Documentation / @ripl/canvas / CanvasContext

Class: CanvasContext

Defined in: canvas/src/context.ts:25

Canvas 2D rendering context implementation, mapping the unified API to CanvasRenderingContext2D.

Extends

• Canvas2DState & CanvasDOMBase<this>

Constructors

Constructor

new CanvasContext(target, options?): CanvasContext

Defined in: canvas/src/context.ts:34

Parameters

Parameter	Type
target	string | HTMLElement
options?	ContextOptions<Record<string, unknown>>

Returns

CanvasContext

Overrides

canvas2DStateMixin(CanvasDOMBase).constructor

Properties

Property	Modifier	Type	Default value	Description	Inherited from	Defined in
context	protected	CanvasRenderingContext2D	undefined	-	-	canvas/src/context.ts:27
currentState	protected	BaseState	undefined	-	canvas2DStateMixin(CanvasDOMBase).currentState	core/src/context/context.ts:104
direction	public	Direction	undefined	The current text direction.	Canvas2DState.direction	canvas/src/mixins.ts:55
element	readonly	HTMLCanvasElement	undefined	The underlying DOM element the context renders into.	canvas2DStateMixin(CanvasDOMBase).element	core/src/context/context.ts:111
fill	public	string	undefined	The current fill style: a color or CSS gradient string. Assigning an empty value is ignored, because native canvas rejects it and the paint already in force stays in use.	Canvas2DState.fill	canvas/src/mixins.ts:51
filter	public	string	undefined	The current filter applied to drawing operations.	Canvas2DState.filter	canvas/src/mixins.ts:53
font	public	string	undefined	The current font used for text rendering.	Canvas2DState.font	canvas/src/mixins.ts:57
fontKerning	public	FontKerning	undefined	The current font kerning mode.	Canvas2DState.fontKerning	canvas/src/mixins.ts:59
globalCompositeOperation	public	unknown	undefined	The current compositing operation used when drawing.	Canvas2DState.globalCompositeOperation	canvas/src/mixins.ts:63
height	public	number	undefined	Current height of the rendering surface, in logical pixels — CSS pixels, unaffected by the device pixel ratio.	canvas2DStateMixin(CanvasDOMBase).height	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.	canvas2DStateMixin(CanvasDOMBase).hitTestHonorsTransform	core/src/context/context.ts:120
lineCap	public	LineCap	undefined	The current line cap style for stroke endpoints.	Canvas2DState.lineCap	canvas/src/mixins.ts:65
lineDash	public	number[]	undefined	The current line dash pattern.	Canvas2DState.lineDash	canvas/src/mixins.ts:67
lineDashOffset	public	number	undefined	The current offset into the line dash pattern.	Canvas2DState.lineDashOffset	canvas/src/mixins.ts:69
lineJoin	public	LineJoin	undefined	The current line join style for stroke corners.	Canvas2DState.lineJoin	canvas/src/mixins.ts:71
lineWidth	public	number	undefined	The current stroke width, in pixels.	Canvas2DState.lineWidth	canvas/src/mixins.ts:73
meta	readonly	TMeta	undefined	Arbitrary metadata attached to the context.	canvas2DStateMixin(CanvasDOMBase).meta	core/src/context/context.ts:113
miterLimit	public	number	undefined	The current miter limit for stroke joins.	Canvas2DState.miterLimit	canvas/src/mixins.ts:75
opacity	public	number	undefined	The current global opacity applied to drawing operations.	Canvas2DState.opacity	canvas/src/mixins.ts:61
parent?	public	EventBus<ContextEventMap>	undefined	The parent event bus that emitted events bubble up to, if any.	canvas2DStateMixin(CanvasDOMBase).parent	core/src/core/event-bus.ts:107
renderDepth	protected	number	0	-	canvas2DStateMixin(CanvasDOMBase).renderDepth	core/src/context/context.ts:105
renderedElements	public	RenderElement[]	undefined	Elements rendered during the current pass, used for hit testing.	canvas2DStateMixin(CanvasDOMBase).renderedElements	core/src/context/context.ts:132
renderElement?	public	RenderElement	undefined	The element currently being rendered, if any.	canvas2DStateMixin(CanvasDOMBase).renderElement	core/src/context/context.ts:130
root	readonly	HTMLElement	undefined	The host DOM element that the context's rendering surface is mounted into.	canvas2DStateMixin(CanvasDOMBase).root	dom/src/context.ts:48
saveDepth	protected	number	0	-	canvas2DStateMixin(CanvasDOMBase).saveDepth	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.	canvas2DStateMixin(CanvasDOMBase).scaleX	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.	canvas2DStateMixin(CanvasDOMBase).scaleY	core/src/context/context.ts:128
shadowBlur	public	number	undefined	The current shadow blur radius.	Canvas2DState.shadowBlur	canvas/src/mixins.ts:77
shadowColor	public	string	undefined	The current shadow color.	Canvas2DState.shadowColor	canvas/src/mixins.ts:79
shadowOffsetX	public	number	undefined	The current horizontal shadow offset.	Canvas2DState.shadowOffsetX	canvas/src/mixins.ts:81
shadowOffsetY	public	number	undefined	The current vertical shadow offset.	Canvas2DState.shadowOffsetY	canvas/src/mixins.ts:83
states	protected	BaseState[]	undefined	-	canvas2DStateMixin(CanvasDOMBase).states	core/src/context/context.ts:103
stroke	public	string	undefined	The current stroke style: a color or CSS gradient string. Assigning an empty value is ignored, because native canvas rejects it and the paint already in force stays in use.	Canvas2DState.stroke	canvas/src/mixins.ts:85
textAlign	public	TextAlignment	undefined	The current horizontal text alignment.	Canvas2DState.textAlign	canvas/src/mixins.ts:87
textBaseline	public	TextBaseline	undefined	The current vertical text baseline.	Canvas2DState.textBaseline	canvas/src/mixins.ts:89
type	readonly	string	undefined	The context type identifier (e.g. canvas, svg).	canvas2DStateMixin(CanvasDOMBase).type	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.	canvas2DStateMixin(CanvasDOMBase).width	core/src/context/context.ts:122
defaultKey	readonly	typeof defaultKey	undefined	The key under which resources are retained when no explicit key is provided.	canvas2DStateMixin(CanvasDOMBase).defaultKey	core/src/core/disposer.ts:11

