I'm usng kivy and the kv languge to make a GUI, I'm still only new to kivy.
In the image below the the buttons were in the black bit on the right side of the GUI but the scrollview buttons on fitted half of the height of the screen to I put an extra floatlayout in the rule and indented everything but now all the buttons are on the wrong side of the screen.
#:kivy 1.9.0
GridLayout:
rows: 1
LeftArea:
RightArea:
<LeftArea#FloatLayout>:
canvas:
Color:
rgb: 0, 1, 0
Rectangle:
size: self.size
pos: self.pos
Image:
source: 'moneyswags.gif'
size: self.size
pos: self.pos
<RightArea#GridLayout>:
cols: 1
size_hint_x: 0.3
spacing: '10dp'
FloatLayout:
ScrollView:
LinksGrid:
id: links_grid
BoxLayout:
cols: 1
rows: 2
GetLinksButton:
links_grid: links_grid
Clearlinkbuttons:
links_grid: links_grid
<LinksGrid#GridLayout>:
cols: 1
spacing: '5dp'
size_hint_y: None
height: self.minimum_height
<GetLinksButton>:
size_hint_y: 0.1
text: 'get links'
on_press: self.get_links()
<Clearlinkbuttons>:
size_hint_y: 0.1
text: 'clear links'
on_press: self.clear_links()
<LinkButton>:
size_hint_y: None
height: '80dp'
Related
I'm trying to create a screen which has a horizontal scrollview at the top of the page, taking up ~25% of the vertical space and a vertical scrollview taking up the rest of the space (and then being able to scroll further down the screen).
I've managed to create a horizontal scrollview but can't get the vertical scrollview to work on the same screen.
py file:
import kivy
from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.image import Image
from
Window.clearcolor = (1,1,1,1)
class Window(Screen):
pass
class MyApp(App):
theme_cls = ThemeManager()
def build(self):
kv = Builder.load_file("kivy.kv")
self.sm = WindowManager()
screens = [Window(name="window")]
for screen in screens:
self.sm.add_widget(screen)
self.sm.current = "window"
return self.sm
if __name__ == '__main__':
MyApp().run()
kv file:
<Window>:
name: "window"
NavigationLayout:
id: nav_layout
MyNavDrawer:
BoxLayout:
orientation: "vertical"
MDToolbar:
pos_hint: {'top': 1}
md_bg_color: 1, 1, 1, 1
ScrollView: #horizontal scrollview - works fine
size_hint_y: 0.5
GridLayout:
rows: 1
id: scroll_horizontal
size_hint_x: None
col_default_width: root.width*0.2
width: self.minimum_width*1.3
spacing: 20
ScrollView: #vertical scrollview, not working
size_hint_y: 0.85
do_scroll_x: False
GridLayout:
id: scroll_vertical
cols: 1
size_hint_y: None
spacing: 40
height: self.minimum_height
canvas:
Color:
rgba: (1, 1, 1, 1)
Rectangle:
size: self.size
pos: self.pos
BoxLayout:
cols: 2
spacing: 10
Button:
size_hint_y: 0.5
text: "Btn1"
Button:
size_hint_y: 0.5
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
Button:
size_hint_y: 0.5
text: "Btn1"
Button:
size_hint_y: 0.5
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
Button:
size_hint_y: 0.5
text: "Btn1"
Button:
size_hint_y: 0.5
text: "Btn2"
I'd like them to be independent of each other, so you can either scroll horizontal on the top scrollview or scroll veritcally through the buttons on the boxlayouts on the vertical scrollview
It took some work to get your MCVE working, but here is the part of your kv that I modified to get scrolling working in both directions with two ScrollViews:
ScrollView: #horizontal
size_hint_y: 0.25
do_scroll_y: False
GridLayout:
rows: 1
