How to get the coordinates for a selection bounding box in Gimp

Question

I'll make a rectangle selection in image. I have to read the left, right, up and down dimensions of this selected region in full image. The following image is an example of this.

Edit:

Can we print the following variables in the window or debug screen?

Units in mm.

L = X of Selection Bounding Box
U = Y of Selection Bounding Box
D = H of Image - (H of Selection Bounding Box + U)
R = W of Image - (W of Selection Bounding Box + L)

Answer 1

This example image is 200px x 200px. If you don't know it, you can find the size by clicking Image > Canvas Size

The Crop Tool options show the X and Y position of the top left corner of the crop, and the X and Y size of the crop. So it's simple arithmetic to work out the distances.

Left = 33px

Up = 49px

Right = 200-33-129 = 38px

Down = 200-49-96 = 55px

Answer 2

A very basic python script that does it:

#!/usr/bin/env python
from gimpfu import *

def selectionMargins(image):
    selection,x1,y1,x2,y2=pdb.gimp_selection_bounds(image)
    if not selection:
        pdb.gimp_message("No selection")
    else:
        gimp.message('L=%d\nU=%d\nR=%d\nD=%d' % (x1,y1,image.width-x2,image.height-y2))

### Registration
desc='Show selection margins'
register(
    'selection-margins',desc,desc,'','','2019',desc,'*',
    [(PF_IMAGE, "image", "Input image", None),],[],
    selectionMargins,menu="<Image>/Select"
)

main()

• Copy the script to a text file with .py extension (note: python is sensitive to the indentation of the code)
• See Edit>Preferences>Folder>Plugins for the folder whre the resulting file should be
• On OSX and Linux, make it executable
• The menu entry is at the bottom of the Select menu in an image window.
• Output is in a dialog or in the error console window if it up

It wouldn't be difficult to improve the script to append to a CSV file a line with the image file name/path and the values.