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Groups > comp.lang.python > #93899

Re: Keypress Input

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On 7/15/2015 9:03 PM, Rick Johnson wrote:

> You may have solved your input capturing problem, and i
> don't think a GUI is the preferred solution for a
> graphically deficient device anyhow, but you may well need a
> GUI in the future, and this would be a fine example from which
> to learn.

This really is a nice example.  Your rationale for defining an app class 
is the best I remember seeing.

To run in 3.x, change the first two lines to

import tkinter as tk
from tkinter.messagebox import showinfo, showerror

> import Tkinter as tk
> from tkMessageBox import showinfo, showerror
>
> MSG1 = """\
> To begin retinal stimulation, press r or g or b on your keyboard
> Hold key down for extended stimulation!
> """
>
> class App(tk.Tk):
>      def __init__(self):
>          tk.Tk.__init__(self)
>          self.bind("<KeyPress>", self.evtKeyDown)
>          self.bind("<KeyRelease>", self.evtKeyUp)
>          self.protocol("WM_DELETE_WINDOW", self.evtDeleteWindow)
>          w = tk.Label(self, text=MSG1)
>          w.pack()
>          self.config(bg='white')
>          self.geometry('500x500')
>          self.focus_set()
>
>      def evtDeleteWindow(self):
>          showinfo("The window is Dying", "Goodbye cruel world!", parent=self)
>          self.destroy()
>
>      def evtKeyDown(self, event):
>          key = event.keysym.lower()
>          alert = False

>          if key == 'r':
>              self.config(bg='red')
>          elif key == 'g':
>              self.config(bg='green')
>          elif key == 'b':
>              self.config(bg='blue')
>          else:

Can condense block above to this easily extended code: (Replacing if 
if/elif/elif/... chains, when possible, is part of mastering Python.)

           try:
               self['bg'] = {'r':'red', 'g':'green', 'b':'blue'}[key]
           except KeyError:

>              msg = 'I *TOLD* you to press r or g or b, not {0!r}!'.format(key)
>              showerror('', msg, parent=self)
>
>      def evtKeyUp(self, event):
>          self.config(bg='white')
>
> if __name__ == '__main__':
>      app = App()
>      app.title('Retina Stimultor')
>      app.mainloop()
>      print "This code only executes *AFTER* the mainloop call returns!"

Adding parens to print, when there is a single object being printed, has 
no effect in 2.x and makes the statement work in 3.x.  The following 
works the same in both.

print("Mainloop has returned")

-- 
Terry Jan Reedy

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Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-03 18:22 +0000
  Re: Keypress Input Laura Creighton <lac@openend.se> - 2015-06-03 20:59 +0200
  Re: Keypress Input Gary Herron <gherron@digipen.edu> - 2015-06-03 12:15 -0700
  Re: Keypress Input Gary Herron <gherron@digipen.edu> - 2015-06-03 11:47 -0700
  Re: Keypress Input Laura Creighton <lac@openend.se> - 2015-06-04 12:50 +0200
  Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-06 18:28 +0000
    Re: Keypress Input Laura Creighton <lac@openend.se> - 2015-06-06 22:52 +0200
    Re: Keypress Input Chris Angelico <rosuav@gmail.com> - 2015-06-07 07:20 +1000
    Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-06-06 22:31 -0600
  Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-15 05:15 +0000
    Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-16 15:09 +0000
    Re: Keypress Input Christian Gollwitzer <auriocus@gmx.de> - 2015-06-19 07:20 +0200
      Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-20 14:59 +0000
      Re: Keypress Input Rick Johnson <rantingrickjohnson@gmail.com> - 2015-07-15 18:03 -0700
        Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-07-15 22:30 -0600
          Re: Keypress Input Rick Johnson <rantingrickjohnson@gmail.com> - 2015-07-16 10:22 -0700
            Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-07-16 15:27 -0600
        Re: Keypress Input Terry Reedy <tjreedy@udel.edu> - 2015-07-16 02:08 -0400
          Re: Keypress Input Rick Johnson <rantingrickjohnson@gmail.com> - 2015-07-16 11:30 -0700
        Re: Keypress Input Terry Reedy <tjreedy@udel.edu> - 2015-07-16 03:10 -0400
        Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-07-16 15:29 -0600
  Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-15 05:23 +0000
    Re: Keypress Input Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2015-06-15 12:22 +0100
      Re: Keypress Input Grant Edwards <invalid@invalid.invalid> - 2015-06-15 15:22 +0000
    Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-06-16 11:15 -0600
      Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-16 20:06 +0000
        Re: Keypress Input Grant Edwards <invalid@invalid.invalid> - 2015-06-16 20:49 +0000
          Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-06-16 19:22 -0600
          Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-06-18 16:42 -0600
      Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-06-20 15:02 +0000
        Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-06-20 10:30 -0600
  Re: Keypress Input Paul Rubin <no.email@nospam.invalid> - 2015-06-16 14:22 -0700
  Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-07-15 19:05 +0000
    Re: Keypress Input Michael Torrie <torriem@gmail.com> - 2015-07-15 13:17 -0600
      Re: Keypress Input John McKenzie <davros@bellaliant.net> - 2015-08-16 19:45 +0000

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