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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>VIPS Reference Manual: VipsRegion</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
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<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="10"><tr valign="middle">
<td width="100%" align="left" class="shortcuts">
<a href="#" class="shortcut">Top</a><span id="nav_description"> <span class="dim">|</span> 
                  <a href="#VipsRegion.description" class="shortcut">Description</a></span><span id="nav_hierarchy"> <span class="dim">|</span> 
                  <a href="#VipsRegion.object-hierarchy" class="shortcut">Object Hierarchy</a></span>
</td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
<td><a accesskey="u" href="ch02.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
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</tr></table>
<div class="refentry">
<a name="VipsRegion"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="VipsRegion.top_of_page"></a>VipsRegion</span></h2>
<p>VipsRegion — small, rectangular parts of images</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="VipsRegion.stability-level"></a><h2>Stability Level</h2>
Stable, unless otherwise indicated
</div>
<div class="refsect1">
<a name="VipsRegion.functions"></a><h2>Functions</h2>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<a class="link" href="VipsRegion.html" title="VipsRegion"><span class="returnvalue">VipsRegion</span></a> *
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-new" title="vips_region_new ()">vips_region_new</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-buffer" title="vips_region_buffer ()">vips_region_buffer</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-image" title="vips_region_image ()">vips_region_image</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-region" title="vips_region_region ()">vips_region_region</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-equalsregion" title="vips_region_equalsregion ()">vips_region_equalsregion</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-position" title="vips_region_position ()">vips_region_position</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-paint" title="vips_region_paint ()">vips_region_paint</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-paint-pel" title="vips_region_paint_pel ()">vips_region_paint_pel</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-black" title="vips_region_black ()">vips_region_black</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-copy" title="vips_region_copy ()">vips_region_copy</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()">vips_region_prepare</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-prepare-to" title="vips_region_prepare_to ()">vips_region_prepare_to</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-prepare-many" title="vips_region_prepare_many ()">vips_region_prepare_many</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-invalidate" title="vips_region_invalidate ()">vips_region_invalidate</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#vips-region-dump-all" title="vips_region_dump_all ()">vips_region_dump_all</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#VIPS-REGION-LSKIP:CAPS" title="VIPS_REGION_LSKIP()">VIPS_REGION_LSKIP</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#VIPS-REGION-N-ELEMENTS:CAPS" title="VIPS_REGION_N_ELEMENTS()">VIPS_REGION_N_ELEMENTS</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#VIPS-REGION-SIZEOF-LINE:CAPS" title="VIPS_REGION_SIZEOF_LINE()">VIPS_REGION_SIZEOF_LINE</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#VIPS-REGION-ADDR:CAPS" title="VIPS_REGION_ADDR()">VIPS_REGION_ADDR</a><span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="define_keyword">#define</td>
<td class="function_name">
<a class="link" href="VipsRegion.html#VIPS-REGION-ADDR-TOPLEFT:CAPS" title="VIPS_REGION_ADDR_TOPLEFT()">VIPS_REGION_ADDR_TOPLEFT</a><span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="VipsRegion.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen">    <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
    <span class="lineart">╰──</span> <a class="link" href="VipsObject.html" title="VipsObject">VipsObject</a>
        <span class="lineart">╰──</span> VipsRegion
</pre>
</div>
<div class="refsect1">
<a name="VipsRegion.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include &lt;vips/vips.h&gt;
</pre>
</div>
<div class="refsect1">
<a name="VipsRegion.description"></a><h2>Description</h2>
<p>A <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> is a small part of an image and some pixels. You use regions to
read pixels out of images without having to have the whole image in memory
at once.</p>
<p>A region can be a memory buffer, part of a memory-mapped file, part of some
other image, or part of some other region.</p>
<p>Regions must be created, used and freed all within the same thread, since
they can reference private per-thread caches. VIPS sanity-checks region
ownership in various places, so you are likely to see <a href="http://library.gnome.org/devel/glib/unstable/glib-Testing.html#g-assert"><code class="function">g_assert()</code></a> errors if
you don't follow this rule.</p>
<p>There
is API to transfer ownership of regions between threads, but hopefully this
is only needed within VIPS, so we don't expose it. Hopefully.</p>
</div>
<div class="refsect1">
<a name="VipsRegion.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="vips-region-new"></a><h3>vips_region_new ()</h3>
<pre class="programlisting"><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="returnvalue">VipsRegion</span></a> *
vips_region_new (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *image</code></em>);</pre>
<p>Create a region. <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> s start out empty, you need to call 
<a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a> to fill them with pixels.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.2.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>image</p></td>
<td class="parameter_description"><p>image to create this region on</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-buffer"></a><h3>vips_region_buffer ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_buffer (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                    <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>);</pre>
