I know it's not possible to grow a selection and keep the sharp corners with the normal "Grow Selection" tool, what I want to know is if there is a way around it... No matter what I do I always get round corners!

- Selection to path, save selection to channel and Select/none
- On transparent layer, stroke the path with the required line width (twice the required growth). Important: open the "Line style" options and make sure you select the "Miter" join.
- Alpha to selection (you selection become the line you stoked)
- In the Channels, right click the saved selection and "Add to selection"
- You can discard the layer with the stroke.

Edit: unfortunately this doesn't work 100% of the time. This may require some twiddling of the generated path. But when it works it works well

Scaling shapes/pathes/etc. will only work if the shape is regular and centered.

If your selection is not soft, there is a work around also stroking paths that I use that I find a bit simpler than ofnuts' suggestion above...

1) Save the selection to a path.
2) Toggle quickmask mode (Shift Q) Ref: http://docs.gimp.org/en/gimp-image-wind ... utton.html
3) With your foreground white, stroke the path. Set the Line Width to 2x the size you want to grow the selection, Solid colour, cap style: butt, join style: miter, slide miter limit to the max, and check anti-aliasing.
4) Toggle quickmask off.

Your selection will now be "grown".

You can also stroke with black, rather than white to "shrink" the selection by the same fashion.

Here is an example. The yellow was the initial selection, the black is after growing it in this manner, and the grey is after shrinking it in this manner:


A couple of the corners get bollixed up, especially if they are real sharp. Using the advanced selection to path might let you get a cleaner path that would end up working better.

Unfortunately, I know of no way to script this, as it appears that the stroke path using a line is not exposed in the pdb.

-Rob A>

*bows*

Stroking the path on the quickmask... never thought about that...

Yes, not be able to use the stroke-line in a script is sorely missed.

Thanks for all suggestions!