Documentation / @ripl/core / Context

Abstract Class: Context<TElement, TMeta>

Defined in: packages/core/src/context/context.ts:99

Abstract rendering context providing a unified API for Canvas and SVG, with state management and coordinate scaling.

Extends

• EventBus<ContextEventMap>

Extended by

• TerminalContext
• DOMContext

Type Parameters

Type Parameter	Default type
TElement extends Element	Element
TMeta extends Record<string, unknown>	Record<string, unknown>

Implements

• BaseState

Constructors

Constructor

new Context<TElement, TMeta>(type, element, options?): Context<TElement, TMeta>

Defined in: packages/core/src/context/context.ts:417

Parameters

Parameter	Type
type	string
element	TElement
options?	ContextOptions<TMeta>

Returns

Context<TElement, TMeta>

Overrides

EventBus.constructor

Properties

Property	Modifier	Type	Default value	Description	Inherited from	Defined in
currentState	protected	BaseState	undefined	-	-	packages/core/src/context/context.ts:104
element	readonly	TElement	undefined	The underlying DOM element the context renders into.	-	packages/core/src/context/context.ts:111
height	public	number	undefined	Current height of the rendering surface, in logical pixels — CSS pixels, unaffected by the device pixel ratio.	-	packages/core/src/context/context.ts:124
hitTestHonorsTransform	public	boolean	false	Whether this context's hit testing natively accounts for element and ancestor group transforms (as SVG does, via the DOM). When false (e.g. canvas), callers map the hit point into the element's local space before testing. See Element.getWorldTransform.	-	packages/core/src/context/context.ts:120
meta	readonly	TMeta	undefined	Arbitrary metadata attached to the context.	-	packages/core/src/context/context.ts:113
parent?	public	EventBus<ContextEventMap>	undefined	The parent event bus that emitted events bubble up to, if any.	EventBus.parent	packages/core/src/core/event-bus.ts:107
renderDepth	protected	number	0	-	-	packages/core/src/context/context.ts:105
renderedElements	public	RenderElement[]	undefined	Elements rendered during the current pass, used for hit testing.	-	packages/core/src/context/context.ts:132
renderElement?	public	RenderElement	undefined	The element currently being rendered, if any.	-	packages/core/src/context/context.ts:130
saveDepth	protected	number	0	-	-	packages/core/src/context/context.ts:106
scaleX	public	Scale<number, number>	undefined	Scale mapping logical x coordinates onto this backend's surface x coordinates. Drives drawing, not a conversion seam for callers — use Context.toSurfacePoint.	-	packages/core/src/context/context.ts:126
scaleY	public	Scale<number, number>	undefined	Scale mapping logical y coordinates onto this backend's surface y coordinates. Drives drawing, not a conversion seam for callers — use Context.toSurfacePoint.	-	packages/core/src/context/context.ts:128
states	protected	BaseState[]	undefined	-	-	packages/core/src/context/context.ts:103
type	readonly	string	undefined	The context type identifier (e.g. canvas, svg).	-	packages/core/src/context/context.ts:109
width	public	number	undefined	Current width of the rendering surface, in logical pixels — CSS pixels, unaffected by the device pixel ratio.	-	packages/core/src/context/context.ts:122
defaultKey	readonly	typeof defaultKey	undefined	The key under which resources are retained when no explicit key is provided.	EventBus.defaultKey	packages/core/src/core/disposer.ts:11

Accessors

$events

Get Signature

get $events(): keyof ContextEventMap[]

Defined in: packages/core/src/context/context.ts:135

The event types a context can emit. See EventBus.$events.

Returns

keyof ContextEventMap[]

Overrides

EventBus.$events

---

currentRenderElement

Get Signature

get currentRenderElement(): RenderElement | undefined

Defined in: packages/core/src/context/context.ts:153

The element currently being rendered; setting a non-abstract element also records it in Context.renderedElements.

Returns

RenderElement | undefined

Set Signature

set currentRenderElement(element): void

Defined in: packages/core/src/context/context.ts:157

Parameters

Parameter	Type
element	RenderElement | undefined

Returns

void

---

direction

Get Signature

get direction(): Direction

Defined in: packages/core/src/context/context.ts:184

Directionality used when rendering text.

