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KivyMD without using kv file

I'm trying to make an expense tracker app using KivyMD. I have built it already using kivy but it's design is awful, then i found out KivyMD and now i want to tweak the app using KivyMD but i want to do it without using a kv file because my app has a lot of nested if statements which are too complex to write in the kv file. Anyway, i'm trying to test KivyMD but running into this nasty ValueError
ValueError: KivyMD: App object must be initialized before loading root widget. See https://github.com/kivymd/KivyMD/wiki/Modules-Material-App#exceptions and idk how to fix it without using a kv file. This question is asked plenty times but every answer uses a kv file. Can someone please help me understand this error and tackle it without kv. Thank you... Here is some code
from kivymd.app import MDApp
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.app import App
from kivymd.uix.boxlayout import MDBoxLayout
from kivymd.uix.stacklayout import MDStackLayout
from kivymd.uix.button import MDRaisedButton, MDRectangleFlatButton
from kivy.metrics import dp,sp
from kivymd.uix.screen import MDScreen
from kivy.uix.textinput import TextInput
from kivymd.uix.textfield import MDTextField
from kivy.uix.screenmanager import ScreenManager
import re
#ALL SCREENS
class MainScreen(MDScreen):
def __init__(self, **kwargs):
super().__init__(**kwargs)
box = MDBoxLayout(orientation="vertical")
b = MDRaisedButton(text="Content",size_hint = (1,0.5))
box.add_widget(b)
t = MDTextField(size_hint=(1,0.5))
box.add_widget(t)
self.add_widget(box)
#ScreenManager
sm = ScreenManager()
sm.add_widget(MainScreen(name="main_screen"))
class MyApp(MDApp):
def build(self):
self.theme_cls.primary_palette = "DeepOrange"
self.theme_cls.accent_palette = "Lime"
return MainScreen()
if __name__ == "__main__":
MyApp().run()
works perfectly fine when i remove the screenmanager and just return the MainScreen.
Any help or guidance is highly appreciated.

is there a way to write Persian in python kivy

i try to write Persian in python kivy but it is not working.
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager,Screen
from kivy.lang import Builder
from kivy import Config
from kivy.uix.label import Label
from kivy.uix.widget import Widget
class MainApp(App):
def build(self):
return Label(text= "فارسی")
if __name__ == "__main__":
MainApp().run()

You need to use some Persian font.
I have done it with Arabic text
You can download the font from here
Then use arabic_reshaper library to get it in shape.
pip install arabic-reshaper
You will also need python-bidi as well to flip the letters
pip install python-bidi
Refer to this https://github.com/mpcabd/python-arabic-reshaper
Code
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager,Screen
from kivy.lang import Builder
from kivy import Config
from kivy.uix.label import Label
from kivy.uix.widget import Widget
import arabic_reshaper
from bidi.algorithm import get_display
class MainApp(App):
def build(self):
reshaped_text = arabic_reshaper.reshape("فارسی")
bidi_text = get_display(reshaped_text)
return Label(text= bidi_text, font_name='Amiri-Regular.ttf', font_size=30)
if __name__ == "__main__":
MainApp().run()
Output

Kivy - I can't see the picture

I am developing a mobile application. There should be a picture in the introduction of my application. Even though I put the picture and show the way, the picture does not appear when I run the application. It is replaced by a white screen. How can I solve it?
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.widget import Widget
from kivy.uix.image import Image
from kivy.animation import Animation, AnimationTransition
class loginImage(Image):
pass
class loginScreen(App):
def build(self):
img = Image()
return img
loginScreen().run()
My .kv code in here:
<-loginScreen>:
source: 'images.jpeg'

kv rules are for widgets, not the App class, so your source isn't applied to anything.
Set the source of the Image widget that you return.

Kivy Does Not Output Plain Text, Only Object Location

So I was trying to create a very basic text editor in Kivy. So I had got around the issue of text not showing up (via lambda). However, a new error appeared on the horizon; saving. I want to save automatically to a plain txt file. However, my current code only save an object (is it a pointer?) of the actual text input. Thank you all, SO!
import kivy
import os
kivy.require('1.10.1') # replace with your current kivy version !
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput
from kivy.uix.label import Label
from kivy.clock import Clock
from kivy.uix.button import Button
from kivy.lang import Builder
class ColdKivyApp(App): # I actually used to call it Zone but changed it to Cold cause it's cold outside ;)
def build(self):
f = BoxLayout(orientation='vertical')
txt = TextInput(multiline=True, cursor_blink=True, background_color=(1,1,1,1))
f.add_widget(txt)
txtstr = str(txt)
Clock.schedule_once(lambda *args: setattr(txt, "focus", True))
with open('testtxt.txt', 'w') as txtwriter:
txtwriter.write("" + txtstr)
txtwriter.close()
return f
if __name__ == '__main__':
ColdKivyApp().run()
Edit: Spelling

TextInput has a text property, that's where the current content is.

Replace txtstr = str(txt) in your code to txtstr = txt.text.

Kivy image not showing

Im working on a basic app using python and kivy and im trying to import an image which I'm basically going to use as a splash screen of sorts but for some reason I couldn't get it to work so I created a .py file and wrote some very simple code to try to get it to work:
from kivy.app import App
from kivy.uix.label import Label
from kivy.core.window import Window
Window.size = (360, 640)
class ImageTestApp(App):
def build(self):
label = Label(source="image.jpg")
return label
if __name__ == "__main__":
ImageTestApp().run()
The image is in the same directory of the .py file and the name of the image is exactly the same, I even made the window size the same as the image size and tried .PNG but nothing worked 😖

Label does not have an attribute called source. You should change Label to Image, and it will works. Please refer to example below for details.
Example
main.py
from kivy.app import App
from kivy.uix.image import Image
from kivy.core.window import Window
Window.size = (360, 640)
class ImageTestApp(App):
def build(self):
return Image(source="image.jpg")
if __name__ == "__main__":
ImageTestApp().run()
Output