id: scroll_horizontal
size_hint: None, 1
col_default_width: root.width*0.2
width: self.minimum_width*1.3
spacing: 20
BoxLayout:
cols: 2
spacing: 10
size_hint_x: None
width: self.minimum_width
Button:
size_hint: None, 1
width: 500
text: "Btn1"
Button:
size_hint: None, 1
width: 500
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
size_hint_x: None
width: self.minimum_width
Button:
size_hint: None, 1
width: 500
text: "Btn1"
Button:
size_hint: None, 1
width: 500
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
size_hint_x: None
width: self.minimum_width
Button:
size_hint: None, 1
width: 500
text: "Btn1"
Button:
size_hint: None, 1
width: 500
text: "Btn2"
ScrollView: # vertical
size_hint_y: 0.75
do_scroll_x: False
GridLayout:
id: scroll_vertical
cols: 1
size_hint: 1.0, None
spacing: 40
# must set height
height: self.minimum_height
BoxLayout:
cols: 2
spacing: 10
size_hint_y: None
Button:
size_hint: 0.5, None
height: 100
text: "Btn1"
Button:
size_hint: 0.5, None
height: 100
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
size_hint_y: None
height: self.minimum_height
Button:
size_hint: 0.5, None
height: 100
text: "Btn1"
Button:
size_hint: 0.5, None
height: 100
text: "Btn2"
BoxLayout:
cols: 2
spacing: 10
size_hint_y: None
height: self.minimum_height
Button:
size_hint: 0.5, None
height: 100
text: "Btn1"
Button:
size_hint: 0.5, None
height: 100
text: "Btn2"
recently I try to make that app with python and kivy. After tons of hours googling everything together i more or less have everything i want. Only one thing is missing:
I have several screens. At the beginning of the App I have a menu. After that i have lots of questions; all of them have the same text and buttons in the bottom of the screen. I managed to make that the following way:
<firstquestion>:
name: "firstquestion"
GridLayout:
cols: 1
size_hint_y: 1
GridLayout:
cols: 1
NeuLabelinBox:
text: "Here the Question"
GridLayout:
cols: 1
size_hint_y: 0.1
UnteresMenue:
Please notice "UnteresMenue" which refer another Class in the kv language. I think I somehow mixed 2 Screens together in one. The kv code of "UnteresMenue"
<UnteresMenue>:
name: "UnteresMenue"
#id: UnteresMenue
GridLayout:
cols: 1
NeuButton:
text: root.labeltext
Now for the python part:
class UnteresMenue(Screen):
labeltext = StringProperty("Answer")
That works fine. But now I want to change the text of the label in this "UnteresMenue", when I press a certain button at the beginning of the app (Start Questions). The label in the "Untermenue" should change to a certain text. So to do this:
text: "Exam"
self.manager.get_screen('UnteresMenue').labeltext = text
For all other classes this method works fine. But not for that certain class "UnteresMenue". Is it because it is implemented in the question and therefor kv does not recognize its properties?
For any small hints I would be more than grateful!
Here an "Mini" Example:
In the Main Menu you get to the "Exam" Section (Press Here in the example). While entering this Section (Prüfungsmodus) the property of the questions should change. "Press Here" again to get to the questions.
Normally it says in the Top of the questions "This should change" And THIS is supposed to change the label into "Zeit" while entering the Prüfungsmodus Screen (Class def on_enter, in the python file), but it doesn't...