Returns

Direction

Set Signature

set direction(value): void

Defined in: packages/core/src/context/context.ts:188

Directionality used when rendering text.

Parameters

Parameter	Type
value	Direction

Returns

void

Directionality used when rendering text.

Implementation of

BaseState.direction

---

fill

Get Signature

get fill(): string

Defined in: packages/core/src/context/context.ts:166

Fill style (CSS color, gradient, or pattern) used to paint filled regions.

Returns

string

Set Signature

set fill(value): void

Defined in: packages/core/src/context/context.ts:170

Fill style (CSS color, gradient, or pattern) used to paint filled regions.

Parameters

Parameter	Type
value	string

Returns

void

Fill style (CSS color, gradient, or pattern) used to paint filled regions.

Implementation of

BaseState.fill

---

filter

Get Signature

get filter(): string

Defined in: packages/core/src/context/context.ts:175

CSS filter string applied to subsequent drawing operations (e.g. blur(4px)).

Returns

string

Set Signature

set filter(value): void

Defined in: packages/core/src/context/context.ts:179

CSS filter string applied to subsequent drawing operations (e.g. blur(4px)).

Parameters

Parameter	Type
value	string

Returns

void

CSS filter string applied to subsequent drawing operations (e.g. blur(4px)).

Implementation of

BaseState.filter

---

font

Get Signature

get font(): string

Defined in: packages/core/src/context/context.ts:193

CSS font shorthand used when rendering text.

Returns

string

Set Signature

set font(value): void

Defined in: packages/core/src/context/context.ts:197

CSS font shorthand used when rendering text.

Parameters

Parameter	Type
value	string

Returns

void

CSS font shorthand used when rendering text.

Implementation of

BaseState.font

---

fontKerning

Get Signature

get fontKerning(): FontKerning

Defined in: packages/core/src/context/context.ts:202

Whether font kerning is applied when rendering text.

Returns

FontKerning

Set Signature

set fontKerning(value): void

Defined in: packages/core/src/context/context.ts:206

Whether font kerning is applied when rendering text.

Parameters

Parameter	Type
value	FontKerning

Returns

void

Whether font kerning is applied when rendering text.

Implementation of

BaseState.fontKerning

---

globalCompositeOperation

Get Signature

get globalCompositeOperation(): unknown

Defined in: packages/core/src/context/context.ts:220

Compositing operation controlling how new drawing is blended with existing content.

Returns

unknown

Set Signature

set globalCompositeOperation(value): void

Defined in: packages/core/src/context/context.ts:224

Compositing operation controlling how new drawing is blended with existing content.

Parameters

Parameter	Type
value	unknown

Returns

void

Compositing operation controlling how new drawing is blended with existing content.

Implementation of

BaseState.globalCompositeOperation

---

lineCap

Get Signature

get lineCap(): LineCap

Defined in: packages/core/src/context/context.ts:229

Cap style drawn at the endpoints of stroked lines.

Returns

LineCap

Set Signature

set lineCap(value): void

Defined in: packages/core/src/context/context.ts:233

Cap style drawn at the endpoints of stroked lines.

Parameters

Parameter	Type
value	LineCap

Returns

void

Cap style drawn at the endpoints of stroked lines.

Implementation of

BaseState.lineCap

---

lineDash

Get Signature

get lineDash(): number[]

Defined in: packages/core/src/context/context.ts:238

Dash pattern as alternating stroke and gap lengths; empty for a solid line.

Returns

number[]

Set Signature

set lineDash(value): void

Defined in: packages/core/src/context/context.ts:242

Dash pattern as alternating stroke and gap lengths; empty for a solid line.

Parameters

Parameter	Type
value	number[]

Returns

void

Dash pattern as alternating stroke and gap lengths; empty for a solid line.

Implementation of

BaseState.lineDash

---

lineDashOffset

Get Signature

get lineDashOffset(): number

Defined in: packages/core/src/context/context.ts:247

Distance into the line dash pattern at which dashing begins.

Returns

number

Set Signature

set lineDashOffset(value): void

Defined in: packages/core/src/context/context.ts:251

Distance into the line dash pattern at which dashing begins.

Parameters

Parameter	Type
value	number

Returns

void

Distance into the line dash pattern at which dashing begins.

