PHP 图像处理

爱被打了一巴掌 2024-04-07 13:52 93阅读 0赞

PHP 提供了丰富的图像处理函数，主要包括：

<table> 
 <tbody> 
  <tr> 
   <th>函数</th> 
   <th>描述</th> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-gd-info.html" title="gd_info()" rel="nofollow">gd_info()</a></td> 
   <td>取得当前安装的 GD 库的信息</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-getimagesize.html" title="getimagesize()" rel="nofollow">getimagesize()</a></td> 
   <td>获取图像信息</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-getimagesizefromstring.html" title="getimagesizefromstring()" rel="nofollow">getimagesizefromstring()</a></td> 
   <td>获取图像信息</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-image-type-to-extension.html" title="image_type_to_extension()" rel="nofollow">image_type_to_extension()</a></td> 
   <td>获取图片后缀</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-image2wbmp.html" title="image_type_to_mime_type()" rel="nofollow">image_type_to_mime_type()</a></td> 
   <td>返回图像的 MIME 类型</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-image2wbmp.html" title="image2wbmp()" rel="nofollow">image2wbmp()</a></td> 
   <td>输出WBMP图片</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imageaffine.html" title="imageaffine()" rel="nofollow">imageaffine()</a></td> 
   <td>返回经过仿射变换后的图像</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imageaffinematrixconcat.html" title="imageaffinematrixconcat()" rel="nofollow">imageaffinematrixconcat()</a></td> 
   <td>连接两个矩阵</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imageaffinematrixget.html" title="imageaffinematrixget()" rel="nofollow">imageaffinematrixget()</a></td> 
   <td>获取矩阵</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagealphablending.html" title="imagealphablending()" rel="nofollow">imagealphablending()</a></td> 
   <td>设定图像的混色模式</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imageantialias.html" title="imageantialias()" rel="nofollow">imageantialias()</a></td> 
   <td>是否使用抗锯齿（antialias）功能</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagearc.html" title="imagearc()" rel="nofollow">imagearc()</a></td> 
   <td>画椭圆弧</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagechar.html" title="imagechar()" rel="nofollow">imagechar()</a></td> 
   <td>写出横向字符</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecharup.html" title="imagecharup()" rel="nofollow">imagecharup()</a></td> 
   <td>垂直地画一个字符</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorallocate.html" title="imagecolorallocate()" rel="nofollow">imagecolorallocate()</a></td> 
   <td>为一幅图像分配颜色</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorallocatealpha.html" title="imagecolorallocatealpha()" rel="nofollow">imagecolorallocatealpha()</a></td> 
   <td>为一幅图像分配颜色和透明度</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorat.html" title="imagecolorat()" rel="nofollow">imagecolorat()</a></td> 
   <td>取得某像素的颜色索引值</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorclosest.html" title="imagecolorclosest()" rel="nofollow">imagecolorclosest()</a></td> 
   <td>取得与指定的颜色最接近的颜色的索引值</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorclosestalpha.html" title="imagecolorclosestalpha()" rel="nofollow">imagecolorclosestalpha()</a></td> 
   <td>取得与指定的颜色加透明度最接近的颜色的索引</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagecolorclosesthwb.html" title="imagecolorclosesthwb()" rel="nofollow">imagecolorclosesthwb()</a></td> 
   <td>取得与指定的颜色最接近的色度的黑白色的索引</td> 
  </tr> 
  <tr> 
   <td><a href="https://www.runoob.com/php/php-imagesx-imagesy.html" title="imagesx() 、imagesy()" rel="nofollow">imagesx() 、imagesy()</a></td> 
   <td>获取图像宽度与高度</td> 
  </tr> 
 </tbody> 
</table>

### GD 库 ###

使用 PHP 图像处理函数，需要加载 GD 支持库。请确定 php.ini 加载了 GD 库：

Window 服务器上：

>     extension = php_gd2.dll

Linux 和 Mac 系统上:

>     extension = php_gd2.so

使用 gd\_info() 函数可以查看当前安装的 GD 库的信息：

>     <?php
>     var_dump(gd_info());
>     ?>

输出大致如下：

array(12) {
      ["GD Version"]=>
      string(26) "bundled (2.1.0 compatible)"
      ["FreeType Support"]=>
      bool(true)
      ["FreeType Linkage"]=>
      string(13) "with freetype"
      ["T1Lib Support"]=>
      bool(false)
      ["GIF Read Support"]=>
      bool(true)
      ["GIF Create Support"]=>
      bool(true)
      ["JPEG Support"]=>
      bool(true)
      ["PNG Support"]=>
      bool(true)
      ["WBMP Support"]=>
      bool(true)
      ["XPM Support"]=>
      bool(false)
      ["XBM Support"]=>
      bool(true)
      ["JIS-mapped Japanese Font Support"]=>
      bool(false)
    }