Python File:
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen, TransitionBase
from kivy.properties import ObjectProperty, NumericProperty
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.core.text import LabelBase
from kivy.core.window import Window
from kivy.graphics import Color, InstructionGroup, Line, Rectangle
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.properties import ListProperty
from kivy.uix.textinput import TextInput
from kivy.uix.checkbox import CheckBox
from kivy.uix.widget import Widget
from kivy.config import Config
from kivy.properties import StringProperty
from kivy.clock import Clock
from functools import partial
from kivy.uix.image import Image
from kivy.garden.navigationdrawer import NavigationDrawer as ND
from kivy.uix.scatter import Scatter
import random
import time
Window.clearcolor = (0.2,0.2, 0.2,1)
Window.size = (480, 800)
#--------------------------------- Hauptmenü -------------------------------------------
class hauptmenue(Screen, Widget):
pass
class Pruefungsmodus(Screen):
labeltext2 = StringProperty("hi")
def on_enter(self):
text = "Zeit"
self.manager.get_screen('OberesMenue').labeltext = text #DAS Klappt nicht
def StartPruefung(self):
sm.current = "ersteFrage"
class UnteresMenue(Screen):
background_color_Kappa = ListProperty([0.2,0.2,0.2, 1])
class OberesMenue(Screen):
BildLabeltext = StringProperty("Bilder\Loesung_Bild_pressed.png")
BildLabeltext2 = StringProperty("Bilder\Loesung_Bild.png")
labeltext = StringProperty("This should change")
class ersteFrage(Screen):
pass
class WindowManager(ScreenManager):
pass
kv = Builder.load_file("my.kv")
sm = WindowManager()
sm.add_widget(hauptmenue(name="hauptmenue"))
sm.add_widget(Pruefungsmodus(name="Pruefungsmodus"))
sm.add_widget(OberesMenue(name="OberesMenue"))
sm.add_widget(UnteresMenue(name="UnteresMenue"))
sm.add_widget(ersteFrage(name="ersteFrage"))
sm.current = "hauptmenue"
class Vorbrereitung(App):
pruefung = ObjectProperty(None)
def build(self):
return sm
if __name__ == "__main__":
Vorbrereitung().run()
my.kv file :
#:include alleFragen.kv
<NeuLabel2#Label>:
halign: "center"
color:1,1,1,1 # <-----------
canvas.before:
Color:
rgba: 0.2,0.2, 0.2,1
Rectangle:
pos: self.pos
size: self.size
<NeuLabelinBox#Label>:
font_size: "22sp"
color:0,0,0,1 # <-----------
canvas.before:
Color:
rgba: 0.949019608, 0.949019608, 0.949019608, 1
Rectangle:
pos: self.pos
size: self.size
<NeuCheckBox#CheckBox>:
color: 0, 0, 0, 1
canvas.before:
Color:
rgba: 0.949019608, 0.949019608, 0.949019608, 1
Rectangle:
pos: self.pos
size: self.size
<NeuButton#Button>:
font_size: "22sp"
background_normal: ''
#background_normal: "background.png"
background_color: 0.92549,0.92549,0.92549, 1
color:0,0,0,1 # <-----------
canvas.before:
Color:
rgba: 0.2,0.2, 0.2,1
Rectangle:
pos: self.pos
size: self.size
<NeuButtonKappa#Button>:
font_size: "40sp"
background_normal: ''
background_color: 0.2,0.2,0.2, 1
color:1,1,1,1 # <-----------
canvas.before:
Color:
rgba: 0.2,0.2, 0.2,1
Rectangle:
pos: self.pos
size: self.size
#---------------------------------- Hauptmenue ---------------------------------------------------------------------------------
<hauptmenue>:
name: "Hauptmenue"
GridLayout:
cols:1
#spacing: 20
GridLayout:
cols:1
padding: 20
size_hint_y: 0.2
NeuLabel2:
size_hint_x: 0.6
text: ""
font_size: (root.width**2 + root.height**2) / 13**4
halign: 'center'
valign: 'middle'
GridLayout:
cols:2
padding: 30
spacing: 20
size_hint_y: 0.5
BoxLayout:
NeuButton:
text: ''
BoxLayout:
NeuButton:
text: 'PRESS HERE'
on_release:
app.root.current = "Pruefungsmodus"
BoxLayout:
NeuButton:
text: ""
halign: 'center'
valign: 'middle'
BoxLayout:
NeuButton:
text: ""
BoxLayout:
padding: 10
size_hint_y: 0.15
NeuButton:
text: ''
#---------------------------------- Pruefungsmodus ---------------------------------------------------------------------------------
<Pruefungsmodus>:
name: "Pruefungsmodus"
#background_color: 1, 1, 1, 1
id: pruefungsmudos
GridLayout:
cols:1
#spacing: 20
GridLayout:
cols:3
padding: 20
size_hint_y: 0.2
Image:
size_hint_x: 0.2
source:"Bilder\Logo.png"
NeuLabel2:
size_hint_x: 0.6
text: 'Pr\u00FCfungs\nmodus'
font_size: (root.width**2 + root.height**2) / 12**4
halign: 'center'
valign: 'middle'
Image:
size_hint_x: 0.2
source:"Bilder\Logo2.png"
GridLayout:
cols:1
padding: 30
spacing: 10
size_hint_y: 0.4
NeuLabelinBox:
id: text2
text: root.labeltext2
color: 0,0,0,1 # <-----------
canvas.before:
Color:
rgba: 0.949019608, 0.949019608, 0.949019608, 1
Rectangle:
pos: self.pos
size: self.size
GridLayout:
cols:2
padding: 30
size_hint_y: 0.2
BoxLayout:
padding: 30
spacing: 10
NeuButton:
size_hint_x: 0.5
text: "Press Here"
on_release:
app.root.current = "ersteFrage"
NeuButton:
size_hint_x: 0.5
text: ""
on_release:
app.root.current = "hauptmenue"
#---------------------------------- Erste Frage ---------------------------------------------------------------------------------
<ersteFrage>:
name: "ersteFrage"
GridLayout:
cols: 1
size_hint_y: 1
GridLayout:
cols: 1
size_hint_y: 0.08
OberesMenue:
GridLayout:
cols: 1
size_hint_y: 0.1
NeuLabel2:
font_size: "18sp"
text: "Wie lautet......."
