How PHP determines whether a GIF picture is a dynamic picture

Source: Internet
Author: User
Tags chr fread

Example

The code is as follows

/*
* Determine whether the picture is a dynamic picture (animation)
*/
function Isanimatedgif ($filename) {
$FP =fopen ($filename, ' RB ');
$filecontent =fread ($fp, FileSize ($filename));
Fclose ($FP);
Return Strpos ($filecontent, Chr (0x21). chr (0xff). chr (0x0b). ' NETSCAPE2.0 ') ===false?0:1;
}

Or do it.
Use PHP to determine if a GIF picture is animated (multiple frames)

The code is as follows
<?php
function Isanimatedgif ($filename)
{
$fp = fopen ($filename, ' RB ');
$filecontent = Fread ($fp, FileSize ($filename));
Fclose ($FP);
Return Strpos ($filecontent, Chr (0x21). chr (0xff). chr (0x0b). ' NETSCAPE2.0 ') = = = False?0:1;
}
Echo isanimatedgif ("51windows.gif");
?>

Example 2

GIF animations are gif89 formatted and find gif89 at the beginning of the file. But a lot of transparent pictures are also used in gif89 format,
Google to: You can check whether the file contains: Chr (0x21). chr (0xff). chr (0x0b). ' NETSCAPE2.0 '
Chr (0x21). Chr (0xff) is the header of an extended feature segment in a GIF image, and ' NETSCAPE2.0 ' is the name of the program that extends the function execution
The program code is as follows:

The code is as follows

<?php
function Check ($image) {
$content = file_get_contents ($image);
if (Preg_match ("/") Chr (0x21). chr (0xff). chr (0x0b). ' NETSCAPE2.0 '. ' /", $content)) {
return true;
}else{
return false;
}
}
if (check ('/home/lyy/luoyinyou/2.gif ')) {
Echo ' really animation ';
}else{
Echo ' is not animated ';
}
?>

The test found that it was sufficient to read 1024 bytes because the stream of data being read contains exactly the Chr (0x21). chr (0xff). chr (0x0b). ' NETSCAPE2.0 '

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