i have a script which should interact with the users input (pressing the arrow keys), but i cannot get the keys. i tried raw_input and some other functions, but they didnt work. this is my sample code, how it should look like (running bool can be set to False in another function)
running = True
while running:
#if input == Arrow_UP:
# do_Sth
#elif ...
display()
time.sleep(1)
another question is, how can i call the display function only once every second, but react on the input immediately?
There are different situations:
If you use a graphical frontend such as TKinter or PyGame, you can bind an event to the arrow key and wait for this event.
Example in Tkinter taken from this answer:
from Tkinter import *
main = Tk()
def leftKey(event):
print "Left key pressed"
def rightKey(event):
print "Right key pressed"
frame = Frame(main, width=100, height=100)
main.bind('<Left>', leftKey)
main.bind('<Right>', rightKey)
frame.pack()
main.mainloop()
If your application stays in the terminal, consider using curses as described in this answer
Curses is designed for creating interfaces that run in terminal (under linux).
If you use curses, the content of the terminal will be cleared when you enter the application, and restored when you exit it. If you don't want this behavior, you can use a getch() wrapper, as described in this answer. Once you have initialized getch with getch = _Getch(), you can store the next input using key = getch()
As to how to call display() every second, it again depends on the situation, but if you work in a single process in a terminal, the process won't be able to call your display() function while it waits for an input. The solution is to use a different thread for the display() function, as in
import threading;
def display ():
threading.Timer(1., display).start ();
print "display"
display ()
Here display schedules itself one second in the future each time it is called. You can of course put some conditions around this call so that the process stops when some conditions are met, in your case when an input has been given. Refer to this answer for a more thoughout discussion.
Related
I'm trying to create a button in Tkinter that only appears (becoming visible) when it finds the word "hello" in a textbox.
I could imagine using Threads, and Global variables but i do not know how to code it,
I've imagined something like :
import Tkinter as *
from threading import Thread
window = Tk()
active = True
def check_for_word():
global active
textbox1 = textbox.get("1,0", "end")
while active == True:
if "hello" in textbox1:
button.pack()
else:
button.pack_forget()
save_button = Button(window)
textbox = scrolledtext.ScrolledText(window)
textbox.pack()
threading = Thread (target=check_for_word)
threading.start()
window.mainloop()
this is something I would suspect to work but ends up not, the button either doesn't show at all like the code isn't even running, or the thread doesn't work properly. So am I doing something wrong, if so, can you help me, please? Thank you!
You don't need to make use of threads to do this, you can use tkinter event bindings instead.
def check_for_word():
if "hello" in textbox.get("1.0", "end"):
save_button.pack()
else:
save_button.pack_forget()
save_button = Button(window)
textbox = scrolledtext.ScrolledText(window)
textbox.bind("<KeyRelease>", lambda event:check_for_word())
textbox.pack()
To make a binding, you use widget.bind. In this case, the widget is textbox and it's binding to <KeyRelease>, which is when the user releases a key. It then calls check_for_word when a key is released. (The lambda part is to ignore the event parameter). check_for_word then does what it did before.
You have to put the textbox1 assignment inside the while loop and before the if condition, otherwise it will check the value one time before entering the loop and will keep checking always the same value.
I also want to point out that the in operator is case sensitive and return True if it find even just a substring inside the variable you are checking and not just the precise single word (but I'm not shure if this is intensional).
For the while loop you don't necessarily need a global variable, you could just use while True: if you want it to continuously check the condition (if you want the button to disappear after the user cancel the word).
I borrowed a design that I found on stackoverflow to redirect console output to a PyQt5 GUI textEdit widget. This works fine, but the text is not displayed in "real-time". It seems to output the text to the GUI once a process has completed. This has not been a problem until I tried to use time.sleep(secs) to print something, pause, then print something else. What ends up happening is that the program pauses for secs, then it prints all of the statements at once.
This class is in the mainWindow file for the GUI:
class EmittingStream(QtCore.QObject):
textWritten = QtCore.pyqtSignal(str)
def write(self, text):
self.textWritten.emit(str(text))
This is in the __init__ method of my event handling file:
sys.stdout = EmittingStream(textWritten=self.normalOutputWritten)
self.case_setup_console.setReadOnly(True)
self.main_console.setReadOnly(True)
This function is in the main class of event handling file (outside __init__):
def normalOutputWritten(self, text):
"""Append text to the QTextEdit."""
