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Add widget dynamically from outside class (error)

I´m learning kivy, and it has passed 3 weeks since i face this problem without encounter a solution, so i hope any of u guys could help me, i would appreciate it.
I have a main file:
from app import MyProgramApp
if __name__ == "__main__":
winapp = MyProgramApp()
winapp.run()
from where i start my app. Then i have a directory called "app", inside there is the following "init.py" file.
from kivy.app import App
from kivy.utils import QueryDict, rgba
from kivy.core.window import Window
from .view import MainWindow
Window.minimum_width = 500
Window.minimum_height = 650
Window.maximize()
class MyProgramApp(App):
colors = QueryDict()
colors.primary = rgba('#2D9CDB')
colors.secondary = rgba('#16213E')
colors.succes = rgba('#1FC98E')
colors.warning = rgba('#F2C94C')
colors.danger = rgba('#E85757')
colors.grey_dark = rgba('#C4C4C4')
colors.grey_light = rgba('#F5F5F5')
colors.black = rgba('#A1A1A1')
colors.white = rgba('#FFFFFF')
def build(self):
return MainWindow()
Same folder app, i have the following "view.py".
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.behaviors import ToggleButtonBehavior
from kivy.properties import StringProperty
from kivy.uix.screenmanager import ScreenManager
class MainWindow(BoxLayout):
username = StringProperty("Usuario")
def __init__(self, **kw):
super().__init__(**kw)
def on_press_home(self):
self.ids.scrn_mngr.current = "scrn_home"
class ViewManager(ScreenManager):
def __init__(self, **kw):
super().__init__(**kw)
class NavTab(ToggleButtonBehavior, BoxLayout):
text = StringProperty('')
icon = StringProperty('')
def __init__(self, **kw):
super().__init__(**kw)
and finally for that folder i have "myprogram.kv"
#:kivy 2.1.0
#:import Home views.home.Home
<MainWindow>:
spacing: dp(8)
canvas.before:
Color:
rgba: app.colors.white
Rectangle:
pos: self.pos
size: self.size
# NAVIGATION BAR
BoxLayout:
id: nav_menu
size_hint_x: .2
orientation: "vertical"
size_hint_min_x: dp(100)
# LOGO
BoxLayout:
id: logo_nbox
size_hint_y: .1
size_hint_min_y: dp(70)
padding: dp(16)
AnchorLayout:
anchor_x: "right"
size_hint_x: None
width: dp(52)
halign: "left"
Label:
text: "COMPANY"
halign: "center"
BoxLayout:
orientation: "vertical"
Label:
text: "COMPANY"
halign: "center"
Label:
text: "Phrase"
halign: "center"
# OPTIONS
GridLayout:
id: tabs_box
cols: 1
spacing: dp(4)
size_hint_y: .5
canvas.before:
Color:
rgba: app.colors.grey_dark
Rectangle:
pos: self.pos
size: [self.size[0], dp(1)]
NavTab:
text: "Home"
state: "down"
on_press: root.on_press_home()
# BODY
BoxLayout:
size_hint_x: .8
spacing: dp(8)
orientation: "vertical"
padding: [dp(16), dp(8), dp(12), dp(8)]
canvas.before:
Color:
rgba: app.colors.grey_light
Rectangle:
pos: self.pos
size: self.size
# SCREENS
BoxLayout:
ViewManager:
id: scrn_mngr
<ViewManager>:
Screen:
name: "scrn_home"
Home:
id: home
<NavTab>:
background_normal: ""
background_down: ""
background_color: [0,0,0,0]
group: "tabs"
size_hint_y: None
height: dp(45)
spacing: dp(4)
canvas.before:
Color:
rgba: [0,0,0,0] if self.state == "normal" else rgba("#E1F1FF")
Rectangle:
pos: self.pos
size: self.size
Color:
rgba: [0,0,0,0] if self.state == "normal" else app.colors.primary
Rectangle:
pos: [self.pos[0]+self.size[0]-dp(1), self.pos[1]]
size: [dp(8), self.size[1]]
Label:
halign: "left"
valign: "middle"
text: root.text
color: app.colors.grey_dark if root.state == "normal" else app.colors.primary
Then i got another folder called "views" inside i have another folder called "home", inside home we encounter 3 files "init.py", "home.kv", "home.py". the first one "init.py" is the following.
from .home import Home
then we got "home.kv".
#:kivy 2.1.0
<Home>:
orientation: "vertical"
Label:
size_hint_y: .1
text: "Other"
Button:
size_hint_y: .1
text: "popup"
on_press: root.open_popup()
BoxLayout:
size_hint_y: .8
id: home_box
<SomePopup>:
title: "SOME TITLE"
title_align: "center"
title_color: app.colors.primary
size_hint: .25, .8
size_hint_min_x: dp(200)
pos_hint: {"x": .1, "top": .9}
BoxLayout:
orientation: "vertical"
padding: [dp(0), dp(12), dp(0), dp(12)]
Label:
text: "Some text"
Button:
text: "create buttons on box"
on_press: root.modify_home_box()
and finally and the problem that i´m facing is whit the following file "home.py"
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.factory import Factory
from kivy.uix.popup import Popup
from kivy.uix.button import Button
from kivy.app import App
Builder.load_file('views/home/home.kv')
class Home(BoxLayout):
def __init__(self, **kwargs):
super().__init__(**kwargs)
def open_popup(self):
Factory.SomePopup().open()
class SomePopup(Popup):
def __init__(self, **kw):
super().__init__(**kw)
def modify_home_box(self):
my_app = App.get_running_app().root
my_box = my_app.ids.home.ids.home_box
custom_button = Button(
text = "something"
)
my_box.add_widget(custom_button)
That i´m trying to do is actually modify "home_box" with is store on ids Home dictionary, i also try with ObjectProperty (but that gives and Attribute Error, since i only could read propertys but doesnt modify it), instance of a new Home class doesnt work... searching for current app in App appear doesnt work since Home is store i think on screenManager...
I need add a button or some widget to "home_box" from outside class "SomePopup". I also drop here a repository on github with the whole code. github_repo
I don't know how to solve my issue, and i try with the resources available here on stack as well other net places... any help would be appreciate.

