You can do it locally with qrencode[1], which is available via MacPorts and Homebrew. It would probably simplify the script, too (especially if converted to bash).

On an X11 environment, I can select some text and get the same results on the command line with something like:

    xsel | qrencode -o - | feh -FZ

None of these commands are standard on any distribution, but you can easily install them or use alternatives. You can also make this an alias, hotkey, etc.

[1] http://fukuchi.org/works/qrencode/

Edit: No need for temporary file