Struct Scrollbar 

pub struct Scrollbar {
    pub target: Entity,
    pub orientation: ControlOrientation,
    pub min_thumb_length: f32,
}

A headless scrollbar widget, which can be used to build custom scrollbars.

Scrollbars operate differently than the other UI widgets in a number of respects.

Unlike sliders, scrollbars don’t have an AccessibilityNode component, nor can they have keyboard focus. This is because scrollbars are usually used in conjunction with a scrollable container, which is itself accessible and focusable. This also means that scrollbars don’t accept keyboard events, which is also the responsibility of the scrollable container.

Scrollbars don’t emit notification events; instead they modify the scroll position of the target entity directly.

A scrollbar can have any number of child entities, but one entity must be the scrollbar thumb, which is marked with the CoreScrollbarThumb component. Other children are ignored. The core scrollbar will directly update the position and size of this entity; the application is free to set any other style properties as desired.

The application is free to position the scrollbars relative to the scrolling container however it wants: it can overlay them on top of the scrolling content, or use a grid layout to displace the content to make room for the scrollbars.

Fields

target: Entity

Entity being scrolled.

orientation: ControlOrientation

Whether the scrollbar is vertical or horizontal.

min_thumb_length: f32

Minimum length of the scrollbar thumb, in pixel units, in the direction parallel to the main scrollbar axis. The scrollbar will resize the thumb entity based on the proportion of visible size to content size, but no smaller than this. This prevents the thumb from disappearing in cases where the ratio of content size to visible size is large.

Implementations

impl Scrollbar

pub fn new( target: Entity, orientation: ControlOrientation, min_thumb_length: f32, ) -> Self

Construct a new scrollbar.

Arguments

• target - The scrollable entity that this scrollbar will control.
• orientation - The orientation of the scrollbar (horizontal or vertical).
• min_thumb_length - The minimum size of the scrollbar’s thumb, in pixels.

Trait Implementations

impl Component for Scrollbar

where Self: Send + Sync + 'static,

const STORAGE_TYPE: StorageType = bevy_ecs::component::StorageType::Table

A constant indicating the storage type used for this component.

type Mutability = Mutable

A marker type to assist Bevy with determining if this component is mutable, or immutable. Mutable components will have Component<Mutability = Mutable>, while immutable components will instead have Component<Mutability = Immutable>.

fn register_required_components( _requiree: ComponentId, required_components: &mut RequiredComponentsRegistrator<'_, '_>, )

Registers required components.

fn clone_behavior() -> ComponentCloneBehavior

Called when registering this component, allowing to override clone function (or disable cloning altogether) for this component.

fn on_add() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_add ComponentHook for this Component if one is defined.

fn on_insert() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_insert ComponentHook for this Component if one is defined.

fn on_replace() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_replace ComponentHook for this Component if one is defined.

fn on_remove() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_remove ComponentHook for this Component if one is defined.

fn on_despawn() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_despawn ComponentHook for this Component if one is defined.

fn map_entities<E>(_this: &mut Self, _mapper: &mut E)

where E: EntityMapper,

Maps the entities on this component using the given EntityMapper. This is used to remap entities in contexts like scenes and entity cloning. When deriving Component, this is populated by annotating fields containing entities with #[entities]

impl Debug for Scrollbar

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromReflect for Scrollbar

fn from_reflect(reflect: &dyn PartialReflect) -> Option<Self>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl GetTypeRegistration for Scrollbar

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl PartialReflect for Scrollbar

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn try_apply(&mut self, value: &dyn PartialReflect) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<Self>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn try_into_reflect( self: Box<Self>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&dyn Reflect>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Attempts to cast this type to a mutable, fully-reflected value.

fn into_partial_reflect(self: Box<Self>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &dyn PartialReflect

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut dyn PartialReflect

Casts this type to a mutable, reflected value.

fn reflect_partial_eq(&self, value: &dyn PartialReflect) -> Option<bool>

Returns a “partial equality” comparison result.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_clone_and_take<T>(&self) -> Result<T, ReflectCloneError>

where T: 'static, Self: Sized + TypePath,

For a type implementing PartialReflect, combines reflect_clone and take in a useful fashion, automatically constructing an appropriate ReflectCloneError if the downcast fails.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn debug(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Debug formatter for the value.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl Reflect for Scrollbar

fn into_any(self: Box<Self>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &dyn Any

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<Self>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &dyn Reflect

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut dyn Reflect

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl Struct for Scrollbar

fn field(&self, name: &str) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field named name as a &dyn PartialReflect.

fn field_mut(&mut self, name: &str) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field named name as a &mut dyn PartialReflect.

fn field_at(&self, index: usize) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field with index index as a &dyn PartialReflect.

fn field_at_mut(&mut self, index: usize) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field with index index as a &mut dyn PartialReflect.

fn name_at(&self, index: usize) -> Option<&str>

Returns the name of the field with index index.

fn field_len(&self) -> usize

Returns the number of fields in the struct.

fn iter_fields(&self) -> FieldIter<'_>

Returns an iterator over the values of the reflectable fields for this struct.

fn to_dynamic_struct(&self) -> DynamicStruct

Creates a new DynamicStruct from this struct.

fn get_represented_struct_info(&self) -> Option<&'static StructInfo>

Will return None if TypeInfo is not available.

impl TypePath for Scrollbar

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl Typed for Scrollbar

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.