GridLayout:
cols: 1
size_hint_y: 0.7
padding: 20
background_color: 0.92549,0.92549,0.92549, 1
rows: 2
BoxLayout:
orientation:'horizontal'
NeuLabelinBox:
text: "h+u=ZU"
NeuCheckBox:
NeuLabelinBox:
text: "h+u=ZU"
NeuCheckBox:
BoxLayout:
orientation:'horizontal'
NeuLabelinBox:
text: "h+u=ZU"
NeuCheckBox:
NeuLabelinBox:
text: "h+u=ZU"
NeuCheckBox:
GridLayout:
cols: 1
size_hint_y: 0.1
UnteresMenue:
and the outsourced Top and Button Menu:
alleFragen.kv
<OberesMenue>:
id: OberesMenueee
name: "OberesMenue"
GridLayout:
cols:1
GridLayout:
#size_hint_y: 0.05
spacing: 20
cols: 3
NeuButton:
text: ""
size_hint_x: 0.16
background_color: 1,1,1, 1
background_down: root.BildLabeltext
background_normal: root.BildLabeltext2
color:1,1,1,1 # <-----------
canvas.before:
Color:
rgba: 0.2,0.2, 0.2,1
Rectangle:
pos: self.pos
size: self.size
NeuLabel2:
size_hint_x: 0.8
text: root.labeltext
NeuButtonKappa:
size_hint_x: 0.1
text: "MENU"
background_down: "Bilder\HintergurndFarbe_app.png"
on_release:
app.root.current = "hauptmenue"
<UnteresMenue>:
name: "UnteresMenue"
id: UnteresMenuee
GridLayout:
cols: 5
spacing: 20
padding: 20
NeuButton:
text: "<=="
NeuButton:
text: "<"
NeuButtonKappa:
text: 'k'
#background_color: root.background_color_Kappa
background_down: "Bilder\HintergurndFarbe_app.png"
NeuButton:
text: ">"
NeuButton:
text: "==>"
The problem is that you have two different instances of the OberesMenue Screen.
There is one created in your python:
sm.add_widget(OberesMenue(name="OberesMenue"))
And you have another created in your kv:
<ersteFrage>:
name: "ersteFrage"
GridLayout:
cols: 1
size_hint_y: 1
GridLayout:
cols: 1
size_hint_y: 0.08
OberesMenue:
In order to acces the second instance of OberesMenue, you can add an id:
<ersteFrage>:
name: "ersteFrage"
GridLayout:
cols: 1
size_hint_y: 1
GridLayout:
cols: 1
size_hint_y: 0.08
OberesMenue:
id: in_ersteFrage
Then in your on_enter() method of Pruefungsmodus, you can change that instance by using:
def on_enter(self):
text = "Zeit"
self.manager.get_screen('ersteFrage').ids.in_ersteFrage.labeltext = text #DAS Klappt nicht
Note that this changes the Label in the second instance of OberesMenue, but has no effect on the first. Your original code was changing the first instance, but not the second. And you can't put the same instance in both places at the same time, since a Widget can have only one parent at a time.
So, if those instances are intended to be identical, then you need to change the Label in both.
If you really want to share the same instance, you can keep your own record of where it is and use remove_widget() and add_widget() to move it from one parent to another.
