How can I add a plain black line in an image in Gimp in specific pixel coordinates for example between (10,15)->(300,116)?
Open the Python console in
get a reference to your image, typing
img = gimp.image_list()
and press enter. Hit the browse button at the botton of the dialog and select
gimp- paintbrush-default and hit apply - it will paste a template for calling that function in the Python console - something like this:
>>> pdb.gimp_paintbrush_default(drawable, num_strokes, strokes)
Go back with the arrow keys and edit it so that it reads:
>>> pdb.gimp_paintbrush_default(img.layers, 4, [10,15,300,116 ])
And press enter.
img.layers parameter is a reference to the layer - "0" is the top most layer in the image, 1, the second from top to bottom, and so on. (Likewise, in the previous command
img = gimp.image_list() retrieves a reference to the last image open in GIMP, and changing the number in square bracktes selects other images).
After the first stroke, you can simply hit up arrow, and get the command back, where you can fill in new coordinates for the line. Also, of course, you can explore the procedures available in the "Browse" button, and use any of them you like.
As few people do this, I'v just noticed a bug: in GIMP 2.8, it ignores the brush size set in the tool options. So you will have to create a brush of the size you want and set it before doing the line.