Recipe11.17.Getting User Input on Mac OS

Recipe 11.17. Getting User Input on Mac OS

Credit: Matteo Rattotti

Problem

You're writing a simple application to run on Mac OS and want to get an input value from the user without frightening the user by opening a scary terminal window.

Solution

Many Mac OS users are frightened by the terminal, so Python scripts that require simple input from the user shouldn't rely on normal textual input but rather should use the EasyDialogs module from the Python Standard Library. Here is an example, a simple image converter and resizer application:

import os, sys, EasyDialogs, Image # instead of relying on sys.argv, ask the user via a simple dialog: rotater = ('Rotate right', 'Rotate image by 90 degrees clockwise') rotatel = ('Rotate left', 'Rotate image by 90 degrees anti-clockwise') scale = ('Makethumb', 'Make a 100x100 thumbnail') str = ['Format JPG', 'Format PNG'] cmd = [rotater, rotatel, scale] optlist = EasyDialogs.GetArgv(str, cmd,               addoldfile=False, addnewfile=False, addfolder=True) # now we can parse the arguments and options (we could use getopt, too): dirs = [  ] format = "JPEG" rotationr = False rotationl = False resize = False for arg in optlist:     if arg == "--Format JPG":         format = "JPEG"     if arg == "--Format PNG":         format = "PNG"     if arg == "Rotate right":         rotationr = True     if arg == "Rotate left":         rotationl = True     if arg == "Makethumb":         resize = True     if os.path.isdir(arg):         dirs.append(arg) if len(dirs) == 0:     EasyDialogs.Message("No directories specified")     sys.exit(0) # Now, another, simpler dialog, uses the system's folder-chooser dialog: path = EasyDialogs.AskFolder("Choose destination directory") if not path:     sys.exit(0) if not os.path.isdir(path) :     EasyDialogs.Message("Destination directory not found")     sys.exit(0) # and now a progress bar: tot_numfiles = sum([ len(os.listdir(d)) for d in dirs ]) bar = EasyDialogs.ProgressBar("Processing", tot_numfiles) for d in dirs:     for item in os.listdir(d):         bar.inc( )         try:             objpict = Image.open(d + "/" + item)             if resize: objpict.thumbnail((100, 100, 1))             if rotationr: objpict = objpict.rotate(-90)             if rotationl: objpict = objpict.rotate(90)             objpict.save(path + "/" + item + "." + format, format)         except:             print item + " is not an image" # and one last dialog...: score = EasyDialogs.AskYesNoCancel("Do you like this program?") if score == 1:     EasyDialogs.Message("Wwowowowow, EasyDialog roolz, ;-)") elif score == 0:     EasyDialogs.Message("Sigh, sorry, will do better next time!-(") elif score == -1:     EasyDialogs.Message("Hey, you didn't answer?!")

Discussion

This recipe's program is quite trivial, mostly meant to show how to use a few of the dialogs in the EasyDialogs standard library module for the Mac. You could add quite a few more features, or do a better job of implementing some of those in this recipe, for example, by using getopt from the Python Standard Library to parse the arguments and options, rather than the roll-your-own approach we've taken.

Since EasyDialogs is in the Python Standard Library for the Mac, you can count on finding that module, as well as Python itself, in any Mac that runs Mac OS X 10.3 Pantherand that's well over ten million Macs, according to Apple. Just build your script into an application with bundlebuilder or, even better, with py2app and distutils. Doing so will enable you to distribute your Python application so that users can park it in the Dock, use drag-and-drop from the Finder to give it arguments, and so on. Documentation for both bundlebuilder and py2app can be found on the Wiki at http://www.pythonmac.org/wiki.

The EasyDialogs module in the Python Standard Library works only on the Mac, but if you like the concept, you can try out Jimmy Retzlaff's port of that module to Windows, available for download at http://www.averdevelopment.com/python/EasyDialogs.html.

Recipe11.17.Getting User Input on Mac OS