Just a very complicated path to the widget of interest. In your modify_home_box() method, try replacing:
my_app = App.get_running_app().root
my_box = my_app.ids.home.ids.home_box
with:
my_app = App.get_running_app().root
my_box = my_app.ids.scrn_mngr.ids.home.ids.home_box

Aligning text position and size in a button kivy

I'm struggling to get the text in a button to align in the centre of the button, it's just sitting at the bottom of the button.
I've tried changing text_size and font_size to the RoundedButton but nothing has worked so far.
FloatLayout:
RoundedButton:
size_hint: 0.417, 0.15625
pos_hint: {"x": 0.0556, "y": 0.15}
text: "Holding text that isn't aligning in the centre of the button'"
color: 0,0,0,1
text_size: self.width , self.height
halign: "center"
font_size: self.height - 75
<RoundedButton#Button>:
background_normal: ""
background_color: 0, 0, 0, 0
back_color: 0.2,0.6,1,1
border_radius: 10
font_size: '25'
color: self.back_color
bold: True
canvas.before:
Color:
rgba: self.back_color
Line:
rounded_rectangle: self.x, self.y, self.width, self.height, self.border_radius
width: 1
and a trimmed version of the python file:
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.core.window import Window
Window.clearcolor = (1,1,1,1)
class WindowManager(ScreenManager):
pass
kv = Builder.load_file("mykivy.kv")
sm = WindowManager()
class MyApp(App):
def build(self):
return sm
if __name__ == '__main__':
MyApp().run()

I've just figured it out, if anyone wants to know the answer in future I had to set valign to "center" (as well as having halign: "center")