Implementation of

BaseState.lineDashOffset

---

lineJoin

Get Signature

get lineJoin(): LineJoin

Defined in: packages/core/src/context/context.ts:256

Join style drawn where two stroked segments meet.

Returns

LineJoin

Set Signature

set lineJoin(value): void

Defined in: packages/core/src/context/context.ts:260

Join style drawn where two stroked segments meet.

Parameters

Parameter	Type
value	LineJoin

Returns

void

Join style drawn where two stroked segments meet.

Implementation of

BaseState.lineJoin

---

lineWidth

Get Signature

get lineWidth(): number

Defined in: packages/core/src/context/context.ts:265

Width, in pixels, of stroked lines.

Returns

number

Set Signature

set lineWidth(value): void

Defined in: packages/core/src/context/context.ts:269

Width, in pixels, of stroked lines.

Parameters

Parameter	Type
value	number

Returns

void

Width, in pixels, of stroked lines.

Implementation of

BaseState.lineWidth

---

miterLimit

Get Signature

get miterLimit(): number

Defined in: packages/core/src/context/context.ts:274

Miter length limit ratio applied to miter line joins.

Returns

number

Set Signature

set miterLimit(value): void

Defined in: packages/core/src/context/context.ts:278

Miter length limit ratio applied to miter line joins.

Parameters

Parameter	Type
value	number

Returns

void

Miter length limit ratio applied to miter line joins.

Implementation of

BaseState.miterLimit

---

opacity

Get Signature

get opacity(): number

Defined in: packages/core/src/context/context.ts:211

Global alpha applied to everything drawn, from 0 to 1. Assignment replaces the current alpha; element and group opacity instead composite multiplicatively through CONTEXT_OPERATIONS.

Returns

number

Set Signature

set opacity(value): void

Defined in: packages/core/src/context/context.ts:215

Global alpha applied to everything drawn, from 0 to 1.

Parameters

Parameter	Type
value	number

Returns

void

Global alpha applied to everything drawn, from 0 to 1.

Implementation of

BaseState.opacity

---

rotation

Get Signature

get rotation(): Rotation

Defined in: packages/core/src/context/context.ts:391

Rotation applied to the element's transform, as radians or a deg/rad string.

Returns

Rotation

Set Signature

set rotation(value): void

Defined in: packages/core/src/context/context.ts:395

Rotation applied to the element's transform, as radians or a deg/rad string.

Parameters

Parameter	Type
value	Rotation

Returns

void

Rotation applied to the element's transform, as radians or a deg/rad string.

Implementation of

BaseState.rotation

---

shadowBlur

Get Signature

get shadowBlur(): number

Defined in: packages/core/src/context/context.ts:283

Gaussian blur radius applied to drawn shadows.

Returns

number

Set Signature

set shadowBlur(value): void

Defined in: packages/core/src/context/context.ts:287

Gaussian blur radius applied to drawn shadows.

Parameters

Parameter	Type
value	number

Returns

void

Gaussian blur radius applied to drawn shadows.

Implementation of

BaseState.shadowBlur

---

shadowColor

Get Signature

get shadowColor(): string

Defined in: packages/core/src/context/context.ts:292

Color of drawn shadows.

Returns

string

Set Signature

set shadowColor(value): void

Defined in: packages/core/src/context/context.ts:296

Color of drawn shadows.

Parameters

Parameter	Type
value	string

Returns

void

Color of drawn shadows.

Implementation of

BaseState.shadowColor

---

shadowOffsetX

Get Signature

get shadowOffsetX(): number

Defined in: packages/core/src/context/context.ts:301

Horizontal offset, in pixels, of drawn shadows.

Returns

number

Set Signature

set shadowOffsetX(value): void

Defined in: packages/core/src/context/context.ts:305

Horizontal offset, in pixels, of drawn shadows.

Parameters

Parameter	Type
value	number

Returns

void

Horizontal offset, in pixels, of drawn shadows.

Implementation of

BaseState.shadowOffsetX

---

shadowOffsetY

Get Signature

get shadowOffsetY(): number

Defined in: packages/core/src/context/context.ts:310

Vertical offset, in pixels, of drawn shadows.