Accessors

$events

Get Signature

get $events(): keyof ContextEventMap[]

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

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

Returns

keyof ContextEventMap[]

Inherited from

canvas2DStateMixin(CanvasDOMBase).$events

---

currentRenderElement

Get Signature

get currentRenderElement(): RenderElement | undefined

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

Parameters

Parameter	Type
element	RenderElement | undefined

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).currentRenderElement

---

rotation

Get Signature

get rotation(): Rotation

Defined in: 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: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).rotation

---

supportsPathCaching

Get Signature

get supportsPathCaching(): boolean

Defined in: canvas/src/context.ts:30

Canvas path creation is a side-effect-free new CanvasPath(), so cached paths may be reused across render cycles.

Returns

boolean

Overrides

canvas2DStateMixin(CanvasDOMBase).supportsPathCaching

---

transformOriginX

Get Signature

get transformOriginX(): TransformOrigin

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

Horizontal origin about which rotation and scaling are applied.

Parameters

Parameter	Type
value	TransformOrigin

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).transformOriginX

---

transformOriginY

Get Signature

get transformOriginY(): TransformOrigin

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

Vertical origin about which rotation and scaling are applied.

Parameters

Parameter	Type
value	TransformOrigin

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).transformOriginY

---

transformScaleX

Get Signature

get transformScaleX(): number

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

Horizontal scale factor applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).transformScaleX

---

transformScaleY

Get Signature

get transformScaleY(): number

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

Vertical scale factor applied to the element's transform.

