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102 lines
5.5 KiB
HTML
102 lines
5.5 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>设置标记以在保存 PNG 图像时保存完整的 alpha 通道信息（与单一透明色相反）</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.imagesavealpha" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">imagesavealpha</h1>
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<p class="verinfo">(PHP 4 >= 4.3.2, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">imagesavealpha</span> — <span class="dc-title">设置标记以在保存 PNG 图像时保存完整的 alpha 通道信息（与单一透明色相反）</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.imagesavealpha-description">
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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>imagesavealpha</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$image</code></span>
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, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$saveflag</code></span>
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) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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<span class="function"><strong>imagesavealpha()</strong></span> 设置标记以在保存
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PNG 图像时保存完整的 alpha 通道信息（与单一透明色相反）。
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</p>
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<p class="para">
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要使用本函数，必须将 alphablending
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清位（<em>imagealphablending($im, false)</em>）。
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</p>
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<p class="para">
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不是所有的浏览器都支持 alpha 通道，如果在你的浏览器上碰到问题，试着用兼容
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alpha 通道的浏览器（例如最新版的 Mozilla）重新加载脚本。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.imagesavealpha-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">image</code></dt>
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<dd>
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<p class="para">由图象创建函数(例如<span class="function"><a href="imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a></span>)返回的图象资源。</p></dd>
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<dt>
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<code class="parameter">saveflag</code></dt>
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<dd>
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<p class="para">
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是否保存透明（alpha）通道。
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默认 <strong><code>FALSE</code></strong>。
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.imagesavealpha-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.imagesavealpha-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-3735">
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<p><strong>Example #1 <span class="function"><strong>imagesavealpha()</strong></span> 例子</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 /></span><span style="color: #FF8000">// 载入带 alpha 通道的 png 图像<br /></span><span style="color: #0000BB">$png </span><span style="color: #007700">= </span><span style="color: #0000BB">imagecreatefrompng</span><span style="color: #007700">(</span><span style="color: #DD0000">'./alphachannel_example.png'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 做些必须的操作<br /><br />// 关闭 alpha 渲染并设置 alpha 标志<br /></span><span style="color: #0000BB">imagealphablending</span><span style="color: #007700">(</span><span style="color: #0000BB">$png</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagesavealpha</span><span style="color: #007700">(</span><span style="color: #0000BB">$png</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 输出图像到浏览器<br /></span><span style="color: #0000BB">header</span><span style="color: #007700">(</span><span style="color: #DD0000">'Content-Type: image/png'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">imagepng</span><span style="color: #007700">(</span><span style="color: #0000BB">$png</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">imagedestroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$png</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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</div>
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<div class="refsect1 notes" id="refsect1-function.imagesavealpha-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数需要 GD 2.0.1 或更高版本(推荐 2.0.28 及更高版本)。</span></p></blockquote>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.imagesavealpha-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="imagealphablending.html" class="function" rel="rdfs-seeAlso">imagealphablending()</a> - 设定图像的混色模式</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |