Re: flood fills

[Calum Benson <calum benson sun com>]

On Wed, 2002-12-18 at 16:18, Bryan Brown wrote:

> In the absence of such a Gtk function I've written my own rather
> unsophisticated function to do it, but it doesn't completely fill regions
> of arbitrary shape in one swell foop the way the Amiga did.

I don't know how the Amiga did it either, but the general algorithm for
flood-filling any arbitrary enclosed shape starting from some interior
point (x,y) is actually pretty easy:

floodFill (x,y, boundaryColour, fillColour)
{
        if pixel(x,y) != boundaryColour
        {
                set pixel(x,y)=fillColour;

                floodFill(x+1, y, boundaryColour, fillColour);
                floodFill(x-1, y, boundaryColour, fillColour);
                floodFill(x, y-1, boundaryColour, fillColour);
                floodFill(x, y+1, boundaryColour, fillColour);
        }
}

Obviously the downside is that it's highly recursive, so if you're
filling big areas you don't want to be running on a machine that's low
on memory...

Cheeri,
Calum.

-- 
CALUM BENSON, Usability Engineer       Sun Microsystems Ireland
mailto:calum benson sun com            GNOME Desktop Group
http://ie.sun.com                      +353 1 819 9771

Any opinions are personal and not necessarily those of Sun Microsystems