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How to compose widgets correctly in python kivy?

I would like to make it so that I can see the progress of the execution of the loop, but the ProgressBar only exits after the execution of this loop. How can I fix this?
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.progressbar import ProgressBar
class MyApp(App):
def build(self):
self.wid = FloatLayout()
self.prog_bar = ProgressBar(max=99999, pos = [0, -150])
self.wid.add_widget(self.prog_bar)
self.prog_bar.value = 0
for i in range(0, 99999):
self.prog_bar.value = i
print(i/99999)
return self.wid
if __name__ == '__main__':
MyApp().run()

Kivy uses the main thread of your App to update its widgets. You are running your loop on the main thread, so Kivy cannot update the ProgressBar until that loop completes. The fix is to do the loop in another thread:
class MyApp(App):
def build(self):
self.wid = FloatLayout()
self.prog_bar = ProgressBar(max=99999, pos=[0, -150])
self.wid.add_widget(self.prog_bar)
self.prog_bar.value = 0
threading.Thread(target=self.do_progress).start()
return self.wid
def do_progress(self):
for i in range(0, 99999):
self.prog_bar.value = i
print(i / 99999)

This is not about composition, but rather about multitasking, the thing is, if you do a locking loop like this, kivy can’t update anything until the loop is done (because nothing else happens while the function runs, no update of the UI or processing of any event). So what you want to do is allow the loop to run "concurrently" to the kivy event loop.
There are multiple ways to do this kind of things, they are all more or less suited to different situations.
kivy Clock allows scheduling a function to run later (schedule_once), possibly multiple times (schedule_interval), so you could have a more atomic function, that just increments the value of the progress bar once (not in a loop), and call this function using schedule interval. The issue is if you want to do actual work in the function, that could take significant enough time for the UI to be visibly blocked between increment of the progressbar value.
If that’s your case, because the function you are trying to run is slow, then you might want to run the function in a Thread instead, so it doesn’t block the kivy UI. You’ll be able to update the value of your progress bar from the the thread, if necessary, using the Clock to schedule a function doing just that (you need to be careful about not doing things that update the OpenGL context from a thread, as OpenGL doesn’t specify the behavior in such situation, so some graphic cards/drivers can be fine with it, but others will crash your program, so anything updating the UI from a thread must use the clock, there is a mainthread decorator provided in the clock module for that).
In some situation, you can (and thus want) avoid doing the long work beforehand, and find a way to do the minimal amount of work each time needed, and go on with the work, there are some abstractions of that idea, like RecycleView, that avoids creating widgets altogether, when you want a very long list of items to display, just creating the data beforehand, and letting it handle the creation/update of the widgets as needed. Of course, this might not apply to your situation, but it’s worth mentioning in case it is.
So in short: don’t do such loops, or do them in threads, think really hard if you actually need such a loop, and use clock events to update your UI when using threads.

