Lazy

Import these from @grafloria/renderer.

Classes

HtmlHostCuller

The per-frame cull decision for HTML-layer node hosts.

Stateless with respect to the hosts themselves: admits() is told whether the host is currently attached rather than remembering it. That is on purpose — a culler holding its own attached-set is a second copy of a fact the DOM already owns, and the two desync the first time a node is removed from the model mid-gesture. The DOM is the record; this is only the policy.

culler.beginFrame(viewport.getViewBox(), viewport.getZoom(), heldByGesture); for (const node of customNodes) { if (culler.admits(node.id, bounds(node), host?.isConnected ?? false)) … }

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class HtmlHostCuller

Methods

• constructor(options: HostCullOptions = {}, freeze: FreezeQuery | null = null)
• getMode(): HostCullMode
• beginFrame(visible: Rectangle, zoom: number, exempt: ReadonlySet<string>): void — Fix this frame's two rects and the set of nodes a live gesture owns.
• admits(id: string, bounds: Rectangle, attached: boolean): boolean — Should this node's host be in the document on this frame?

ProgressiveMounter

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class ProgressiveMounter

Methods

• constructor( engine: DiagramEngine, lifecycle: ViewLifecycle, frame: MountFrame, deferred: DeferredQuery )
• isRunning(): boolean
• mount(viewport: Rectangle, zoom: number, options: ProgressiveMountOptions = {}): Promise<MountStats> — Bring the scene up in rAF-yielded slices. Resolves when everything culling admits has a view (or when the mount is cancelled).
• cancel(): void — Stop mounting. Whatever is not yet mounted is mounted by the next normal render — the gate is handed back here, so a cancelled mount can never strand half a diagram on screen.
• dispose(): void

ViewLifecycle

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class ViewLifecycle implements MountGate

Methods

• constructor(options: ViewLifecycleOptions = {})
• freeze(kind: EntityKind, id: string): void — Give up this entity's view. It keeps its model and its spatial-index entry; it stops being drawn and stops costing anything per frame.
• unfreeze(kind: EntityKind, id: string): void — Give it a view again. It is rebuilt on the next frame that can see it.
• isFrozen(kind: EntityKind, id: string): boolean
• isExplicitlyFrozen(kind: EntityKind, id: string): boolean — Explicitly frozen only — NOT the ones autoFreeze is holding off-screen.
• unfreezeAll(): void
• setAutoFreeze(on: boolean): void
• isAutoFreeze(): boolean
• retainedCount(): number — The views currently retained — i.e. what the renderer is paying for.
• frozenCount(): number
• retainVisible(visible: ReadonlyArray<readonly [EntityKind, string]>): void — Called by the renderer each frame with what culling admitted, BEFORE the gate is applied. Anything that was on screen and no longer is gets its view dropped.
• beginDeferred(): void — Defer EVERYTHING. Nothing has a view until admit() says so.
• admit(kind: EntityKind, id: string): void — Let this entity's view be built from now on.
• admitAll(kind: EntityKind): void — Admit a whole KIND without naming its members. Slice 0 uses this for nodes: a node's view is cheap (no routing), and enumerating 10k ids to admit them one at a time would cost more than building the ~56 views culling actually keeps.
• endDeferred(): void — The mount is over (finished, cancelled, or pre-empted). Gate opens fully.
• admits(kind: EntityKind, id: string): boolean — May the renderer build (or refresh) this entity's view on this frame?
• isDeferring(): boolean — True while a progressive mount is running — the renderer's cue that the scene is being brought up in slices and is not yet whole.
• setChangeHook(hook: (() => void) | null): void — Tell the renderer that what it would draw has changed, even though the model has not. Set by SVGRenderer.setViewLifecycle; see changeHook.

Interfaces

FreezeQuery

The sliver of ViewLifecycle that host culling honours.

isExplicitlyFrozen, NOT admits, and the distinction is load-bearing. admits is also false for anything autoFreeze is holding off-screen, and autoFreeze decides that against the bare viewport with no margin — routing custom hosts through it would silently override the hysteresis band with a zero-width one. isExplicitlyFrozen is the signal that a HOST deliberately said "this node has no view", which is a decision custom nodes should obey.

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interface FreezeQuery

Members

• isExplicitlyFrozen(kind: EntityKind, id: string): boolean

HostCullOptions

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interface HostCullOptions

Properties

MountGate

The gate the renderer consults before instantiating an entity's VIEW.

A gate can only ever SUBTRACT from what culling already admitted — it never adds an off-screen entity back in. That asymmetry is deliberate: a gate bug can make something arrive late, never wrong.

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interface MountGate

Members

• admits(kind: EntityKind, id: string): boolean — May the renderer build (or refresh) this entity's view on this frame?
• isDeferring?(): boolean — True while a progressive mount is running — the renderer's cue that the scene is being brought up in slices and is not yet whole.

MountStats

What one mount() actually did — the numbers the claim lives on.

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interface MountStats

Properties

ProgressiveMountOptions

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interface ProgressiveMountOptions

Properties

ViewLifecycleOptions

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interface ViewLifecycleOptions

Properties

Types

DeferredQuery

What the renderer deferred on the last frame — culling admitted it, the gate did not.

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type DeferredQuery = () => ReadonlyArray<readonly [EntityKind, string]>;

EntityKind

Also has every member of String, listed on its own entry.

The two things that have views.

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type EntityKind = 'node' | 'link';

HostCullMode

Also has every member of String, listed on its own entry.

What a cull does to the host element.

'detach' — remove the element from the document and keep the reference. Re-entry re-appends the SAME element: renderCustomNode is NOT called again, removeCustomNode is NOT called on the cull, and everything inside the widget survives byte for byte.

'destroy' — fire removeCustomNode and drop the element. Re-entry re-creates the host and re-runs renderCustomNode. Frees the widget's memory; costs a full re-init and every piece of state the widget was holding.

'detach' is the default, and the reasoning is that the cost this feature exists to remove is a cost of being ATTACHED. Layout, style recalc, paint, compositing and hit testing are all charged per element IN THE DOCUMENT; a detached subtree is inert heap. Detaching therefore captures essentially the whole win while keeping the mount-once guarantee that makes custom nodes usable at all. Measured on a 300-widget board with ~16 tiles on screen: 2720 DOM nodes under the canvas fall to 164, a 94% reduction, and a pan away and back re-runs the painter exactly zero times.

What 'detach' does NOT bound is the RETAINED set. A host mounted once is kept for the life of the instance, so panning a 10,000-widget board end to end eventually holds 10,000 detached elements — the same "cache versus leak" distinction ViewLifecycle's header draws about autoFreeze, and the honest reason 'destroy' exists. (Same board, after a sweep across and back: 20 attached, 78 retained off-screen.) Choose 'destroy' when the widgets are individually huge — a WebGL scene, a 50k-row grid — and heap rather than frame time is the binding constraint. It is opt-in inside an opt-in, because a host that asks for it is accepting that its painter re-runs and its widget state is lost.

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type HostCullMode = 'detach' | 'destroy';

MountFrame

Produce and PRESENT one frame. Deliberately not "the SVG renderer": the SVG patcher, the canvas backend and the tier-switching backend all satisfy this, so a progressive mount works on any of them.

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type MountFrame = (viewport: Rectangle, zoom: number) => void;