I can't find the syntax for setting on_press in python code to change the screen anywhere. I keep getting errors for anything like Button(text = 'hi', on_press = self.current = 'start_menu. Here's the code and it works as is.
class LoadMenu(Screen):
def __init__(self, **kwargs):
super(LoadMenu, self).__init__(**kwargs)
Clock.schedule_once(self.update)
def update(self, dt):
L = [x for x in range(len(os.listdir('saves')))]
for x in L:
x = self.add_widget(Button(text = os.listdir('saves')[x]))
I haven't positioned the buttons so they just are on top of each other but I can fix that later. What I need to happen is for each button to change to the play screen on press so that will be the same for each button but I also need each one to load the Shelve file they a referencing.(I know I'll need another function for that) Can I have an on_press trigger two events at once, and again how do I set it in the python code?
Consider the following programme:
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import Screen
from kivy.uix.button import Button
from kivy.clock import Clock
from kivy.properties import StringProperty
dirlist = ['aaa', 'bbb', 'ccc', 'ddd']
class MyButton(Button):
prop = StringProperty('')
def on_press(self):
print "Class-defined on_press handler (I'm {})".format(self.text)
def other_on_press_handler(sender):
print "other_on_press_handler, from {}".format(sender.text)
def some_func(text):
print "yeah: " + text
class LoadMenu(Screen):
def __init__(self, **kwargs):
super(LoadMenu, self).__init__(**kwargs)
Clock.schedule_once(self.update)
def on_press_handler(self, sender):
print "on_press_handler, from {}".format(sender.text)
self.parent.current = 'sc2'
def yet_another_on_press_handler(self, sender):
print "yet_another_on_press_handler, from {}".format(sender.text)
self.parent.current = 'sc2'
def update(self, dt):
for x in range(len(dirlist)):
my_b = Button(text = dirlist[x], on_press=self.on_press_handler)
self.parent.ids.button_container.add_widget(my_b)
if x > 1:
my_b.bind(on_press=other_on_press_handler)
if x == 3:
my_b.bind(on_press=lambda sender: some_func("Whoa, lambda was here ({})".format(sender.text)))
for x in range(len(dirlist)):
my_b = MyButton(text = 'my '+ dirlist[x], prop="{} {}".format(dirlist[x], x))
self.parent.ids.button_container.add_widget(my_b)
my_b.bind(on_press=self.yet_another_on_press_handler)
root = Builder.load_string("""
ScreenManager:
LoadMenu:
name: 'sc1'
GridLayout:
cols: 4
id: button_container
Screen:
name: 'sc2'
BoxLayout:
Button:
text: "Go back"
on_press: root.current = 'sc1'
""")
class MyApp(App):
def build(self):
return root
if __name__ == '__main__':
a = MyApp()
a.run()
Let's start by looking at the update method in LoadMenu: In the first loop, a bunch of buttons is generated, and each receives an on_press callback at creation. The last two buttons in the loop get bound to another callback, and the last example shows how to use a lambda expression to generate a callback.
In the second for loop, we instantiate object of class MyButton, a child of Button. Note that we also define an on_press handler in the class definition; this gets called in addition to other functions we may have bound.
But really, this is actually all pretty nicely explained in the kivy Events and Properties docs.
Related
In my Kivy-App, i generate Buttons via a python-class based on a dictionary (in the following example i use a list but that's just an example for the underlying problem).
Within the App, the dictionary gets changed and i want to display that change (obviously) in my App (by adding/ removing/ rearranging the Buttons).
To achieve this, my approach is to either restart the entire App or only reload that particular BoxLayout. Unfortunately, non of my attempts worked out so far and i could not find any (working) solution on the internet.
This is my code example:
Python Code:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
buttonlist = []
counter = 0
class MainWindow(BoxLayout):
def addbutton(self):
global buttonlist
global counter
buttonlist.append(counter)
counter += 1
class ButtonBox(BoxLayout):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.orientation = "vertical"
global buttonlist
for button in buttonlist:
b = Button(text=str(button))
self.add_widget(b)
class KivyApp(App):
def build(self):
return MainWindow()
KivyApp().run()
KV Code:
<MainWindow>:
BoxLayout:
ButtonBox:
Button:
text: "add Button"
on_press: root.addbutton()
My closest attempt was something containing a restart-Method like:
def restart(self):
self.stop()
return KivyApp().run()
and calling:
App.get_running_app().restart()
But for some reason, this does not stop the App but opens a second instance of the App within the first one (resulting in App in App in App in App if pressed often)
You can rebuild the ButtonBox by first calling clear_widgets() on the ButtonBox instance. Here is a modified version of your code that does that:
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
kv = '''
<MainWindow>:
BoxLayout:
ButtonBox:
id: box
Button:
text: "add Button"
on_press: root.addbutton()
'''
buttonlist = ['Abba', 'Dabba', 'Doo']
counter = 3
class MainWindow(BoxLayout):
def addbutton(self):
global buttonlist
global counter
buttonlist.append(str(counter))
counter += 1
self.ids.box.reload()
class ButtonBox(BoxLayout):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.orientation = "vertical"
self.reload()
def reload(self):
# method to rebuild the ButtonBox contents
global buttonlist
self.clear_widgets()
for button in buttonlist:
b = Button(text=str(button))
self.add_widget(b)
class KivyApp(App):
def build(self):
Builder.load_string(kv)
return MainWindow()
KivyApp().run()
I used your kv as a string, just for my own convenience.
