function.imagesavealpha.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>Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images</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.imagerotate.html">imagerotate</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagesetbrush.html">imagesetbrush</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.imagesavealpha" class="refentry"> <div class="refnamediv"> <h1 class="refname">imagesavealpha</h1> <p class="verinfo">(PHP 4 >= 4.3.2, PHP 5)</p><p class="refpurpose"><span class="refname">imagesavealpha</span> — <span class="dc-title">Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><b><b>imagesavealpha</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$image</tt></span> , <span class="methodparam"><span class="type">bool</span> <tt class="parameter">$saveflag</tt></span> )</div> <p class="para rdfs-comment"> <b>imagesavealpha()</b> sets the flag to attempt to save full alpha channel information (as opposed to single-color transparency) when saving PNG images. </p> <p class="para"> You have to unset alphablending (<i>imagealphablending($im, false)</i>), to use it. </p> <p class="para"> Alpha channel is not supported by all browsers, if you have problem with your browser, try to load your script with an alpha channel compliant browser, e.g. latest Mozilla. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt><span class="term"><i><tt class="parameter">image</tt></i></span><dd><p class="para">An image resource, returned by one of the image creation functions, such as <a href="function.imagecreatetruecolor.html" class="function">imagecreatetruecolor()</a>.</p></dd></dt> <dt> <span class="term"><i><tt class="parameter">saveflag</tt></i></span> <dd> <p class="para"> Whether to save the alpha channel or not. Default to <b><tt>FALSE</tt></b>. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <b><tt>TRUE</tt></b> on success or <b><tt>FALSE</tt></b> on failure. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>imagesavealpha()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Load a png image with alpha channels<br /></span><span style="color: #0000BB">$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">// Do required operations<br /><br />// Turn off alpha blending and set alpha flag<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">// Output image to browser<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></span></code></div> </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.imagealphablending.html" class="function" rel="rdfs-seeAlso">imagealphablending()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.imagerotate.html">imagerotate</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.imagesetbrush.html">imagesetbrush</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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