export function rescale()

in packages/utilities/fast-colors/src/color-palette.ts [268:318]

• 46 lines of code
• 12 McCabe index (conditional complexity)

export function rescale(
    input: ColorRGBA64[],
    targetSize: number,
    preserveInputColors: boolean
): ColorRGBA64[] {
    if (input.length <= 1 || targetSize <= 1) {
        throw new Error("The input array and targetSize must both be greater than 1");
    }
    if (preserveInputColors && targetSize <= input.length) {
        throw new Error(
            "If preserveInputColors is true then targetSize must be greater than the length of the input array"
        );
    }

    const stops: ColorScaleStop[] = new Array(input.length);

    if (preserveInputColors) {
        for (let i: number = 0; i < input.length; i++) {
            const p: number = i / (input.length - 1);
            let bestFitValue: number = 2;
            let bestFitIndex: number = 0;
            for (let j: number = 0; j < targetSize; j++) {
                const fitValue: number = Math.abs(j / (targetSize - 1) - p);
                if (fitValue < bestFitValue) {
                    bestFitValue = fitValue;
                    bestFitIndex = j;
                }
                if (fitValue === 0) {
                    break;
                }
            }
            stops[i] = {
                color: input[i],
                position: bestFitIndex / (targetSize - 1),
            };
        }
    } else {
        for (let i: number = 0; i < stops.length; i++) {
            stops[i] = { color: input[i], position: i / (input.length - 1) };
        }
    }

    const scale: ColorScale = new ColorScale(stops);

    const retVal: ColorRGBA64[] = new Array(targetSize);
    for (let i: number = 0; i < targetSize; i++) {
        retVal[i] = scale.getColor(i / (targetSize - 1));
    }

    return retVal;
}