Returns

number

Set Signature

set shadowOffsetY(value): void

Defined in: packages/core/src/context/context.ts:314

Vertical offset, in pixels, of drawn shadows.

Parameters

Parameter	Type
value	number

Returns

void

Vertical offset, in pixels, of drawn shadows.

Implementation of

BaseState.shadowOffsetY

---

stroke

Get Signature

get stroke(): string

Defined in: packages/core/src/context/context.ts:319

Stroke style (CSS color, gradient, or pattern) used to paint outlines.

Returns

string

Set Signature

set stroke(value): void

Defined in: packages/core/src/context/context.ts:323

Stroke style (CSS color, gradient, or pattern) used to paint outlines.

Parameters

Parameter	Type
value	string

Returns

void

Stroke style (CSS color, gradient, or pattern) used to paint outlines.

Implementation of

BaseState.stroke

---

supportsPathCaching

Get Signature

get supportsPathCaching(): boolean

Defined in: packages/core/src/context/context.ts:733

Whether cached ContextPaths may be safely reused across render cycles. false by default; backends whose Context.createPath is free of per-frame side effects (e.g. canvas) override this to true. SVG, for example, returns false because createPath registers the path into a per-frame virtual DOM tree.

Returns

boolean

---

textAlign

Get Signature

get textAlign(): TextAlignment

Defined in: packages/core/src/context/context.ts:328

Horizontal alignment of text relative to the drawing position.

Returns

TextAlignment

Set Signature

set textAlign(value): void

Defined in: packages/core/src/context/context.ts:332

Horizontal alignment of text relative to the drawing position.

Parameters

Parameter	Type
value	TextAlignment

Returns

void

Horizontal alignment of text relative to the drawing position.

Implementation of

BaseState.textAlign

---

textBaseline

Get Signature

get textBaseline(): TextBaseline

Defined in: packages/core/src/context/context.ts:337

Vertical baseline used when positioning text.

Returns

TextBaseline

Set Signature

set textBaseline(value): void

Defined in: packages/core/src/context/context.ts:341

Vertical baseline used when positioning text.

Parameters

Parameter	Type
value	TextBaseline

Returns

void

Vertical baseline used when positioning text.

Implementation of

BaseState.textBaseline

---

transformOriginX

Get Signature

get transformOriginX(): TransformOrigin

Defined in: packages/core/src/context/context.ts:400

Horizontal origin about which rotation and scaling are applied.

Returns

TransformOrigin

Set Signature

set transformOriginX(value): void

Defined in: packages/core/src/context/context.ts:404

Horizontal origin about which rotation and scaling are applied.

Parameters

Parameter	Type
value	TransformOrigin

Returns

void

Horizontal origin about which rotation and scaling are applied.

Implementation of

BaseState.transformOriginX

---

transformOriginY

Get Signature

get transformOriginY(): TransformOrigin

Defined in: packages/core/src/context/context.ts:409

Vertical origin about which rotation and scaling are applied.

Returns

TransformOrigin

Set Signature

set transformOriginY(value): void

Defined in: packages/core/src/context/context.ts:413

Vertical origin about which rotation and scaling are applied.

Parameters

Parameter	Type
value	TransformOrigin

Returns

void

Vertical origin about which rotation and scaling are applied.

Implementation of

BaseState.transformOriginY

---

transformScaleX

Get Signature

get transformScaleX(): number

Defined in: packages/core/src/context/context.ts:373

Horizontal scale factor applied to the element's transform.

Returns

number

Set Signature

set transformScaleX(value): void

Defined in: packages/core/src/context/context.ts:377

Horizontal scale factor applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Horizontal scale factor applied to the element's transform.

Implementation of

BaseState.transformScaleX

---

transformScaleY

Get Signature

get transformScaleY(): number

Defined in: packages/core/src/context/context.ts:382

Vertical scale factor applied to the element's transform.

Returns

number

Set Signature

set transformScaleY(value): void

Defined in: packages/core/src/context/context.ts:386

Vertical scale factor applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Vertical scale factor applied to the element's transform.

Implementation of

BaseState.transformScaleY

---

translateX

Get Signature

get translateX(): number

Defined in: packages/core/src/context/context.ts:355

Horizontal translation, in pixels, applied to the element's transform.

