cropping with gd library

[whatson]

So I have

imagecopyresampled ($dst_image , $src_image, 0, 0, $src_x, $src_y, $new_width, $new_height, $image_width-$src_x, $image_height-$src_y);

src_x and src_y are the co-ordinates I want to crop the image from, but I am not sure how how to create the co-ordinates of where to cut them to - i.e. set the crop height and width. I have been working on this for hours testing every permutation under the sun, and cant figure it out. How is this done?

[phranque]

you'll have to calculate the width and height from the coordinates.

http://php.net/manual/en/function.imagecopyresampled.php [php.net]:

imagecopyresampled ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h )
...
imagecopyresampled() will take a rectangular area from src_image of width src_w and height src_h at position (src_x,src_y)...

[whatson]

Yes, I have been doing all that but I can't understand how to crop e.g. 50px from the left and 50px from the right, I can just do one or the other, but not both. If I was to crop 50 on each side, what are the two variables I need to adjust by 50?

[phranque]

$src_x would be 50 and$src_w would be ([source image width] - 100)