Im creating a very simple aplication for pratice, and I´m having some trouble with Kivy GUI.
I would like to get all the images on the same size,and if it´s possible creat aline that separetes all the vertical box layouts.
:
name:'Prices'
BoxLayout:
orientation:'vertical'
canvas.before:
Rectangle:
source:'back_azul.png'
pos: self.pos
size: self.size
BoxLayout:
orientation:'horizontal'
height:'30dp'
size_hint_y:None
Button:
size_hint_x:0.25
text:"Back to Menu"
opacity: 1 if self.state == 'normal' else .5
background_color:0,0,0,0
on_release:app.root.current="main"
font_size:20
BoxLayout:
background_color:0,10,10,1
padding:5
Image:
source:"camisa.jpg"
Label:
text:"01 Camisa social"
bold:True
font_size:11
Label:
text:"R$: 8,00"
font_size:15
BoxLayout:
padding:5
Image:
source:"peca.jpg"
Label:
text:"01 Camisa Polo"
font_size:11
bold:True
Label:
text:"R$:6,00"
font_size:10
BoxLayout:
padding:5
Image:
source:"terno.jpg"
Label:
text:"01 Terno c/Calca"
font_size:11
bold:True
Label:
text:"R$: 28,00"
font_size:10
BoxLayout:
padding:5
Image:
source:"vestido.jpg"
Label:
text:"01 Vestido"
font_size:11
bold:True
Label:
text:"R$: 70,00"
font_size:10
Same width of the images:
Option 1: you can set the width, but must set the corresponding size hint to None.
Image:
size_hint_y: None
source:"Astronaut3.jpg"
width: 100
allow_stretch: True
Option2: use the size_hint
Image:
source:"Astronaut2.jpg"
size_hint_x: 0.4
allow_stretch: True
Creating a line
Again there are different options. You could use the Line from kivy Graphics. An easy and straightforward solution is to use a Label and make it your color of choice and then make it really small.
Label:
canvas.before:
Color:
rgba: (1,1,1,1)
Rectangle:
size: self.size
pos: self.pos
size_hint_y: None
height: 1
Sample App
Here are all the things mentioned in one sample App. It is not good practice to repeat yourself when coding, but I am doing it here to mirror your question as close as possible.
sample app example:
from kivy.app import App
from kivy.base import Builder
from kivy.properties import StringProperty
from kivy.uix.boxlayout import BoxLayout
Builder.load_string("""
<rootwi>:
orientation:'vertical'
BoxLayout:
padding:5
Image:
source:"Astronaut2.jpg"
size_hint_x: 0.4
allow_stretch: True
Label:
text:"01 Camisa Polo"
font_size:11
bold:True
Label:
text:"R$:6,00"
font_size:10
Label:
canvas.before:
Color:
rgba: (1,1,1,1)
Rectangle:
size: self.size
pos: self.pos
size_hint_y: None
height: 1
BoxLayout:
padding:5
Image:
source:"Astronaut3.jpg"
size_hint_x: 0.4
allow_stretch: True
Label:
text:"01 Camisa Polo"
font_size:11
bold:True
Label:
text:"R$:6,00"
font_size:10
Label:
canvas.before:
Color:
rgba: (1,1,1,1)
Rectangle:
size: self.size
pos: self.pos
size_hint_y: None
height: 1
BoxLayout:
padding:5
Image:
size_hint_y: None
source:"Astronaut2.jpg"
width: 100
allow_stretch: True
Label:
text:"01 Camisa Polo"
font_size:11
bold:True
Label:
text:"R$:6,00"
font_size:10
Label:
canvas.before:
Color:
rgba: (1,1,1,1)
Rectangle:
size: self.size
pos: self.pos
size_hint_y: None
height: 1
BoxLayout:
padding:5
Image:
size_hint_y: None
source:"Astronaut3.jpg"
width: 100
allow_stretch: True
Label:
text:"01 Camisa Polo"
font_size:11
bold:True
Label:
text:"R$:6,00"
font_size:10
""")
class rootwi(BoxLayout):
pass
class MyApp(App):
def build(self):
return rootwi()
if __name__ == '__main__':
MyApp().run()
I would like to ask your help.
