Documentation / @ripl/core / Context

Abstract Class: Context<TElement, TMeta>

Defined in: packages/core/src/context/context.ts:111

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:414

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
buffer	public	boolean	false	Whether drawing is buffered rather than committed to the surface immediately.	-	packages/core/src/context/context.ts:121
currentState	protected	BaseState	undefined	-	-	packages/core/src/context/context.ts:144
element	readonly	TElement	undefined	The underlying DOM element the context renders into.	-	packages/core/src/context/context.ts:116
height	public	number	undefined	Current height, in pixels, of the rendering surface.	-	packages/core/src/context/context.ts:131
hitTestHonoursTransform	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 getWorldTransform.	-	packages/core/src/context/context.ts:127
meta	readonly	TMeta	undefined	Arbitrary metadata attached to the context.	-	packages/core/src/context/context.ts:118
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:89
renderDepth	protected	number	0	-	-	packages/core/src/context/context.ts:145
renderedElements	public	RenderElement[]	undefined	Elements rendered during the current pass, used for hit testing.	-	packages/core/src/context/context.ts:141
renderElement?	public	RenderElement	undefined	The element currently being rendered, if any.	-	packages/core/src/context/context.ts:139
saveDepth	protected	number	0	-	-	packages/core/src/context/context.ts:146
scaleDPR	public	Scale<number, number>	undefined	Scale mapping logical pixels to device pixels using the device pixel ratio.	-	packages/core/src/context/context.ts:137
scaleX	public	Scale<number, number>	undefined	Scale mapping domain x coordinates to surface x coordinates.	-	packages/core/src/context/context.ts:133
scaleY	public	Scale<number, number>	undefined	Scale mapping domain y coordinates to surface y coordinates.	-	packages/core/src/context/context.ts:135
states	protected	BaseState[]	undefined	-	-	packages/core/src/context/context.ts:143
type	readonly	string	undefined	The context type identifier (e.g. canvas, svg).	-	packages/core/src/context/context.ts:114
width	public	number	undefined	Current width, in pixels, of the rendering surface.	-	packages/core/src/context/context.ts:129
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

currentRenderElement

Get Signature

get currentRenderElement(): RenderElement | undefined

Defined in: packages/core/src/context/context.ts:150

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:154

Parameters

Parameter	Type
element	RenderElement | undefined

Returns

void

---

direction

Get Signature

get direction(): Direction

Defined in: packages/core/src/context/context.ts:181

Directionality used when rendering text.

Returns

Direction

Set Signature

set direction(value): void

Defined in: packages/core/src/context/context.ts:185

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:163

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

Returns

string

Set Signature

set fill(value): void

Defined in: packages/core/src/context/context.ts:167

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

Parameters

Parameter	Type
value	string

Returns

void

Fill style (CSS colour, 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:172

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:176

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:190

CSS font shorthand used when rendering text.

Returns

string

Set Signature

set font(value): void

Defined in: packages/core/src/context/context.ts:194

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:199

Whether font kerning is applied when rendering text.

Returns

FontKerning

Set Signature

set fontKerning(value): void

Defined in: packages/core/src/context/context.ts:203

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:217

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:221

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:226

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:230

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:235

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:239

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:244

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:248

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:253

Join style drawn where two stroked segments meet.

Returns

LineJoin

Set Signature

set lineJoin(value): void

Defined in: packages/core/src/context/context.ts:257

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:262

Width, in pixels, of stroked lines.

Returns

number

Set Signature

set lineWidth(value): void

Defined in: packages/core/src/context/context.ts:266

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:271

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:275

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:208

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

Returns

number

Set Signature

set opacity(value): void

Defined in: packages/core/src/context/context.ts:212

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:388

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:392

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:280

Gaussian blur radius applied to drawn shadows.

Returns

number

Set Signature

set shadowBlur(value): void

Defined in: packages/core/src/context/context.ts:284

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:289

Colour of drawn shadows.

Returns

string

Set Signature

set shadowColor(value): void

Defined in: packages/core/src/context/context.ts:293

Colour of drawn shadows.

Parameters

Parameter	Type
value	string

Returns

void

Colour of drawn shadows.

Implementation of

BaseState.shadowColor

---

shadowOffsetX

Get Signature

get shadowOffsetX(): number

Defined in: packages/core/src/context/context.ts:298

Horizontal offset, in pixels, of drawn shadows.

