Kivy framework provides BoxLayout class with which we can arrange the widgets sequentially. The sequence is determined by the orientation property of BoxLayout object and can be a string: either ”vertical” or ”horizontal”.

The BoxLayout class is defined in the “kivy.uix.boxlayout” module. To declare a BoxLayout object, use.

from kivy.uix.boxlayout import BoxLayout
blo = BoxLayout(**kwargs)

Properties

• orientation − Orientation of the layout. orientation is an OptionProperty and defaults to ”horizontal”. Can be ”vertical” or ”horizontal”.

• padding − Padding between layout box and children: [padding_left, padding_top, padding_right, padding_bottom]. padding also accepts a two argument form [padding_horizontal, padding_vertical] and a one
  argument form [padding].

• minimum_height − Automatically computed minimum height needed to contain all children. The minimum_height is a NumericProperty and defaults to 0. It is read only.

• minimum_size − Automatically computed minimum size needed to contain all children.minimum_size is a ReferenceListProperty of (minimum_width, minimum_height) properties. It is read only.

• minimum_width − Automatically computed minimum width needed to contain all children. minimum_width is a NumericProperty and defaults to 0. It is read only.

The BoxLayout class also inherits the add_widget() and remove_widget() methods, which we have already discussed earlier.

Vertical BoxLayout

Typical use of BoxLayout is shown here. We add a label, a text input and a button in a vertical box layout.

Example

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.uix.boxlayout import BoxLayout
from kivy.core.window import Window
Window.size = (720,200)

class DemoApp(App):
   def build(self):
      lo = BoxLayout(orientation = ''vertical'')
      self.l1 = Label(text=''Enter your name'', font_size=20)
      self.t1 = TextInput(font_size = 30)
      self.b1 = Button(text = ''Submit'', size_hint = (None, None),pos_hint={''x'':.4, ''y'':.2}, size = (200,75))
      lo.add_widget(self.l1)
      lo.add_widget(self.t1)
      lo.add_widget(self.b1)
      return lo

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

Output

It will produce the following output −

You can use the following “Demo.kv” file to construct the above GUI −

BoxLayout:
   orientation : ''vertical''
   Label:
      id : l1
      text : ''Enter your name''
      font_size : ''20pt''
   TextInput:
      id : t1
      font_size : 30
   Button:
      id : b1
      text : ''Submit''
      size_hint : (None, None)
      pos_hint : {''x'':.4, ''y'':.2}
      size : (200,75)

Horizontal BoxLayout

In the following program, we have placed a label, a text input box and a button in Box layout with horizontal orientation.

Example

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.textinput import TextInput
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from kivy.core.window import Window

Window.size = (720,200)

class DemoApp(App):
   def build(self):
      self.lo = BoxLayout(orientation = ''horizontal'')
      self.l1 = Label(text=''Enter your name'', font_size=20)
      self.t1 = TextInput(font_size = 30, pos_hint={''y'':0.25}, pos = (0,100), size_hint = (None, None), size = (650,100))
      self.b1 = Button(text = ''Submit'', size_hint = (None, None),pos_hint={''x'':.4, ''y'':.35}, size = (75, 40))
      self.lo.add_widget(self.l1)
      self.lo.add_widget(self.t1)
      self.lo.add_widget(self.b1)
      return self.lo

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

Output

It will produce the following output −

You can obtain the same GUI design with the following “Demo.kv” file −

BoxLayout:
   orientation : ''horizontal''
   Label:
      text : ''Enter your name''
      font_size : ''20pt''
   TextInput :
      font_size : ''30pt''
      pos_hint : {''y'':0.25}
      pos : (0,100)
      size_hint : (None, None)
      size : (650,100)
   Button :
      text : ''Submit''
      size_hint : (None, None)
      pos_hint : {''x'':.4, ''y'':.35}
      size : (75, 40)