Develop Reference

Tkinter gets slow when resizing the window. Can I have the resize command activate when the user settles instead of activating it continuously? [duplicate]

I am trying to write a function to dynamically resize an image displayed in a tkinter window.
Therefore I bound this function to the Configure event:
connroot.bind( "<Configure>", connresiz)
My problems are:
That the connresiz() function gets called 3 times (why 3?) at program start, and
More troublesome, that dynamically resizing the window calls the function continuously as I drag the mouse! How can avoid this?
I thought about checking at the simultaneous presence of a <Configure> and <ButtonRelease-1> events, but I don't know how to code it.

1) We don't know that, since we can't see your code...
2) Short answer is: you can't, because that's exactly what <Configure> event does! Long answer, you can, with a little trick/hack. Since anytime the window is changing, it will call all the binded functions to <Configure>, and the same happens anytime as the mouse button released (right after the last <Configure> call) we can create a flag/switch which will tell us, if the window was "configured" then we can check that switch anytime the mouse button is released, and switch it back to the default value after we ran some actions.
So if you want the image to resized only, when the mouse was released and the window was changed this is the code you need:
from tkinter import *
class Run:
def __init__(self):
self.root = Tk()
self.clicked = False
self.root.bind('<ButtonRelease-1>', self.image_resize)
self.root.bind('<Configure>', lambda e: self.click(True))
def image_resize(self, event):
if self.clicked:
print("I'm printed after <Configure>.") # the action goes here!
self.click(False)
def click(self, value):
self.clicked = value
app = Run()
app.root.mainloop()

According to the official tk documentation, <Configure> events fire "whenever its size, position, or border width changes, and sometimes when it has changed position in the stacking order." This can happen several times during startup.
It is called continuously while you resize the window because the size of the widget is changing. That's what it's defined to do. You can't prevent it from being called, though you can certainly modify what you do in the callback. For example, you could delay resizing the image until you've not received another <Configure> event for a second or two -- which likely means the user has stopped interactive resizing.

stop self.after when interrupt happens

I started coding snake in python 3. As GUI i use Tkinter.
I got a timer which waits for a second an then calls the method again. Well now my question is how to i stop the self.wait?
I know i could work around this pretty easily, but i had this problem already somewhere else, so it would be nice to know how i can stop this.
This is the method which moves the snake around. (Only the timer is critical). The timer is here so it moves every second.
def move_snake(self):
self.after(1000, self.move_snake)
# code goes on
Now if i change the direction (by pressing a button) i do following:
def change_direction(self, event):
self.pressed = event.keysym
self.move_snake()
If i do this this way the "old" timer still is active and therefore the method gets called multiple times (it adds an additional timer when you press an button).
It would be nice that just the latest timer is activated.
Do you need more information?

Assuming that move_snake uses self.pressed, you don't need to call move_snake inside of change_direction.
However, if you really want to stop the old loop and start a new loop, you can save the id that is returned from after and give that to after_cancel:
def move_snake(self):
self.after_id = self.after(1000, self.move_snake)
# code goes on
def change_direction(self, event):
self.pressed = event.keysym
# cancel the old loop
self.after_cancel(self.after_id)
# start a new loop
self.move_snake()

