Struct gdk4::ScrollEvent

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#[repr(transparent)]
pub struct ScrollEvent { /* private fields */ }

Expand description

An event related to a scrolling motion.

Implementations§

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impl ScrollEvent

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pub fn deltas(&self) -> (f64, f64)

Extracts the scroll deltas of a scroll event.

The deltas will be zero unless the scroll direction is ScrollDirection::Smooth.

For the representation unit of these deltas, see unit().

Returns

`delta_y`

return location for y scroll delta

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pub fn direction(&self) -> ScrollDirection

Extracts the direction of a scroll event.

pub fn unit(&self) -> ScrollUnit

Available on crate feature v4_8 only.

Extracts the scroll delta unit of a scroll event.

The unit will always be ScrollUnit::Wheel if the scroll direction is not ScrollDirection::Smooth.

pub fn is_stop(&self) -> bool

Check whether a scroll event is a stop scroll event.

Scroll sequences with smooth scroll information may provide a stop scroll event once the interaction with the device finishes, e.g. by lifting a finger. This stop scroll event is the signal that a widget may trigger kinetic scrolling based on the current velocity.

Stop scroll events always have a delta of 0/0.

Returns

true if the event is a scroll stop event

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impl ScrollEvent

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pub fn upcast(self) -> Event

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pub fn upcast_ref(&self) -> &Event

Methods from Deref<Target = Event>§

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pub const NONE: Option<&'static Event> = None

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pub fn axes(&self) -> Option<Vec<f64>>

Extracts all axis values from an event.

To find out which axes are used, use DeviceTool::axes() on the device tool returned by device_tool().

Returns

true on success, otherwise false

`axes`

the array of values for all axes

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pub fn axis(&self, axis_use: AxisUse) -> Option<f64>

Extract the axis value for a particular axis use from an event structure.

To find out which axes are used, use DeviceTool::axes() on the device tool returned by device_tool().

`axis_use`

the axis use to look for

Returns

true if the specified axis was found, otherwise false

`value`

location to store the value found

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pub fn device(&self) -> Option<Device>

Returns the device of an event.

Returns

a Device

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pub fn device_tool(&self) -> Option<DeviceTool>

Returns a DeviceTool representing the tool that caused the event.

If the was not generated by a device that supports different tools (such as a tablet), this function will return None.

Note: the DeviceTool will be constant during the application lifetime, if settings must be stored persistently across runs, see DeviceTool::serial().

Returns

The current device tool

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pub fn display(&self) -> Option<Display>

Retrieves the display associated to the @self.

Returns

a Display

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pub fn event_sequence(&self) -> EventSequence

Retuns the event sequence to which the event belongs.

Related touch events are connected in a sequence. Other events typically don’t have event sequence information.

Returns

the event sequence that the event belongs to

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pub fn event_type(&self) -> EventType

Retrieves the type of the event.

Returns

a EventType

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pub fn history(&self) -> Vec<TimeCoord>

Retrieves the history of the device that @self is for, as a list of time and coordinates.

The history includes positions that are not delivered as separate events to the application because they occurred in the same frame as @self.

Note that only motion and scroll events record history, and motion events do it only if one of the mouse buttons is down, or the device has a tool.

Returns

an array of time and coordinates

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pub fn modifier_state(&self) -> ModifierType

Returns the modifier state field of an event.

Returns

the modifier state of @self

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pub fn is_pointer_emulated(&self) -> bool

Returns whether this event is an ‘emulated’ pointer event.

Emulated pointer events typically originate from a touch events.

Returns

true if this event is emulated

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pub fn position(&self) -> Option<(f64, f64)>

Extract the event surface relative x/y coordinates from an event.

Returns

`x`

location to put event surface x coordinate

`y`

location to put event surface y coordinate

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pub fn seat(&self) -> Option<Seat>

Returns the seat that originated the event.

Returns

a Seat.

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pub fn surface(&self) -> Option<Surface>

Extracts the surface associated with an event.

Returns

The Surface associated with the event

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pub fn time(&self) -> u32

Returns the timestamp of @self.

Not all events have timestamps. In that case, this function returns GDK_CURRENT_TIME.

Returns

timestamp field from @self

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pub fn triggers_context_menu(&self) -> bool

Returns whether a Event should trigger a context menu, according to platform conventions.

The right mouse button typically triggers context menus.

This function should always be used instead of simply checking for event->button == GDK_BUTTON_SECONDARY.

Returns

true if the event should trigger a context menu.

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pub fn angle(&self, event: impl AsRef<Event>) -> Option<f64>

Returns the relative angle from @event1 to @event2.

The relative angle is the angle between the X axis and the line through both events’ positions. The rotation direction for positive angles is from the positive X axis towards the positive Y axis.

This assumes that both events have X/Y information. If not, this function returns false.