ImageLayer

A layer that renders a 2D slice of a chunked multi-channel image source.

Image layer streams chunks from a source such as OmeZarrImageSource according to its streaming policy, which decides which resolution levels and chunks to load for the current view. Per-channel appearance is controlled with ChannelProps and the visible slice is selected with SliceCoordinates. The layer holds sliceCoords by reference, so mutating the object it was constructed with moves through the data.

const source = await OmeZarrImageSource.fromHttp({ url });

const layer = new ImageLayer({
  source,
  sliceCoords: { t: 0, z: 0, c: [0, 1] },
  channelProps: [
    { color: Color.GREEN, contrastLimits: [0, 1024] },
    { color: Color.MAGENTA, contrastLimits: [0, 1024] },
  ],
});

viewport.addLayer(layer);

Extends Layer and inherits all public properties and methods.

Constructor

Creates an image layer for the given source and slice.

new ImageLayer(props): ImageLayer;

Parameter	Description
props: ImageLayerProps	Initialization properties.

Types

ImageLayerProps

Initialization properties for constructing an image layer.

Property	Description
source: ChunkSource	The chunked image source to stream from.
sliceCoords: SliceCoordinates	The slice to display in world units.
policy?: ImageSourcePolicy	Streaming policy. Defaults to the exploration policy.
orientation?: SliceOrientation	Slice plane orientation. Defaults to "XY".
channelProps?: ChannelProps[]	Per-channel appearance. Length must match the source.
onPickValue?: (info) => void	Called with the picked value when the layer is clicked.
opacity?: number	Layer opacity in [0, 1]. Defaults to 1.
blendMode?: BlendMode	How the layer blends. Defaults to "additive".
occludes?: boolean	Hides content behind. Defaults to true.

Properties

type overrides

Identifies the layer type as ImageLayer.

readonly type: "ImageLayer" = "ImageLayer";

Accessors

orientation SliceOrientation

The slice plane the layer displays.

get orientation(): SliceOrientation;

lastPresentationTimeCoord number | undefined

The t coordinate of the most recently presented slice.

get lastPresentationTimeCoord(): number | undefined;

sliceCoords SliceCoordinates

The slice coordinates the layer displays. This is the object passed at construction and may be mutated to move through the data.

get sliceCoords(): SliceCoordinates;

source ChunkSource

The chunked image source the layer streams from.

get source(): ChunkSource;

imageSourcePolicy Readonly<ImageSourcePolicy>

The streaming policy in effect. Assign a new policy to reschedule loading at runtime, for example when switching between exploration and playback.

get imageSourcePolicy(): Readonly<ImageSourcePolicy>;

set imageSourcePolicy(newPolicy): void;

Parameter	Description
newPolicy: ImageSourcePolicy	The policy to apply.

debugMode boolean

Whether chunk wireframes are drawn colored by level of detail.

get debugMode(): boolean;

set debugMode(debug): void;

Parameter	Description
debug: boolean	Whether to draw chunk wireframes.

channelProps ChannelProps[] | undefined

The current per-channel appearance settings.

get channelProps(): ChannelProps[] | undefined;

Methods

update() void overrides

Streams chunks for the current view and refreshes the visible slice.

update(viewport?): void;

Parameter	Description
viewport?: Viewport	The viewport being rendered.

setOrientation() void

Changes the slice orientation at runtime. Visible renderables are rebuilt for the new plane and chunks already resident in the shared cache are reused.

setOrientation(orientation): void;

Parameter	Description
orientation: SliceOrientation	The new slice plane.

onEvent() void overrides

Handles click picking for onPickValue. Called automatically for each pointer event.

onEvent(event): void;

Parameter	Description
event: EventContext	The event with clip and world coordinates attached.

getValueAtWorld() Promise<number | null>

Reads the data value at a world position from the resident chunks. Prefers the current level of detail and falls back to other resident levels.

getValueAtWorld(world): Promise<number | null>;

Parameter	Description
world: vec3	The world-space position to sample.

setChannelProps() void

Applies new per-channel appearance settings to all visible chunks and notifies channel change callbacks.

setChannelProps(channelProps): void;

Parameter	Description
channelProps: ChannelProps[]	One entry per source channel.

resetChannelProps() void

Restores the channel settings passed at construction.

resetChannelProps(): void;

addChannelChangeCallback() void

Registers a callback invoked after every channel settings change.

addChannelChangeCallback(callback): void;

Parameter	Description
callback: () => void	The callback to add.

removeChannelChangeCallback() void

Removes a previously registered channel change callback.

removeChannelChangeCallback(callback): void;

Parameter	Description
callback: () => void	The callback to remove.