Delete all from TkInter Canvas and put new items while in mainloop

The goal is to achieve different "screens" in TkInter and change between them. The easiest to imagine this is to think of a mobile app, where one clicks on the icon, for example "Add new", and new screen opens. The application has total 7 screens and it should be able to change screens according to user actions.
Setup is on Raspberry Pi with LCD+touchscreen attached. I am using tkinter in Python3. Canvas is used to show elements on the screen.
Since I am coming from embedded hardware world and have very little experience in Python, and generally high-level languages, I approached this with switch-case logic. In Python this is if-elif-elif...
I have tried various things:
Making global canvas object. Having a variable programState which determines which screen is currently shown. This obviously didn't work because it would just run once and get stuck at the mainloop below.
from tkinter import *
import time
root = Tk()
programState = 0
canvas = Canvas(width=320, height=480, bg='black')
canvas.pack(expand=YES, fill=BOTH)
if(programState == 0):
backgroundImage = PhotoImage(file="image.gif")
canvas.create_image(0,0, image=backgroundImage, anchor=NW);
time.sleep(2)
canvas.delete(ALL) #delete all objects from canvas
programState = 1
elif(programState == 1):
....
....
....
root.mainloop()
Using root.after function but this failed and wouldn't show anything on the screen, it would only create canvas. I probably didn't use it at the right place.
Trying making another thread for changing screens, just to test threading option. It gets stuck at first image and never moves to second one.
from tkinter import *
from threading import Thread
from time import sleep
def threadFun():
while True:
backgroundImage = PhotoImage(file="image1.gif")
backgroundImage2 = PhotoImage(file="image2.gif")
canvas.create_image(0,0,image=backgroundImage, anchor=NW)
sleep(2)
canvas.delete(ALL)
canvas.create_image(0,0,image=backgroundImage2, anchor=NW)
root = Tk()
canvas = Canvas(width=320, height=480, bg='black')
canvas.pack(expand=YES, fill=BOTH)
# daemon=True kills the thread when you close the GUI, otherwise it would continue to run and raise an error.
Thread(target=threadFun, daemon=True).start()
root.mainloop()
I expect this app could change screens using a special thread which would call a function which redraws elements on the canvas, but this has been failing so far. As much as I understand now, threads might be the best option. They are closest to my way of thinking with infinite loop (while True) and closest to my logic.
What are options here? How deleting whole screen and redrawing it (what I call making a new "screen") can be achieved?

Tkinter, like most GUI toolkits, is event driven. You simply need to create a function that deletes the old screen and creates the new, and then does this in response to an event (button click, timer, whatever).
Using your first canvas example
In your first example you want to automatically switch pages after two seconds. That can be done by using after to schedule a function to run after the timeout. Then it's just a matter of moving your redraw logic into a function.
For example:
def set_programState(new_state):
global programState
programState = new_state
refresh()
def refresh():
canvas.delete("all")
if(programState == 0):
backgroundImage = PhotoImage(file="image.gif")
canvas.create_image(0,0, image=backgroundImage, anchor=NW);
canvas.after(2000, set_programState, 1)
elif(programState == 1):
...
Using python objects
Arguably a better solution is to make each page be a class based off of a widget. Doing so makes it easy to add or remove everything at once by adding or removing that one widget (because destroying a widget also destroys all of its children)
Then it's just a matter of deleting the old object and instantiating the new. You can create a mapping of state number to class name if you like the state-driven concept, and use that mapping to determine which class to instantiate.
For example:
class ThisPage(tk.Frame):
def __init__(self):
<code to create everything for this page>
class ThatPage(tk.Frame):
def __init__(self):
<code to create everything for this page>
page_map = {0: ThisPage, 1: ThatPage}
current_page = None
...
def refresh():
global current_page
if current_page:
current_page.destroy()
new_page_class = page_map[programstate]
current_page = new_page_class()
current_page.pack(fill="both", expand=True)
The above code is somewhat ham-fisted, but hopefully it illustrates the basic technique.
Just like with the first example, you can call update() from any sort of event: a button click, a timer, or any other sort of event supported by tkinter. For example, to bind the escape key to always take you to the initial state you could do something like this:
def reset_state(event):
global programState
programState = 0
refresh()
root.bind("<Escape>", reset_state)

