TkInter keypress, keyrelease events

Question

I understood that the Tk keypress and keyrelease events were supposed only to fire when the key was actually pressed or released?

However with the following simple c

Answer 1

Autorepeat behavior is system dependent. In Win7,

down a
down a
down a
...
down a
up a

This is for less than a second.

Answer 2

Ok some more research found this helpful post which shows this is occuring because of X's autorepeat behaviour. You can disable this by using

os.system('xset r off')

and then reset it using "on" at the end of your script. The problem is this is global behaviour - not just my script - which isn't great so I'm hoping someone can come up with a better way.

Answer 3

how about;

from Tkinter import *

wn = Tk()
wn.title('KeyDetect')

m = 0

def down(e):
    if m == 0:
        print 'Down\n', e.char, '\n', e
        global m
        m = 1

def up(e):
    if m == 1:
        print 'Up\n', e.char, '\n', e
        global m
        m = 0

wn.bind('<KeyPress>', down)
wn.bind('<KeyRelease>', up)

wn.mainloop()

now it won't repeat.

Answer 4

Well, this is a bit late now, but I have a solution that works. It's not great, but it does not require os.system overwriting system settings, which is nice.

Basically, I make a class that records the timing of key presses. I say that a key is down when it has been pressed in the last short amount of time (here, .1ms). To get a press, it is easy enough: if the key is not registered as pressed, trigger the event. For releases, the logic is harder: if there is a suspected release event, set a timer for a short time (here, .1s) and then check to make sure the key is not down.

Once you have validated a press or release, call the on_key_press or on_key_release methods in your code. As for those, just implement them the way you originally wanted them

I know this is not perfect, but I hope it helps!!

Here is the code:

Where you are initializing keypress events:

key_tracker = KeyTracker()
window.bind_all('<KeyPress>', key_tracker.report_key_press)
window.bind_all('<KeyRelease>', key_tracker.report_key_release)
key_tracker.track('space')

Here is my custom KeyTracker class:

class KeyTracker():
    key = ''
    last_press_time = 0
    last_release_time = 0

    def track(self, key):
        self.key = key

    def is_pressed(self):
        return time.time() - self.last_press_time < .1

    def report_key_press(self, event):
        if event.keysym == self.key:
            if not self.is_pressed():
                on_key_press(event)
            self.last_press_time = time.time()

    def report_key_release(self, event):
        if event.keysym == self.key:
            timer = threading.Timer(.1, self.report_key_release_callback, args=[event])
            timer.start()

    def report_key_release_callback(self, event):
        if not self.is_pressed():
            on_key_release(event)
        self.last_release_time = time.time()