$r </span><span style="color: #007700">> </span><span style="color: #0000BB">0</span><span style="color: #007700">; </span><span style="color: #0000BB">$r </span><span style="color: #007700">-= </span><span style="color: #0000BB">10</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">arc</span><span style="color: #007700">(</span><span style="color: #0000BB">50</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">, </span><span style="color: #0000BB">$r</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">2 </span><span style="color: #007700">* </span><span style="color: #0000BB">M_PI</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">stroke</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">$c</span><span style="color: #007700">-></span><span style="color: #0000BB">fill</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">$s</span><span style="color: #007700">-></span><span style="color: #0000BB">writeToPng</span><span style="color: #007700">(</span><span style="color: #0000BB">dirname</span><span style="color: #007700">(</span><span style="color: #0000BB">__FILE__</span><span style="color: #007700">) . </span><span style="color: #DD0000">'/CairoContext__arc.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
<div class="example" id="example-2849">
<p><strong>Example #2 Procedural style</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /><br />$s </span><span style="color: #007700">= </span><span style="color: #0000BB">cairo_image_surface_create</span><span style="color: #007700">(</span><span style="color: #0000BB">CAIRO_SURFACE_TYPE_IMAGE</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= </span><span style="color: #0000BB">cairo_create</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">cairo_set_source_rgb</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">cairo_paint</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">cairo_set_source_rgb</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">cairo_set_line_width</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br />for (</span><span style="color: #0000BB">$r </span><span style="color: #007700">= </span><span style="color: #0000BB">50</span><span style="color: #007700">; </span><span style="color: #0000BB">$r </span><span style="color: #007700">> </span><span style="color: #0000BB">0</span><span style="color: #007700">; </span><span style="color: #0000BB">$r </span><span style="color: #007700">-= </span><span style="color: #0000BB">10</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">cairo_arc</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">, </span><span style="color: #0000BB">$r</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">2 </span><span style="color: #007700">* </span><span style="color: #0000BB">M_PI</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">cairo_stroke</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">cairo_fill</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">cairo_surface_write_to_png</span><span style="color: #007700">(</span><span style="color: #0000BB">$s</span><span style="color: #007700">, </span><span style="color: #0000BB">dirname</span><span style="color: #007700">(</span><span style="color: #0000BB">__FILE__</span><span style="color: #007700">) . </span><span style="color: #DD0000">'/cairo_arc.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-cairocontext.arc-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="methodname"><a href="cairocontext.arcnegative.html" class="methodname" rel="rdfs-seeAlso">CairoContext::arcNegative()</a> - Adds a negative arc</span></li>
</ul>
</p>
</div>
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