php gd imagecreatefromstring() 和图像 mime 类型

Question

is there a way to use imagecreatefromstring() and get somehow what is the image type?

Answer 1

When you use imagecreatefrom... methods, the image is loaded into memory as the uncompressed bitmap. there is not really a image type at this point. you can save it back out as whatever type you wish using the image... function.

$img = imagecreatefromstring($data);

imagepng($img, "file path and name");

imagedestroy($img);

http://us2.php.net/manual/en/function.imagecreatefromstring.php

Answer 2

Before using imagecreatefromstring( $string ) , the actual $string you're providing as the argument for that function can be used to determine the image type:

$imgstring = "...";
// imagecreatefromstring( $imgstring ); -- DON'T use this just yet

$f = finfo_open();

$mime_type = finfo_buffer($f, $imgstring, FILEINFO_MIME_TYPE);
// $mime_type will hold the MIME type, e.g. image/png

Credit: https://stackoverflow.com/a/6061602/3705191

You'll have to compare the string you get with the MIME type of common image files ( image/jpeg , image/png , image/gif , etc.).

$img = imagecreatefromstirng( $imgstring );

if( $mime_type == "image/png" )
  imagepng( $img, $filepath_to_save_to );
if( $mime_type == "image/jpeg" )
  imagejpeg( $img, $filepath_to_save_to );
// ...

Check this List of Common MIME Types for reference.