Returns

number

Set Signature

set shadowOffsetX(value): void

Defined in: packages/core/src/context/context.ts:302

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:307

Vertical offset, in pixels, of drawn shadows.

Returns

number

Set Signature

set shadowOffsetY(value): void

Defined in: packages/core/src/context/context.ts:311

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:316

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

Returns

string

Set Signature

set stroke(value): void

Defined in: packages/core/src/context/context.ts:320

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

Parameters

Parameter	Type
value	string

Returns

void

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

Implementation of

BaseState.stroke

---

textAlign

Get Signature

get textAlign(): TextAlignment

Defined in: packages/core/src/context/context.ts:325

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:329

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:334

Vertical baseline used when positioning text.

Returns

TextBaseline

Set Signature

set textBaseline(value): void

Defined in: packages/core/src/context/context.ts:338

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:397

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:401

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:406

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:410

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:370

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:374

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:379

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:383

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:352

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:356

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:361

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:365

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:343

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:347

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:650

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:655

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:558

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

Parameters

Parameter	Type
group	Element

Returns

void

---

applyStroke()

applyStroke(path): void

Defined in: packages/core/src/context/context.ts:660

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:514

Clears the rendering surface and brackets the callback in markRenderStart/markRenderEnd, returning the callback's result.

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:481

Clears the entire rendering surface.

Returns

void

---

createPath()

createPath(id?): ContextPath

Defined in: packages/core/src/context/context.ts:635

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:640

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:703

Destroys the context and disposes all resources.

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:645

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:137

Emits an event, invoking all matching handlers and bubbling to the parent if applicable.

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:138

Emits an event, invoking all matching handlers and bubbling to the parent if applicable.

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:698

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:444

Returns

BaseState

---

has()

has(type): boolean

Defined in: packages/core/src/core/event-bus.ts:94

Returns whether there are any listeners registered for the given event type.

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:679

Tests which rendered elements intersect the given point for the given event types, returning them sorted by zIndex (highest first).

Parameters

Parameter	Type
events	string[]
x	number
y	number

Returns

RenderElement[]

---

invalidateTrackedElements()

invalidateTrackedElements(event?): void

Defined in: packages/core/src/context/context.ts:491

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:665

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

Parameters

Parameter	Type
path	ContextPath
x	number
y	number
fillRule?	FillRule

Returns

boolean

---

isPointInStroke()

isPointInStroke(path, x, y): boolean

Defined in: packages/core/src/context/context.ts:670

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

Parameters

Parameter	Type
path	ContextPath
x	number
y	number

Returns

boolean

---

layer()

layer<TResult>(body): TResult

Defined in: packages/core/src/context/context.ts:470

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:509

Signals the end of a render pass.

Returns

void

---

markRenderStart()

markRenderStart(): void

Defined in: packages/core/src/context/context.ts:500

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:630

Measures text dimensions using the context's current font or an optional override.

Parameters

Parameter	Type
text	string
font?	string

Returns

TextMetrics

---

off()

off<TEvent>(type, handler): void

Defined in: packages/core/src/core/event-bus.ts:112

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:99

Subscribes a handler to the given event type and returns a disposable for cleanup.

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:127

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:578

Closes the most recently opened group boundary, unwinding the state stack back to the depth captured at Context.pushGroup. 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:538

Opens a group boundary: saves the current drawing state and applies the group's own transform, inherited paint, and opacity, 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

---

rescale()

protected rescale(width, height): void

Defined in: packages/core/src/context/context.ts:434

Parameters

Parameter	Type
width	number
height	number

Returns

void

---

reset()

reset(): void

Defined in: packages/core/src/context/context.ts:486

Resets the context to its initial state.

Returns

void

---

restore()

restore(): void

Defined in: packages/core/src/context/context.ts:460

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:587

Applies a rotation transformation.

Parameters

Parameter	Type
angle	number

Returns

void

---

save()

save(): void

Defined in: packages/core/src/context/context.ts:453

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:592

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:611

Replaces the current transformation matrix with [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

---

transform()

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

Defined in: packages/core/src/context/context.ts:625

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:597

Applies a translation transformation.

Parameters

Parameter	Type
x	number
y	number

Returns

void