Checkbox UI element

from ui import Checkbox
contents = [
["Apples", 'apples'],
["Oranges", 'oranges'],
["Bananas", 'bananas']]
selected_fruits = Checkbox(checkbox_contents, i, o).activate()

class ui.checkbox.Checkbox(contents, i, o, name='Menu', entry_height=1, default_state=False, append_exit=True)

Implements a checkbox which can be used to enable or disable some functions in your application.

Attributes:

• contents: list of checkbox elements which was passed either to Checkbox constructor or to checkbox.set_contents().

  Checkbox element structure is a list, where:

  • element[0] (element’s representation) is either a string, which simply has the element’s value as it’ll be displayed, such as “Menu element 1”, or, in case of entry_height > 1, can be a list of strings, each of which represents a corresponding display row occupied by the element.
  • element[1] (element’s name) is a name returned by the checkbox upon its exit in a dictionary along with its boolean value.
  • element[2] (element’s state) is the default state assumed by the checkbox. If not present, assumed to be default_state.

  If you want to set contents after the initalisation, please, use set_contents() method.

• _contents: “Working copy” of checkbox contents, basically, a contents attribute which has been processed by self.process_contents.

• pointer: currently selected menu element’s number in self._contents.

• in_foreground : a flag which indicates if checkbox is currently displayed. If it’s not active, inhibits any of menu’s actions which can interfere with other menu or UI element being displayed.

• first_displayed_entry : Internal flag which points to the number of self._contents element which is at the topmost position of the checkbox menu as it’s currently displayed on the screen

• last_displayed_entry : Internal flag which points to the number of self._contents element which is at the lowest position of the checkbox menu as it’s currently displayed on the screen

__init__(contents, i, o, name='Menu', entry_height=1, default_state=False, append_exit=True)

Initialises the Checkbox object.

Args:

• contents: a list of element descriptions, which can be constructed as described in the Checkbox object’s docstring.
• i, o: input&output device objects

Kwargs:

• name: Checkbox name which can be used internally and for debugging.
• entry_height: number of display rows one checkbox element occupies.
• default_state: default state of the element if not supplied.

activate()

A method which is called when checkbox needs to start operating. Is blocking, sets up input&output devices, renders the checkbox and waits until self.in_background is False, while checkbox callbacks are executed from the input device thread.

print_contents()

A debug method. Useful for hooking up to an input event so that you can see the representation of checkbox’s contents.

print_name()

A debug method. Useful for hooking up to an input event so that you can see which UI element is currently processing input events.

set_contents(contents)

Sets the checkbox contents, as well as additionally re-sets last & first_displayed_entry pointers and calculates the value for last_displayed_entry pointer.