Today, 05:29 AM
Sorry to say, I'm not familiar with your specific situation (printer, drivers, GIMP version, operating system). However, when I find myself getting what seems like paradoxical results, two things always seem to help:
1. I keep track, in detail, of all the information that I have about the situation -- pretty much as you've done. "GIMP says my Canvas Size is currently X pixels by Y pixels, at Z ppi. The numbers in the Print Resolution dialog do (or don't) agree with that: so many inches by so many inches, at so many pixels/inch. When I go to print, I get all (or part) of my image in an area so many inches wide by so many inches high. That is (or isn't) what I expected according to the other numbers."
2. I experiment, and again keep track of all the relevant information:
"When I change the Canvas Size to such-and-such while keeping the resolution the same, all (or part) of the image prints at such-and-such size."
"When I set the resolution to such-and-such, while keeping the Canvas Size the same, all (or part) of the image prints at such-and-such size."
From the results, I eventually figure out what changes in the settings might give me the result that I'm looking for. I make those changes and try printing again. If the result isn't what I expected, I experiment some more. The purpose of the detailed notes is so that if I find myself doing what seems to be the same thing twice with the same settings but getting different results, I can go back to my notes and see why it might not really have been the same thing twice.
1. I keep track, in detail, of all the information that I have about the situation -- pretty much as you've done. "GIMP says my Canvas Size is currently X pixels by Y pixels, at Z ppi. The numbers in the Print Resolution dialog do (or don't) agree with that: so many inches by so many inches, at so many pixels/inch. When I go to print, I get all (or part) of my image in an area so many inches wide by so many inches high. That is (or isn't) what I expected according to the other numbers."
2. I experiment, and again keep track of all the relevant information:
"When I change the Canvas Size to such-and-such while keeping the resolution the same, all (or part) of the image prints at such-and-such size."
"When I set the resolution to such-and-such, while keeping the Canvas Size the same, all (or part) of the image prints at such-and-such size."
From the results, I eventually figure out what changes in the settings might give me the result that I'm looking for. I make those changes and try printing again. If the result isn't what I expected, I experiment some more. The purpose of the detailed notes is so that if I find myself doing what seems to be the same thing twice with the same settings but getting different results, I can go back to my notes and see why it might not really have been the same thing twice.