Pyglet custom Event Loop fails with multiple windows

I have a custom Event Loop for Pyglet that can be simplified to this simple piece of code
while True:
pyglet.clock.tick()
for window in pyglet.app.windows:
window.switch_to()
# rendering code
window.flip()
window.dispatch_events() # <--- program hangs
When there is only one window, the event loop works fine but when I attempt to have two windows, the loop hangs at window.dispatch_events(). Calling the functions in different order yield the same problem. I also tried debugging:
pyglet.options['debug_win32'] = True
Error Message:
...
_user32.UnregisterHotKey(self._hwnd, 0)
b'Hot key is not registered.\r\n'
After some more tinkering I managed to get the windows responsive with a dirty hack, but still there are quite a few issues that arise with event processing. Fix was calling an update immediately after setting window visible.
Sample Initialisation code:
if __name__=="__main__":
engine = Engine()
engine.run()
class Engine: # test program
def __init__(self):
self.application = customLib.Application()
# define windows, by default they are set as not visible
self.window1 = self.application.guiManager.createWindow("Window 1",
(1000, 700),
cursorPath="../data/cursor.png")
self.window2 = self.application.guiManager.createWindow("Window 2",
(1000, 700),
cursorPath="../data/cursor.png")
# load up code such as loading textures and .obj files
self.window1.pygletWindow.set_visible()
self.window1.update() # calling this after setting self.window2 visible will cause original error
self.window2.pygletWindow.set_visible()
self.window2.update()
def run(self):
self.application.run()
### CUSTOMLIB ###
class Application:
...
def run(self):
while True:
pyglet.clock.tick()
self.guiManager.update()
class GUIManager: # manages windows
...
def update(self):
for window in self.windows:
window.update()
class Window: # pyglet window higher level wrapper
pygletWindow = None
...
def update(self):
e = self.pygletWindow.dispatch_events()
# all events are intercepted by a custom class, it transforms all unhandled events (keyboard, mouse, and close button for now) into a list of events that can then be looped through rather than requiring twenty different functions.
# the event list is acquired, looped through and then cleared
for event in self.eventManager.get():
if event.type == customLib.CLOSE:
# close application
elif event.type == customLib.K_W:
# move player forward
# rendering
self.pygletWindow.switch_to()
# window is cleared
# window content rendered
self.pygletWindow.flip()
The way around the previous problem seems a little foolish and not robust. With the current event loop I have, window feedback sometimes does not work. For example, to close the window I must sometimes click it several times or, when moving the window around it won't always grab the window. I dispatch_events() at every loop and my custom event handler does not handle window motion events. The glitching of event handling only occurs with multiple windows. With a single window the event loop is flawless. This "bug" can be fixed by using varients of pyglet EventLoop.
I have concluded that a custom Event Loops' cons outweigh its pros. It is much easier to subclass EventLoop (since it's optimised for the OS) and override any pesky routines. Even better is to make a whole new event loop copying initialisation code of EventLoop and any backend routines (utilising PlatformEventLoop), which then allows you to very easily implement custom routines. I will be leaving this question up because there is very little documentation about this matter.

Tkinter Frame Not Recognizing Keypresses

This question is NOT a duplicate of this question: Why doesn't the .bind() method work with a frame widget in Tkinter?
As you can see, I set the focus to the current frame in my game_frame() method.
I'm writing a Chip-8 emulator in Python and using Tkinter for my GUI. The emulator is running, but I can't get Tkinter to recognize keypresses. Here is my code:
def game_frame(self):
self.screen = Frame(self.emulator_frame, width=640, height=320)
self.screen.focus_set()
self.canvas = Canvas(self.screen, width=640, height=320, bg="black")
self._root.bind("<KeyPress-A>", self.hello)
for key in self.CPU.KEY_MAP.keys():
print(key)
self.screen.bind(key, self.hello)
self.screen.pack()
self.canvas.pack()
def hello(self, event):
if event.keysym in self.CPU.KEY_MAP.keys():
self.CPU.keypad[self.CPU.KEY_MAP[event.keysym]] = 1
self.CPU.key_pressed = True
self.CPU.pc += 2
sys.exit()
def run_game(self, event):
self.game_frame()
self.CPU.load_rom("TANK")
while True:
self._root.update()
self.after(0, self.CPU.emulate_cycle)
Could you please help me figure out what's going wrong? I think it might have something to do with my game loop interfering with the key bindings, but I'm not sure. The hello method never gets called when I run the game because the program continues to run in an infinite loop and never exits, regardless of what key is pressed. Thank you!

