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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 | 1x 1x 1x 7x 7x 1x 6x 3x 3x 2x 1x 2x 2x 1x 1x 3x 6x 6x 6x 2x 4x 2x 2x | const chroma = require('chroma-js')
const { CodedError } = require('../helpers/errors')
module.exports = { createColorRamp }
function createColorRamp (params = {}) {
const {
classification,
colorRamps,
type = 'algorithmic',
fromColor = [0, 255, 0],
toColor = [0, 0, 255],
algorithm = 'HSVAlgorithm'
} = params
if (!classification || classification.length === 0) {
throw new Error('Must supply classification')
}
if (type === 'algorithmic') {
return createAlgorithmicRamp({
fromColor,
toColor,
algorithm,
classificationCount: classification.length
})
}
if (type === 'multipart') {
return createMultipartRamp({ colorRamps, classificationCount: classification.length })
}
throw new CodedError(`Invalid color ramp type: ${type}`, 400)
}
function createMultipartRamp (options) {
const { colorRamps, classificationCount } = options
if (!colorRamps || !Array.isArray(colorRamps)) {
throw new CodedError(
'Multipart color-ramps need a valid color-ramp configuration array'
)
}
return colorRamps.map((ramp) => {
return createAlgorithmicRamp({
...ramp,
classificationCount
})
})
}
function createAlgorithmicRamp (options) {
const { fromColor, toColor, algorithm, classificationCount } = options
const colorRamp = chroma.scale([fromColor.slice(0, 3), toColor.slice(0, 3)])
if (algorithm === 'esriCIELabAlgorithm') {
return colorRamp.mode('lab').colors(classificationCount, 'rgb')
}
if (algorithm === 'esriLabLChAlgorithm') {
return colorRamp.mode('lch').colors(classificationCount, 'rgb')
}
return colorRamp.mode('hsl').colors(classificationCount, 'rgb')
}
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