Parameters

Parameter	Type
value	number

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).transformScaleY

---

translateX

Get Signature

get translateX(): number

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

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

Parameters

Parameter	Type
value	number

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).translateX

---

translateY

Get Signature

get translateY(): number

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

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

Parameters

Parameter	Type
value	number

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).translateY

---

zIndex

Get Signature

get zIndex(): number

Defined in: 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: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).zIndex

Methods

applyClip()

Call Signature

applyClip(path, fillRule?): void

Defined in: canvas/src/mixins.ts:129

Clips subsequent drawing operations to the given path.

Parameters

Parameter	Type
path	CanvasPath
fillRule?	FillRule

Returns

void

Inherited from

Canvas2DState.applyClip

Call Signature

applyClip(path, fillRule?): void

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

Clips subsequent drawing operations to the given path.

Parameters

Parameter	Type
path	ContextPath
fillRule?	FillRule

Returns

void

Inherited from

Canvas2DState.applyClip

---

applyFill()

Call Signature

applyFill(element, fillRule?): void

Defined in: canvas/src/mixins.ts:133

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

Parameters

Parameter	Type
element	ContextText | CanvasPath
fillRule?	FillRule

Returns

void

Inherited from

Canvas2DState.applyFill

Call Signature

applyFill(path, fillRule?): void

Defined in: 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

Inherited from

Canvas2DState.applyFill

---

applyGroupPaint()

protected applyGroupPaint(group): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).applyGroupPaint

---

applyStroke()

Call Signature

applyStroke(element): void

Defined in: canvas/src/mixins.ts:135

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

Parameters

Parameter	Type
element	ContextText | CanvasPath

Returns

void

Inherited from

Canvas2DState.applyStroke

Call Signature

applyStroke(path): void

Defined in: 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

Inherited from

Canvas2DState.applyStroke

---

batch()

batch<TResult>(body): TResult

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).batch

---

clear()

clear(): void

Defined in: canvas/src/mixins.ts:95

Clears the entire canvas surface.

Returns

void

Inherited from

Canvas2DState.clear

---

createPath()

Call Signature

createPath(id?): CanvasPath

Defined in: canvas/src/mixins.ts:127

Creates a new CanvasPath, optionally reusing an id for diffing efficiency.

Parameters

Parameter	Type
id?	string

Returns

CanvasPath

Inherited from

Canvas2DState.createPath

Call Signature

createPath(id?): ContextPath

Defined in: 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

Inherited from

Canvas2DState.createPath

---

createText()

createText(options): ContextText

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

Creates a new text element from the given options.

Parameters

Parameter	Type
options	TextOptions

Returns

ContextText

Inherited from

canvas2DStateMixin(CanvasDOMBase).createText

---

destroy()

destroy(): void

Defined in: canvas/src/context.ts:78

Destroys the context, releasing its cached paint and the canvas backing store on top of the base teardown.

Returns

void

Overrides

canvas2DStateMixin(CanvasDOMBase).destroy

---

disableInteraction()

disableInteraction(): void

Defined in: dom/src/context.ts:388

Disables DOM interaction events, unwinding any hover with a final mouseleave per element.

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).disableInteraction

---

dispose()

protected dispose(key?): void

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).dispose

---

drawImage()

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

Defined in: canvas/src/mixins.ts:131

Draws an image onto the canvas at the given position, sized to the given width and height; a dimension given on its own is taken with the image's intrinsic size for the other.

Parameters

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

Returns

void

Inherited from

Canvas2DState.drawImage

---

emit()

Call Signature

emit<TEvent>(event): TEvent

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).emit

Call Signature

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

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).emit

---

enableInteraction()

enableInteraction(): void

Defined in: dom/src/context.ts:344

Enables DOM interaction events (mouse enter, leave, move, down, up, click, drag) with element hit testing.

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).enableInteraction

---

export()

export(): ContextExport

Defined in: canvas/src/context.ts:73

Captures a snapshot of the canvas and returns format-specific exporters (see ContextExport).