trying to draw over sprite or change picture pyglet

I am trying to learn pyglet and practice some python coding with a questionnaire thing, but I am unable to find a way to make the background picture be removed or drawn on top of or something for 10 seconds. I am new and am lacking in a lot of the knowledge I would need, thank you for helping!
import pyglet
from pyglet.window import Window
from pyglet.window import key
from pyglet import image
import time
card1 = False
cat_image = pyglet.image.load("cat.png")
dog_image = pyglet.image.load("dog.png")
image = pyglet.image.load("backg.png")
background_sprite = pyglet.sprite.Sprite(image)
cat = pyglet.sprite.Sprite(cat_image)
dog = pyglet.sprite.Sprite(dog_image)
window = pyglet.window.Window(638, 404, "Life")
mouse_pos_x = 0
mouse_pos_y = 0
catmeme = pyglet.image.load("catmeme.png")
sprite_catmeme = pyglet.sprite.Sprite(catmeme)
#window.event
def on_draw():
window.clear()
background_sprite.draw()
card_draw1(63, 192, 385, 192)
def card1():
while time.time() < (time.time() + 10):
window.clear()
sprite_catmeme.draw()
#window.event
def card_draw1(x1, y1, x2, y2):
cat.set_position(x1, y1)
dog.set_position(x2, y2)
cat.draw()
dog.draw()
def card_draw2():
pass
#window.event
def on_mouse_press(x, y, button, modifiers):
if x > cat.x and x < (cat.x + cat.width):
if y > cat.y and y < (cat.y + cat.height):
card1()
game = True
while game:
on_draw()
pyglet.app.run()

There's a few flaws in the order and in which you do things.
I will try my best to describe them and give you a piece of code that might work better for what your need is.
I also think your description of the problem is a bit of an XY Problem which is quite common when asking for help on complex matters where you think you're close to a solution, so you're asking for help on the solution you've come up with and not the problem.
I'm assuming you want to show a "Splash screen" for 10 seconds, which happens to be your background? And then present the cat.png and dog.png ontop of it, correct?
If that's the case, here's where you probably need to change things in order for it to work:
The draw() function
It doesn't really update the screen much, it simply adds things to the graphical memory. What updates the screen is you or something telling the graphics library that you're done adding things to the screen and it's time to update everything you've .draw()'n. So the last thing you need in the loop would be window.flip() in order for the things you've drawn to actually show.
Your things might show if you try to wiggle the window around, it should trigger a re-draw of the scene because of how the internal mechanics of pyglet work..
If you don't call .flip() - odds are probable that the redraw() call will never occur - which again, is a internal mechanism of Pyglet/GL that tells the graphics card that something has been updated, we're done updating and it's time to redraw the scene.
a scene
This is the word most commonly used for what the user is seeing.
I'll probably throw this around a lot in my text, so it's good to know that this is what the user is seeing, not what you've .draw()'n or what's been deleted, it's the last current rendering of the graphics card to the monitor.
But because of how graphical buffers work we've might have removed or added content to the memory without actually drawing it yet. Keep this in mind.
The pyglet.app.run() call
This is a never ending loop in itself, so having that in a while game: loop doesn't really make sense because .run() will "hang" your entire application, any code you want to execute needs to be in def on_draw or an event that is generated from within the graphical code itself.
To better understand this, have a look at my code, i've pasted it around a couple of times here on SO over the years and it's a basic model of two custom classes that inherits the behavior of Pyglet but lets you design your own classes to behave slightly differently.
And most of the functionality is under on_??? functions, which is almost always a function used to catch Events. Pyglet has a lot of these built in, and we're going to override them with our own (but the names must be the same)
import pyglet
from pyglet.gl import *
key = pyglet.window.key
class CustomSprite(pyglet.sprite.Sprite):
def __init__(self, texture_file, x=0, y=0):
