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exif_imagetype (PHP 4 >= 4.3.0, PHP 5) exif_imagetype -- Determine the type of an image 说明int exif_imagetype ( string filename )
exif_imagetype() reads the first bytes of an image and
checks its signature.
exif_imagetype() can be used to avoid calls to other
exif functions with unsupported file types
or in conjunction with $_SERVER['HTTP_ACCEPT'] to check
whether or not the viewer is able to see a specific image in the browser.
参数
- filename
The image being checked.
返回值
When a correct signature is found, the appropriate constant value will be
returned otherwise the return value is FALSE. The return value is the
same value that getimagesize() returns in index 2 but
exif_imagetype() is much faster.
预定义常量
The following constants are defined, and represent possible
exif_imagetype() return values:
表格 1. Imagetype Constants | Value | Constant |
|---|
| 1 | IMAGETYPE_GIF | | 2 | IMAGETYPE_JPEG | | 3 | IMAGETYPE_PNG | | 4 | IMAGETYPE_SWF | | 5 | IMAGETYPE_PSD | | 6 | IMAGETYPE_BMP | | 7 | IMAGETYPE_TIFF_II (intel byte order) | | 8 |
IMAGETYPE_TIFF_MM (motorola byte order)
| | 9 | IMAGETYPE_JPC | | 10 | IMAGETYPE_JP2 | | 11 | IMAGETYPE_JPX | | 12 | IMAGETYPE_JB2 | | 13 | IMAGETYPE_SWC | | 14 | IMAGETYPE_IFF | | 15 | IMAGETYPE_WBMP | | 16 | IMAGETYPE_XBM |
例
例子 1. exif_imagetype() example |
<?php
if (exif_imagetype('image.gif') != IMAGETYPE_GIF) {
echo 'The picture is not a gif';
}
?>
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Exif