# Maybe QTextEdit.append() works as well, but this is how I do it:
cursor = self.case_setup_console.textCursor()
cursor.movePosition(QtGui.QTextCursor.End)
cursor.insertText(text)
self.case_setup_console.setTextCursor(cursor)
self.case_setup_console.ensureCursorVisible()
This works as intended to re-route the output to the text edit widget self.case_setup_console. But, when I try to run a code such as:
print('This is the first message')
time.sleep(5)
print('This should print 5 seconds later')
What happens is that the program waits 5 seconds, then it prints both statements together.
When programing for GUI code, there is a fundamental shift in how the program is designed. To make it short: after building and initialisation, the program is all the time running in an "event loop" provided by the GUI framework, and your code is only called when specific events take place.
That is in contrast with a terminal application where your code is running all the time, and you tell when to do "print"s, "input"s and pauses with "time.sleep".
The GUI code is responsible for taking notes of events (keyboard, UI, network, etc...), redrawing window contents and calling your code in response to events, or just when it is time to redraw a content that is defined in your code (like updating a background image).
So, it can only render the text that is supposed to show up in a window, with your redirected "print", when the control is passed back to its event loop. When you do time.sleep you pause the return - no code in the event loop is run, and it can't, of course, do any screen drawing.
What is needed is that you write your pauses in the program in a way that during the pause, the GUI event loop is running - not "time.sleep", that just suspends your whole thread.
In Qt the way to do that is create a QTimer object to call the code you want to use to print text at a particular moment, and then just surrender the execution to the the QtMainloop by returning from your function.
Thanks to Python's support for nested functions, that can be done in painless ways, even using lambda functions when setting the timer itself.
...
print('This is the first message')
timer = QtCore.QTimer
timer.singleShot(5000, lambda *_: print('This should print 5 seconds later'))
Should work for the given example. (The call, as usual for UIs, takes the pause time in miliseconds rather than in seconds).
If you will need to schedule more text to be printed after each phrase is output, you will need to call the scheduling inside the callback itself, and will need a little more sophistication, but it still could be as simple as:
phrases = iter(("hello", "world", "I", "am", "talking", "slowly!"))
timer = QtCore.QTimer()
def talker(*_):
phrase = next(phrases, None)
if not phrase:
return
print(phrase)
timer.singleShot(1000, talker)
timer.singleShot(1000, talker)
(Note that there is nothing special about the *_ parameter name either: I am just indicating that there might be any number of positional arguments for the callback - (The "*" part, that is Python syntax) - and that I won't care about then (I call the argument sequence as "_" to indicate I don't care how this is called, as it won't be used anyway - that is a coding convention) )
The iter and next calls are more "Python dialect" than one might be used, but one could just use a list and a counter up to the list length all the same.
I would like to know how to get user input in python without using the command line or an input box.
Let me explain. I do not want to do this
#All code is python 3
name=input("What is your name?")
Why? When running scripts, the command line is not auto-focused. Furthermore, it pops up another window, something I do not want because I can't hit escape to close it in a hurry (Something which you may want to do if you're playing a game).
What have I tried?
I looked at WX and it's dialog function, something like this:
import wx
app=wx.App()
def text_entry(title,message):
result=None
dlg=wx.TextEntryDialog(None, message,title)
if dlg.ShowModal()==wx.ID_OK: result=dlg.GetValue()
dlg.Destroy()
return result
text_entry("Text entry","Enter something here")
While this works, it pops up another window which again, I do not want. However, it is closer to what I am ultimately looking for, because I can hit escape to make it go away.
I have tried using pygame and it's key.get_pressed() function, but it inserts a lot of the same letter into the entry, even if I gently tap the key. Also, when I implemented it into the project, it can only pick up on normal letters. Writing 26 if statements to detect key presses for a single letter with or without the shift key seems a little counter intuitive.
Finally, I am a bit hesitant to try tkinter. I happen to be blind, and from what I read, tk is very visual, which makes me concerned that it won't play nicely with my screen reader (NVDA).
So, I'm here. After searching on google for "getting input without using command line in python 3", "input in the same window", and "input without using input()" yielded nothing.
To recap, I want to accept user input without using the input() function, and without any additional windows popping up for the duration of me doing so.
Thank you.