I need to know how to reference dynamically created objects. Like in the example, how can I change text of the buttons after creation? Normaly I would do it using their ids, but as far as I know, you can't give ids to objects created in python.
.py code
from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.uix.button import Button
from kivy.clock import mainthread
NUMBER_OF_BUTTONS = 5
class MapScreen(Screen):
#mainthread
def on_enter(self):
for i in range(NUMBER_OF_BUTTONS):
button = Button(text="B_" + str(i))
self.ids.grid.add_widget(button)
class Test(App):
pass
Test().run()
.kv code
ScreenManager:
MapScreen:
<MapScreen>:
name: 'map'
GridLayout:
id: grid
cols: 1
You could just keep a list of the Buttons:
def on_enter(self):
self.buttons = []
for i in range(NUMBER_OF_BUTTONS):
button = Button(text="B_" + str(i))
self.buttons.append(button)
self.ids.grid.add_widget(button)
or you could create your own dictionary:
def on_enter(self):
self.buttons = {}
for i in range(NUMBER_OF_BUTTONS):
text = "B_" + str(i)
button = Button(text=text)
self.buttons[text] = button
self.ids.grid.add_widget(button)
New to kivy, and OOP.
I'm trying to update a label in kivy with data I pull from a temp sensor. The code that pulls in the sensor data is in labeltempmod. I created a function getTheTemp() that is called every second. In the function I try to assign the text of the label via Label(text=(format(thetemp)), font_size=80). The program ignores this. What am I doing wrong here?
#This is a test to see if I can write the temp to label
import labeltempmod
import kivy
from kivy.app import App
from kivy.clock import Clock
from kivy.uix.label import Label
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.textinput import TextInput
from kivy.uix.boxlayout import BoxLayout
def getTheTemp(dt):
thetemp = labeltempmod.readtemp()
Label(text=(format(thetemp)), font_size=80)
print thetemp
class LabelWidget(BoxLayout):
pass
class labeltestApp(App):
def build(self):
# call get_temp 0.5 seconds
Clock.schedule_interval(getTheTemp, 1)
return LabelWidget()
if __name__ == "__main__":
labeltestApp().run()
Here is the kivy language file:
<LabelWidget>:
orientation: 'vertical'
TextInput:
id: my_textinput
font_size: 80
size_hint_y: None
height: 100
text: 'default'
FloatLayout:
Label:
id: TempLabel
font_size: 150
text: 'Temp Test'
Thanks.
Sorry but you never update something You are just creating another label
Try this:
class LabelWidget(BoxLayout):
def __init__(self, **kwargs):
super(LabelWidget, self).__init__(**kwargs)
Clock.schedule_interval(self.getTheTemp, 1)
def getTheTemp(self, dt):
thetemp = labeltempmod.readtemp()
self.ids.TempLabel.text = thetemp
print thetemp
class labeltestApp(App):
def build(self):
return LabelWidget()
if __name__ == "__main__":
labeltestApp().run()
Update : for your last request, I think the best way to do that is:
...
class LabelWidget(BoxLayout):
def __init__(self, **kwargs):
super(LabelWidget, self).__init__(**kwargs)
self.Thetemp = None
Clock.schedule_interval(self.getTheTemp, 1)
def getTheTemp(self, dt):
if self.Thetemp is None:
self.thetemp = labeltempmod.readtemp()
else:
self.thetemp = labeltempmod.readtemp(self.theTemp)
self.ids.TempLabel.text = str(self.thetemp)
I am using kivy for UI. there is a Time_consuming function and when it runs, kivy ui will goes in black, so I used Threading.
I want to disable buttons until Time_consuming function finishes, and then enable button again. I have been used something like below:
from threading import Thread
from kivy.clock import Clock
from functools import partial
def run():
self.run_button.disabled=True
self.back_button.disabled=True
t=Thread(target=Time_consuming(), args=())
t.start()
Clock.schedule_interval(partial(disable, t.isAlive()), 8)
def disable(t, what):
print(t)
if not t:
self.run_button.disabled=False
self.back_button.disabled=False
but this dose not work, t.isAlive() in disable() even when Time_consuming() finishes, is True. where is the problem ?
question2: another problem is, Clock.schedule_interval will continue to run for ever. how can stop it when function finished?