Returns

number

Set Signature

set translateX(value): void

Defined in: packages/core/src/context/context.ts:359

Horizontal translation, in pixels, applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Horizontal translation, in pixels, applied to the element's transform.

Implementation of

BaseState.translateX

---

translateY

Get Signature

get translateY(): number

Defined in: packages/core/src/context/context.ts:364

Vertical translation, in pixels, applied to the element's transform.

Returns

number

Set Signature

set translateY(value): void

Defined in: packages/core/src/context/context.ts:368

Vertical translation, in pixels, applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Vertical translation, in pixels, applied to the element's transform.

Implementation of

BaseState.translateY

---

zIndex

Get Signature

get zIndex(): number

Defined in: packages/core/src/context/context.ts:346

Stacking order used to sort elements during rendering; higher values draw on top.

Returns

number

Set Signature

set zIndex(value): void

Defined in: packages/core/src/context/context.ts:350

Stacking order used to sort elements during rendering; higher values draw on top.

Parameters

Parameter	Type
value	number

Returns

void

Stacking order used to sort elements during rendering; higher values draw on top.

Implementation of

BaseState.zIndex

Methods

applyClip()

applyClip(path, fillRule?): void

Defined in: packages/core/src/context/context.ts:753

Clips subsequent drawing operations to the given path.

Parameters

Parameter	Type
path	ContextPath
fillRule?	FillRule

Returns

void

---

applyFill()

applyFill(path, fillRule?): void

Defined in: packages/core/src/context/context.ts:758

Fills the given path or text element using the current fill style.

Parameters

Parameter	Type
path	ContextElement
fillRule?	FillRule

Returns

void

---

applyGroupPaint()

protected applyGroupPaint(group): void

Defined in: packages/core/src/context/context.ts:603

Applies a group's own inherited paint (fill, stroke, opacity, font, line, shadow, text) to the context so descendants pick it up from the copied state. Transforms are applied separately, so they are skipped here.

Two boundary semantics are fixed here and every backend must honour them:

• Opacity composites multiplicatively. CONTEXT_OPERATIONS multiplies rather than assigns, so nested groups compound and a leaf's own alpha stacks under its ancestors' instead of replacing it.
• A group's gradient or pattern resolves against the group's own box. The group is the Context.currentRenderElement for the duration of the boundary, so a paint that bakes geometry at set time (canvas) and one that resolves it per leaf (SVG) agree on the same reference box: group.getBoundingBox(true), never a sibling's and never the surface.

Parameters

Parameter	Type
group	Element

Returns

void

---

applyStroke()

applyStroke(path): void

Defined in: packages/core/src/context/context.ts:763

Strokes the given path or text element using the current stroke style.

Parameters

Parameter	Type
path	ContextElement

Returns

void

---

batch()

batch<TResult>(body): TResult

Defined in: packages/core/src/context/context.ts:534

Clears the rendering surface and brackets the callback in markRenderStart/markRenderEnd, returning the callback's result. On exit the state stack is unwound to the depth captured on entry, giving the scene root the same guarantee Context.popGroup gives a group: a root-level clip: true shape deliberately skips its own restore() so the clip persists to later siblings, and with no enclosing group to absorb it that save would otherwise leak one state per frame, unbounded.

The surface is only cleared at render depth 0: a pass entered while an outer one is open continues it (matching Context.markRenderStart) rather than wiping what it drew.

Type Parameters

Type Parameter	Default type
TResult	void

Parameters

Parameter	Type
body	() => TResult

Returns

TResult

---

clear()

clear(): void

Defined in: packages/core/src/context/context.ts:483

Clears the entire rendering surface.

Returns

void

---

createPath()

createPath(id?): ContextPath

Defined in: packages/core/src/context/context.ts:738

Creates a new path element, optionally reusing an id for SVG diffing efficiency.

Parameters

Parameter	Type
id?	string

Returns

ContextPath

---

createText()

createText(options): ContextText

Defined in: packages/core/src/context/context.ts:743

Creates a new text element from the given options.

Parameters

Parameter	Type
options	TextOptions

Returns

ContextText

---

destroy()

destroy(): void

Defined in: packages/core/src/context/context.ts:837

Destroys the context and disposes all resources, releasing the element graph it retains for hit testing.

