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phab/src/applications/files/PhabricatorImageTransformer.php
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PhabricatorImageTransformer.php
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<?php
/**
* @task enormous Detecting Enormous Images
* @task save Saving Image Data
*/
final class PhabricatorImageTransformer extends Phobject {
/* -( Saving Image Data )-------------------------------------------------- */
/**
* Save an image resource to a string representation suitable for storage or
* transmission as an image file.
*
* Optionally, you can specify a preferred MIME type like `"image/png"`.
* Generally, you should specify the MIME type of the original file if you're
* applying file transformations. The MIME type may not be honored if
* Phabricator can not encode images in the given format (based on available
* extensions), but can save images in another format.
*
* @param resource GD image resource.
* @param string? Optionally, preferred mime type.
* @return string Bytes of an image file.
* @task save
*/
public static function saveImageDataInAnyFormat($data, $preferred_mime = '') {
$preferred = null;
switch ($preferred_mime) {
case 'image/gif':
$preferred = self::saveImageDataAsGIF($data);
break;
case 'image/png':
$preferred = self::saveImageDataAsPNG($data);
break;
}
if ($preferred !== null) {
return $preferred;
}
$data = self::saveImageDataAsJPG($data);
if ($data !== null) {
return $data;
}
$data = self::saveImageDataAsPNG($data);
if ($data !== null) {
return $data;
}
$data = self::saveImageDataAsGIF($data);
if ($data !== null) {
return $data;
}
throw new Exception(pht('Failed to save image data into any format.'));
}
/**
* Save an image in PNG format, returning the file data as a string.
*
* @param resource GD image resource.
* @return string|null PNG file as a string, or null on failure.
* @task save
*/
private static function saveImageDataAsPNG($image) {
if (!function_exists('imagepng')) {
return null;
}
// NOTE: Empirically, the highest compression level (9) seems to take
// up to twice as long as the default compression level (6) but produce
// only slightly smaller files (10% on avatars, 3% on screenshots).
ob_start();
$result = imagepng($image, null, 6);
$output = ob_get_clean();
if (!$result) {
return null;
}
return $output;
}
/**
* Save an image in GIF format, returning the file data as a string.
*
* @param resource GD image resource.
* @return string|null GIF file as a string, or null on failure.
* @task save
*/
private static function saveImageDataAsGIF($image) {
if (!function_exists('imagegif')) {
return null;
}
ob_start();
$result = imagegif($image);
$output = ob_get_clean();
if (!$result) {
return null;
}
return $output;
}
/**
* Save an image in JPG format, returning the file data as a string.
*
* @param resource GD image resource.
* @return string|null JPG file as a string, or null on failure.
* @task save
*/
private static function saveImageDataAsJPG($image) {
if (!function_exists('imagejpeg')) {
return null;
}
ob_start();
$result = imagejpeg($image);
$output = ob_get_clean();
if (!$result) {
return null;
}
return $output;
}
}
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