Struct gtk4::EventControllerScroll[][src]

pub struct EventControllerScroll(_);
Expand description

EventControllerScroll 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 signal::EventControllerScroll::scroll signal. Deltas in the discrete case are multiples of 1.

In the case of continuous scroll events, EventControllerScroll encloses all signal::EventControllerScroll::scroll emissions between two signal::EventControllerScroll::scroll-begin and signal::EventControllerScroll::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 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 EventControllerScrollFlags::VERTICAL, EventControllerScrollFlags::HORIZONTAL and EventControllerScrollFlags::BOTH_AXES. If any axis is disabled, the respective signal::EventControllerScroll::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 EventControllerScrollFlags::DISCRETE. This can be used to implement discrete actions triggered through scroll events (e.g. switching across combobox options).

The EventControllerScrollFlags::KINETIC flag toggles the emission of the signal::EventControllerScroll::decelerate signal, emitted at the end of scrolling with two X/Y velocity arguments that are consistent with the motion that was received.

Implements

EventControllerExt, glib::ObjectExt

Implementations

Creates a new event controller that will handle scroll events.

flags

flags affecting the controller behavior

Returns

a new EventControllerScroll

Creates a new builder-pattern struct instance to construct EventControllerScroll objects.

This method returns an instance of EventControllerScrollBuilder which can be used to create EventControllerScroll objects.

Gets the flags conditioning the scroll controller behavior.

Returns

the controller flags.

Sets the flags conditioning scroll controller behavior.

flags

flags affecting the controller behavior

Emitted after scroll is finished if the 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.

vel_x

X velocity

vel_y

Y velocity

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

dx

X delta

dy

Y delta

Returns

true if the scroll event was handled, false otherwise.

Signals that a new scrolling operation has begun.

It will only be emitted on devices capable of it.

Signals that a scrolling operation has finished.

It will only be emitted on devices capable of it.

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