Kivy input values for simple calculations

Question

I'm quite new to Kivy (started yesterday) and am trying to create a simple enough app that has input boxes for several values of height and area to calculate volumes. I cant find any working methods of doing this. So far all I have got is this:

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen


Builder.load_string("""
<MenuScreen>:
    FloatLayout:

        Label:
            text: 'Please Select an Area to Work With:'
            pos: 230, 490
            size_hint: .15, .05
            font_size: 23



        Button:
            text: "A"
            pos: 230, 100
            size_hint: .4,.1
            font_size: 23
            on_press: root.manager.current = 'settings'


        Button:
            text: "B"
            pos: 230, 210
            size_hint: .4,.1
            font_size: 23
            on_press: root.manager.current = 'settings'


        Button:
            text: "C"
            pos: 230, 320
            size_hint: .4,.1
            font_size: 23
            on_press: root.manager.current = 'settings'



        Button:
            text: "D"
            pos: 230, 420
            size_hint: .4,.1
            font_size: 23
            on_press: root.manager.current = 'settings'






<SettingsScreen>:
    GridLayout:
        Label:
            text: 'Room 1'
            pos: 6, 460
            size_hint: .15, .05
            font_size: 23

        Label:
            text: 'Room 2'
            pos: 6, 420
            size_hint: .15, .05
            font_size: 23

        Label:
            text: 'Room 3'
            pos: 6, 380
            size_hint: .15, .05
            font_size: 23

        Label:
            text: 'Room 4'
            pos: 6, 340
            size_hint: .15, .05
            font_size: 23

        Label:
            text: 'Room 5'
            pos: 6, 300
            size_hint: .15, .05
            font_size: 23

        Label:
            text: 'Room 6'
            pos: 6, 260
            size_hint: .15, .05
            font_size: 23

        TextInput:
            text1: "0"
            multiline: False
            pos: 200,420
            font_size: 23
            on_text: viewer.text = self.text1
            size_hint: .001, .001

        TextInput:
            text2: "0"
            multiline: False
            pos: 200, 420
            font_size: 23
            on_text: viewer.text = self.text2
            size_hint: .001, .001

        TextInput:
            text3: "0"
            multiline: False
            pos: 200,380
            font_size: 23
            on_text: viewer.text = self.text3
            size_hint: .001, .001

        TextInput:
            text4: "0"
            multiline: False
            pos: 200,340
            font_size: 23
            on_text: viewer.text = self.text4
            size_hint: .001, .001


        TextInput:
            text5: "0"
            multiline: False
            pos: 200,300
            font_size: 23
            on_text: viewer.text = self.text5
            size_hint: .001, .001

        TextInput:
            text6: "0"
            multiline: False
            pos: 200,240
            font_size: 23
            on_text: viewer.text = self.text6
            size_hint: .001, .001
""")

# Declare both screen
class MenuScreen(Screen):
    pass

class SettingsScreen(Screen):
    pass

# Create the screen manager
sm = ScreenManager()
sm.add_widget(MenuScreen(name='menu'))
sm.add_widget(SettingsScreen(name='settings'))

class TestApp(App):

    def build(self):
        return sm

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

Im planning to have the second page unique for each button pressed, but want Any help would be appreciated.

Answer 1

I hope I got to understand your question. You are asking for methods to do this. The plain answer is that you have the whole Python to do all the operations you want. Kivy is a library that provides a lot of components to design GUI. It also provides you with a language that is parsed by the Builder.load_string(). Here is an example that might be more or less what you are looking for. It is sort of a calculator on the first screen. The second screen is empty and you can move between them with the bottom buttons.

The calculator on the first screen has two InputTexts and two buttons (Sum and Product). The Sum Button has the implementation of a sum directly on the kivy language. The Product Button calls a method in the root (an instance of Calc). The method doesn't exist by itself. I created in the python code below the kivy section. There is some comments on the code for what I am saying.

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout

Builder.load_string("""
<Calc>:
    # This are attributes of the class Calc now
    a: _a
    b: _b
    result: _result
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'top'
        ScreenManager:
            size_hint: 1, .9
            id: _screen_manager
            Screen:
                name: 'screen1'
                GridLayout:
                    cols:1
                    TextInput:
                        id: _a
                        text: '3'
                    TextInput:
                        id: _b
                        text: '5'
                    Label:
                        id: _result
                    Button:
                        text: 'sum'
                        # You can do the opertion directly
                        on_press: _result.text = str(int(_a.text) + int(_b.text))
                    Button:
                        text: 'product'
                        # Or you can call a method from the root class (instance of calc)
                        on_press: root.product(*args)
            Screen:
                name: 'screen2'
                Label: 
                    text: 'The second screen'
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'bottom'
        BoxLayout:
            orientation: 'horizontal'
            size_hint: 1, .1
            Button:
                text: 'Go to Screen 1'
                on_press: _screen_manager.current = 'screen1'
            Button:
                text: 'Go to Screen 2'
                on_press: _screen_manager.current = 'screen2'""")

class Calc(FloatLayout):
    # define the multiplication of a function
    def product(self, instance):
        # self.result, self.a and self.b where defined explicitely in the kv
        self.result.text = str(int(self.a.text) * int(self.b.text))

class TestApp(App):
    def build(self):
        return Calc()

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