What about this solution using the msvcrt module. At any time if you press escape then the program will exit. Python sys.exit(), and built-ins exit() and quit() all call raise SystemExit so this is just one less call to perform. If you press the enter or return key then the while loop ends and you can use the keys that were pressed later in your program as they are stored in the variable user_input. The print at the end just proves that the pressed keys are stored in user_input variable and the input() function simply to leave the window open so you can see it working.
import msvcrt
user_input = b''
while True:
pressed_key = msvcrt.getche() # getch() will not echo key to window if that is what you want
if pressed_key == b'\x1b': # b'\x1b' is escape
raise SystemExit
elif pressed_key == b'\r': # b'\r' is enter or return
break
else:
user_input += pressed_key
print('\n' + user_input.decode('utf-8')) # this just shows you that user_input variable can be used now somewhere else in your code
input() # input just leaves the window open so you can see before it exits you may want to remove
So after doing some more research, I found this:
https://codeload.github.com/Nearoo/pygame-text-input/zip/master
I think this is what I am looking for, though it still needs to be slightly modified. Thank you for the assistance
I am pretty new to python and have been working with a program that was originally meant for the command line. As such, it uses the input() function quite a bit, especially in the middle of loops. Mostly, the original code would do something like this:
for item in list:
# some logic here
user_input - input("prompt")
# uses user_input
I've decided I want to make a GUI for it, but I also want to make it optional. I have a class called Viewer that decorates the original program, and I am struggling to figure out how to best to handle the calls to input().
My first thought was just to inject a new input function altogether so that way it looks for input in my GUI text box instead the sys.stdout. I found many Stack Overflow answers on how to print sys.stdout to a GUI element (like this), but not how to take input from one. All of my attempts either ended in freezing the GUI by creating a loop, or the program not pausing for input and simply grabbing what was in the box when the prompt was put forward.
Secondly, I tried to break apart my functions to better match the code examples for buttons. So, button 1 would trigger a function_part_1, which would go until it required an input. If the GUI flag was turned off, it would automatically go to an input function, otherwise it would return and a button press would trigger function_part_2:
def function_part_1(list):
item = list[0]
# do some logic on item 1
if GUI:
print("prompt")
return
# After this, the GUI waits for a button press, and then calls function_part_2
else:
function_input(list)
def function_input(list):
user_input = input("prompt")
function_part_2(user_input, list)
def function_part_2(user_input, list):
# uses user_input on item
list.remove(list[0])
if list:
function_part_1(list)
else:
return
However, this turned ugly really quickly. First, it broke apart many loops which would require a lot of refactoring to keep the logic in tact (Especially for the nested loops). It also requires that I pass all my local variables from function-part to function-part, which exploded the function headers. In order to have only a single input box for the user, the GUI has to have logic to know which function is executing and what function-part comes next. It made my functions harder to follow and hurt readability.
Is there a nicer way to do this?
I am using appJar for the GUI, which is based around Tkinter. I am willing to switch to pure Tkinter if that would make things easier.
The easiest way is to overwrite the input function. Here's a working example using tkinter:
import tkinter as tk
def input(prompt=''):
win= tk.Tk()
label= tk.Label(win, text=prompt)
label.pack()
userinput= tk.StringVar(win)
entry= tk.Entry(win, textvariable=userinput)
entry.pack()
# pressing the button should stop the mainloop
button= tk.Button(win, text="ok", command=win.quit)
button.pack()
# block execution until the user presses the OK button
win.mainloop()
# mainloop has ended. Read the value of the Entry, then destroy the GUI.
userinput= userinput.get()
win.destroy()
return userinput
print(input('foobar'))
I am writing a program using tkinter, but I do not understand how it works. Normally, code is executed top-down, but with tkinter it obviously does not.
For example, I have bound a function to the left mouse button, and this function is executed every time I click the button. But how is the other code around that treated? My problem is that I in the start of my program initialize a variable that is used as an argument in the bound function, and then it is changed in the function and returned. But every time the function is called, the variable seems to be reset to its initial value.
Does anyone know why this is?
I have it written like this:
var = "black"
var = c.bind("<Button-1>", lambda event: func(event, arg=var))
The function "func" changes var and returns it, but the next time I press the button the variable is always "black".
Thanks in advance!
Tkinter does indeed run top down. What makes tkinter different is what happens when it gets to the bottom.
Typically, the last executable statement in a tkinter program is a call to the mainloop method of the root window. Roughtly speaking, tkinter programs look like this:
# top of the program logic
root = tkinter.Tk()
...
def some_function(): ...
...
some_widget.bind("<1>", some_function)
...
# bottom of the program logic
root.mainloop()
mainloop is just a relatively simple infinite loop. You can think of it as having the following structure:
while the_window_has_not_been_destroyed():
event = wait_for_next_event()
process_event(event)
The program is in a constant state of waiting. It waits for an event such as a button click or key click, and then processes that event. Conceptually, it processes the event by scanning a table to find if that event has been associated with the widget that caught the event. If it finds a match, it runs the command that is bound to that widget+event combination.
When you set up a binding or associate a command with a button, you are adding something to that table. You are telling tkinter "if event X happens on widget Y, run function Z".
You can't use a return result because it's not your code that is calling this function. The code that calls the function is mainloop, and it doesn't care what the function returns. Anything that gets returned is simply ignored.