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<title>Define a color as transparent</title>
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<div class="refnamediv">
<h1 class="refname">imagecolortransparent</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">imagecolortransparent</span> — <span class="dc-title">Define a color as transparent</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.imagecolortransparent-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">int</span> <span class="methodname"><strong>imagecolortransparent</strong></span>
( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$color</code></span>
] )</div>
<p class="para rdfs-comment">
Sets the transparent color in the given <em><code class="parameter">image</code></em>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.imagecolortransparent-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">
image</code></em></span><dd>
<p class="para">An image resource, returned by one of the image creation functions,
such as <span class="function"><a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a></span>.</p></dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">color</code></em></span>
<dd>
<p class="para">
A color identifier created with
<span class="function"><a href="function.imagecolorallocate.html" class="function">imagecolorallocate()</a></span>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.imagecolortransparent-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
The identifier of the new (or current, if none is specified)
transparent color is returned. If <em><code class="parameter">color</code></em>
is not specified, and the image has no transparent color, the
returned identifier will be -1.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.imagecolortransparent-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-3199">
<p><strong>Example #1 <span class="function"><strong>imagecolortransparent()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Create a 55x30 image<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatetruecolor</span><span style="color: #007700">(</span><span style="color: #0000BB">55</span><span style="color: #007700">, </span><span style="color: #0000BB">30</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$red </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorallocate</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">255</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$black </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorallocate</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Make the background transparent<br /></span><span style="color: #0000BB">imagecolortransparent</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">$black</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Draw a red rectangle<br /></span><span style="color: #0000BB">imagefilledrectangle</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">, </span><span style="color: #0000BB">25</span><span style="color: #007700">, </span><span style="color: #0000BB">$red</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Save the image<br /></span><span style="color: #0000BB">imagepng</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #DD0000">'./imagecolortransparent.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagedestroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output
something similar to:</p></div>
<div class="mediaobject">
<div class="imageobject">
<img src="images/21009b70229598c6a80eef8b45bf282b-imagecolortransparent.png" alt="Output of example : imagecolortransparent()" width="55" height="30" />
</div>
</div>
</div>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.imagecolortransparent-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Transparency is copied only with <span class="function"><a href="function.imagecopymerge.html" class="function">imagecopymerge()</a></span> and
true color images, not with <span class="function"><a href="function.imagecopy.html" class="function">imagecopy()</a></span> or pallete images.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
The transparent color is a property of the image, transparency is not a
property of the color. Once you have set a color to be the transparent
color, any regions of the image in that color that were drawn previously
will be transparent.
</p>
</p></blockquote>
</div>
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