pythonbuttonkivy

How to create an buttonloop with parameter in kivy, after the GUI has generated?

I have an problem with the Kivy library. I'm currently writing the front end for a ShoppinglistApp. I have an main menu, where you can select what you want to do (add List/ Shop) from where you can get to the Shop selection.

  1. In the shop selection Menu are 4 shops
  2. all items (Produkt) are stored in a list
  3. If you select the shop, then for each item (from this shop), a button should be created.

I tried this solution:

from kivy.app import App
from kivy.metrics import dp
from kivy.lang import Builder
from kivy.properties import StringProperty
from kivy.uix.stacklayout import StackLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen

# the rest
class Produkt:
    def __init__(self, name, amount, market):
        self.name = name
        self.amount = amount
        self.market = market

eklist = []
for i in range(0, 100):
    nn = "Banane" + str(i)
    eklist.append(Produkt(nn, 0, "Baumarkt"))

# Define Screens

class FirstWindow(Screen):
    pass

class SecondWindow(Screen):
    pass

class ThirdWindow(Screen):
    pass

class WindowManager(ScreenManager):
    pass

"""Anfang der Chose"""

class Box(BoxLayout):
    pass

# Gvar is a class I created for the purpose of transporting variable(s). Especially the selected shop.

class Gvar:
    def __init__(self, var1):
        self.var1 = var1

    def get(self):
        return self.var1

gvar = Gvar("default")

# SetBox ist the Class for changing the variable through the shop selection menu.
class SetBox(BoxLayout):

    def set(self, market):
        gvar.var1 = market
        print("Set")
        print(gvar.var1)


class BLE(BoxLayout):
    pass

# This is the Menus which makes Problems.
class SLE(StackLayout):

    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        for p in eklist:
            # In theory, this if request should always be triggered. In reality, I made the else Request to debug.
            # for Text normally would appear p.name, but I changed it for debugging. Text shown(gvar.var1) is "default".
            if p.market == str(gvar.get()):
                b = Button(text=str(gvar.get()), size_hint=(None, None), color="blue", size=(dp(200), dp(100)),
                           on_press=lambda *args: self.test1(*args, str(p.name)))
                b.prod = p
                self.add_widget(b)

            else:
                b = Button(text=str(gvar.get()), size_hint=(None, None), color="green", size=(dp(200), dp(100)),
                           on_press=lambda *args: self.test1(*args, str(p.name)))
                b.prod = p
                self.add_widget(b)
    market = None

# test 1 is a placeholder for a backend function
# Here I print the Produkt and gvar.var1, to debug. Here it get for gvar.var1 the in the GUI selected Value.
    def test1(self, b, i):
        print("Initialize test2, please wait...")
        print(b.prod.name, b.prod.amount, b.prod.market, gvar.var1)

"""Ende der Chose"""

kv = Builder.load_file('einkaufsliste.kv')

class EinkaufsApp(App):
    def build(self):
        return kv

if __name__ == '__main__':
    EinkaufsApp().run()
</code></pre>    +

Here is the Kivy file:

WindowManager:
    FirstWindow:
    SecondWindow:
    ThirdWindow:


&ltFirstWindow&gt:
    name: "first"

    Box:
        orientation: "vertical"
        size :root.width, root.height

        Label:
            text: "Hauptmenü"
            size_hint: 1, .2
            font_size: 32

        Button:
            text: "Einkaufen"
            font_size: 32
            background_normal: ' '
            background_color: "#666e00"
            on_release:
                app.root.current = "third"
                root.manager.transition.direction = "left"

        Button:
            text: "Einkaufsliste updaten"
            font_size: 32
            background_normal: ' '
            background_color: "#660000"
            on_release:
                app.root.current = "second"
                root.manager.transition.direction = "left"

&ltSecondWindow&gt:
    name: "second"

    BLE:
        id: BLE
        orientation: "vertical"
        Button:
            text: "to first"
            size_hint: 1, .1
            font_size: 24
            on_release:
                app.root.current = "first"
                root.manager.transition.direction = "right"
        TextInput:
            multiline: False
            size_hint: 1, .1
        SVE:

&ltThirdWindow&gt:
    name: "third"

    SetBox:
        orientation: "vertical"
        size :root.width, root.height
        id:SetBox

        Box:
            orientation: "horizontal"
            size_hint: 1, .4
            Button:
                text: "to first"
                size_hint: .2, 1
                font_size: 24
                on_release:
                    app.root.current = "first"
                    root.manager.transition.direction = "right"

            Label:
                text: "Markt auswählen"
                size_hint: .8, 1
                font_size: 32

        Button:
            text: "Supermarkt"
            font_size: 32
            background_normal: ' '
            background_color: "#a1b2e3"
            on_release:
                app.root.current = "second"
                root.manager.transition.direction = "left"
            on_press: SetBox.set("Supermarkt")

        Button:
            text: "Drogerie"
            font_size: 32
            background_normal: ' '
            background_color: "#c7bbc9"
            on_release:
                app.root.current = "second"
                root.manager.transition.direction = "left"
            on_press: SetBox.set("Drogerie")

        Button:
            text: "Baumarkt"
            font_size: 32
            background_normal: ' '
            background_color: "#b4eeb4"
            on_release:
                app.root.current = "second"
                root.manager.transition.direction = "left"
            on_press: SetBox.set("Baumarkt")

        Button:
            text: "Elektrogerätefachhandel"
            font_size: 32
            background_normal: ' '
            background_color: "#f4c2c2"
            on_release:
                app.root.current = "second"
                root.manager.transition.direction = "left"
            on_press: SetBox.set("Elektrogerätefachhandel")

&ltSVE@ScrollView&gt:
    SLE:
        id: Scrollwin
        size_hint: 1, None
        height: self.minimum_height

&ltSLE&gt:
    # orientation: "rl-bt"
    # spacing: "1dp", "1dp"

I think the problem is that kivy creates the whole GUI before I can change the variable.

Is there a way to reload the screen or do I have to make for each market/shop another screen?

Solution

  • It's possible to do what you want. You have to add the items to the corresponidng layout. I'll give you an example with a project I did some time ago:

    class ExmapleApp(App):
    def build(self):
        #Create GridLayout where you will add and remove widgets
        self.gridRooms = gridRooms = GridLayout(cols=10, padding=10, spacing=10,
                                    row_force_default=True, row_default_height=50, size_hint_y=None)
        gridRooms.bind(minimum_height=gridRooms.setter('height'))

        # Generate 10 Rooms items
        for i in range(10):
            labl = NewLabel() #Instace of NewLabel
            labl.num = str(i+1) #Number of room
            labl.roomName = "Room "+str(labl.num) # Room name
            labl.filename = '12916_sweet_trip_mm_kwik_mod_01.wav'
            roomsList.append(labl) #This add the room to a list for further reference
            gridRooms.add_widget(labl) #This add the rooms to a grid

    Here's an image of how it looks so far: enter image description here

    Finally, you can add widgets to that GridLayout:

            #Create the object you want to Add
        labl = NewLabel() #Instace of NewLabel
        labl.num = str(11) #Number of room
        labl.roomName = "Room "+str(labl.num) # Room name
        labl.filename = '12916_sweet_trip_mm_kwik_mod_01.wav'
        roomsList.append(labl) #This add the room to a list for further reference

        #This add the widgets 3 secs after the program starts
        Clock.schedule_once(lambda x: gridRooms.add_widget(roomsList[10]), 3) #Add room 11

    enter image description here

    You can even have a callback to create a new widget everytime you press a button. To remove a widget just:

    gridRooms.remove_widget(roomsList[10]) #Removes Room 11