py files

main.py:

from classes import *
from screens import *

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.config import Config

from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.lang import Builder

Config.set('graphics','height',500)
Config.set('graphics','width',350)

layout = Builder.load_file("main.kv")
class MainApp(App):
    def build(self):
        return layout

if __name__ == '__main__':
    MainApp().run()



classes.py:

class Object:
    def __init__(self,name,category,img):
        self.name=name
        self.category=category
        self.img=img
    def GetName(self):
        return self.name
    def GetCategory(self):
        return self.category
    def GetImg(self):
        return self.img



screens.py:

from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.properties import StringProperty

from classes import *
#======================================#
#=========  SCREENS ===================#
#======================================#

class ScreenManagement(ScreenManager):
    pass

class MainScreen(Screen):
    pass

class CategorySelectScreen(Screen):
    selected = "All"

class DictScreen(Screen):

    def NextItem(self,obj,i):
        if i==len(obj)-1:
            i=0
        else:
            i=i+1
        print "\nNEXT ITEM\nAktualny indeks:"+str(i)
        return i

    def PrevItem(self,obj,i):
        if i==0:
            i=len(obj)-1
        else:
            i=i-1
        print "\nPREVIOUS ITEM\nAktualny indeks:"+str(i)
        return i

    def ChangeLabel(self,obj,i):
        name_text=obj[i].GetName()
        print "Aktualna nazwa:"+name_text
        print obj[i].name
        return name_text

    def ChangeImage(self,obj,i):
        imagepath = "data/img/"+str(obj[i].GetImg())
        print "Aktualny obrazek:"+imagepath
        return imagepath

    def ChangeCategory(self,obj,i):
        categoryname_text=obj[i].GetCategory()
        print "Aktualna kategoria:"+categoryname_text
        return categoryname_text

    def CategorySelect(self,obj,cat):
        current=[]
        if cat=="All":
            return obj
        else:
            for item in obj:
                if item.category==cat:
                    current.append(item)
            return current


    index=0
    objects=[]
    current_category = "All"
    selected_objects=[]

# test objects #

    obj1 = Object("Bike","Sport","bike.jpg")
    obj2 = Object("Ball","Sport","ball.jpg")
    obj3 = Object("Volleyball","Sport","volleyball.jpg")
    obj4 = Object("Basketball","Sport","basketball.jpg")

    obj5 = Object("Apple","Food","apple.jpg")
    obj6 = Object("Bread","Food","bread.jpg")
    obj7 = Object("Chicken","Food","chicken.jpg")
    obj8 = Object("Potato","Food","potato.jpg")

    objects.append(obj1)
    objects.append(obj2)
    objects.append(obj3)
    objects.append(obj4)
    objects.append(obj5)
    objects.append(obj6)
    objects.append(obj7)
    objects.append(obj8)