Returns

void

Overrides

EventBus.destroy

---

dispose()

protected dispose(key?): void

Defined in: packages/core/src/core/disposer.ts:25

Disposes all resources under the given key, or all resources if no key is provided.

Parameters

Parameter	Type
key?	PropertyKey

Returns

void

Inherited from

EventBus.dispose

---

drawImage()

drawImage(image, x, y, width?, height?): void

Defined in: packages/core/src/context/context.ts:748

Draws an image onto the rendering surface at the given position and optional size.

Parameters

Parameter	Type
image	CanvasImageSource
x	number
y	number
width?	number
height?	number

Returns

void

---

emit()

Call Signature

emit<TEvent>(event): TEvent

Defined in: packages/core/src/core/event-bus.ts:185

Emits an event, invoking all matching handlers and bubbling to the parent if applicable. Handlers for the event's own type run first, then EVENT_WILDCARD subscriptions.

Type Parameters

Type Parameter	Default type
TEvent extends Event<undefined>	Event<undefined>

Parameters

Parameter	Type
event	TEvent

Returns

TEvent

Inherited from

EventBus.emit

Call Signature

emit<TEvent>(type, data): Event<ContextEventMap[TEvent]>

Defined in: packages/core/src/core/event-bus.ts:186

Emits an event, invoking all matching handlers and bubbling to the parent if applicable. Handlers for the event's own type run first, then EVENT_WILDCARD subscriptions.

Type Parameters

Type Parameter
TEvent extends keyof ContextEventMap

Parameters

Parameter	Type
type	TEvent
data	ContextEventMap[TEvent]

Returns

Event<ContextEventMap[TEvent]>

Inherited from

EventBus.emit

---

export()

export(): ContextExport

Defined in: packages/core/src/context/context.ts:832

Captures a snapshot of the current context surface and returns format-specific exporters (see ContextExport). The base implementation is unsupported; each context overrides this with the formats relevant to it (image, url, string).

Returns

ContextExport

---

getDefaultState()

protected getDefaultState(): BaseState

Defined in: packages/core/src/context/context.ts:446

Returns

BaseState

---

has()

has(type): boolean

Defined in: packages/core/src/core/event-bus.ts:123

Returns whether there are any listeners registered for the given event type. Wildcard subscriptions (EVENT_WILDCARD) are not listeners for any concrete type, so a bus observed only through the wildcard still reports false here.

Parameters

Parameter	Type
type	keyof ContextEventMap

Returns

boolean

Inherited from

EventBus.has

---

hitTest()

protected hitTest(events, x, y): RenderElement[]

Defined in: packages/core/src/context/context.ts:808

Tests which rendered elements intersect the given point for the given event types, returning them topmost-first — the exact reverse of the order they were painted in.

The point is in logical space — the space pointer event payloads report — so a handler passes the coordinates it was given straight through.

Paint order is the sole key. Context.renderedElements already records the resolved stacking order (groups paint as contiguous stacking contexts), whereas RenderElement.zIndex is additive across the parent chain and so says nothing about two descendants of different groups; sorting by it discarded correct information.

Parameters

Parameter	Type
events	string[]
x	number
y	number

Returns

RenderElement[]

---

invalidateTrackedElements()

invalidateTrackedElements(event?): void

Defined in: packages/core/src/context/context.ts:496

Clears the cached list of tracked elements for interaction, forcing a rebuild on the next hit test.

Parameters

Parameter	Type
event?	string

Returns

void

---

isPointInPath()

isPointInPath(path, x, y, fillRule?): boolean

Defined in: packages/core/src/context/context.ts:776

Tests whether a point is inside the filled region of a path.

Parameters

Parameter	Type	Description
path	ContextPath	The path to test against.
x	number	X coordinate in logical space (CSS pixels relative to the context's top-left); a backend whose native test wants its own drawing coordinates converts internally.
y	number	Y coordinate in logical space (CSS pixels relative to the context's top-left).
fillRule?	FillRule	The fill rule determining what counts as inside. Defaults to the backend's own default.

Returns

boolean

Whether the point lies inside the path's fill.

---

isPointInStroke()

isPointInStroke(path, x, y): boolean

Defined in: packages/core/src/context/context.ts:788

Tests whether a point is on the stroked outline of a path.

