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recycleex

Watch the video Kivyschool link: https://kivyschool.com/blog/2024/06/10/recycleview-explained/

  • Recycleview VS Scrollview example and explanation
  • kivy recycleview tutorial DEEP DIVE for beginners: recycleview vs scrollview, examples, and analysis
  • github repo: https://github.com/kivy-school/recycleex
  • What is recycleview?
    • a widget that displays a selection of many widgets at once
  • Why use recycleview? (telling) PT1
    • very performant (not laggy)
    • lets your app handle a LOT of data without having to DRAW the data (aka lag out your app)
    • use case:
      • handling inventory
      • handling a library of songs
      • handling complex widgets that are lagging out scrollview
      • concrete example:
        • note: using always on top = True
        • have workers that you need to pay! (signified by the selection behavior)
        • workers_paid.py
  • WHY USE Recycleview (showing) PT2
  • EXAMPLES:
  • REQUIREMENTS FOR A RECYCLEVIEW (use basic example 1)
    • go LINE BY LINE on rv basic and elliot's example
      • NOTE: using Builder.load_string() to load kv instead of having a separate kv file
    • reference: https://stackoverflow.com/a/68364350
    • #1: RV widget CLASS (kv and py defs)
    • #2: Layout (kv and py defs)
      • SelectableRecycleBoxLayout, RecycleLayout
    • #3: actual viewclass (kv and py defs)
      • defined as viewclass: or key_viewclass
    • #4: .data attribute
      • self.data (the data attribute of the recycleview widget that a list of dictionaries)
      • could be something else, see ElliotDG line:
        • data: self.rv_data_list
      • .data is a LIST and each element is a DICT
      • Example:
        • need: data: data AND it is a Listproperty
          • equivalent to setting rv.data attribute
      • proof: type(self.data), type(self.data[0]), use pdb (line 68)
      • pdb hints:
        • App.get_running_app().root
        • hint: in ElliotDG.py, just look at rv.data:
        • App.get_running_app().root.ids['rv'].data
        • every widget needs an id for "widget drilling" to work?
      • populated during __init__, can be updated at any time
    • #5: ISSUES WITH WIDGET EXAMPLE FROM KIVY ORG:
SOLUTION 1 (ELLIOTDG) PRO SOLUTION 1(ELLIOTDG) CON
structure is flat (handle everything through Viewclass Widget and properties) you have to manually remember to property EVERYTHING
have to set everything up correctly a bit hard to manipulate the boxlayout viewclass as easily (I have been trying for 2 days)
still might have to call refresh_from_data if you modify data in place
not everything can be done in kv (kv lang MUST be perfectly set up)
method is the best, but also easier if you are an expert.

What I mean by a flat structure of Solution 1, all you have to handle is Viewclass Widget and Properties

  • handle KV
  • declare everything as a property correctly
  • structure the app to be easy to make with kv (not always possible or immediately obvious, like with complex apps)
  • might have to manually force update anyways
graph BT
 subgraph KivyApp
  A((RecycleView))
  AA[RecycleView.data]
  B((Simple Viewclass Widget))
  BB[Properties, String, List, any property from kivy.properties]
  C((Viewclass Widget Instances))
  A -- initially updates on __init__ --> AA
  AA -- data is picked up on init --> B
  B -- updates after init --> AA
  B -- handles updates --> BB
  BB -- defines --> C
end
  D{{user input}}
  E{{dev manipulation}}
  D -- is handled by ----> B
  E -- implements behavior through KV and properties ----> B
Loading
SOLUTION 2 (KIVYSCHOOL/PENGUIN) PRO SOLUTION 2 (KIVYSCHOOL/PENGUIN) CON
can use/manipulate very complex widgets by referencing with id you must manually update the recycleview with recycleview.refresh_from_data(). easiest way is on_touch_down, on_touch_up looks laggy
all you have to do is set ids more complicated to update from kv after init, you cannot reference recycleview data because it is not instantiated yet
You can modify kv at any time calling rv.refresh_from_data() from viewclass causes infinite refreshes (because each viewclass widget will cause a refresh...)
color example App.get_running_app().root.data[index]['employee_name_labelID.color'] = (170,170,170) SelectableBoxLayout's apply_selection will have infinite updates
trade in property structure for id structure (which you NEED for widget drilling). Widget drilling is App.get_running_app().root.ids ids ids ids.... have to manually call refresh_from_data
  • you have to keep track of 2 things: Recycleview data and forcing updates
  • my expectation is that manipulating data forces an update. It is not always the case with updating data in place, so recycleview.refresh_from_data() may be required.

Structure of Solution 2, the dev must handle RecycleView Data and manual refreshes

graph BT

 subgraph KivyApp
	A((RecycleView))
	AA[RecycleView.data]
	B((Simple Viewclass Widget))
	C((Viewclass Widget Instances))
		A -- initially updates on __init__ --> AA
	AA -- data is picked up on init --> B
	B -- determines format of --> C
end
D{{user input}}
E{{dev manipulation}}

D -- interacts with ----> B
B -- sends inputs for devs to handle ----> E

E -- correctly manipulates  ----> AA
E -- calls manual updates  ----> B
Loading

  • why 2 parents at self.parent.parent.refresh_from_data() in workers_paid.py?

    • use pdb
      • notes:
        • canvas.before goes before everything else
        • how to use pdb to check out what's going on:

  • =-=-=-==-=-=-==-=-= FINISH ! =-==-=-=-==-=-=-==-=-=-=

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Recycleview VS Scrollview example and explanation

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