<p>The region is transformed so that at least <em class="parameter"><code>r</code></em>
 pixels are available as a
memory buffer.</p>
<div class="refsect3">
<a name="id-1.3.9.8.3.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to be able to address</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.3.6"></a><h4>Returns</h4>
<p> 0 on success, or -1 for error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-image"></a><h3>vips_region_image ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_image (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                   <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>);</pre>
<p>The region is transformed so that at least <em class="parameter"><code>r</code></em>
 pixels are available directly
from the image. The image needs to be a memory buffer or represent a file
on disc that has been mapped or can be mapped.</p>
<div class="refsect3">
<a name="id-1.3.9.8.4.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to be able to address</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.4.6"></a><h4>Returns</h4>
<p> 0 on success, or -1 for error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-region"></a><h3>vips_region_region ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_region (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                    <em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *dest</code></em>,
                    <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>,
                    <em class="parameter"><code><span class="type">int</span> x</code></em>,
                    <em class="parameter"><code><span class="type">int</span> y</code></em>);</pre>
<p>Make <a class="link" href="VipsRegion.html#VIPS-REGION-ADDR:CAPS" title="VIPS_REGION_ADDR()"><code class="function">VIPS_REGION_ADDR()</code></a> on <em class="parameter"><code>reg</code></em>
 go to <em class="parameter"><code>dest</code></em>
 instead. </p>
<p><em class="parameter"><code>r</code></em>
 is the part of <em class="parameter"><code>reg</code></em>
 which you want to be able to address (this
effectively becomes the valid field), (<em class="parameter"><code>x</code></em>
, <em class="parameter"><code>y</code></em>
) is the top LH corner of the
corresponding area in <em class="parameter"><code>dest</code></em>
.</p>
<p>Performs all clipping necessary to ensure that <em class="parameter"><code>reg-&gt;valid</code></em>
 is indeed
valid.</p>
<p>If the region we attach to is modified, we can be left with dangling 
pointers! If the region we attach to is on another image, the two images 
must have 
the same sizeof( pel ).</p>
<div class="refsect3">
<a name="id-1.3.9.8.5.8"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>dest</p></td>
<td class="parameter_description"><p>region to connect to</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to be able to address</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>x</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>y</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.5.9"></a><h4>Returns</h4>
<p> 0 on success, or -1 for error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-equalsregion"></a><h3>vips_region_equalsregion ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_equalsregion (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg1</code></em>,
                          <em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg2</code></em>);</pre>
<p>Do two regions point to the same piece of image? ie. </p>
<div class="informalexample"><pre class="programlisting">
	VIPS_REGION_ADDR( reg1, x, y ) == VIPS_REGION_ADDR( reg2, x, y ) &amp;&amp;
	*VIPS_REGION_ADDR( reg1, x, y ) == 
		*VIPS_REGION_ADDR( reg2, x, y ) for all x, y, reg1, reg2.
</pre></div>
<p></p>
<div class="refsect3">
<a name="id-1.3.9.8.6.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg1</p></td>
<td class="parameter_description"><p>region to test</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>reg2</p></td>
<td class="parameter_description"><p>region to test</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.6.8"></a><h4>Returns</h4>
<p> non-zero on equality.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-position"></a><h3>vips_region_position ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_position (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                      <em class="parameter"><code><span class="type">int</span> x</code></em>,
                      <em class="parameter"><code><span class="type">int</span> y</code></em>);</pre>
<p>Set the position of a region. This only affects reg-&gt;valid, ie. the way
pixels are addressed, not reg-&gt;data, the pixels which are addressed. Clip
against the size of the image. Do not allow negative positions, or
positions outside the image.</p>
<div class="refsect3">
<a name="id-1.3.9.8.7.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>x</p></td>
<td class="parameter_description"><p>position to move to</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>y</p></td>
<td class="parameter_description"><p>position to move to</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.7.6"></a><h4>Returns</h4>
<p> 0 on success, or -1 for error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-paint"></a><h3>vips_region_paint ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_paint (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                   <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>,
                   <em class="parameter"><code><span class="type">int</span> value</code></em>);</pre>
<p>Paints <em class="parameter"><code>value</code></em>
 into <em class="parameter"><code>reg</code></em>
 covering rectangle <em class="parameter"><code>r</code></em>
. <em class="parameter"><code>value</code></em>
 is passed to
<code class="function">memset()</code>, so it usually needs to be 0 or 255. <em class="parameter"><code>r</code></em>
 is clipped against
<em class="parameter"><code>reg-&gt;valid</code></em>
.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-black" title="vips_region_black ()"><code class="function">vips_region_black()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.8.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p>area to paint</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>value</p></td>
