#------------------------------------------------------------------------------
# Copyright (c) 2011, Enthought, Inc.
# All rights reserved.
#------------------------------------------------------------------------------
from traits.api import Bool, List, Int, Property, Unicode, cached_property
from .control import Control
[docs]class ComboBox(Control):
""" A drop-down list from which one item can be selected at a time.
Use a combo box to select a single item from a collection of items.
"""
#: The unicode strings to display in the combo box.
items = List(Unicode)
#: The integer index of the currently selected item. If the given
#: index falls outside of the range of items, the item will be
#: deselected.
index = Int(-1)
#: Whether the text in the combo box can be edited by the user.
editable = Bool(False)
#: A readonly property that will return the currently selected
#: item. If the index falls out of range, the selected item will
#: be the empty string.
selected_item = Property(Unicode, depends_on=['index', 'items[]'])
#: How strongly a component hugs it's contents' width. ComboBoxes
#: hug width weakly, by default.
hug_width = 'weak'
#--------------------------------------------------------------------------
# Initialization
#--------------------------------------------------------------------------
[docs] def snapshot(self):
""" Returns the dict of creation attributes for the combo box.
"""
snap = super(ComboBox, self).snapshot()
snap['items'] = self.items
snap['index'] = self.index
snap['editable'] = self.editable
return snap
[docs] def bind(self):
""" A method called after initialization which allows the widget
to bind any event handlers necessary.
"""
super(ComboBox, self).bind()
self.publish_attributes('index', 'editable')
self.on_trait_change(self._send_items, 'items, items_items')
def _send_items(self):
""" Send the 'set_items' action to the client widget.
"""
content = {'items': self.items}
self.send_action('set_items', content)
#--------------------------------------------------------------------------
# Message Handling
#--------------------------------------------------------------------------
[docs] def on_action_index_changed(self, content):
""" The message handler for the 'index_changed' action from the
client widget. The content will contain the selected 'index'.
"""
index = content['index']
self.set_guarded(index=index)
#--------------------------------------------------------------------------
# Property Handlers
#--------------------------------------------------------------------------
@cached_property
def _get_selected_item(self):
""" The getter for the `selected_item` property.
"""
items = self.items
idx = self.index
if idx < 0 or idx >= len(items):
return u''
return items[idx]