Prevent TabbedPanel from redrawing during animation

Any assistance is much appreciated.
Here's an example code to show the problem,
when the ('Press me') button is pressed and the widget resized(white box come within view), the TabbedPanel redraws like a glitch (even though its not).
I've tried changing the layout order and toyed a bit with the animation, no
I wish to prevent that blinking behaviour of the tabbedpanel on the left.
import kivy
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.animation import Animation
from kivy.lang import Builder
Builder.load_string('''
<Main>:
BoxLayout:
orientation:'vertical'
BoxLayout:
id: main_screen
orientation: 'horizontal'
TabbedPanel:
do_default_tab: False
tab_pos: 'left_top'
tab_width: main_screen.height/4
TabbedPanelItem:
text: 'four'
TabbedPanelItem:
text: 'three'
TabbedPanelItem:
text: 'two'
TabbedPanelItem:
text: 'one'
BoxLayout:
id: swidget
slide: 0
size_hint: None, None
height: main_screen.height
width: self.slide
canvas:
Color:
rgba: 1,1,1,1
Rectangle:
pos: self.pos
size: self.size
Button:
size_hint_y: None
height: '33dp'
text: 'Press me'
on_release: root.display_widget(swidget)
''')
class Main(BoxLayout):
def __init__(self, **kwargs):
super(Main, self).__init__(**kwargs)
def display_widget(self, widget):
swidget = widget
if swidget.slide == 0:
anim = Animation(slide=105, duration=0.6)
anim.start(widget)
else:
anim = Animation(slide=0, duration=0.6)
anim.start(widget)
class TabbedApp(App):
def build(self):
return Main()
TabbedApp().run()

Add AnchorLayout to be the parent of swidget / BoxLayout and when the animation starts, it won't impact the instantiated TabbedPanel.
Snippets
AnchorLayout:
anchor_x: 'right'
anchor_y: 'top'
size_hint_x: None
width: 0
BoxLayout:
id: swidget
slide: 0
size_hint_x: None
width: self.slide
canvas:
Color:
rgba: 1,1,1,1
Rectangle:
pos: self.pos
size: self.size

kivy scrollview inside gridlayout on label

I trying to create a one screen app with one root rule set. by pressing a button i should see a scrollable text in the grid next to the button. In all the example solutions I see that scrollview is working in similar KV files that I have seen in other questions. Could someone please identify what I have missed in KV file.
my .py file:
import kivy
import string
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.gridlayout import GridLayout
from kivy.properties import ObjectProperty
from kivy.properties import StringProperty
from kivy.uix.scrollview import ScrollView
from kivy.core.window import Window
class RootContainer(BoxLayout):
instance = ObjectProperty(None)
def __init__(self, **kwargs):
super(RootContainer, self).__init__(**kwargs)
def clickAction1(self, instance):
#identify the button pressed
buttonText = instance.text
self.lbl1.text = instance.text + " some text goes here ... "
myresult = " this is scrolling text.\n " * 30
self.lbl5.text = myresult
class MBApp(App):
def build(self):
return RootContainer()
if __name__ == '__main__':
MBApp().run()
my KV file:
#:kivy 1.0.9
<RootContainer>:
id: theRoot
lbl1: my_labelC
lbl5: my_labelCS
BoxLayout:
orientation: 'vertical'
spacing: 20
padding: 20
canvas:
Color:
rgb: 0, .33, 0
Rectangle:
pos: self.pos
size: self.size
Button:
text: "This is 1st button"
text_size: self.size
size_hint: (.5,1)
on_press: theRoot.clickAction1(self)
Button:
text: "This is 2nd button"
text_size: self.size
size_hint: (.5,1)
on_press: root.clickAction1(self)
GridLayout:
rows: 2
cols: 1
spacing: 10
padding: 10
canvas:
Color:
rgb: .7, .63, 0
Rectangle:
pos: self.pos
size: self.size
Label:
id: my_labelC
canvas.before:
Color:
rgb: 0,0,0
Rectangle:
pos: self.pos
size: self.size
text: "Header text for button clicked ......."
text_size: self.size
ScrollView:
GridLayout:
cols:1
rows:1
height: self.minimum_height
Label:
id: my_labelCS
text: "Scrolling text goes here ....."
I hope this is not a duplicate. Any other suggestions to code are also welcome. Thank you.

