php getimagesize length and width detection code for uploaded images_PHP tutorial

getimagesize — Get image size
Description
array getimagesize ( string $filename [, array &$imageinfo ] )
getimagesize() function will measure any GIF, JPG, PNG, SWF, SWC, PSD, TIFF, The size of a BMP, IFF, JP2, JPX, JB2, JPC, XBM or WBMP image file and returns the dimensions of the image along with the file type and a height/width text string that can be used in an tag in a normal HTML file.
If the image specified by filename cannot be accessed or is not a valid image, getimagesize() will return FALSE and generate an E_WARNING level error.
Note: Support for JPC, JP2, JPX, JB2, XBM and WBMP is available since PHP 4.3.2. Support for SWC is available since PHP 4.3.0. Support for TIFF was added in PHP 4.2.0.
Note: JPEG 2000 support was added in PHP 4.3.2. Note that JPC and JP2 can have different color depth components. In this case, the value of "bits" is the highest bit depth encountered. Additionally, a JP2 file may contain multiple JPEG 2000 code streams, in which case getimagesize() returns the value of the first code stream encountered in the top level of the file.
Note: This function does not require the GD image library.
Returns an array with four cells. Index 0 contains the pixel values ​​for the width of the image, and index 1 contains the pixel values ​​for the height of the image. Index 2 is the tag of the image type: 1 = GIF, 2 = JPG, 3 = PNG, 4 = SWF, 5 = PSD, 6 = BMP, 7 = TIFF(intel byte order), 8 = TIFF(motorola byte order), 9 = JPC, 10 = JP2, 11 = JPX, 12 = JB2, 13 = SWC, 14 = IFF, 15 = WBMP, 16 = XBM. These tags correspond to the new IMAGETYPE constant added in PHP 4.3.0. Index 3 is a text string with the content "height="yyy" width="xxx"" and can be used directly in the IMG tag.
Example #1 getimagesize (file)

Copy code The code is as follows:

list ($width, $height, $type, $attr) = getimagesize("img/flag.jpg");
echo "";
?>

URL support was added in PHP 4.0.5.
Example #2 getimagesize(URL)

Copy code The code is as follows:

$ size = getimagesize("http://www.jb51.net/images/logo.gif");
// if the file name has space in it, encode it properly
$size = getimagesize("http ://www.example.com/gifs/lo go.gif");
?>

For JPG images, two more indices are returned: channels and bits. channels has a value of 3 for RGB images and 4 for CMYK images. bits is the number of bits per color.
As of PHP 4.3.0, bits and channels also exist for other image types. But these values ​​can be confusing. For example, GIFs always use 3 channels per pixel, but for animated GIFs the number of bits per pixel cannot be calculated from the global color table.
Some formats may contain no images or contain multiple images. In this case, getimagesize() may not be used to accurately determine the size of the image. At this point getimagesize() will return zero for width and height.
Since PHP 4.3.0, getimagesize() also returns an additional parameter mime, conforming to the MIME type of the image. This information can be used to send the correct information in the HTTP Content-type header:
Example #3 getimagesize() and MIME type

Copy code The code is as follows:

$size = getimagesize($filename);
$fp=fopen($filename, "rb");
if ($ size && $fp) {
header("Content-type: {$size['mime']}");
fpassthru($fp);
exit;
} else {
// error
}
?>

The optional imageinfo parameter allows to extract some extended information from the image file. Currently this will return the different JPG APP IDs in an associative array. Some programs use these APP identifiers to embed textual information in images. A very common one is the IPTC » http://www.iptc.org/ information embedded in the APP13 logo. The iptcparse() function can be used to parse the binary APP13 identifier into readable information.
Example #4 getimagesize() returns IPTC

Copy code The code is as follows:

$size = getimagesize("testimg.jpg", &$info);
if (isset($info["APP13"])) {
$iptc = iptcparse($info["APP13"]);
var_dump($iptc);
}
?>

php has an image GD library getimagesize() function.
There is a function to get the basic information of the image.
getimagesize()
$img=getimagesize('image source');
Width is=$img[0];
Height is=$img[1];
Format is= $img[2];
If you want it simple, it can be simpler like

Copy the code The code is as follows:

$picpath = 'http://www.jb51.net/images/logo.gif';
$array = getimagesize($picpath);
print_r( $array );
echo 'The image width is '.$array[0];
echo 'The height of the picture is'.$array[1];
echo 'The format of the picture is'.$array[2];

/ /Another code that uses getimagesize to display thumbnails

Copy code The code is as follows:

function show_thumbnail($file)
{
$max = 200 // Max. thumbnail width and height
$size = getimagesize($file);
if ( $size[0] <= $max && $size[1] <= $max )
{
$ret = '';
}
else
{
$k = ( $size[0] >= $size[1] ) ? $size[0] / $max : $size[1] / $max;
$ret = '';
$ret .= '';
}
return $ret;
}

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