kivy dynamically add custom widget to layout via python

Question

I was able to get my layout working with static kivy language but I need to be able to add items to my list via python. I've tried several things but can't seem to get anything working correctly. Here's what I have working statically.

main.py

#!/usr/bin/python
import os
import kivy
kivy.require('1.8.0')
from kivy.app import App
from kivy.core.window import Window
from kivy.logger import Logger
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
class CustomButton(Button):
 pass
 def click(button):
 Logger.info(button.title + ": wid=" + button.wid)
class SelectFruit(App, BoxLayout):
 icon = 'ico/fruit.png'
 title = 'Awesome Fruit Picker'
 def build(self):
 Window.size = 400, (4 * 78) 
 return SelectFruit()
if __name__ in ('__main__'):
 SelectFruit().run()

selectfruit.kv

#:kivy 1.8.0
<CustomButton@Button>:
 wid: ""
 image: ''
 title: ''
 label: ''
 on_press: self.click()
 BoxLayout:
 orientation: "horizontal"
 size: self.parent.size # match the button's size
 pos: self.parent.pos # match the button's position
 padding: 5 
 spacing: 10
 Image:
 size_hint: None, 1
 source: root.image
 size: 64, 64
 valign: "middle"
 Label:
 size_hint: None, 1
 text: root.label
 valign: "middle"
 size: 400, 64
 text_size: self.size
<SelectFruit>
 orientation: "vertical"
 padding: 2
 CustomButton:
 wid: "0"
 image: "ico/apple.png"
 title: "apple"
 label: "Apple: Super Sweet\nPicked On: 12/26/2014, 2:01 PM"
 CustomButton:
 wid: "1"
 image: "ico/banana.png"
 title: "banana"
 label: "Banana: Want a bunch?\nPicked On: 2/18/2014, 2:01 PM"
 CustomButton:
 wid: "2"
 image: "ico/strawberry.png"
 title: "strawberry"
 label: "Strawberry: Yummy Yummy\nPicked On: 5/6/2014, 2:01 PM"
 CustomButton:
 wid: "3"
 image: "ico/orange.png"
 title: "orange"
 label: "Orange: Florida's Best\nPicked On: 4/21/2014, 2:01 PM"

I just need to be able to add each CustomButton programmatically to my layout rather than via the kivy language file. Any help is greatly appreciated.

Answer 1

Here's the working code showing some items added in kivy language and then some additional items added programmatically. I also added the ScrollView, a configuration setting to keep the window from being resized and code to highlight the selected item.

I hope this is helpful to someone in the future. :)

main.py

#!/usr/bin/python
from kivy.config import Config
Config.set('graphics','resizable',0)
import kivy
kivy.require('1.8.0')
from kivy.app import App
from kivy.core.window import Window
from kivy.properties import ObjectProperty, StringProperty
from kivy.logger import Logger
from kivy.uix.scrollview import ScrollView
from kivy.uix.gridlayout import GridLayout
from kivy.uix.button import Button
class ButtonListItem(Button):
 wid = StringProperty('')
 image = StringProperty('')
 title = StringProperty('')
 label = StringProperty('')
 pass
 def click(button):
 global app
 app.clearSelection()
 button.background_color = (0,160,66,.9)
 Logger.info(button.title + ": wid=" + button.wid)
class ButtonList(GridLayout):
 pass
class SelectFruit(App):
 icon = 'ico/fruit.png'
 title = 'Awesome Fruit Picker'
 def build(self):
 Window.size = 400, (4 * 90)
 self.layout = ButtonList()
 self.layout.size = 400, (8 * 78)
 self.root = ScrollView(
 size_hint=(None, None), 
 size=Window.size,
 scroll_type=['bars', 'content']
 )
 self.root.add_widget(self.layout)
 ib = ButtonListItem(
 wid="0", 
 image="ico/apple.png", 
 title="apple", 
 label="Apple: Super Sweet\nPicked On: 12/26/2014, 2:01 PM"
 )
 self.layout.add_widget(ib)
 ib = ButtonListItem(
 wid="1", 
 image="ico/banana.png", 
 title="banana", 
 label="Banana: Want a bunch?\nPicked On: 2/18/2014, 2:01 PM"
 )
 self.layout.add_widget(ib)
 ib = ButtonListItem(
 wid="2", 
 image="ico/strawberry.png", 
 title="strawberry", 
 label="Strawberry: Yummy Yummy\nPicked On: 5/6/2014, 2:01 PM"
 )
 self.layout.add_widget(ib)
 ib = ButtonListItem(
 wid="3", 
 image="ico/orange.png", 
 title="orange", 
 label="Orange: Florida's Best\nPicked On: 4/21/2014, 2:01 PM"
 )
 self.layout.add_widget(ib)
 return self.root
 def clearSelection(self):
 for child in self.layout.children:
 child.background_color = (1,1,1,1)
if __name__ == "__main__":
 app = SelectFruit()
 app.run()

