problem with offset in geometry for method "extent" in magick++

[christophe milard]

Hi,

If, from the command shell, I run:
convert b.jpg -extent 200x200-50-50 c.jpg
where b is a 100x100 picture, then b gets centered in my 200x200 c.jpg. As
expected.

If I use magick++ (the C++ interface), and run the extent method with the
same geometry specification, the resulting image has the correct size
(200x200) but the original image is placed at the top left corner:
It behaves as is the xoffset and yoffset were 0...

code extract:
ss_geometry << new_size_x << "x" << new_size_y << "-" <<
(new_size_x-kenburns_im->columns())/2 << "-" <<
(new_size_y-kenburns_im->rows())/2;
Geometry geometry(ss_geometry.str());
kenburns_im->extent(geometry);


I am using this:
ImageMagick-c++-6.5.8.10-6.fc13.i686
ImageMagick-devel-6.5.8.10-6.fc13.i686
ImageMagick-c++-devel-6.5.8.10-6.fc13.i686
ImageMagick-6.5.8.10-6.fc13.i686

Where the extent method only seems to expect one single geometry parameter
(no gravity or background color as described in new doc).

Did I miss something obvious?

Thanks in advance