function.imagecolorclosestalpha.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 closest color to the specified color + alpha</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.imagecolorclosest.html">imagecolorclosest</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagecolorclosesthwb.html">imagecolorclosesthwb</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.imagecolorclosestalpha" class="refentry"> <div class="refnamediv"> <h1 class="refname">imagecolorclosestalpha</h1> <p class="verinfo">(PHP 4 >= 4.0.6, PHP 5)</p><p class="refpurpose"><span class="refname">imagecolorclosestalpha</span> — <span class="dc-title">Get the index of the closest color to the specified color + alpha</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>imagecolorclosestalpha</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$image</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$red</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$green</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$blue</tt></span> , <span class="methodparam"><span class="type">int</span> <tt class="parameter">$alpha</tt></span> )</div> <p class="para rdfs-comment"> Returns the index of the color in the palette of the image which is "closest" to the specified <acronym title="Red-Green-Blue">RGB</acronym> value and <i><tt class="parameter">alpha</tt></i> level. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt><span class="term"><i><tt class="parameter">image</tt></i></span><dd><p class="para">An image resource, returned by one of the image creation functions, such as <a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a>.</p></dd></dt> <dt> <span class="term"><i><tt class="parameter">red</tt></i></span> <dd> <p class="para"> Value of red component. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">green</tt></i></span> <dd> <p class="para"> Value of green component. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">blue</tt></i></span> <dd> <p class="para"> Value of blue component. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">alpha</tt></i></span> <dd> <p class="para"> A value between <i>0</i> and <i>127</i>. <i>0</i> indicates completely opaque while <i>127</i> indicates completely transparent. </p> </dd> </dt> </dl> The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF. </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the index of the closest color in the palette. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Search for a set of colors in an image</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Start with an image and convert it to a palette-based image<br /></span><span style="color: #0000BB">$im </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefrompng</span><span style="color: #007700">(</span><span style="color: #DD0000">'figures/imagecolorclosest.png'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagetruecolortopalette</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">, </span><span style="color: #0000BB">255</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Search colors (RGB)<br /></span><span style="color: #0000BB">$colors </span><span style="color: #007700">= array(<br /> array(</span><span style="color: #0000BB">254</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">154</span><span style="color: #007700">, </span><span style="color: #0000BB">50</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">153</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">188</span><span style="color: #007700">, </span><span style="color: #0000BB">127</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">153</span><span style="color: #007700">, </span><span style="color: #0000BB">90</span><span style="color: #007700">, </span><span style="color: #0000BB">145</span><span style="color: #007700">, </span><span style="color: #0000BB">0</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">255</span><span style="color: #007700">, </span><span style="color: #0000BB">137</span><span style="color: #007700">, </span><span style="color: #0000BB">92</span><span style="color: #007700">, </span><span style="color: #0000BB">84</span><span style="color: #007700">)<br />);<br /><br /></span><span style="color: #FF8000">// Loop through each search and find the closest color in the palette.<br />// Return the search number, the search RGB and the converted RGB match<br /></span><span style="color: #007700">foreach(</span><span style="color: #0000BB">$colors </span><span style="color: #007700">as </span><span style="color: #0000BB">$id </span><span style="color: #007700">=> </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorclosestalpha</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">], </span><span style="color: #0000BB">$rgb</span><span style="color: #007700">[</span><span style="color: #0000BB">3</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecolorsforindex</span><span style="color: #007700">(</span><span style="color: #0000BB">$im</span><span style="color: #007700">, </span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #DD0000">"({$result['red']}, {$result['green']}, {$result['blue']}, {$result['alpha']})"</span><span style="color: #007700">;<br /><br /> echo </span><span style="color: #DD0000">"#$id: Search ($rgb[0], $rgb[1], $rgb[2], $rgb[3]); Closest match: $result.\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">imagedestroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$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="example-contents"><pre><div class="cdata"><pre>#0: Search (254, 145, 154, 50); Closest match: (252, 150, 148, 0).#1: Search (153, 145, 188, 127); Closest match: (148, 150, 196, 0).#2: Search (153, 90, 145, 0); Closest match: (148, 90, 156, 0).#3: Search (255, 137, 92, 84); Closest match: (252, 150, 92, 0).</pre></div> </pre></div> </div> </p> </div> <div class="refsect1 notes"> <h3 class="title">Notes</h3> <blockquote><p><b class="note">Note</b>: <span class="simpara">This function requires GD 2.0.1 or later (2.0.28 or later is recommended).</span></p></blockquote> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.imagecolorexactalpha.html" class="function" rel="rdfs-seeAlso">imagecolorexactalpha()</a></li> <li class="member"><a href="function.imagecolorclosest.html" class="function" rel="rdfs-seeAlso">imagecolorclosest()</a></li> <li class="member"><a href="function.imagecolorclosesthwb.html" class="function" rel="rdfs-seeAlso">imagecolorclosesthwb()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagecolorclosest.html">imagecolorclosest</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagecolorclosesthwb.html">imagecolorclosesthwb</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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