Parameters

Parameter	Type	Description
path	ContextPath	The path to test against.
x	number	X coordinate in logical space (CSS pixels relative to the context's top-left); a backend whose native test wants its own drawing coordinates converts internally.
y	number	Y coordinate in logical space (CSS pixels relative to the context's top-left).

Returns

boolean

Whether the point lies on the path's stroke.

---

layer()

layer<TResult>(body): TResult

Defined in: packages/core/src/context/context.ts:472

Executes a callback within a save/restore pair, returning the callback's result.

Type Parameters

Type Parameter	Default type
TResult	void

Parameters

Parameter	Type
body	() => TResult

Returns

TResult

---

markRenderEnd()

markRenderEnd(): void

Defined in: packages/core/src/context/context.ts:519

Signals the end of a render pass. Clamped at zero, so an unbalanced call cannot drive the depth negative and make backends that gate their flush on depth 0 fire mid-frame.

Returns

void

---

markRenderStart()

markRenderStart(): void

Defined in: packages/core/src/context/context.ts:510

Signals the start of a render pass; resets the rendered-elements list at depth 0.

Returns

void

---

measureText()

measureText(text, font?): TextMetrics

Defined in: packages/core/src/context/context.ts:719

Measures text dimensions using the context's current font, text alignment, and baseline, or an optional font override. actualBoundingBox* is anchor-relative, so the alignment and baseline have to be forwarded or the reported box is anchored at the wrong corner.

Parameters

Parameter	Type
text	string
font?	string

Returns

TextMetrics

---

off()

off<TEvent>(type, handler): void

Defined in: packages/core/src/core/event-bus.ts:144

Removes a previously registered handler for the given event type.

Type Parameters

Type Parameter
TEvent extends keyof ContextEventMap

Parameters

Parameter	Type
type	TEvent
handler	EventHandler<ContextEventMap[TEvent]>

Returns

void

Inherited from

EventBus.off

---

on()

on<TEvent>(type, handler, options?): Disposable

Defined in: packages/core/src/core/event-bus.ts:131

Subscribes a handler to the given event type and returns a disposable for cleanup. Pass EVENT_WILDCARD to receive every event emitted on the bus regardless of type.

Type Parameters

Type Parameter
TEvent extends keyof ContextEventMap

Parameters

Parameter	Type
type	TEvent
handler	EventHandler<ContextEventMap[TEvent]>
options?	EventSubscriptionOptions

Returns

Disposable

Inherited from

EventBus.on

---

once()

once<TEvent>(type, handler, options?): Disposable

Defined in: packages/core/src/core/event-bus.ts:159

Subscribes a handler that is automatically removed after it fires once.

Type Parameters

Type Parameter
TEvent extends keyof ContextEventMap

Parameters

Parameter	Type
type	TEvent
handler	EventHandler<ContextEventMap[TEvent]>
options?	EventSubscriptionOptions

Returns

Disposable

Inherited from

EventBus.once

---

popGroup()

popGroup(): void

Defined in: packages/core/src/context/context.ts:620

Closes the most recently opened group boundary, unwinding the state stack back to the depth captured at Context.pushGroup and restoring the render element that was current before it. This absorbs any dangling save() left by a group-scoped clip (which deliberately skips its own restore so the clip persists to later siblings), confining the clip to the group rather than leaking it to the scene.

Returns

void

---

pushGroup()

pushGroup(group): void

Defined in: packages/core/src/context/context.ts:573

Opens a group boundary: saves the current drawing state and applies the group's own transform and inherited paint (see applyGroupPaint for the opacity and gradient-bounds semantics every backend must honour), so that descendant elements render within the group's coordinate system, inherit its paint through the copied state (the render-tree cascade), and composite under its opacity. Any group-scoped clip is confined to the group. Every Context.pushGroup must be balanced by a matching Context.popGroup. Backends that render hierarchy structurally (such as SVG) override this to nest descendants under a group node.

Parameters

Parameter	Type	Description
group	Element	The group element whose boundary is being entered.

Returns

void

---

requestRender()

requestRender(): void

Defined in: packages/core/src/context/context.ts:505

Requests that the bound scene repaint on the next frame, for context-level changes (e.g. a 3D camera move) that mutate no element and so would otherwise be skipped by the renderer's dirty check.