## Must load the texture as a image resource before initializing class:Sprite()
self.texture = pyglet.image.load(texture_file)
super(CustomSprite, self).__init__(self.texture)
self.x = x
self.y = y
def _draw(self):
self.draw()
class MainScreen(pyglet.window.Window):
def __init__ (self):
super(MainScreen, self).__init__(800, 600, fullscreen = False)
self.x, self.y = 0, 0
self.bg = CustomSprite('bg.jpg')
self.sprites = {}
self.alive = 1
def on_draw(self):
self.render()
def on_close(self):
self.alive = 0
def on_key_press(self, symbol, modifiers):
if symbol == key.ESCAPE: # [ESC]
self.alive = 0
elif symbol == key.C:
print('Rendering cat')
self.sprites['cat'] = CustomSprite('cat.png', x=10, y=10)
elif symbol == key.D:
self.sprites['dog'] = CustomSprite('dog.png', x=100, y=100)
def render(self):
self.clear()
self.bg.draw()
for sprite_name, sprite_obj in self.sprites.items():
sprite_obj._draw()
self.flip()
def run(self):
while self.alive == 1:
self.render()
# -----------> This is key <----------
# This is what replaces pyglet.app.run()
# but is required for the GUI to not freeze
#
event = self.dispatch_events()
x = MainScreen()
x.run()
Now, this code is kept simple on purpose, the full code I usually paste on SO can be found at Torxed/PygletGui, the gui.py is where most of this comes from and it's the main loop.
What I do here is simply replace the Decorators by using "actual" functions inside a class. The class itself inherits the functions from a traditional pyglet.window.Window, and as soon as you name the functions the same as the inherited onces, you replace the core functionality of Window() with whatever you decide.. In this case, i mimic the same functions but add a few of my own.
on_key_press
One such example is on_key_press(), which normally just contain a pass call and does nothing, here, we check if key.C is pressed, and if so - we add a item to self.sprites.. self.sprites just so happen to be in our render() loop, anything in there will be rendered ontop of a background.
Here's the pictures I used:
(named bg.jpg, cat.png, dog.png - note the different file endings)
class:CustomSprite
CustomSprite is a very simple class designed to make your life easier at this point, nothing else. It's very limited in functionality but the little it do is awesome.
It's soul purpose is to take a file name, load it as an image and you can treat the object like a traditional pyglet.sprite.Sprite, meaning you can move it around and manipulate it in many ways.
It saves a few lines of code having to load all the images you need and as you can see in gui_classes_generic.py you can add a heap of functions that's "invisible" and normally not readily availbale to a normal sprite class.
I use this a bunch! But the code gets complicated real fast so I kept this post simple on purpose.
the flip function
Even in my class, I still need to use flip() in order to update the contents of the screen. This is because .clear() clears the window as you would expect, that also triggers a redraw of the scene.
bg.draw() might in some cases trigger a redraw if the data is big enough or if something else happens, for instance you move the window.
but calling .flip() will tell the GL backend to force a redraw.
Further optimizations
There's a thing called batched rendering, basically the graphic card is designed to take enormous ammounts of data and render it in one go, so calling .draw() on several items will only clog the CPU before the GPU even gets a chance to shine. Read more about Batched rendering and graphics! It will save you a lot of frame rates.
Another thing is to keep as little functionality as possible in the render() loop and use the event triggers as your main source of coding style.
Pyglet does a good job of being fast, especially if you only do things on event driven tasks.
Try to avoid timers, but if you really do need to use time for things, such as removing cat.png after a certain ammount of time, use the clock/time event to call a function that removes the cat. Do not try to use your own t = time() style of code unless you know where you're putting it and why. There's a good timer, I rarely use it.. But you should if you're starting off.
This has been one hell of a wall of text, I hope it educated you some what in the life of graphics and stuff. Keep going, it's a hurdle to get into this kind of stuff but it's quite rewarding once you've mastered it (I still haven't) :)

