📄 function.imagecolorat.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Get the index of the color of a pixel</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagecolorallocatealpha.html">imagecolorallocatealpha</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagecolorclosest.html">imagecolorclosest</a></div> <div class="up"><a href="ref.image.html">GD Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.imagecolorat" class="refentry"> <div class="refnamediv"> <h1 class="refname">imagecolorat</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">imagecolorat</span> — <span class="dc-title">Get the index of the color of a pixel</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>imagecolorat</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$image</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$x</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$y</tt></span> )</div> <p class="para rdfs-comment"> Returns the index of the color of the pixel at the specified location in the image specified by <i><tt class="parameter">image</tt></i>. </p> <p class="para"> If PHP is compiled against GD library 2.0 or higher and the image is a truecolor image, this function returns the RGB value of that pixel as integer. Use bitshifting and masking to access the distinct red, green and blue component values: </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt><span class="term"><i><tt class="parameter">image</tt></i></span><dd><p class="para">An image resource, returned by one of the image creation functions, such as <a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a>.</p></dd></dt> <dt> <span class="term"><i><tt class="parameter">x</tt></i></span> <dd> <p class="para"> x-coordinate of the point. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">y</tt></i></span> <dd> <p class="para"> y-coordinate of the point. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the index of the color. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Access distinct RGB values</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefrompng</span><span style="color: #007700">(</span><span style="color: #DD0000">"php.png"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$rgb </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorat</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">15</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$r </span><span style="color: #007700">= (</span><span style="color: #0000BB">$rgb </span><span style="color: #007700">>> </span><span style="color: #0000BB">16</span><span style="color: #007700">) & </span><span style="color: #0000BB">0xFF</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$g </span><span style="color: #007700">= (</span><span style="color: #0000BB">$rgb </span><span style="color: #007700">>> </span><span style="color: #0000BB">8</span><span style="color: #007700">) & </span><span style="color: #0000BB">0xFF</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= </span><span style="color: #0000BB">$rgb </span><span style="color: #007700">& </span><span style="color: #0000BB">0xFF</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$r</span><span style="color: #007700">, </span><span style="color: #0000BB">$g</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p>The above example will output something similar to:</p></div> <div class="example-contents"><pre><div class="cdata"><pre>int(119)int(123)int(180)</pre></div> </pre></div> </div> <div class="example"> <p><b>Example #2 Human-readable RGB values using <a href="function.imagecolorsforindex.html" class="function">imagecolorsforindex()</a></b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefrompng</span><span style="color: #007700">(</span><span style="color: #DD0000">"php.png"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$rgb </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorat</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">10</span><span style="color: #007700">, </span><span style="color: #0000BB">15</span><span style="color: #007700">);<br /><br />list(</span><span style="color: #0000BB">$r</span><span style="color: #007700">, </span><span style="color: #0000BB">$g</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">, </span><span style="color: #0000BB">$alpha</span><span style="color: #007700">) = </span><span style="color: #0000BB">imagecolorsforindex</span><span style="color: #007700">(</span><span style="color: #0000BB">$rgb</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$r</span><span style="color: #007700">, </span><span style="color: #0000BB">$g</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">, </span><span style="color: #0000BB">$alpha</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="example-contents"><pre><div class="cdata"><pre>int(119)int(123)int(180)int(127)</pre></div> </pre></div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.imagecolorset.html" class="function" rel="rdfs-seeAlso">imagecolorset()</a></li> <li class="member"><a href="function.imagecolorsforindex.html" class="function" rel="rdfs-seeAlso">imagecolorsforindex()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagecolorallocatealpha.html">imagecolorallocatealpha</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagecolorclosest.html">imagecolorclosest</a></div> <div class="up"><a href="ref.image.html">GD Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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