"""
Creating a multi-select list box

How to use a TabularEditor to create a multi-select list box.

This demo uses two TabularEditors, side-by-side. Selections from the left table
are shown in the right table. Each table has only one column.

"""

from __future__ import absolute_import
from traits.api import HasPrivateTraits, List, Str, Property
from traitsui.api import View, HGroup, UItem, TabularEditor
from traitsui.tabular_adapter import TabularAdapter


class MultiSelectAdapter(TabularAdapter):
    """ This adapter is used by both the left and right tables
    """

    # Titles and column names for each column of a table.
    # In this example, each table has only one column.
    columns = [('', 'myvalue')]

    # Magically named trait which gives the display text of the column named
    # 'myvalue'. This is done using a Traits Property and its getter:
    myvalue_text = Property

    # The getter for Property 'myvalue_text' simply takes the value of the
    # corresponding item in the list being displayed in this table.
    # A more complicated example could format the item before displaying it.
    def _get_myvalue_text(self):
        return self.item


class MultiSelect(HasPrivateTraits):
    """ This is the class used to view two tables
    """
    # FIXME (TraitsUI defect #14): When multi-select is done by keyboard
    # (shift+arrow), the 'selected' trait list does not update.

    # FIXME (TraitsUI defect #15): In Windows wx, when show_titles is False,
    # left table does not draw until selection passes through all rows.
    # (Workaround here: set show_titles True and make column titles empty.)

    choices = List(Str)
    selected = List(Str)

    view = View(
        HGroup(
            UItem('choices',
                  editor=TabularEditor(
                      show_titles=True,
                      selected='selected',
                      editable=False,
                      multi_select=True,
                      adapter=MultiSelectAdapter())
                  ),
            UItem('selected',
                  editor=TabularEditor(
                      show_titles=True,
                      editable=False,
                      adapter=MultiSelectAdapter())
                  )
        ),
        resizable=True,
        width=200,
        height=300
    )

# Create the demo:
demo = MultiSelect(choices=['one', 'two', 'three', 'four', 'five', 'six',
                            'seven', 'eight', 'nine', 'ten'])

# Run the demo (if invoked from the command line):
if __name__ == '__main__':
    demo.configure_traits()