Flood-filling
There are four options for floodfilling which are explained below.

- The bounded flood-fill takes the point on which the user clicks and works
outwards in all directions changing the pixels until it meets
a boundary where there is a color that is different from the color originally clicked
on. Unfortunately this is a very memory intensive operation and the program
deliberately limits this type of flood fill to 10,000 pixel changes. Even with this
limit and insufficient memory a fatal memory condition may occur. If you must fill
a large image the saturation filling is recommended.
- Saturation filling is much more straight forward. IconPainter will go through all
the pixels in the image that are the same color as the pixel clicked on, and change
them to the new color. Boundaries between colors are ignored. This technique can
be quite useful in providing color gradient shading that is done behind objects already
in an image.
- Filling the entire background will perform a flood-fill for every pixel whose
color is the background color. This is a useful option if you have created an image with
some shapes on it but want to change just the background color. As long as the new fill color
is not too different from the original background, any antialiasing on the shapes
will still look good.
- Filling the entire foreground will perform a flood-fill for every pixel whose
color is not the background color. This can be useful for changing the colors
of predrawn shapes but has the disadvantage that it will not reproduce any antialiasing
on the original shapes.