Memory leak when embedding and updating a matplotlib graph in a PyQt GUI

I am trying to embed a matplotlib graph that updates every second into a PyQt GUI main window.
In my program I call an update function every second using threading.Timer via the timer function shown below. I have a problem: my program grows bigger every second - at a rate of about 1k every 4 seconds. My initial thoughts are that the append function (that returns a new array in update_figure) does not delete the old array? Is it possible this is the cause of my problem?
def update_figure(self):
self.yAxis = np.append(self.yAxis, (getCO22()))
self.xAxis = np.append(self.xAxis, self.i)
# print(self.xAxis)
if len(self.yAxis) > 10:
self.yAxis = np.delete(self.yAxis, 0)
if len(self.xAxis) > 10:
self.xAxis = np.delete(self.xAxis, 0)
self.axes.plot(self.xAxis, self.yAxis, scaley=False)
self.axes.grid(True)
self.i = self.i + 1
self.draw()
This is my timer function - this is triggered by the click of a button in my PyQt GUI and then calls itself as you can see:
def timer(self):
getCH4()
getCO2()
getConnectedDevices()
self.dc.update_figure()
t = threading.Timer(1.0, self.timer)
t.start()
EDIT: I cant post my entire code because it requires a lot of .dll includes. So i'll try to explain what this program does.
In my GUI I want to show the my CO2 value over time. My get_co22 function just returns a float value and I'm 100% sure this works fine. With my timer, shown above, I want to keep append a value to a matplotlib graph - the Axes object is available to me as self.axes. I try to plot the last 10 values of the data.
EDIT 2: After some discussion in chat, I tried putting the call to update_figure() in a while loop and using just one thread to call it and was able to make this minimal example http://pastebin.com/RXya6Zah. This changed the structure of the code to call update_figure() to the following:
def task(self):
while True:
ui.dc.update_figure()
time.sleep(1.0)
def timer(self):
t = Timer(1.0, self.task())
t.start()
but now the program crashes after 5 iterations or so.

The problem is definitely not with how you are appending to your numpy array, or truncating it.
The problem here is with your threading model. Integrating calculation loops with a GUI control loop is difficult.
Fundamentally, you need your GUI threading to have control of when your update code is called (spawning a new thread to handle it if necessary) - so that
your code does not block the GUI updating,
the GUI updating does not block your code executing and
you don't spawn loads of threads holding multiple copies of objects (which might be where your memory leak comes from).
In this case, as your main window is controlled by PyQt4, you want to use a QTimer (see a simple example here)
So - alter your timer code to
def task(self):
getCH4()
getCO2()
getConnectedDevices()
self.dc.update_figure()
def timer(self):
self.t = QtCore.QTimer()
self.t.timeout.connect(self.task)
self.t.start(1000)
and this should work. Keeping the reference to the QTimer is essential - hence self.t = QtCore.QTimer() rather than t = QtCore.QTimer(), otherwise the QTimer object will be garbage collected.
Note:
This is a summary of a long thread in chat clarifying the issue and working through several possible solutions. In particular - the OP managed to mock up a simpler runnable example here: http://pastebin.com/RXya6Zah
and the fixed version of the full runnable example is here: http://pastebin.com/gv7Cmapr
The relevant code and explanation is above, but the links might help anyone who wants to replicate / solve the issue. Note that they require PyQt4 to be installed

if you are creating a new figure for every time this is quite common.
matplotlib do not free the figures you create, unless you ask it, somethink like:
pylab.close()
see How can I release memory after creating matplotlib figures

How to Refresh Python Script Once in Awhile?

So I've created a class, which contains GUI using wxPython.
How do you make it so that it refreshes itself say every minute?

For things that happen on intervals, use a Timer. From WxPyWiki:
def on_timer(event):
pass # do whatever
TIMER_ID = 100 # pick a number
timer = wx.Timer(panel, TIMER_ID) # message will be sent to the panel
timer.Start(100) # x100 milliseconds
wx.EVT_TIMER(panel, TIMER_ID, on_timer) # call the on_timer function
For some reason, this code didn't work when I tried it. The reason was the timer had to be a class member. If you put that code into the init() method and add self. before timer, it should work. If it doesn't, try making on_timer() a class member too. -- PabloAntonio
I've had problems closing my frame, when there was a Timer running.
Here's how I handled it:
def on_close(event):
timer.Stop()
frame.Destroy()
wx.EVT_CLOSE(frame, on_close)

I don't work with wxPython, but if there is a method called refresh or something alike, you could start a Thread calling that method every minute.
from threading import Thread
from time import sleep
def refreshApp(app, timespan):
while app.isRunning:
app.refresh()
sleep(timespan)
refresher = Thread(target=worker, args=(myAppInstance, 60))
refresher.start()
EDIT: fixed code so it fits into PEP8

As Niklas suggested I think you're looking for the Refresh() method: http://wxpython.org/docs/api/wx.Window-class.html#Refresh .