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>imagecreatefrompng</H1
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><P
> (PHP 3 >= 3.0.13, PHP 4, PHP 5)</P
>imagecreatefrompng -- 从 PNG 文件或 URL 新建一图像</DIV
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><H2
>说明</H2
>resource <B
CLASS="methodname"
>imagecreatefrompng</B
> ( string filename )<BR
></BR
><P
> <B
CLASS="function"
>imagecreatefrompng()</B
>
返回一图像标识符，代表了从给定的文件名取得的图像。
</P
><P
> <B
CLASS="function"
>imagecreatefrompng()</B
>
在失败时返回一个空字符串，并且输出一条错误信息，不幸地在浏览器中显示为断链接。为减轻调试工作下面的例子会产生一个错误
<ACRONYM
CLASS="acronym"
>PNG</ACRONYM
>：
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>例 1. 处理创建过程中的错误</B
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><code><font color="#000000">
<font color="#0000BB"><?php<br /></font><font color="#007700">function </font><font color="#0000BB">LoadPNG</font><font color="#007700">(</font><font color="#0000BB">$imgname</font><font color="#007700">)<br />{<br /> </font><font color="#0000BB">$im </font><font color="#007700">= @</font><font color="#0000BB">imagecreatefrompng</font><font color="#007700">(</font><font color="#0000BB">$imgname</font><font color="#007700">); </font><font color="#FF8000">/* Attempt to open */<br /> </font><font color="#007700">if(!</font><font color="#0000BB">$im</font><font color="#007700">) { </font><font color="#FF8000">/* See if it failed */<br /> </font><font color="#0000BB">$im </font><font color="#007700">= </font><font color="#0000BB">imagecreatetruecolor</font><font color="#007700">(</font><font color="#0000BB">150</font><font color="#007700">, </font><font color="#0000BB">30</font><font color="#007700">); </font><font color="#FF8000">/* Create a blank image */<br /> </font><font color="#0000BB">$bgc </font><font color="#007700">= </font><font color="#0000BB">imagecolorallocate</font><font color="#007700">(</font><font color="#0000BB">$im</font><font color="#007700">, </font><font color="#0000BB">255</font><font color="#007700">, </font><font color="#0000BB">255</font><font color="#007700">, </font><font color="#0000BB">255</font><font color="#007700">);<br /> </font><font color="#0000BB">$tc </font><font color="#007700">= </font><font color="#0000BB">imagecolorallocate</font><font color="#007700">(</font><font color="#0000BB">$im</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">);<br /> </font><font color="#0000BB">imagefilledrectangle</font><font color="#007700">(</font><font color="#0000BB">$im</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#0000BB">0</font><font color="#007700">, </font><font color="#0000BB">150</font><font color="#007700">, </font><font color="#0000BB">30</font><font color="#007700">, </font><font color="#0000BB">$bgc</font><font color="#007700">);<br /> </font><font color="#FF8000">/* Output an errmsg */<br /> </font><font color="#0000BB">imagestring</font><font color="#007700">(</font><font color="#0000BB">$im</font><font color="#007700">, </font><font color="#0000BB">1</font><font color="#007700">, </font><font color="#0000BB">5</font><font color="#007700">, </font><font color="#0000BB">5</font><font color="#007700">, </font><font color="#DD0000">"Error loading $imgname"</font><font color="#007700">, </font><font color="#0000BB">$tc</font><font color="#007700">);<br /> }<br /> return </font><font color="#0000BB">$im</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
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><B
>提示: </B
>如果<A
HREF="ref.filesystem.html#ini.allow-url-fopen"
>“fopen wrappers”</A
>已经被激活，则在本函数中可以把
URL 作为文件名来使用。请参阅 <A
HREF="function.fopen.html"
><B
CLASS="function"
>fopen()</B
></A
>
函数来获取怎样指定文件名的详细信息以及支持 URL 封装协议的列表：<A
HREF="wrappers.html"
>附录 N</A
>。</P
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>警告</B
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>Windows 版本的 PHP
在 4.3.0 版之前不支持本函数的远程文件访问，即使
<A
HREF="ref.filesystem.html#ini.allow-url-fopen"
>allow_url_fopen</A
> 选项已被激活。</P
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