kivy/examples/widgets/list_cascade.py

from kivy.uix.gridlayout import GridLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.listview import ListView, ListAdapter
from kivy.uix.mixins.selection import SelectionObserver, SelectableItem
from kivy.properties import ListProperty, StringProperty, ObjectProperty


# This is an expansion on the "master-detail" example to illustrate
# cascading from the selection of one list view to another.

# Generic list item will do fine for both list views:

class ListItem(SelectableItem, Button):
    selected_color = ListProperty([1., 0., 0., 1])
    deselected_color = None

    def __init__(self, list_adapter, **kwargs):
        self.list_adapter = list_adapter
        super(ListItem, self).__init__(**kwargs)

        # Set deselected_color to be default Button bg color.
        self.deselected_color = self.background_color

        self.bind(on_release=self.handle_selection)

    def handle_selection(self, button):
        if self.is_selected:
            self.select()
        else:
            self.deselect()

        self.list_adapter.handle_selection(self)

    def select(self, *args):
        print self.text, 'is now selected'
        self.background_color = self.selected_color

    def deselect(self, *args):
        print self.text, 'is now unselected'
        self.background_color = self.deselected_color

    def __repr__(self):
        return self.text


class FruitsListView(SelectionObserver, ListView):
    # The fruit categories list view can be a simple ListView,
    # but the fruits list, showing fruits for a given category,
    # will be a SelectionObserver, changing when fruit category
    # changes.
    def __init__(self, **kwargs):
        super(FruitsListView, self).__init__(**kwargs)

    def observed_selection_changed(self, observed_selection):
        if len(observed_selection.selection) == 0:
            return

        self.item_view_instances = {}

        self.selection = []

        selected_object = observed_selection.selection[0]

        if type(selected_object) is str:
            fruit_category = selected_object
        else:
            fruit_category = str(selected_object)

        # Reset item_keys for the adapter. This will trigger a call
        # to update_selection().
        self.adapter.item_keys = fruit_categories[fruit_category]

        self.populate()

        # Manually call update_selection(), because items are new objects.
        self.adapter.update_selection()

        print 'just added or updated fruit category'


class DetailView(SelectionObserver, GridLayout):
    fruit_name = StringProperty('')

    def __init__(self, **kwargs):
        kwargs['cols'] = 2
        super(DetailView, self).__init__(**kwargs)
        self.bind(fruit_name=self.redraw)

    def redraw(self, *args):
        self.clear_widgets()
        self.add_widget(Label(text="Name:", halign='right'))
        self.add_widget(Label(text=self.fruit_name))
        for category in descriptors:
            self.add_widget(Label(text="{0}:".format(category),
                                  halign='right'))
            self.add_widget(
                    Label(text=str(fruit_data[self.fruit_name][category])))

    def observed_selection_changed(self, observed_selection):
        if len(observed_selection.selection) == 0:
            return

        selected_object = observed_selection.selection[0]

        if type(selected_object) is str:
            self.fruit_name = selected_object
        else:
            self.fruit_name = str(selected_object)
        print 'just added or updated detail label'


class CascadingView(GridLayout):
    '''Implementation of a master-detail style view, with a scrollable list
    of fruit categories on the left (source list), a list of fruits for the
    selected category in the middle, and a detail view on the right.
    '''

    fruit_categories_list_adapter = ObjectProperty(None)
    fruit_categories_list_view = ObjectProperty(None)

    fruits_list_adapter = ObjectProperty(None)
    fruits_list_view = ObjectProperty(None)

    detail_view = ObjectProperty(None)

    def __init__(self, fruit_categories, fruits, **kwargs):
        kwargs['cols'] = 3
        kwargs['size_hint'] = (1.0, 1.0)
        super(CascadingView, self).__init__(**kwargs)

        list_item_args_converter = lambda x: {'text': x,
                                              'size_hint_y': None,
                                              'height': 25}

        # Fruit categories list on the left:
        #
        self.fruit_categories_list_adapter = \
                ListAdapter(fruit_categories,
                        args_converter=list_item_args_converter,
                        selection_mode='single',
                        allow_empty_selection=False,
                        cls=ListItem)
        self.fruit_categories_list_view = \
                ListView(adapter=self.fruit_categories_list_adapter,
                         size_hint=(.2, 1.0))
        self.add_widget(self.fruit_categories_list_view)

