Class: ColorMap

Defined in: src/display/ColorMap.ts:159

ColorMap is responsible for mapping numerical data to colors (RGB or RGBA). It supports:

• Setting a [min, max] range that is scaled into the color ramp.
• Thresholding a [low, high] band for full transparency.
• Optional alpha array or global alpha for transparency control.

Constructors

Constructor

new ColorMap(colors, options?): ColorMap;

Defined in: src/display/ColorMap.ts:173

Constructs a ColorMap with given colors and optional configuration.

Parameters

colors

Color[]

An array of color entries. Each color is [R, G, B] or [R, G, B, A] in [0..1].

options?

ColorMapOptions = {}

Additional settings for range, threshold, alpha, etc.

Returns

ColorMap

Properties

name

name: string;

Defined in: src/display/ColorMap.ts:165

---

isCustom

isCustom: boolean;

Defined in: src/display/ColorMap.ts:166

---

GRAY_SCALE

readonly static GRAY_SCALE: ColorMap;

Defined in: src/display/ColorMap.ts:205

A built-in static ColorMap instance from black to white. This is commonly used as a baseline or fallback map.

Accessors

hasAlpha

Get Signature

get hasAlpha(): boolean;

Defined in: src/display/ColorMap.ts:606

Indicates whether this color map has an alpha channel (based on the first color or forced by setAlpha()).

Returns

boolean

---

presetMaps

Get Signature

get static presetMaps(): object;

Defined in: src/display/ColorMap.ts:643

Lazy getter for preset colormaps, returning a dictionary from preset name to array of hex color strings. We also add "Grayscale" as a known preset.

Returns

object

Methods

on()

on<K>(type, handler): void;

Defined in: src/display/ColorMap.ts:215

Subscribe to color map events such as "rangeChanged," "thresholdChanged," or "alphaChanged."

Type Parameters

K

K extends keyof ColorMapEvents

Parameters

type

K

The event name, e.g. 'rangeChanged'.

handler

(args) => void

Function to call when the event fires.

Returns

void

---

off()

off<K>(type, handler): void;

Defined in: src/display/ColorMap.ts:224

Unsubscribe from color map events.

Type Parameters

K

K extends keyof ColorMapEvents

Parameters

type

K

The event name.

handler

(args) => void

The specific function to remove.

Returns

void

---

getColorMap()

getColorMap(): Color[];

Defined in: src/display/ColorMap.ts:232

Returns the raw internal array of color stops used for mapping. Useful if you want to examine or iterate over the color map in detail.

Returns

Color[]

---

toStops()

toStops(n?): object[];

Defined in: src/display/ColorMap.ts:237

Sample the current lookup table across its data range for a legend.

Parameters

n?

number = 9

Returns

object[]

---

toCSSGradient()

toCSSGradient(direction?): string;

Defined in: src/display/ColorMap.ts:249

CSS gradient built from every LUT entry, including the transparent threshold band.

Parameters

direction?

string = '90deg'

Returns

string

---

setRange()

setRange(range?): void;

Defined in: src/display/ColorMap.ts:291

Sets the data range [min, max] for color mapping. Data below min maps to the first color, data above max maps to the last color.

Parameters

range?

[number, number]

The [min, max] values; if invalid, defaults to [0, 1].

Returns

void

---

setThreshold()

setThreshold(threshold?): void;

Defined in: src/display/ColorMap.ts:309

Sets the threshold values [low, high]. Data strictly between low and high is fully transparent, outside that region is fully visible. If low >= high, thresholding is disabled.

Parameters

threshold?

[number, number]

The new threshold values; default [0, 0] (no threshold).

Returns

void

---

getRange()

getRange(): [number, number];

Defined in: src/display/ColorMap.ts:326

Gets the current range

Returns

[number, number]

---

getThreshold()

getThreshold(): [number, number];

Defined in: src/display/ColorMap.ts:333

Gets the current threshold

Returns

[number, number]

---

setAlpha()

setAlpha(alpha?): void;

Defined in: src/display/ColorMap.ts:378

Sets a global alpha or per-color alpha array. Rebuilds the internal color array to ensure alpha is included if any is provided.

Parameters

alpha?

number | number[]

Either a single alpha in [0..1] or an array of length = number of colors, or undefined to preserve the current alpha.

Returns

void

---

getColor()

getColor(value): Color;

Defined in: src/display/ColorMap.ts:416

Maps a single numeric data value to a color, applying range scaling and threshold-based transparency if present.

Parameters

value

number

The numeric value to map.

Returns

Color

An [R, G, B] or [R, G, B, A] color (in [0..1]).

---

fillImageData()

fillImageData(imageData, values): ImageData;

Defined in: src/display/ColorMap.ts:470

Fills a provided ImageData object with RGBA values derived from this color map.

Parameters

imageData

ImageData

An ImageData object to fill.

values

number[] | NumericTypedArray

A numerical array or TypedArray of the same length as the number of pixels in imageData.

Returns

ImageData

The modified ImageData (same object).

---

getColorArray()

getColorArray(values): Float32Array;

Defined in: src/display/ColorMap.ts:529

Maps a numeric array to a Float32Array of color components (RGB or RGBA). This is often used for GPU-based rendering or custom shader pipelines.

Parameters

values

number[] | NumericTypedArray

An array or numeric TypedArray (any voxel datatype) of scalar values.

Returns

Float32Array

A Float32Array of length = values.length * (3 or 4).

---

getColors()

getColors(values): Color[];

Defined in: src/display/ColorMap.ts:595

Returns an array of color entries for each data value in the input array, i.e., calling getColor() on each value in sequence.

Parameters

values

number[]

A numeric array to map.

Returns

Color[]

An array of Colors in [0..1].

---

length()

length(): number;

Defined in: src/display/ColorMap.ts:613

Returns the number of color stops in this color map.

Returns

number

---

copy()

copy(newColors, newName?): ColorMap;

Defined in: src/display/ColorMap.ts:623

Creates a new ColorMap as a copy of the current one but with a changed color array or name. Range, threshold, etc. are duplicated from the original.

Parameters

newColors

Color[]

The array of new color stops.

newName?

string

Optional new name. Defaults to something like "<oldName> (Copy)".

Returns

ColorMap

---

generatePreset()

static generatePreset(name): string[];

Defined in: src/display/ColorMap.ts:684

Generates a 256-color scale from the named ColorBrewer scale if available, else defaults to a black-white scale.

Parameters

name

string

The scale name, e.g., "Viridis" or "RdYlBu".

Returns

string[]

---

getAvailableMaps()

static getAvailableMaps(): string[];

Defined in: src/display/ColorMap.ts:699

Retrieves a list of all known preset map names. This includes both official ColorBrewer sets and the "Grayscale" fallback.

Returns

string[]

---

fromPreset()

static fromPreset(name, options?): ColorMap;

Defined in: src/display/ColorMap.ts:710

Returns a new ColorMap using a named preset. If "existingColorMap" is provided and name is "Custom", a copy is created from the existing color map's colors.

Parameters

name

string

The preset name (must exist in ColorMap.presetMaps).

options?

ColorMapOptions & object = {}

Additional options. If 'existingColorMap' is provided with name="Custom", a direct copy is performed.

Returns

ColorMap