Class: ScrollViewSystem

Drives ScrollViewComponent. Runs in PreRender (once per rendered frame, unlike the fixed-step Update phase which can fire 0..N times per frame) so drag tracking and inertia are frame-smooth on any refresh rate, and positions are set before TransformSystem composes them.

Drag: pointer-down on the viewport starts a drag tracked via the global pointer stream (entity move/up stop firing once the pointer leaves the node). The move handler updates the offset and estimates release velocity from real elapsed time (smoothed) — NOT from per-tick deltas, which the catch-up loop corrupts. OnRender applies the offset to the content child's transform every frame, clamps to [0, contentSize - viewportSize], and decays inertia after release.

Offsets are the single source of truth — code writing offsetX/Y (or SetPercent*) scrolls through the same clamp + apply path.

Extends

• System

Constructors

Constructor

new ScrollViewSystem(): ScrollViewSystem;

Returns

ScrollViewSystem

Inherited from

System.constructor

Properties

Property	Modifier	Type	Default value	Inherited from
enabled	public	boolean	true	System.enabled
parallel	public	boolean	false	System.parallel

Methods

GetName()

GetName(): string;

Returns

string

Overrides

System.GetName

---

GetOrder()

GetOrder(): SystemOrder;

Ordered: the scroll composes into world transforms the same frame.

Returns

SystemOrder

---

GetPhase()

GetPhase(): SystemPhase;

Returns

SystemPhase

Overrides

System.GetPhase

---

GetWrites()

GetWrites(): readonly string[];

Returns

readonly string[]

---

OnClose()

OnClose(): void;

Returns

void

Inherited from

System.OnClose

---

OnInit()

OnInit(engine): void;

Parameters

Parameter	Type
engine	IEngine

Returns

void

Overrides

System.OnInit

---

OnRender()

OnRender(scene, _renderer): void;

Parameters

Parameter	Type
scene	Scene
_renderer	IRenderer

Returns

void

Overrides

System.OnRender

---

OnRendererChanged()

OnRendererChanged(_renderer): void;

Parameters

Parameter	Type
_renderer	IRenderer

Returns

void

Inherited from

System.OnRendererChanged

---

OnStart()

OnStart(scene, _renderer): void;

Parameters

Parameter	Type
scene	Scene
_renderer	IRenderer

Returns

void

Overrides

System.OnStart

---

OnStop()

OnStop(_scene): void;

Parameters

Parameter	Type
_scene	Scene

Returns

void

Overrides

System.OnStop

---

OnUpdate()

OnUpdate(_scene, _dt): void | Promise<void>;

Parameters

Parameter	Type
_scene	Scene
_dt	number

Returns

void | Promise<void>

Inherited from

System.OnUpdate