@urban-toolkit/autk-core

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@urban-toolkit/autk-core / ColorMap

Class: ColorMap

Defined in: colormap.ts:74

Color utility for resolving domains, sampling color scales, and building legend and texture representations.

ColorMap decides whether a scheme should be treated as categorical, sequential, or diverging; derives a compatible domain from data and configuration; and exposes helpers for sampling colors or generating flat RGBA textures for GPU upload.

Constructors

Constructor

new ColorMap(): ColorMap

Returns

ColorMap

Methods

computeLabels()

static computeLabels(domain): string[]

Defined in: colormap.ts:349

Derives human-readable legend labels from a domain.

Categorical domains are returned as-is. Numeric domains are formatted with a magnitude-aware d3 formatter so legend labels remain compact for large values and readable for small decimals.

Parameters

domain

ResolvedDomain

Any supported color-scale domain.

Returns

string[]

Ordered label strings suitable for a legend.

Throws

Never throws.

Example

ColorMap.computeLabels([0, 500000, 1000000]); // ['0', '500,000', '1M']
ColorMap.computeLabels(['low', 'mid', 'high']); // ['low', 'mid', 'high']

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computeMinMaxRange()

static computeMinMaxRange(values): [number, number]

Defined in: colormap.ts:194

Computes the numeric minimum and maximum of a value array.

Parameters

values

number[] | TypedArray

Numeric values to inspect.

Returns

[number, number]

Two-element tuple [min, max], or [0, 0] when the input is empty.

Throws

Never throws. Empty input returns [0, 0].

Example

ColorMap.computeMinMaxRange([3, 7, 2, 9, 4]); // [2, 9]

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getCategoricalSchemeSize()

static getCategoricalSchemeSize(interpolator): number | null

Defined in: colormap.ts:241

Returns the number of colors in a categorical color scheme.

Parameters

interpolator

ColorMapInterpolator

Interpolator identifier to inspect.

Returns

number | null

Scheme size for categorical interpolators, or null otherwise.

Throws

Never throws.

Example

ColorMap.getCategoricalSchemeSize(ColorMapInterpolator.CAT_SET1);  // 9
ColorMap.getCategoricalSchemeSize(ColorMapInterpolator.SEQ_VIRIDIS);  // null

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getColor()

static getColor(value, color, domain?): ColorRGB

Defined in: colormap.ts:87

Samples a color interpolator at a normalized value, returning RGBA.

Parameters

value

number

Normalized sample position in [0, 1].

color

ColorMapInterpolator

Interpolator identifier to sample.

domain?

SequentialDomain | DivergingDomain | CategoricalDomain

Optional explicit domain used to parameterize the scale.

Returns

ColorRGB

Sampled color in RGBA object form.

Throws

Never throws.

Example

const c = ColorMap.getColor(0.5, ColorMapInterpolator.SEQ_VIRIDIS);
// c → { r: 33, g: 144, b: 141, alpha: 1 }

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getColorArray()

static getColorArray(color, res?, domain?): ColorRGB[]

Defined in: colormap.ts:137

Builds an array of sampled RGBA color objects from a color scheme.

Parameters

color

ColorMapInterpolator

Interpolator identifier to sample.

res?

number = DEFAULT_COLORMAP_RESOLUTION

Number of samples to generate (default 256).

domain?

SequentialDomain | DivergingDomain | CategoricalDomain

Optional explicit domain used to parameterize the scale.

Returns

ColorRGB[]

Array of sampled RGBA color objects.

Throws

Never throws. Non-positive res returns an empty array.

Example

const colors = ColorMap.getColorArray(ColorMapInterpolator.CAT_SET1, 3);
// colors → [{ r: 228, g: 26, b: 28, alpha: 1 }, ...]

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getColorMap()

static getColorMap(color, res?, domain?): ColorTEX

Defined in: colormap.ts:105

Builds a flat RGBA texture array for GPU upload from a color scheme.

Parameters

color

ColorMapInterpolator

Interpolator identifier to sample.

res?

number = DEFAULT_COLORMAP_RESOLUTION

Number of texels to generate (default 256).

domain?

SequentialDomain | DivergingDomain | CategoricalDomain

Optional explicit domain used to parameterize the scale.

Returns

ColorTEX

Flat RGBA texture values [r, g, b, a, ...].

Throws

Never throws. Non-positive res returns an empty array.

Example

const tex = ColorMap.getColorMap(ColorMapInterpolator.SEQ_VIRIDIS, 4);
// tex → [68, 1, 84, 1, 59, 82, 139, 1, 33, 144, 141, 1, 253, 231, 37, 1]

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hexToRgb()

static hexToRgb(color): ColorRGB

Defined in: colormap.ts:180

Converts a hex color string into an RGBA color object.

Parameters

color

`#${string}`

Hexadecimal color string to convert.

Returns

ColorRGB

RGBA color object with alpha fixed to 1.

Throws

Never throws.

Example

ColorMap.hexToRgb('#ff8000'); // { r: 255, g: 128, b: 0, alpha: 1 }

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isCategorical()

static isCategorical(interpolator): boolean

Defined in: colormap.ts:216

Returns true when an interpolator uses a discrete categorical scheme.

Parameters

interpolator

ColorMapInterpolator

Interpolator identifier to classify.

Returns

boolean

true for categorical schemes, otherwise false.

Throws

Never throws.

Example

ColorMap.isCategorical(ColorMapInterpolator.CAT_SET1);  // true
ColorMap.isCategorical(ColorMapInterpolator.SEQ_VIRIDIS);  // false

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resolveDomainFromData()

static resolveDomainFromData(values, config): ResolvedDomain

Defined in: colormap.ts:386

Resolves a color domain from data and configuration.

The method infers categorical handling when the selected interpolator is categorical, when a USER domain contains string values, or when the input array contains non-numeric strings. Numeric-looking strings in normal arrays are still treated as numeric values. Unsupported domain shapes are not coerced beyond this inference.

Parameters

values

string[] | number[] | TypedArray

Source values used to derive the domain.

config

ColorMapConfig

Color-map configuration controlling the resolution mode.

Returns

ResolvedDomain

Resolved categorical or numeric domain.

Throws

When USER domain has invalid shape for the selected interpolator (e.g. non-numeric values for a sequential interpolator).

Example

const domain = ColorMap.resolveDomainFromData(
  [10, 50, 30, 80, 20],
  { interpolator: ColorMapInterpolator.SEQ_VIRIDIS, domainSpec: { type: ColorMapDomainStrategy.MIN_MAX } }
);
// domain → [10, 80]

---

rgbToHex()

static rgbToHex(color): `#${string}`

Defined in: colormap.ts:166

Converts an RGBA color object into a hex color string.

Parameters

color

ColorRGB

RGB color to convert.

Returns

`#${string}`

Hexadecimal color string.

Throws

Never throws.

Example

ColorMap.rgbToHex({ r: 255, g: 128, b: 0, alpha: 1 }); // '#ff8000'