侠岚之弋痕夕

黄智勇

PHP exif_imagetype note #1　　
Windows users: If you get the fatal error "Fatal error:  Call to undefined function exif_imagetype()", and you have enabled php_exif.dll, make sure you enable php_mbstring.dll.
　　You must put mbstring before exif in the php.ini, i.e.:
　　

　　
extension=php_mbstring.dll
　　
extension=php_exif.dll
　　

　　
You can check whether this has worked by calling () and searching for exif.
　　
PHP exif_imagetype note #2
　　
If the function exif_imagetype() is not available,
　　
you can try the following workaround:
　　

　　
if ( ! function_exists( 'exif_imagetype' ) ) {
　　function exif_imagetype ( $filename ) {
　　if ( ( list($width, $height, $type, $attr) = getimagesize( $filename ) ) !== false ) {
　　return $type;
　　}
　　return false;
　　}
　　
}
　　
PHP exif_imagetype note #3
　　
By trial and error, it seems that a  has to be 12 bytes or larger in order to avoid a "Read error!".  Here's a work-around to avoid an error being thrown:
　　

　　
// exif_imagetype throws "Read error!" if file is too small
　　
if (filesize($uploadfile) > 11)
　　$mimetype = exif_imagetype($uploadfile);
　　
else
　　$mimetype = false;
　　
PHP exif_imagetype note #4

　　
Seems to give a 'Read error' warning if the>　　
PHP exif_imagetype note #5

　　
libexif can also be used to parse image info out of>　　

　　
exif_read_data("mp3_with_2.4ID3TAGS, '', true, false);
　　
PHP exif_imagetype note #6

　　
After looking for hours, I found a very good source for exif>
　　
It lists exif specifications (pdf), a few good links to exif>