# Source code for enaml.widgets.split_item

    #------------------------------------------------------------------------------
    # Copyright (c) 2013-2025, Nucleic Development Team.
    #
    # Distributed under the terms of the Modified BSD License.
    #
    # The full license is in the file LICENSE, distributed with this software.
    #------------------------------------------------------------------------------
    from atom.api import Bool, Range, Value, Typed, ForwardTyped

    from enaml.core.declarative import d_, observe

    from .container import Container
    from .widget import Widget, ProxyWidget

    class ProxySplitItem(ProxyWidget):
        """ The abstract definition of a proxy SplitItem object.

        """
        #: A reference to the SplitItem declaration.
        declaration = ForwardTyped(lambda: SplitItem)

        def set_stretch(self, stretch):
            raise NotImplementedError

        def set_collapsible(self, collapsible):
            raise NotImplementedError

    class SplitItem(Widget):
        """ A widget which can be used as an item in a Splitter.

        A SplitItem is a widget which can be used as a child of a Splitter
        widget. It can have at most a single child widget which is an
        instance of Container.

        """
        #: The stretch factor for this item. The stretch factor determines
        #: how much an item is resized relative to its neighbors when the
        #: splitter space is allocated.
        stretch = d_(Range(low=0, value=1))

        #: Whether or not the item can be collapsed to zero width by the
        #: user. This holds regardless of the minimum size of the item.
        collapsible = d_(Bool(True))

        #: This is a deprecated attribute. It should no longer be used.
        preferred_size = d_(Value())

        #: A reference to the ProxySplitItem object.
        proxy = Typed(ProxySplitItem)

        def split_widget(self):
            """ Get the split widget defined on the item.

            The split widget is the last child Container.

            """
            for child in reversed(self.children):
                if isinstance(child, Container):
                    return child

        #--------------------------------------------------------------------------
        # Observers
        #--------------------------------------------------------------------------
        @observe('stretch', 'collapsible')
        def _update_proxy(self, change):
            """ An observer which sends state change to the proxy.

            """
            # The superclass handler implementation is sufficient.
            super(SplitItem, self)._update_proxy(change)