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47 lines
3.8 KiB
HTML
47 lines
3.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>取得某像素的颜色索引值</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.imagecolorat" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">imagecolorat</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">imagecolorat</span> — <span class="dc-title">取得某像素的颜色索引值</span></p>
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</div>
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<div class="refsect1 unknown-seealsp" id="refsect1-function.imagecolorat-unknown-seealsp">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>imagecolorat</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$x</code></span>
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, <span class="methodparam"><span class="type">int</span> <code class="parameter">$y</code></span>
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) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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返回 <code class="parameter">image</code> 所指定的图形中指定位置像素的颜色索引值。
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</p>
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<p class="para">
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如果 PHP 编译时加上了 GD 库 2.0
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或更高的版本并且图像是真彩色图像，则本函数以整数返回该点的 RGB
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值。用移位加掩码来取得红，绿，蓝各自成分的值：
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<div class="example" id="example-3664">
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<p><strong>Example #1 取得各自的 RGB 值</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$im </span><span style="color: #007700">= </span><span style="color: #0000BB">ImageCreateFromPng</span><span style="color: #007700">(</span><span style="color: #DD0000">"rockym.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">100</span><span style="color: #007700">, </span><span style="color: #0000BB">100</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 /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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<p class="para">
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参见 <span class="function"><a href="imagecolorset.html" class="function">imagecolorset()</a></span> 和
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<span class="function"><a href="imagecolorsforindex.html" class="function">imagecolorsforindex()</a></span>。
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</p>
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</div>
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</div></div></div></body></html> |