selectfruit.kv

#:kivy 1.8.0
<ButtonListItem@Button>:
 wid: self.wid
 image: self.image
 title: self.title
 label: self.label
 on_press: self.click()
 BoxLayout:
 orientation: "horizontal"
 size: self.parent.size # match the button's size
 pos: self.parent.pos # match the button's position
 padding: 5 
 spacing: 10
 Image:
 size_hint: None, 1
 source: root.image
 size: 64, 64
 valign: "middle"
 Label:
 size_hint: None, 1
 text: root.label
 valign: "middle"
 size: 400, 64
 text_size: self.size
<ButtonList@GridLayout>
 id: output
 cols: 1
 size_hint_y: None
 height: self.minimum_height
 ButtonListItem:
 wid: "0"
 image: "ico/apple.png"
 title: "xapple"
 label: "Apple: Super Sweet\nPicked On: 12/26/2014, 2:01 PM"
 ButtonListItem:
 wid: "1"
 image: "ico/banana.png"
 title: "xbanana"
 label: "Banana: Want a bunch?\nPicked On: 2/18/2014, 2:01 PM"
 ButtonListItem:
 wid: "2"
 image: "ico/strawberry.png"
 title: "xstrawberry"
 label: "Strawberry: Yummy Yummy\nPicked On: 5/6/2014, 2:01 PM"
 ButtonListItem:
 wid: "3"
 image: "ico/orange.png"
 title: "xorange"
 label: "Orange: Florida's Best\nPicked On: 4/21/2014, 2:01 PM"

Answer 2

def click(button):

It is normal to call the first argument of a method self, referring to the instance whose method was called.

class SelectFruit(App, BoxLayout):

This seems like a recipe for disaster, there's no need to have the App also be a Widget and it has the potential for weird bugs since it means you'll have two Apps running at once. You should separate this into separate widget and app classes.

I need to be able to add items to my list via python

I'm not clear on exactly which part of this is the problem, but you should be able to add to (for instance) the root widget with App.get_running_app().root.add_widget(your_widget), where your_widget is for instance a new instance of CustomButton.

• techknowpro: I'm new to python and kivy. I've based this code off multiple examples and that is how I got things working. I see what you mean though. I will try to change that up. I need to be able to add my CustomButton programmatically and get the same results that I'm getting with using the .kv file. Any ideas there?
• inclement: I noticed another mistake, <CustomButton@Button>: should just be <CustomButton> since this widget has a python declaration of its basic type.
• inclement: And I'm not clear on what your problem is with getting the same results as in kv, but maybe you mean you want to set those properties, in which case you should declare them in the CustomButton declaration (e.g. wid = StringProperty('')) and then can set them in the instantiation (e.g. CustomButton(wid="4")).
• techknowpro: I appreciate your feedback but I was hoping to see a modified copy of my code. I think I understand what you are saying but a working example would be more clear. How would you write it to get the same results as what I have already?
• techknowpro: Using the StringProperty() method was helpful insetting up the properties of my custom control.