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ce86248b1e
* feat: add RGB to HSL color format conversion algorithm * test: add self-tests for rgb to hsl conversion algorithm * fix: change function code to concise format * fix: use throw and segregate the test cases * chore: clean up the test format * chore: use correct styling
86 lines
2.0 KiB
JavaScript
86 lines
2.0 KiB
JavaScript
/**
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* Given a color in RGB format, convert it to HSL format.
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*
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* For more info: https://www.niwa.nu/2013/05/math-behind-colorspace-conversions-rgb-hsl/
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*
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* @param {number[]} colorRgb - One dimensional array of integers (RGB color format).
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* @returns {number[]} - One dimensional array of integers (HSL color format).
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*
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* @example
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* const colorRgb = [24, 98, 118]
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*
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* const result = rgbToHsl(colorRgb)
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*
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* // The function returns the corresponding color in HSL format:
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* // result = [193, 66, 28]
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*/
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const checkRgbFormat = (colorRgb) => colorRgb.every((c) => c >= 0 && c <= 255)
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const rgbToHsl = (colorRgb) => {
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if (!checkRgbFormat(colorRgb)) {
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throw new Error('Input is not a valid RGB color.')
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}
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let colorHsl = colorRgb
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let red = Math.round(colorRgb[0])
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let green = Math.round(colorRgb[1])
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let blue = Math.round(colorRgb[2])
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const limit = 255
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colorHsl[0] = red / limit
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colorHsl[1] = green / limit
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colorHsl[2] = blue / limit
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let minValue = Math.min(...colorHsl)
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let maxValue = Math.max(...colorHsl)
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let channel = 0
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if (maxValue === colorHsl[1]) {
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channel = 1
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} else if (maxValue === colorHsl[2]) {
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channel = 2
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}
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let luminance = (minValue + maxValue) / 2
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let saturation = 0
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if (minValue !== maxValue) {
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if (luminance <= 0.5) {
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saturation = (maxValue - minValue) / (maxValue + minValue)
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} else {
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saturation = (maxValue - minValue) / (2 - maxValue - minValue)
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}
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}
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let hue = 0
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if (saturation !== 0) {
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if (channel === 0) {
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hue = (colorHsl[1] - colorHsl[2]) / (maxValue - minValue)
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} else if (channel === 1) {
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hue = 2 + (colorHsl[2] - colorHsl[0]) / (maxValue - minValue)
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} else {
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hue = 4 + (colorHsl[0] - colorHsl[1]) / (maxValue - minValue)
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}
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}
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hue *= 60
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if (hue < 0) {
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hue += 360
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}
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colorHsl[0] = Math.round(hue)
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colorHsl[1] = Math.round(saturation * 100)
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colorHsl[2] = Math.round(luminance * 100)
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return colorHsl
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}
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export { rgbToHsl }
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