:right-sidebar: True

DisplayManager
===================================================================

.. currentmodule:: gi.repository.Gdk





.. class:: DisplayManager(**properties: ~typing.Any)
   :no-contents-entry:


Superclasses: :class:`~gi.repository.GObject.Object`





A singleton object that offers notification when displays appear or
disappear.

You can use :obj:`~gi.repository.Gdk.DisplayManager.get` to obtain the ``GdkDisplayManager``
singleton, but that should be rarely necessary. Typically, initializing
GTK opens a display that you can work with without ever accessing the
``GdkDisplayManager``\.

The GDK library can be built with support for multiple backends.
The ``GdkDisplayManager`` object determines which backend is used
at runtime.

In the rare case that you need to influence which of the backends
is being used, you can use :obj:`~gi.repository.Gdk.set_allowed_backends`\. Note
that you need to call this function before initializing GTK.

Backend-specific code
--------------------------------------------------------------------------------

When writing backend-specific code that is supposed to work with
multiple GDK backends, you have to consider both compile time and
runtime. At compile time, use the ``GDK_WINDOWING_X11``\, ``GDK_WINDOWING_WIN32``
macros, etc. to find out which backends are present in the GDK library
you are building your application against. At runtime, use type-check
macros like GDK_IS_X11_DISPLAY() to find out which backend is in use:


.. code-block:: c
    :dedent:

    #ifdef GDK_WINDOWING_X11
      if (GDK_IS_X11_DISPLAY (display))
        {
          // make X11-specific calls here
        }
      else
    #endif
    #ifdef GDK_WINDOWING_MACOS
      if (GDK_IS_MACOS_DISPLAY (display))
        {
          // make Quartz-specific calls here
        }
      else
    #endif
      g_error ("Unsupported GDK backend");




Methods
-------

.. rst-class:: interim-class

.. class:: DisplayManager
   :no-index:


   .. classmethod:: get() -> ~gi.repository.Gdk.DisplayManager

      Gets the singleton ``GdkDisplayManager`` object.

      When called for the first time, this function consults the
      ``GDK_BACKEND`` environment variable to find out which of the
      supported GDK backends to use (in case GDK has been compiled
      with multiple backends).

      Applications can use :obj:`~gi.repository.Gdk.set_allowed_backends` to limit what
      backends will be used.









   .. method:: get_default_display() -> ~gi.repository.Gdk.Display | None

      Gets the default ``GdkDisplay``\.









   .. method:: list_displays() -> list[~gi.repository.Gdk.Display]

      List all currently open displays.









   .. method:: open_display(name: str | None = None) -> ~gi.repository.Gdk.Display | None

      Opens a display.






      :param name: the name of the display to open




   .. method:: set_default_display(display: ~gi.repository.Gdk.Display) -> None

      Sets ``display`` as the default display.






      :param display: a ``GdkDisplay``








Properties
----------

.. rst-class:: interim-class

.. class:: DisplayManager
   :no-index:
   

   .. attribute:: props.default_display
      :type: ~gi.repository.Gdk.Display

      The type of the None singleton.











Signals
-------

.. rst-class:: interim-class

.. class:: DisplayManager.signals
   :no-index:
   

   .. method:: display_opened(display: ~gi.repository.Gdk.Display) -> None

      The type of the None singleton.







      :param display: the opened display