:right-sidebar: True

EventControllerScroll
===================================================================

.. currentmodule:: gi.repository.Gtk





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


Superclasses: :class:`~gi.repository.Gtk.EventController`, :class:`~gi.repository.GObject.Object`





``GtkEventControllerScroll`` is an event controller that handles scroll
events.

It is capable of handling both discrete and continuous scroll
events from mice or touchpads, abstracting them both with the
:obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll` signal. Deltas in
the discrete case are multiples of 1.

In the case of continuous scroll events, ``GtkEventControllerScroll``
encloses all :obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll` emissions
between two :obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll_begin` and
:obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll_end` signals.

The behavior of the event controller can be modified by the flags
given at creation time, or modified at a later point through
:obj:`~gi.repository.Gtk.EventControllerScroll.set_flags` (e.g. because the scrolling
conditions of the widget changed).

The controller can be set up to emit motion for either/both vertical
and horizontal scroll events through :const:`~gi.repository.Gtk.EventControllerScrollFlags.VERTICAL`,
:const:`~gi.repository.Gtk.EventControllerScrollFlags.HORIZONTAL` and :const:`~gi.repository.Gtk.EventControllerScrollFlags.BOTH_AXES`.
If any axis is disabled, the respective :obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll`
delta will be 0. Vertical scroll events will be translated to horizontal
motion for the devices incapable of horizontal scrolling.

The event controller can also be forced to emit discrete events on all
devices through :const:`~gi.repository.Gtk.EventControllerScrollFlags.DISCRETE`. This can be used
to implement discrete actions triggered through scroll events (e.g.
switching across combobox options).

The :const:`~gi.repository.Gtk.EventControllerScrollFlags.KINETIC` flag toggles the emission of the
:obj:`~gi.repository.Gtk.EventControllerScroll.signals.decelerate` signal, emitted at the end
of scrolling with two X/Y velocity arguments that are consistent with the
motion that was received.



Constructors
------------

.. rst-class:: interim-class

.. class:: EventControllerScroll
   :no-index:


   .. classmethod:: new(flags: ~gi.repository.Gtk.EventControllerScrollFlags) -> ~gi.repository.Gtk.EventController

      Creates a new event controller that will handle scroll events.







      :param flags: flags affecting the controller behavior









Methods
-------

.. rst-class:: interim-class

.. class:: EventControllerScroll
   :no-index:


   .. method:: get_flags() -> ~gi.repository.Gtk.EventControllerScrollFlags

      Gets the flags conditioning the scroll controller behavior.










   .. method:: get_unit() -> ~gi.repository.Gdk.ScrollUnit

      Gets the scroll unit of the last
      :obj:`~gi.repository.Gtk.EventControllerScroll.signals.scroll` signal received.

      Always returns ``%GDK_SCROLL_UNIT_WHEEL`` if the
      :const:`~gi.repository.Gtk.EventControllerScrollFlags.DISCRETE` flag is set.



      .. versionadded:: 4.8








   .. method:: set_flags(flags: ~gi.repository.Gtk.EventControllerScrollFlags) -> None

      Sets the flags conditioning scroll controller behavior.







      :param flags: flags affecting the controller behavior









Properties
----------

.. rst-class:: interim-class

.. class:: EventControllerScroll
   :no-index:
   

   .. attribute:: props.flags
      :type: ~gi.repository.Gtk.EventControllerScrollFlags

      The flags affecting event controller behavior.











Signals
-------

.. rst-class:: interim-class

.. class:: EventControllerScroll.signals
   :no-index:
   

   .. method:: decelerate(vel_x: float, vel_y: float) -> None

      Emitted after scroll is finished if the
      :const:`~gi.repository.Gtk.EventControllerScrollFlags.KINETIC` flag is set.

      ``vel_x`` and ``vel_y`` express the initial velocity that was
      imprinted by the scroll events. ``vel_x`` and ``vel_y`` are expressed in
      pixels/ms.







      :param vel_x: X velocity


      :param vel_y: Y velocity





   .. method:: scroll(dx: float, dy: float) -> bool

      Signals that the widget should scroll by the
      amount specified by ``dx`` and ``dy``.

      For the representation unit of the deltas, see
      :obj:`~gi.repository.Gtk.EventControllerScroll.get_unit`.







      :param dx: X delta


      :param dy: Y delta





   .. method:: scroll_begin() -> None

      Signals that a new scrolling operation has begun.

      It will only be emitted on devices capable of it.










   .. method:: scroll_end() -> None

      Signals that a scrolling operation has finished.

      It will only be emitted on devices capable of it.