Returns

void

---

rescale()

protected rescale(width, height): void

Defined in: packages/core/src/context/context.ts:436

Parameters

Parameter	Type
width	number
height	number

Returns

void

---

reset()

reset(): void

Defined in: packages/core/src/context/context.ts:488

Resets the context to its initial state: drops the saved-state stack, restores the default drawing state, and closes any open group boundary.

Returns

void

---

restore()

restore(): void

Defined in: packages/core/src/context/context.ts:462

Restores the most recently saved state from the stack.

Returns

void

---

retain()

protected retain(value, key?): void

Defined in: packages/core/src/core/disposer.ts:14

Registers a disposable resource under an optional key for later cleanup.

Parameters

Parameter	Type	Default value
value	Disposable	undefined
key	PropertyKey	Disposer.defaultKey

Returns

void

Inherited from

EventBus.retain

---

rotate()

rotate(angle): void

Defined in: packages/core/src/context/context.ts:634

Applies a rotation transformation.

Parameters

Parameter	Type
angle	number

Returns

void

---

save()

save(): void

Defined in: packages/core/src/context/context.ts:455

Pushes the current state onto the stack and continues with a copy of it, so nested scopes inherit the enclosing drawing state (matching native canvas). This is what lets a group's paint, applied once at its boundary via Context.pushGroup, cascade to descendants.

Returns

void

---

scale()

scale(x, y): void

Defined in: packages/core/src/context/context.ts:639

Applies a scale transformation.

Parameters

Parameter	Type
x	number
y	number

Returns

void

---

setTransform()

setTransform(a, b, c, d, e, f): void

Defined in: packages/core/src/context/context.ts:663

Replaces the current transformation matrix with [a, b, c, d, e, f].

The matrix is in logical space, so the identity (1, 0, 0, 1, 0, 0) restores the context's own baseline rather than the backend's — on canvas that baseline is the device pixel ratio, which the backend composes back underneath. Translations are therefore in CSS pixels.

Parameters

Parameter	Type	Description
a	number	Horizontal scaling.
b	number	Vertical skewing.
c	number	Horizontal skewing.
d	number	Vertical scaling.
e	number	Horizontal translation, in logical pixels.
f	number	Vertical translation, in logical pixels.

Returns

void

---

toLogicalPoint()

toLogicalPoint(x, y): [number, number]

Defined in: packages/core/src/context/context.ts:697

Maps a point from surface space — this backend's own drawing coordinates, as produced by Context.scaleX and Context.scaleY — into the logical space elements are authored in and every public coordinate is expressed in.

Backends disagree on what surface space is: canvas maps logical coordinates onto device pixels while SVG leaves them identity, so a backend has to invert what this context actually does rather than assume the device pixel ratio.

This is a seam for backend implementors, not for consumers — nothing crossing the public API is in surface space, so a caller holding a pointer coordinate already has a logical one.

Parameters

Parameter	Type	Description
x	number	X coordinate in surface space.
y	number	Y coordinate in surface space.

Returns

[number, number]

The [x, y] pair in logical space.

---

toSurfacePoint()

toSurfacePoint(x, y): [number, number]

Defined in: packages/core/src/context/context.ts:710

Maps a point from the logical space elements are authored in into this backend's own drawing coordinates. The inverse of Context.toLogicalPoint, and likewise a seam for backend implementors rather than consumers.

Parameters

Parameter	Type	Description
x	number	X coordinate in logical space.
y	number	Y coordinate in logical space.

Returns

[number, number]

The [x, y] pair in surface space.

---

transform()

transform(a, b, c, d, e, f): void

Defined in: packages/core/src/context/context.ts:677

Multiplies the current transformation matrix by [a, b, c, d, e, f].

Parameters

Parameter	Type	Description
a	number	Horizontal scaling.
b	number	Vertical skewing.
c	number	Horizontal skewing.
d	number	Vertical scaling.
e	number	Horizontal translation.
f	number	Vertical translation.

Returns

void

---

translate()

translate(x, y): void

Defined in: packages/core/src/context/context.ts:644

Applies a translation transformation.

Parameters

Parameter	Type
x	number
y	number

Returns

void