.. default-domain:: py
.. highlight:: py
.. currentmodule:: UI

Dropdown
========


.. class:: Dropdown

   A control for choosing one of a list of options, which are shown when it is clicked.
   Added to a :class:`Canvas` or a :class:`Panel`.

   .. attribute:: rect_transform

      The rect transform for the UI object.

      :Attribute: Read-only, cannot be set
      :rtype: :class:`RectTransform`
   

   .. attribute:: layout_element

      How much space the UI object asks a layout for.

      :Attribute: Read-only, cannot be set
      :rtype: :class:`LayoutElement`
   

      .. note::

         Only has an effect when the object is in a panel that has a layout. A canvas is
         not inside a layout and does not have one.

   .. attribute:: visible

      Whether the UI object is visible.

      :Attribute: Can be read or written
      :rtype: bool
   

      .. note::

         This is the object's own setting, which is what it was last set to. An object is
         only drawn when everything it is inside is visible as well, so an interface can
         be built with its parts visible, inside a panel that is not, and shown all at
         once by making that panel visible.

   .. attribute:: options

      The options that the dropdown offers.

      :Attribute: Can be read or written
      :rtype: list(str)
   

      .. note::

         Setting the options resets the selection to the first of them, or to nothing
         when the list is empty.

   .. attribute:: selected_index

      The position in :attr:`Dropdown.options` of the option that is chosen.

      :Attribute: Can be read or written
      :rtype: int
   

      .. note::

         Zero while the dropdown has no options, as there is nothing to choose.

   .. attribute:: changed

      Whether the chosen option has been changed.

      :Attribute: Can be read or written
      :rtype: bool
   

      .. note::

         This property is set to true when the user chooses an option, and not when a
         client chooses one.
         A client script should reset the property to false in order to detect subsequent changes.

   .. attribute:: interactable

      Whether the control responds to the user.

      :Attribute: Can be read or written
      :rtype: bool
   

      .. note::

         A control that is not interactable is drawn grayed out and ignores the user,
         but is still visible. Set its visibility to false to hide it instead.

   .. attribute:: color

      The color the control is tinted with. White, the default, leaves the control drawn
      as the skin has it.

      :Attribute: Can be read or written
      :rtype: :class:`StdLib.ColorRGBA`
   

      .. note::

         The tint multiplies the sprite the control is drawn with, in every state, so
         a control can show a state of its own, an engaged autopilot for instance, by
         color. It is applied to the part of the control that responds to the user:
         the body of a button, dropdown or input field, the box of a toggle, and the
         handle of a slider. A control's label is tinted through the color of its
         text.

   .. attribute:: tooltip

      A short piece of text shown beside the pointer while it rests on the
      control. Empty, the default, shows nothing.

      :Attribute: Can be read or written
      :rtype: str
   

   .. method:: remove()

      Remove the UI object.