The problem could be due to two things. Without seeing all your code it's impossible to say for sure.
For one, you are binding to a capital "A" rather than a lowercase "a" -- have you testing that the binding works or not when you press a capital A?
Also, you are using after and update incorrectly. You may be starving the event loop, preventing it from processing key presses. The right way to run a function periodically is to have a function that (re)schedules itself.
class CPU_Class():
...
def run_cycle(self):
self.emulate_cycle()
self._root.after(1, self.run_cycle)
Two things to note:
don't use after(0, ...) -- you need to give tkinter at least a ms or so to process other events.
the run_cycle function is responsible for running one cycle, and then scheduling the next cycle to run in the future.
Once you do that, you no longer need your while loop. You can simply call run_cycle once, and that will start the CPU running.

Python using turtle button

I am attempting for a homework assignment to implement Simon Says in python. I'm trying to do it using the turtle library (a requirement).
However, I've run into a stumbling block in that while I can get the screen to register click events (currently just printing the x,y coordinates) I can't get it to wait for a click event.
Specifically what I'm planning on doing is having areas on the screen that when they click within that location it is considered as if they had clicked a button. Screen clears and game does whatever.
However, in experiments in trying to get a working 'button' all that it does is set it so it prints the x,y coordinates but the rest of the program finishes. Didn't wait for the user to click anything. I tried a blocking method of...
while clicked == False:
pass
or
while clicked == False:
time.sleep(1)
but both methods hangs the program until I manually interrupt and then it'll print the clicks.
Am I missing an option somewhere?

Turtles don´t have buttons, but they do have callbacks for clicks.
Furthermore, you should use onclick for Screen to detect general clicks and onclick for turtle to detect clicking in turtles. You can, for example, make a 4 BIG turtles with different colors by using a dynamic shape.
Also, turtle is based on Tk, so you must be aware of things like mainloop()
The following program give some hints for Python 2.7.5.
import turtle as t
from random import randint
class MyTurtle(t.Turtle) :
def __init__(self,**args) :
t.Turtle.__init__(self,**args)
def mygoto(self,x,y) :
t1.goto(x,y)
print x,y
def randonics(self,x,y) :
self.left(randint(90,270))
def minegoto(x,y) :
print x,y
t1.goto(x,y)
wt=t.Screen()
t1=MyTurtle()
wt.register_shape("big",((0,0),(30,0),(30,30),(0,30)))
t1.shape("big")
wt.onclick(t1.mygoto,btn=1)
wt.onclick(minegoto,btn=2)
t1.onclick(t1.randonics,btn=3)
t1.goto(100,100)
t.mainloop()

So after extensive search there isn't necessarily a way pause execution of the code in python while using turtle to wait for some click event. Maybe in Tk I could do that but not in turtle.
However, there is a way to get around that. As an example. A method sets up the fake button on the screen, sets the click event, and terminates. The click event when clicked calls the next method needed for execution. So until the button is clicked the actual code isn't doing anything but remains in memory for use.
So more specifically.
1. Create a 'button'.
2. Have your program behave normally until it needs to wait for a click event.
3. Set up the on screen click (or on turtle) in such a way when the 'button' is clicked the next part of the code is run.
Special note. The code in question can't depend on waiting for a click event for later on in code. Instead, the click causes the next part of the execution of your code.

You can make the function registered with onclick() test the x,y position. If it is inside some region you do whatever you must.
I don´t see the difference between what you want to do and what this code does, the modification of turtle position is just an example, you can do anything when a click is captured by onclick(), even start a thread if you really need it (using Creating Threads in python)
import turtle as t
from random import randint
from threading import Thread
from time import sleep
def threaded_function(arg,t1):
for i in range(arg):
print "running",i
sleep(1)
t1.forward(i*10)
def minegoto(x,y) :
print x,y
t1.goto(x,y)
thread = Thread(target = threaded_function, args = (10,t1 ))
thread.start()
thread.join()
print "thread finished...exiting"
wt=t.Screen()
t1=t.Turtle()
wt.register_shape("big",((0,0),(30,0),(30,30),(0,30)))
t1.shape("big")
wt.onclick(minegoto,btn=1)
t1.goto(100,100)
t.mainloop()