Creating a *system tray icon*
-----------------------------

In order to create a *system tray icon*, the class ``pystray.Icon`` is used::

    import pystray

    from PIL import Image, ImageDraw


    def create_image(width, height, color1, color2):
        # Generate an image and draw a pattern
        image = Image.new('RGB', (width, height), color1)
        dc = ImageDraw.Draw(image)
        dc.rectangle(
            (width // 2, 0, width, height // 2),
            fill=color2)
        dc.rectangle(
            (0, height // 2, width // 2, height),
            fill=color2)

        return image


    # In order for the icon to be displayed, you must provide an icon
    icon = pystray.Icon(
        'test name',
        icon=create_image(64, 64, 'black', 'white'))


    # To finally show you icon, call run
    icon.run()


The call to ``pystray.Icon.run()`` is blocking, and it must be performed from
the main thread of the application. The reason for this is that the *system tray
icon* implementation for *OSX* will fail unless called from the main thread, and
it also requires the application runloop to be running. ``pystray.Icon.run()``
will start the runloop.

If you only target *Windows*, calling ``run()`` from a thread other than the
main thread is safe.

The ``run()`` method accepts an optional argument: ``setup``, a callable.

The ``setup`` function will be run in a separate thread once the *system tray
icon* is ready. The icon does not wait for it to complete, so you may put any
code that would follow the call to ``pystray.Icon.run()`` in it.

The call to ``pystray.Icon.run()`` will not complete until ``stop()`` is called.


Getting input from the *system tray icon*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to receive notifications about user interaction with the icon, a
popup menu can be added with the ``menu`` constructor argument.

This must be an instance of ``pystray.Menu``. Please see the reference for more
information about the format.

It will be displayed when the right-hand button has been pressed on the icon on
*Windows*, and when the icon has been clicked on other platforms. Menus are not
supported on *X*.

Menus also support a default item. On *Windows*, and *X*, this item will be
activated when the user clicks on the icon using the primary button. On other
platforms it will be activated if the menu contains no visible entries; it does
not have to be visible.

All properties of menu items, except for the callback, can be dynamically
calculated by supplying callables instead of values to the menu item
constructor. The properties are recalculated every time the icon is clicked or
any menu item is activated.

If the dynamic properties change because of an external event, you must ensure
that ``Icon.update_menu`` is called. This is required since not all supported
platforms allow for the menu to be generated when displayed.