        # Fruits, for a given category, in the middle:
        #
        self.fruits_list_adapter = \
                ListAdapter(fruits,
                        args_converter=list_item_args_converter,
                        selection_mode='single',
                        allow_empty_selection=False,
                        cls=ListItem)
        self.fruits_list_view = \
                FruitsListView(adapter=self.fruits_list_adapter,
                         size_hint=(.2, 1.0))
        self.add_widget(self.fruits_list_view)

        # Set the fruits_list_view as an observer of the selection of
        # the fruit category.
        self.fruit_categories_list_adapter.register_selection_observer(
                self.fruits_list_view)

        # Detail view, for a given fruit, on the right:
        #
        self.detail_view = DetailView(size_hint=(.6, 1.0))
        self.add_widget(self.detail_view)

        # Manually initialize detail view to show first object of list view,
        # which will be auto-selected, but the observed_selection_changed
        # call would have already fired.
        #
        self.fruits_list_adapter.register_selection_observer(self.detail_view)

# Data from http://www.fda.gov/Food/LabelingNutrition/\
#                FoodLabelingGuidanceRegulatoryInformation/\
#                InformationforRestaurantsRetailEstablishments/\
#                ucm063482.htm
fruit_categories = \
        {'Melons': ['Cantaloupe', 'Honeydew Melon', 'Watermelon'],
         'Tree Fruits': ['Apple', 'Avocado, California', 'Banana', 'Nectarine',
                         'Peach', 'Pear', 'Pineapple', 'Plums',
                         'Sweet Cherries'],
         'Citrus Fruits': ['Grapefruit', 'Lemon', 'Lime', 'Orange',
                           'Tangerine'],
         'Miscellaneous Fruits': ['Grapes', 'Kiwifruit', 'Strawberries']}
descriptors = """(gram weight/ ounce weight)	Calories	Calories from Fa
t	Total Fat	Sodium	Potassium	Total Carbo-hydrate	Dietary Fiber	Suga
rs	Protein	Vitamin A	Vitamin C	Calcium	Iron""".replace('\n', '')
descriptors = [item.strip() for item in descriptors.split('\t')]
units = """(g) 	(%DV)	(mg) 	(%DV)	(mg) 	(%DV)	 (g) 	(%DV)	 (g)
(%DV)	 (g) 	 (g) 	(%DV)	(%DV)	(%DV)	(%DV)""".replace('\n', '')
units = [item.strip() for item in units.split('\t')]
raw_fruit_data = [
{'name':'Apple',
 'Serving Size': '1 large (242 g/8 oz)',
 'data': [130, 0, 0, 0, 0, 0, 260, 7, 34, 11, 5, 20, 25, 1, 2, 8, 2, 2]},
{'name':'Avocado, California',
 'Serving Size': '1/5 medium (30 g/1.1 oz)',
 'data': [50, 35, 4.5, 7, 0, 0, 140, 4, 3, 1, 1, 4, 0, 1, 0, 4, 0, 2]},
{'name':'Banana',
 'Serving Size': '1 medium (126 g/4.5 oz)',
 'data': [110, 0, 0, 0, 0, 0, 450, 13, 30, 10, 3, 12, 19, 1, 2, 15, 0, 2]},
{'name':'Cantaloupe',
 'Serving Size': '1/4 medium (134 g/4.8 oz)',
 'data': [50, 0, 0, 0, 20, 1, 240, 7, 12, 4, 1, 4, 11, 1, 120, 80, 2, 2]},
{'name':'Grapefruit',