<td class="parameter_description"><p>value to paint</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-paint-pel"></a><h3>vips_region_paint_pel ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_paint_pel (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                       <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>,
                       <em class="parameter"><code><span class="type">VipsPel</span> *ink</code></em>);</pre>
<p>Paints <em class="parameter"><code>ink</code></em>
 into <em class="parameter"><code>reg</code></em>
 covering rectangle <em class="parameter"><code>r</code></em>
. <em class="parameter"><code>r</code></em>
 is clipped against 
<em class="parameter"><code>reg-&gt;valid</code></em>
.</p>
<p><em class="parameter"><code>ink</code></em>
 should be a byte array of the same size as an image pixel containing
the binary value to write into the pixels.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-paint" title="vips_region_paint ()"><code class="function">vips_region_paint()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.9.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p>area to paint</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>ink</p></td>
<td class="parameter_description"><p>value to paint</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-black"></a><h3>vips_region_black ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_black (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>);</pre>
<p>Paints 0 into the valid part of <em class="parameter"><code>reg</code></em>
.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-paint" title="vips_region_paint ()"><code class="function">vips_region_paint()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.10.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to operate upon</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-copy"></a><h3>vips_region_copy ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_copy (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                  <em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *dest</code></em>,
                  <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>,
                  <em class="parameter"><code><span class="type">int</span> x</code></em>,
                  <em class="parameter"><code><span class="type">int</span> y</code></em>);</pre>
<p>Copy from one region to another. Copy area <em class="parameter"><code>r</code></em>
 from inside <em class="parameter"><code>reg</code></em>
 to <em class="parameter"><code>dest</code></em>
,
positioning the area of pixels at <em class="parameter"><code>x</code></em>
, <em class="parameter"><code>y</code></em>
. The two regions must have pixels
which are the same size.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-paint" title="vips_region_paint ()"><code class="function">vips_region_paint()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.11.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>source region </p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>dest</p></td>
<td class="parameter_description"><p>destination region </p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to copy</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>x</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>y</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-prepare"></a><h3>vips_region_prepare ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_prepare (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                     <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>);</pre>
<p>vips_region_prepare() fills <em class="parameter"><code>reg</code></em>
 with pixels. After calling, 
you can address at least the area <em class="parameter"><code>r</code></em>
 with <a class="link" href="VipsRegion.html#VIPS-REGION-ADDR:CAPS" title="VIPS_REGION_ADDR()"><code class="function">VIPS_REGION_ADDR()</code></a> and get 
valid pixels.</p>
<p>vips_region_prepare() runs in-line, that is, computation is done by 
the calling thread, no new threads are involved, and computation 
blocks until the pixels are ready.</p>
<p>Use <a class="link" href="libvips-generate.html#vips-sink-screen" title="vips_sink_screen ()"><code class="function">vips_sink_screen()</code></a> to calculate an area of pixels in the 
background.</p>
<p>See also: <a class="link" href="libvips-generate.html#vips-sink-screen" title="vips_sink_screen ()"><code class="function">vips_sink_screen()</code></a>, 
<a class="link" href="VipsRegion.html#vips-region-prepare-to" title="vips_region_prepare_to ()"><code class="function">vips_region_prepare_to()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.12.8"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to prepare</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to be able to address</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.12.9"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-prepare-to"></a><h3>vips_region_prepare_to ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_prepare_to (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>,
                        <em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *dest</code></em>,
                        <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>,
                        <em class="parameter"><code><span class="type">int</span> x</code></em>,
                        <em class="parameter"><code><span class="type">int</span> y</code></em>);</pre>
<p>Like <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>: fill <em class="parameter"><code>reg</code></em>
 with data, ready to be read from by 
our caller. Unlike <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>, rather than allocating memory 
local to <em class="parameter"><code>reg</code></em>
 for the result, we guarantee that we will fill the pixels 
in <em class="parameter"><code>dest</code></em>
 at offset <em class="parameter"><code>x</code></em>
, <em class="parameter"><code>y</code></em>
. In other words, we generate an extra copy 
operation if necessary. </p>
<p>Also unlike <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>, <em class="parameter"><code>dest</code></em>
 is not set up for writing for 
you with
<a class="link" href="VipsRegion.html#vips-region-buffer" title="vips_region_buffer ()"><code class="function">vips_region_buffer()</code></a>. You can
point <em class="parameter"><code>dest</code></em>
 at anything, and pixels really will be written there. 
