[Gimp-developer] Enlarge image canvas with gimp_image _resize procedure

[Alessandro Francesconi <alessandrofrancesconi live it>]

I need to enlarge the area of an image using one of the available GIMP’s procedures. So, instead of using the 
GIMP’s graphical interface and this tool http://docs.gimp.org/en/gimp-image-resize.html, I want to be able to 
have the same effects on a C code.


The function that should be called is this one, right? 
http://oldhome.schmorp.de/marc/pdb/gimp_image_resize.html


But it works when I need to shrink the canvas: on a 640x480 image, if I input smaller values the canvas is 
actually cut. Instead, if I want to add a 20px transparent border along the area (so I type 680 and 520 px, 
also with consistent offset values), the function just returns the original image.


How does it work? Thanks

Ale