src/applications/files/PhabricatorImageTransformer.php

   1 <?php
   2
   3 /**
   4  * @task enormous Detecting Enormous Images
   5  * @task save     Saving Image Data
   6  */
   7 final class PhabricatorImageTransformer extends Phobject {
   8
   9
  10 /* -(  Saving Image Data  )-------------------------------------------------- */
  11
  12
  13   /**
  14    * Save an image resource to a string representation suitable for storage or
  15    * transmission as an image file.
  16    *
  17    * Optionally, you can specify a preferred MIME type like `"image/png"`.
  18    * Generally, you should specify the MIME type of the original file if you're
  19    * applying file transformations. The MIME type may not be honored if
  20    * Phabricator can not encode images in the given format (based on available
  21    * extensions), but can save images in another format.
  22    *
  23    * @param   resource  GD image resource.
  24    * @param   string?   Optionally, preferred mime type.
  25    * @return  string    Bytes of an image file.
  26    * @task save
  27    */
  28   public static function saveImageDataInAnyFormat($data, $preferred_mime = '') {
  29     $preferred = null;
  30     switch ($preferred_mime) {
  31       case 'image/gif':
  32         $preferred = self::saveImageDataAsGIF($data);
  33         break;
  34       case 'image/png':
  35         $preferred = self::saveImageDataAsPNG($data);
  36         break;
  37     }
  38
  39     if ($preferred !== null) {
  40       return $preferred;
  41     }
  42
  43     $data = self::saveImageDataAsJPG($data);
  44     if ($data !== null) {
  45       return $data;
  46     }
  47
  48     $data = self::saveImageDataAsPNG($data);
  49     if ($data !== null) {
  50       return $data;
  51     }
  52
  53     $data = self::saveImageDataAsGIF($data);
  54     if ($data !== null) {
  55       return $data;
  56     }
  57
  58     throw new Exception(pht('Failed to save image data into any format.'));
  59   }
  60
  61
  62   /**
  63    * Save an image in PNG format, returning the file data as a string.
  64    *
  65    * @param resource      GD image resource.
  66    * @return string|null  PNG file as a string, or null on failure.
  67    * @task save
  68    */
  69   private static function saveImageDataAsPNG($image) {
  70     if (!function_exists('imagepng')) {
  71       return null;
  72     }
  73
  74     // NOTE: Empirically, the highest compression level (9) seems to take
  75     // up to twice as long as the default compression level (6) but produce
  76     // only slightly smaller files (10% on avatars, 3% on screenshots).
  77
  78     ob_start();
  79     $result = imagepng($image, null, 6);
  80     $output = ob_get_clean();
  81
  82     if (!$result) {
  83       return null;
  84     }
  85
  86     return $output;
  87   }
  88
  89
  90   /**
  91    * Save an image in GIF format, returning the file data as a string.
  92    *
  93    * @param resource      GD image resource.
  94    * @return string|null  GIF file as a string, or null on failure.
  95    * @task save
  96    */
  97   private static function saveImageDataAsGIF($image) {
  98     if (!function_exists('imagegif')) {
  99       return null;
 100     }
 101
 102     ob_start();
 103     $result = imagegif($image);
 104     $output = ob_get_clean();
 105
 106     if (!$result) {
 107       return null;
 108     }
 109
 110     return $output;
 111   }
 112
 113
 114   /**
 115    * Save an image in JPG format, returning the file data as a string.
 116    *
 117    * @param resource      GD image resource.
 118    * @return string|null  JPG file as a string, or null on failure.
 119    * @task save
 120    */
 121   private static function saveImageDataAsJPG($image) {
 122     if (!function_exists('imagejpeg')) {
 123       return null;
 124     }
 125
 126     ob_start();
 127     $result = imagejpeg($image);
 128     $output = ob_get_clean();
 129
 130     if (!$result) {
 131       return null;
 132     }
 133
 134     return $output;
 135   }
 136
 137
 138 }