How to Offset and Duplicate Paths in GIMP

Creating uniform parallel vector lines in GIMP requires duplicating and offsetting an existing path. While GIMP does not feature a dedicated vector "offset" tool like some vector-focused illustration software, you can achieve precise, uniform parallel paths natively by converting your path to a selection, modifying the selection's boundaries, and converting it back into a vector path.

Step 1: Select Your Base Path

1. Open the Paths dialog dock (accessible via Windows > Dockable Dialogs > Paths if not already visible).
2. Click on the path you want to duplicate to make it the active path.

Step 2: Convert the Path to a Selection

1. Go to the top menu and select Select > From Path (or press Shift + V).
2. You will see the "marching ants" marquee outlining your path.

Step 3: Offset the Selection

1. To create an outward parallel line, go to Select > Grow...
2. To create an inward parallel line, go to Select > Shrink...
3. In the dialog box that appears, enter the exact distance (in pixels or your preferred measurement unit) you want between the original path and the new parallel line.
4. Click OK. The selection outline will shift uniformly away from or toward the original path.

Step 4: Convert the Selection Back to a Path

1. Go to Select > To Path.
2. Open the Paths dialog. A new path named "Selection" will appear in the list.
3. Make the new path visible by clicking the eye icon next to it.
4. Deselect your current selection by choosing Select > None (or pressing Shift + Ctrl + A).

Step 5: Adjust and Clean Up Open Paths

If the original path was an open stroke rather than a closed shape, growing the selection will create a closed loop around the original line:

1. Select the Paths Tool from the Toolbox (shortcut B).
2. Click on the newly generated path to display its nodes.
3. Hold Ctrl + Shift and click on any unwanted nodes or line segments (such as the rounded caps or opposite side) to delete them, leaving only your desired parallel line.