The scrollable structure under the link is what I want to generate.
As the Scrollview accept only one element, I used a GridLayout. Somehow I cannot put any Boxlayout in the GridLayout.
Could you help me? Did I made a mistake? Should I use maybe an other Layout? if yes, which one?
Thank you.
Here is the output of my .kv file: http://imgur.com/etilRPg
Here is the result, if I change cols:1 to cols:2 : http://imgur.com/ihWla4Y
Here is the code I tried in the .kv file:
#:kivy 1.8.0
RootWidget:
# import container
container: container
# fill container
BoxLayout:
id: container
orientation: 'vertical'
padding: 0
spacing: 3
ScrollView:
size_hint: 1, 1
pos_hint: {'center_x': .5, 'center_y': .5}
GridLayout:
cols: 1
padding: 0
spacing: 3
size_hint: 1, None
height: self.minimum_height
do_scroll_x: False
BoxLayout:
height: 260
orientation: 'horizontal'
canvas.before:
Color:
rgb: 0.7, 0.7, 0.9
Rectangle:
size: self.size
pos: self.pos
BoxLayout:
height: 260
orientation: 'horizontal'
canvas.before:
Color:
rgb: 0.7, 0.7, 0.9
Rectangle:
size: self.size
pos: self.pos
BoxLayout:
height: 260
orientation: 'horizontal'
canvas.before:
Color:
rgb: 0.7, 0.7, 0.9
Rectangle:
size: self.size
pos: self.pos
#type
Label:
height: 260
size_hint: 1, None
text: 'Typ'
BoxLayout:
height: 260
orientation: 'horizontal'
canvas.before:
Color:
rgb: 0.7, 0.7, 0.9
Rectangle:
size: self.size
pos: self.pos
If you want to set height or width or anything else with sizing you need to do something first in a widget you want to set it for:
size_hint: None, None
This will disable setting those properties according to parent's size and some other stuff i.e. number of widgets in parent (three widgets = parent's size / 3 for each) at least for layouts such as BoxLayout or GridLayout. Check docs for more.
Alternatively use size_hint_x: None or size_hint_y: None and let the other part be set automatically if you only want to set one of height or width.
I want to create a Widget changing only the text of a label inside it, but all the ways I find how to change this are by changing it in the python code instead of reusing only Kivy objects.
So I have a widget like the following:
<AmiLabel#Label>
color: .1, .5, .8, 1
font_size: 16
<AmiTextInput#TextInput>
font_size: 16
<PropertyInputForm>:
BoxLayout:
size: root.size
pos: root.pos
orientation: 'horizontal'
AmiLabel:
text: 'Folder Location'
size_hint_x: .5
AmiTextInput:
text: 'None'
size_hint_x: .5
<MainFormWidget>:
BoxLayout:
size: root.size
pos: root.pos
id: foo_bar
padding: 5
spacing: 5
canvas:
Color:
rgb: (1, 1, 1)
Rectangle:
pos: self.pos
size: self.size
orientation: 'vertical'
AmiLabel:
height: 36
size_hint_x: 1
size_hint_y: None
text: 'Project Name'
PropertyInputForm:
height: 36
size_hint_x: 1
size_hint_y: None
# I WANT TO CHANGE THE TEXT OF THE LABEL IN HERE
PropertyInputForm:
height: 36
size_hint_x: 1
size_hint_y: None
# I WANT TO CHANGE THE TEXT OF THE LABEL IN HERE
All I want to is change the text of the label from another widget in another level without touching the python code.
¿Is that possible?
One simple way would be to add a new property to your PropertyInputForm and reference or set that.
<PropertyInputForm>:
new_text_property: ''
BoxLayout:
size: root.size
pos: root.pos
orientation: 'horizontal'
AmiLabel:
text: root.new_text_property
size_hint_x: .5
AmiTextInput:
text: 'None'
size_hint_x: .5
and later
PropertyInputForm:
height: 36
size_hint_x: 1
size_hint_y: None
new_text_property: 'whatever'
You may also need to declare new_text_property in the python class to have it be a StringProperty rather than an ObjectProperty, though even that is I think not necessary in kivy 1.8.