Returns

ContextExport

Overrides

canvas2DStateMixin(CanvasDOMBase).export

---

getDefaultState()

protected getDefaultState(): BaseState

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

Returns

BaseState

Inherited from

canvas2DStateMixin(CanvasDOMBase).getDefaultState

---

has()

has(type): boolean

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).has

---

hitTest()

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

Defined in: 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[]

Inherited from

canvas2DStateMixin(CanvasDOMBase).hitTest

---

init()

protected init(): void

Defined in: dom/src/context.ts:85

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).init

---

invalidateTrackedElements()

invalidateTrackedElements(event?): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).invalidateTrackedElements

---

isPointInPath()

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

Defined in: canvas/src/mixins.ts:137

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

Parameters

Parameter	Type
path	ContextPath
x	number
y	number
fillRule?	FillRule

Returns

boolean

Inherited from

Canvas2DState.isPointInPath

---

isPointInStroke()

isPointInStroke(path, x, y): boolean

Defined in: canvas/src/mixins.ts:139

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

Parameters

Parameter	Type
path	ContextPath
x	number
y	number

Returns

boolean

Inherited from

Canvas2DState.isPointInStroke

---

layer()

layer<TResult>(body): TResult

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).layer

---

markRenderEnd()

markRenderEnd(): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).markRenderEnd

---

markRenderStart()

markRenderStart(): void

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

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

Returns

void

Inherited from

canvas2DStateMixin(CanvasDOMBase).markRenderStart

---

measureText()

measureText(text, font?): TextMetrics

Defined in: canvas/src/mixins.ts:125

Measures text dimensions using the canvas context's current font, text alignment, and baseline, or an optional font override.

Parameters

Parameter	Type
text	string
font?	string

Returns

TextMetrics

Inherited from

Canvas2DState.measureText

---

off()

off<TEvent>(type, handler): void

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).off

---

on()

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

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).on

---

once()

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

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).once

---

popGroup()

popGroup(): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).popGroup

---

pushGroup()

pushGroup(group): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).pushGroup

---

requestRender()

requestRender(): void

Defined in: 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

Inherited from

canvas2DStateMixin(CanvasDOMBase).requestRender

---

rescale()

protected rescale(width, height): void

Defined in: canvas/src/context.ts:53

Parameters

Parameter	Type
width	number
height	number

Returns

void

Overrides

canvas2DStateMixin(CanvasDOMBase).rescale

---

reset()

reset(): void

Defined in: canvas/src/mixins.ts:97

Resets the context to its default state, dropping the saved-state stack and re-installing the device-pixel-ratio transform the surface is drawn through.

Returns

void

Inherited from

Canvas2DState.reset

---

restore()

restore(): void

Defined in: canvas/src/mixins.ts:93

Restores the most recently saved drawing state from the stack; a no-op when the stack is empty.

Returns

void

Inherited from

Canvas2DState.restore

---

retain()

protected retain(value, key?): void

Defined in: 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

canvas2DStateMixin(CanvasDOMBase).retain

---

rotate()

rotate(angle): void

Defined in: canvas/src/mixins.ts:99

Applies a rotation transformation, in radians.

Parameters

Parameter	Type
angle	number

Returns

void

Inherited from

Canvas2DState.rotate

---

save()

save(): void

Defined in: canvas/src/mixins.ts:91

Saves the current drawing state, including the resolved Canvas2DState.fill and Canvas2DState.stroke strings, onto the state stack.

Returns

void

Inherited from

Canvas2DState.save

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scale()

scale(x, y): void

Defined in: canvas/src/mixins.ts:101

Applies a scale transformation.

Parameters

Parameter	Type
x	number
y	number

Returns

void

Inherited from

Canvas2DState.scale

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setTransform()

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

Defined in: canvas/src/mixins.ts:113

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

Inherited from

Canvas2DState.setTransform

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toLogicalPoint()

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

Defined in: 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.

Inherited from

canvas2DStateMixin(CanvasDOMBase).toLogicalPoint

---

toSurfacePoint()

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

Defined in: 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.

Inherited from

canvas2DStateMixin(CanvasDOMBase).toSurfacePoint

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transform()

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

Defined in: canvas/src/mixins.ts:123

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

Inherited from

Canvas2DState.transform

---

translate()

translate(x, y): void

Defined in: canvas/src/mixins.ts:103

Applies a translation transformation.

Parameters

Parameter	Type
x	number
y	number

Returns

void

Inherited from

Canvas2DState.translate