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이 문서에서는 PHP 중국어 웹사이트 매뉴얼 풀어 주다
(PHP 4 >= 4.3.0, PHP 5, PHP 7)
exif_imagetype — 判断一个图像的类型
$filename
)exif_imagetype() 读取一个图像的第一个字节并检查其签名。
本函数可用来避免调用其它 exif 函数用到了不支持的文件类型上或和 $_SERVER['HTTP_ACCEPT'] 结合使用来检查浏览器是否可以显示某个指定的图像。
filename
如果发现了恰当的签名则返回一个对应的常量,否则返回
FALSE
。返回值和 getimagesize()
返回的数组中的索引 2 的值是一样的,但本函数快得多。
版本 | 说明 |
---|---|
4.3.2 | 支持 JPC,JP2,JPX,JB2,XBM 以及 WBMP |
4.3.0 | 支持 SWC |
定义有以下常量,并代表了 exif_imagetype() 可能的返回值:
值 | 常量 |
---|---|
1 | IMAGETYPE_GIF |
2 | IMAGETYPE_JPEG |
3 | IMAGETYPE_PNG |
4 | IMAGETYPE_SWF |
5 | IMAGETYPE_PSD |
6 | IMAGETYPE_BMP |
7 | IMAGETYPE_TIFF_II (Intel 字节顺序) |
8 | IMAGETYPE_TIFF_MM (Motorola 字节顺序)
|
9 | IMAGETYPE_JPC |
10 | IMAGETYPE_JP2 |
11 | IMAGETYPE_JPX |
12 | IMAGETYPE_JB2 |
13 | IMAGETYPE_SWC |
14 | IMAGETYPE_IFF |
15 | IMAGETYPE_WBMP |
16 | IMAGETYPE_XBM |
Example #1 exif_imagetype() 例子
<?php
if ( exif_imagetype ( "image.gif" ) != IMAGETYPE_GIF ) {
echo "The picture is not a gif" ;
}
?>
[#1] vuatintac at yahoo dot com [2015-04-01 17:32:41]
to checking file is image, I used this:
function is_image($path)
{
$a = getimagesize($path);
$image_type = $a[2];
if(in_array($image_type , array(IMAGETYPE_GIF , IMAGETYPE_JPEG ,IMAGETYPE_PNG , IMAGETYPE_BMP)))
{
return true;
}
return false;
}
[#2] web-coder at ukr dot net [2014-12-01 13:44:43]
validate file exists and the image type
if(file_exists($path_image) && in_array(exif_imagetype($path_image),array(1, 2, 3, 6))){ ... }
[#3] sourabh dot deshmukh at snstech dot com [2013-12-10 13:42:46]
This functions showing up a warning message that "warnings stream does not support seeking". Is it related to size of file which you mentioned in earlier post or something else. Also how do I get rid of that warning?
[#4] christophe dot tournayre at univ*bpclermont dot Fr [2013-09-18 09:01:01]
Because I only want to check for jpeg or png from a memory string, this is my 2 functions that are quick and don't have any dependencies :
<?php
function is_jpeg(&$pict)
{
return (bin2hex($pict[0]) == 'ff' && bin2hex($pict[1]) == 'd8');
}
function is_png(&$pict)
{
return (bin2hex($pict[0]) == '89' && $pict[1] == 'P' && $pict[2] == 'N' && $pict[3] == 'G');
}
?>
[#5] admin at leonard !spam challis dot com [2010-11-03 08:02:44]
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 phpinfo() and searching for exif.
[#6] tom dot ghyselinck at telenet dot be [2008-01-13 01:36:23]
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 $type;
}
return false;
}
}
[#7] Tim [2007-11-19 08:40:07]
By trial and error, it seems that a file has to be 12 bytes or larger in order to avoid a "Read error!". Here's a work-around to avoid an error being thrown:
// exif_imagetype throws "Read error!" if file is too small
if (filesize($uploadfile) > 11)
$mimetype = exif_imagetype($uploadfile);
else
$mimetype = false;
[#8] [2006-11-09 16:43:11]
Seems to give a 'Read error' warning if the size of the file is very small (2 bytes). I think this is because it needs a min 3 bytes to determine the file type
[#9] tom at tomvergote dot be [2004-02-07 14:11:39]
libexif can also be used to parse image info out of id3 tags:
exif_read_data("mp3_with_2.4ID3TAGS, '', true, false);