 'Serving Size': '1/2 medium (154 g/5.5 oz)',
 'data': [60, 0, 0, 0, 0, 0, 160, 5, 15, 5, 2, 8, 11, 1, 35, 100, 4, 0]},
{'name':'Grapes',
 'Serving Size': '3/4 cup (126 g/4.5 oz)',
 'data': [90, 0, 0, 0, 15, 1, 240, 7, 23, 8, 1, 4, 20, 0, 0, 2, 2, 0]},
{'name':'Honeydew Melon',
 'Serving Size': '1/10 medium melon (134 g/4.8 oz)',
 'data': [50, 0, 0, 0, 30, 1, 210, 6, 12, 4, 1, 4, 11, 1, 2, 45, 2, 2]},
{'name':'Kiwifruit',
 'Serving Size': '2 medium (148 g/5.3 oz)',
 'data': [90, 10, 1, 2, 0, 0, 450, 13, 20, 7, 4, 16, 13, 1, 2, 240, 4, 2]},
{'name':'Lemon',
 'Serving Size': '1 medium (58 g/2.1 oz)',
 'data': [15, 0, 0, 0, 0, 0, 75, 2, 5, 2, 2, 8, 2, 0, 0, 40, 2, 0]},
{'name':'Lime',
 'Serving Size': '1 medium (67 g/2.4 oz)',
 'data': [20, 0, 0, 0, 0, 0, 75, 2, 7, 2, 2, 8, 0, 0, 0, 35, 0, 0]},
{'name':'Nectarine',
 'Serving Size': '1 medium (140 g/5.0 oz)',
 'data': [60, 5, 0.5, 1, 0, 0, 250, 7, 15, 5, 2, 8, 11, 1, 8, 15, 0, 2]},
{'name':'Orange',
 'Serving Size': '1 medium (154 g/5.5 oz)',
 'data': [80, 0, 0, 0, 0, 0, 250, 7, 19, 6, 3, 12, 14, 1, 2, 130, 6, 0]},
{'name':'Peach',
 'Serving Size': '1 medium (147 g/5.3 oz)',
 'data': [60, 0, 0.5, 1, 0, 0, 230, 7, 15, 5, 2, 8, 13, 1, 6, 15, 0, 2]},
{'name':'Pear',
 'Serving Size': '1 medium (166 g/5.9 oz)',
 'data': [100, 0, 0, 0, 0, 0, 190, 5, 26, 9, 6, 24, 16, 1, 0, 10, 2, 0]},
{'name':'Pineapple',
 'Serving Size': '2 slices, 3" diameter, 3/4" thick (112 g/4 oz)',
 'data': [50, 0, 0, 0, 10, 0, 120, 3, 13, 4, 1, 4, 10, 1, 2, 50, 2, 2]},
{'name':'Plums',
 'Serving Size': '2 medium (151 g/5.4 oz)',
 'data': [70, 0, 0, 0, 0, 0, 230, 7, 19, 6, 2, 8, 16, 1, 8, 10, 0, 2]},
{'name':'Strawberries',
 'Serving Size': '8 medium (147 g/5.3 oz)',
 'data': [50, 0, 0, 0, 0, 0, 170, 5, 11, 4, 2, 8, 8, 1, 0, 160, 2, 2]},
{'name':'Sweet Cherries',
 'Serving Size': '21 cherries; 1 cup (140 g/5.0 oz)',
 'data': [100, 0, 0, 0, 0, 0, 350, 10, 26, 9, 1, 4, 16, 1, 2, 15, 2, 2]},
{'name':'Tangerine',
 'Serving Size': '1 medium (109 g/3.9 oz)',
 'data': [50, 0, 0, 0, 0, 0, 160, 5, 13, 4, 2, 8, 9, 1, 6, 45, 4, 0]},
{'name':'Watermelon',
 'Serving Size': '1/18 medium melon; 2 cups diced pieces (280 g/10.0 oz)',
 'data': [80, 0, 0, 0, 0, 0, 270, 8, 21, 7, 1, 4, 20, 1, 30, 25, 2, 4]}]

fruit_data = {}
descriptors_and_units = dict(zip(descriptors, units))
for row in raw_fruit_data:
    fruit_data[row['name']] = {}
    fruit_data[row['name']] = dict({'Serving Size': row['Serving Size']},
            **dict(zip(descriptors_and_units.keys(), row['data'])))

if __name__ == '__main__':

    from kivy.base import runTouchApp

    # All fruit categories will be shown in the left left (first argument),
    # and the first category will be auto-selected -- Melons. So, set the
    # second list to show the melon fruits (second argument).
    fruit_categories_detail = CascadingView(fruit_categories.keys(),
            fruit_categories['Melons'], width=800)

    runTouchApp(fruit_categories_detail)