I see you already answered your question. I was also building an example app to help you, while you were answering. I think it still can be of value to you and therefore I am posting it. One button shows you threading and the other one scheduling once. Happy coding :).
from kivy.app import App
from kivy.base import Builder
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
import time
import threading
Builder.load_string("""
<rootwi>:
label_to_be_changed1: label_to_be_changed1
label_to_be_changed2: label_to_be_changed2
button1: button1
button2: button2
orientation: 'vertical'
Button:
id: button1
text:'Button1 - Threading'
on_press: root.change_Label_text1()
Button:
id: button2
text: 'Button2 - schedule'
on_press: root.change_Label_text2()
Label:
id: label_to_be_changed1
Label:
id: label_to_be_changed2
""")
class rootwi(BoxLayout):
label_to_be_changed1 = ObjectProperty()
label_to_be_changed2 = ObjectProperty()
button1 = ObjectProperty()
button2 = ObjectProperty()
def change_Label_text1(self):
self.button1.disabled = True
threading.Thread(target=self.timeconsuming).start()
def timeconsuming(self):
#do your stuff
time.sleep(5)
self.label_to_be_changed1.text = 'thread has ended'
self.button1.disabled = False
def change_Label_text2(self):
self.button2.disabled = True
Clock.schedule_once(self.change_Label_text2_callback, 4)
def change_Label_text2_callback(self, *largs):
self.label_to_be_changed2.text = 'schedule has ended'
self.button2.disabled = False
class MyApp(App):
def build(self):
return rootwi()
if __name__ == '__main__':
MyApp().run()
I have found that:
question1: pass t instead of t.isAlive().this :
Clock.schedule_interval(partial(disable, t.isAlive()), 8)
changed to :
Clock.schedule_interval(partial(disable, t), 8)
question2: If the disable() returns False, the schedule will be canceled and won’t repeat.
def run_model():
self.run_button.disabled=True
self.back_button.disabled=True
t=Thread(target=run, args=())
t.start()
Clock.schedule_interval(partial(disable, t), 8)
def disable(t, what):
if not t.isAlive():
self.run_button.disabled=False
self.back_button.disabled=False
return False
Consider following code. I would like to update multiple widget instances when prefix changes. As it is the same for all the instances it seems efficient to store/update it only once on class level (so that when instance does not have its own self.prefix, it will automatically refer to class level prefix attribute)
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.properties import StringProperty
import random
kivy_lang = '''
<MainWidget>:
Button:
id: my_button
text: 'increase indice'
<MyLabel>:
on_prefix: self.text = self.prefix +':'+ self.indice
on_indice: self.text = self.prefix +':'+ self.indice
'''
class MyLabel(Label):
prefix = StringProperty('1')
indice = StringProperty('0')
pass
class MainWidget(BoxLayout):
def __init__(self, **kwargs):
super(MainWidget, self).__init__(**kwargs)
self.my_label1 = MyLabel()
self.my_label2 = MyLabel()
self.add_widget(self.my_label1)
self.add_widget(self.my_label2)
self.ids.my_button.bind(on_press=self.my_method)
def my_method(self,*args,**kwargs):
MyLabel.prefix = str(random.randint(0,9))
self.my_label1.indice = str(int(self.my_label1.indice) + 1)
# my_label2 would also be updated if its 'indice' got changed as below
# self.my_label2.indice = str(int(self.my_label2.indice) + 2)
class MyApp(App):
def build(self):
Builder.load_string(kivy_lang)
return MainWidget()
if __name__ == '__main__':
MyApp().run()
As from the python side this seems right, from Kivy side it looks like kivy has problem recognising when prefix got changed (my_label1 only gets updated because indice was also updated and on_indice is triggered).
Is there a way to get 'class level Property' prefix change to trigger on_prefix ?
I don't think this is possible directly, but you could mimic that functionality with AliasProperty and another property stored, say, on App. As long as the instance of MyLabel hasn't changed prefix, the value set for App is used (and automatically updated). Once prefix is set on an instance, _my_prefix is not None, and will be used to retrieve the value for prefix.
Change the <MyLabel> rule to
<MyLabel>:
_prefix: app.prefix
text: self.prefix +':'+ self.indice
And change the python code to
class MyLabel(Label):
indice = StringProperty('0')
_prefix = StringProperty('')
_my_prefix = StringProperty(None)
def get_prefix(self):
if self._my_prefix is None:
return self._prefix
else:
return self._my_prefix
def set_prefix(self, value):
self._my_prefix = value
prefix = AliasProperty(get_prefix, set_prefix, bind=('_prefix', '_my_prefix'))
[...]
def my_method(self,*args,**kwargs):
App.get_running_app().prefix = str(random.randint(0,9))
self.my_label1.indice = str(int(self.my_label1.indice) + 1)
if int(self.my_label1.indice) == 2:
self.my_label2.prefix = 'changed'
[...]
class MyApp(App):
prefix = StringProperty('1')