[magick-users] GetFillColor and extract_info

[Rick Mabry]

In the function GetFillColor, found in draw-private.h (ver 6.3.0), there is 
the line

 fill_color=AcquireOnePixel(pattern,
    (x-pattern->extract_info.x) % pattern->columns,
    (y-pattern->extract_info.y) % pattern->rows,&pattern->exception);

In what ways is extract_info intended to be used here? It looks as if it's 
purpose is to provide an offset to the Draw functions when used with the tile 
option, which is exactly what I was hunting for. How can the offset be handed 
to extract_info struct via PerlMagick or the command line? If I use it in 
C++, what unintended mischief might I do?

Thanks,
Rick