You don't set the size of your Label, so the default applies, as any widget, the defaults are
size: 100, 100
size_hint: 1, 1
since size_hintis 1, 1, and the parent is a layout, size itself is overriden by the parent's available space
since you set size: minimum_size in the parent layout, it'll give the minimum size its children require, but the Label doesn't ask for any space, it's size_hint of 1, 1 means that it's happy to take all the available space. Kivy solve this situation by not giving it any space, so the Label size ends up being 0, 0, and the GridLayout's size as well.
So you want to disable size_hint (at least for the height, of the Label, and instead set it to the texture heights
size_hint_y: None
height: self.texture_size[1]
Which is usually sided with setting the texture width to the available width, by setting text_size.
text_size: self.width, None
size_hint_x: 1 # this is the default, so this line is not required, but you want to be sure not to disable this default

Do you really need the GridLayout inside your scrollview? This works for me:
ScrollView:
Label:
id: my_labelCS
size_hint: 1, None
text_size: self.width, None
height: self.texture_size[1]
text: "Scrolling text goes here ....."

Read the text from Textinput dynamically when text changed in text box?

I'm new to kivy , I'm trying to write an application using kivy in python, I got struck at one point where i have to read text from textinput whenever it is changed and based on that i want to implement my button's functionality - I have gone through all the documentation but i couldn't figure out how to do it - Can any body tell me how can I resolve this or am I missing something?
from __future__ import print_function
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.core.image import Image
from kivy.uix.floatlayout import FloatLayout
from kivy.graphics import *
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.uix.popup import Popup
from kivy.properties import ObjectProperty
import walascan
from kivy.clock import Clock
import os
kv = """
<KartScan>:
IntroScreen:
<IntroScreen#Screen>:
orientation: 'horizontal'
name: 'introscreen'
canvas.before:
Rectangle:
pos: self.pos
size: self.size
source: 'index.png'
AnchorLayout:
anchor_x: 'center'
anchor_y: 'center'
BoxLayout:
orientation:'horizontal'
size_hint: .5, .1
canvas:
Color:
rgb: 1, 1, 1
Rectangle:
pos: self.pos
size: self.size
spacing: 20
pos_hint: {'center_x':.8, 'center_y': .8}
AnchorLayout:
anchor_x: 'left'
size_hint_x: .5
TextInput:
id: waybill
width: 20
text: "Enter Waybill No."
multiline: False
height: self.minimum_height
size_hint_y: None
font_size: 30
focus: True
on_text_validate: app.on_waybill()
AnchorLayout:
anchor_x: 'right'
size_hint_x: None
Button:
size_hint: None, None
height: 50
width: self.texture_size[0]
padding: 10, 10
text: "Add"
on_press:app.buttonClicked()
on_release: root.current = 'mainpage'
AnchorLayout:
anchor_x: 'right'
size_hint_x: None
Button:
size_hint: None, None
height: 50
width: self.texture_size[0]
padding: 10, 10
text: "Compare"
on_press:app.buttonClicked()
on_release: root.current = 'mainpage'
"""
Builder.load_string(kv)
waybill = TextInput(text="Enter Waybill No.", multiline=False)
class KartScan(FloatLayout):
def __init__(self, **kwargs):
super(KartScan, self).__init__(**kwargs)
self.register_event_type('on_text_validate')
def on_text(self, *args):
print('new value is ', waybill.text)
def on_text_validate(self):
pass
def on_focus(self, obj, focused):
if not focused:
self.dispatch('on_text_validate')
class KartScanApp(App):
def build(self):
return KartScan()
def buttonClicked(self):
popup = Popup(title='Result',
content=Label(text=self.on_waybill()),
size_hint=(None, None), size=(100, 100))
popup.bind()
popup.open()
def getwlbtstate(self):
return walascan.mainAntennas()
def on_waybill(self):
waybill.bind(text=KartScan.on_text_validate)
# popup = Popup(title='Result',
# content=Label(text=waybill.text),
# size_hint=(None, None), size=(100, 100))
# popup.bind()
# popup.open()
return waybill.text
if __name__ == '__main__':
KartScanApp().run()

kv file
TextInput:
on_text: print(self.text)
You could use on_text to call a function when the text changes. I think it sometimes even triggers when no change has occured.

TextInput has a text property, and in kivy, all properties have associated on_xxx events, that you can bind to to react to them, so when reading the doc, even if it's not explicitly mentionned for them, everytime you see something is defined as a Property (or any subclass of it, like StringPropertyNumericProperty,ObjectProperty,AliasProperty`).
TextInput:
on_text: do_something(self.text)
or in python
t = TextInput(text='', on_text=do_something)
or
t = TextInput(text='')
t.bind(on_text=do_something)