This makes <code class="function">vips_prepare_to()</code> useful for making the ends of pipelines, since
it (effectively) makes a break in the pipe.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>, <a class="link" href="libvips-generate.html#vips-sink-disc" title="vips_sink_disc ()"><code class="function">vips_sink_disc()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.13.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to prepare</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>dest</p></td>
<td class="parameter_description"><p>region to write to</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>r</p></td>
<td class="parameter_description"><p><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> of pixels you need to be able to address</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>x</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>y</p></td>
<td class="parameter_description"><p>postion of <em class="parameter"><code>r</code></em>
in <em class="parameter"><code>dest</code></em>
</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.13.8"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-prepare-many"></a><h3>vips_region_prepare_many ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_region_prepare_many (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> **reg</code></em>,
                          <em class="parameter"><code><a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> *r</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-invalidate"></a><h3>vips_region_invalidate ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_invalidate (<em class="parameter"><code><a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a> *reg</code></em>);</pre>
<p>Mark a region as containing invalid pixels. Calling this function means
that the next time <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a> is called, the region will be
recalculated.</p>
<p>This is faster than calling <a class="link" href="VipsImage.html#vips-image-invalidate-all" title="vips_image_invalidate_all ()"><code class="function">vips_image_invalidate_all()</code></a>, but obviously only
affects a single region. </p>
<p>See also: <a class="link" href="VipsImage.html#vips-image-invalidate-all" title="vips_image_invalidate_all ()"><code class="function">vips_image_invalidate_all()</code></a>, <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.15.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>reg</p></td>
<td class="parameter_description"><p>region to invalidate</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-region-dump-all"></a><h3>vips_region_dump_all ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_region_dump_all (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="VIPS-REGION-LSKIP:CAPS"></a><h3>VIPS_REGION_LSKIP()</h3>
<pre class="programlisting">#define             VIPS_REGION_LSKIP( R )</pre>
<div class="refsect3">
<a name="id-1.3.9.8.17.4"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>R</p></td>
<td class="parameter_description"><p>a <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.17.5"></a><h4>Returns</h4>
<p> The number of bytes to add to move down a scanline.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VIPS-REGION-N-ELEMENTS:CAPS"></a><h3>VIPS_REGION_N_ELEMENTS()</h3>
<pre class="programlisting">#define             VIPS_REGION_N_ELEMENTS( R )</pre>
<div class="refsect3">
<a name="id-1.3.9.8.18.4"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>R</p></td>
<td class="parameter_description"><p>a <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.18.5"></a><h4>Returns</h4>
<p> The number of band elements across a region.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VIPS-REGION-SIZEOF-LINE:CAPS"></a><h3>VIPS_REGION_SIZEOF_LINE()</h3>
<pre class="programlisting">#define             VIPS_REGION_SIZEOF_LINE( R )</pre>
<div class="refsect3">
<a name="id-1.3.9.8.19.4"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>R</p></td>
<td class="parameter_description"><p>a <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.19.5"></a><h4>Returns</h4>
<p> The number of bytes across a region.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VIPS-REGION-ADDR:CAPS"></a><h3>VIPS_REGION_ADDR()</h3>
<pre class="programlisting">#define             VIPS_REGION_ADDR( R, X, Y )</pre>
<p>This macro returns a pointer to a pixel in a region. The (<em class="parameter"><code>X</code></em>
, <em class="parameter"><code>Y</code></em>
) 
coordinates need to be within the <a class="link" href="libvips-rect.html#VipsRect" title="VipsRect"><span class="type">VipsRect</span></a> (<em class="parameter"><code>R-&gt;valid</code></em>
).</p>
<p>If DEBUG is defined, you get a version that checks bounds for you.</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.20.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>R</p></td>
<td class="parameter_description"><p>a <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>X</p></td>
<td class="parameter_description"><p>x coordinate</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>Y</p></td>
<td class="parameter_description"><p>y coordinate</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.20.8"></a><h4>Returns</h4>
<p> The address of pixel (<em class="parameter"><code>X</code></em>
,<em class="parameter"><code>Y</code></em>
) in <em class="parameter"><code>R</code></em>
.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VIPS-REGION-ADDR-TOPLEFT:CAPS"></a><h3>VIPS_REGION_ADDR_TOPLEFT()</h3>
<pre class="programlisting">#define VIPS_REGION_ADDR_TOPLEFT( R ) ((R)-&gt;data)
</pre>
<p>This macro returns a pointer to the top-left pixel in the <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a>, that 
is, the pixel at (<em class="parameter"><code>R-&gt;valid.left</code></em>
, <em class="parameter"><code>R-&gt;valid.top</code></em>
).</p>
<p>See also: <a class="link" href="VipsRegion.html#vips-region-prepare" title="vips_region_prepare ()"><code class="function">vips_region_prepare()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.9.8.21.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>R</p></td>
<td class="parameter_description"><p>a <a class="link" href="VipsRegion.html" title="VipsRegion"><span class="type">VipsRegion</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.9.8.21.7"></a><h4>Returns</h4>
<p> The address of the top-left pixel in the region.</p>
<p></p>
</div>
</div>
</div>
<div class="refsect1">
<a name="VipsRegion.other_details"></a><h2>Types and Values</h2>
</div>
<div class="refsect1">
<a name="VipsRegion.see-also"></a><h2>See Also</h2>
image, 
<a class="link" href="libvips-generate.html" title="generate">generate</a>
</div>
</div>
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