This tutorial shows you how to crop images on the fly using PHP. The aspect ratio is preserved so that the images are not distorted. You either display the cropped image on the fly (as in the demo below) or save the cropped image.

Normal:

Cropped To 100px by 100px:

In order for this to work, you will need to have PHP installed with the GD library installed.

Option 1: Cropping And Displaying On The Fly

Create a file called crop.php with the following code:

<?
header ("Content-type: image/jpeg");
$file_name=$_GET['f'];
$crop_height=$_GET['h'];
$crop_width=$_GET['w'];
$file_type= explode('.', $file_name);
$file_type = $file_type[count($file_type) -1];
$file_type=strtolower($file_type);

$original_image_size = getimagesize($file_name);
$original_width = $original_image_size[0];
$original_height = $original_image_size[1];

if($file_type=='jpg')
{
$original_image_gd = imagecreatefromjpeg($file_name);
}

if($file_type=='gif')
{ $original_image_gd = imagecreatefromgif($file_name);
}

if($file_type=='png')
{
$original_image_gd = imagecreatefrompng($file_name);
}

$cropped_image_gd = imagecreatetruecolor($crop_width, $crop_height);
$wm = $original_width /$crop_width;
$hm = $original_height /$crop_height;
$h_height = $crop_height/2;
$w_height = $crop_width/2;

if($original_width > $original_height )
{
$adjusted_width =$original_width / $hm;
$half_width = $adjusted_width / 2;
$int_width = $half_width - $w_height;

imagecopyresampled($cropped_image_gd ,$original_image_gd ,-$int_width,0,0,0, $adjusted_width, $crop_height, $original_width , $original_height );
}
elseif(($original_width < $original_height ) || ($original_width == $original_height ))
{
$adjusted_height = $original_height / $wm;
$half_height = $adjusted_height / 2;
$int_height = $half_height - $h_height;

imagecopyresampled($cropped_image_gd , $original_image_gd ,0,-$int_height,0,0, $crop_width, $adjusted_height, $original_width , $original_height );
}
else {

imagecopyresampled($cropped_image_gd , $original_image_gd ,0,0,0,0, $crop_width, $crop_height, $original_width , $original_height );
}
imagejpeg($cropped_image_gd);

?>

The above script will take three parameters:
h= the desired height of cropped image (in pixels)
w= the desired width of cropped image (in pixels)
f= the filename of original image - use the correct path if necessary

To display the image example:

<img src="crop.php?h=100&w=100&f=bmw.jpg" />

Option 2: Saving The Cropped Image Only

1. Remove or comment out the first line of the script.
2. Replace the last two lines of the script with:
$dest ="test/bmw_cropped.jpg"; //edit filename for cropped image
//use the correct path if necessary
imagejpeg($cropped_image_gd ,$dest,100);