Creating the menu
~~~~~~~~~~~~~~~~~

*This is not supported on Xorg; please check Icon.HAS_MENU at runtime for
support on the current platform.*

A menu can be attached to a system tray icon by passing an instance of
:class:`pystray.Menu` as the ``menu`` keyword argument.

A menu consists of a list of menu items, optionally separated by menu
separators.

Separators are intended to group menu items into logical groups. They will not
be displayed as the first and last visible item, and adjacent separators will be
hidden.

A menu item has several attributes:

*text* and *action*
    The menu item text and its associated action.

    These are the only required attributes. Please see *submenu* below for
    alternate interpretations of *action*.

*checked*
    Whether the menu item is checked.

    This can be one of three values:

    ``False``
        The item is decorated with an unchecked check box.

    ``True``
        The item is decorated with a checked check box.

    ``None``
        There is no hint that the item is checkable.

    If you want this to actually be togglable, you must pass a callable that
    returns the current state::

        from pystray import Icon as icon, Menu as menu, MenuItem as item

        state = False

        def on_clicked(icon, item):
            global state
            state = not item.checked

        # Update the state in `on_clicked` and return the new state in
        # a `checked` callable
        icon('test', create_image(), menu=menu(
            item(
                'Checkable',
                on_clicked,
                checked=lambda item: state))).run()

*radio*
    *This is not supported on macOS; please check Icon.HAS_MENU_RADIO at
    runtime for support on the current platform.*

    Whether this is a radio button.

    This is used only if ``checked`` is ``True`` or ``False``, and only has a
    visual meaning. The menu has no concept of radio button groups::

        from pystray import Icon as icon, Menu as menu, MenuItem as item

        state = 0

        def set_state(v):
            def inner(icon, item):
                global state
                state = v
            return inner

        def get_state(v):
            def inner(item):
                return state == v
            return inner

        # Let the menu items be a callable returning a sequence of menu
        # items to allow the menu to grow
        icon('test', create_image(), menu=menu(lambda: (
            item(
                'State %d' % i,
                set_state(i),
                checked=get_state(i),
                radio=True)
            for i in range(max(5, state + 2))))).run()

*default*
    *This is not supported on Darwin and using AppIndicator; please check
    Icon.HAS_DEFAULT at runtime for support on the current platform.*

    Whether this is the default item.

    It is drawn in a distinguished style and will be activated as the default
    item on platforms that support default actions. On *X*, this is the only
    action available.

*visible*
    Whether the menu item is visible.

*enabled*
    Whether the menu item is enabled. Disabled menu items are displayed, but are
    greyed out and cannot be activated.

*submenu*
    The submenu, if any, that is attached to this menu item. Either a submenu
    or an action can be passed as the second argument to the constructor.

    The submenu must be an instance of :class:`Menu`::

        from pystray import Icon as icon, Menu as menu, MenuItem as item

        icon('test', create_image(), menu=menu(
            item(
                'With submenu',
                menu(
                    item(
                        'Submenu item 1',
                        lambda icon, item: 1),
                    item(
                        'Submenu item 2',
                        lambda icon, item: 2))))).run()

Once created, menus and menu items cannot be modified. All attributes except for
the menu item callbacks can however be set to callables returning the current
value. This also applies to the sequence of menu items belonging to a menu: this
can be a callable returning the current sequence.


Displaying notifications
~~~~~~~~~~~~~~~~~~~~~~~~

*This is not supported on macOS and Xorg; please check Icon.HAS_NOTIFICATION
at runtime for support on the current platform.*

To display a system notification, use :meth:`pystray.Icon.notify`::

    from pystray import Icon as icon, Menu as menu, MenuItem as item

    icon('test', create_image(), menu=menu(
        item(
            'With submenu',
            menu(
                item(
                    'Show message',
                    lambda icon, item: icon.notify('Hello World!')),
                item(
                    'Submenu item 2',
                    lambda icon, item: icon.remove_notification()))))).run()


Integrating with other frameworks
---------------------------------

The *pystray* ``run`` method is blocking, and must be called from the main
thread to maintain platform independence. This is troublesome when attempting
to use frameworks with an event loop, since they may also require running in
the main thread.

For this case you can use ``run_detached``. This allows you to setup the icon
and then pass control to the framework. Please see the documentation for more
information.


Selecting a backend
-------------------

*pystray* aims to provide a unified *API* for all supported platforms. In some
cases, however, that is not entirely possible.

This library supports a number of backends. On *macOS* and *Windows*, the
operating system has system tray icons built-in, so the default backends should
be used, but on *Linux* you may have to make a decision depending on your
needs.

By setting the environment variable ``PYSTRAY_BACKEND`` to one of the strings in
the next section, the automatic selection is turned off.


Supported backends
~~~~~~~~~~~~~~~~~~

*appindicator*
    This is one of the backends available on *Linux*, and is the preferred
    choice. All *pystray* features except for a menu default action are
    supported, and if the *appindicator* library is installed on the system
    and the desktop environment supports it, the icon is guaranteed to be
    displayed.

    If the *appindicator* library is not available on the system, a fallback on
    *ayatana-appindicator* is attempted.

*darwin*
    This is the default backend when running on *macOS*. All *pystray* features
    are available.

*gtk*
    This is one of the backends available on *Linux*, and is prioritised above
    the *XOrg* backend. It uses *GTK* as underlying library. All *pystray*
    features are available, but it may not actually result in a visible icon:
    when running a *gnome-shell* session, an third party plugin is required to
    display legacy tray icons.

*win32*
    This is the default backend when running on *Windows*. All *pystray*
    features are available.

*xorg*
    This is one of the backends available on *Linux*. It is used as a fallback
    when no other backend can be loaded. It does not support any menu
    functionality except for a default action.
