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<?php
namespace PhpOffice\PhpSpreadsheet\Style;
/**
* Class to handle tint applied to color.
* Code borrows heavily from some Python projects.
*
* @see https://docs.python.org/3/library/colorsys.html
* @see https://gist.github.com/Mike-Honey/b36e651e9a7f1d2e1d60ce1c63b9b633
*/
class RgbTint
{
private const ONE_THIRD = 1.0 / 3.0;
private const ONE_SIXTH = 1.0 / 6.0;
private const TWO_THIRD = 2.0 / 3.0;
private const RGBMAX = 255.0;
/**
* MS excel's tint function expects that HLS is base 240.
*
* @see https://social.msdn.microsoft.com/Forums/en-US/e9d8c136-6d62-4098-9b1b-dac786149f43/excel-color-tint-algorithm-incorrect?forum=os_binaryfile#d3c2ac95-52e0-476b-86f1-e2a697f24969
*/
private const HLSMAX = 240.0;
/**
* Convert red/green/blue to hue/luminance/saturation.
*
* @param float $red 0.0 through 1.0
* @param float $green 0.0 through 1.0
* @param float $blue 0.0 through 1.0
*
* @return float[]
*/
private static function rgbToHls(float $red, float $green, float $blue): array
{
$maxc = max($red, $green, $blue);
$minc = min($red, $green, $blue);
$luminance = ($minc + $maxc) / 2.0;
if ($minc === $maxc) {
return [0.0, $luminance, 0.0];
}
$maxMinusMin = $maxc - $minc;
if ($luminance <= 0.5) {
$s = $maxMinusMin / ($maxc + $minc);
} else {
$s = $maxMinusMin / (2.0 - $maxc - $minc);
}
$rc = ($maxc - $red) / $maxMinusMin;
$gc = ($maxc - $green) / $maxMinusMin;
$bc = ($maxc - $blue) / $maxMinusMin;
if ($red === $maxc) {
$h = $bc - $gc;
} elseif ($green === $maxc) {
$h = 2.0 + $rc - $bc;
} else {
$h = 4.0 + $gc - $rc;
}
$h = self::positiveDecimalPart($h / 6.0);
return [$h, $luminance, $s];
}
/** @var mixed */
private static $scrutinizerZeroPointZero = 0.0;
/**
* Convert hue/luminance/saturation to red/green/blue.
*
* @param float $hue 0.0 through 1.0
* @param float $luminance 0.0 through 1.0
* @param float $saturation 0.0 through 1.0
*
* @return float[]
*/
private static function hlsToRgb($hue, $luminance, $saturation): array
{
if ($saturation === self::$scrutinizerZeroPointZero) {
return [$luminance, $luminance, $luminance];
}
if ($luminance <= 0.5) {
$m2 = $luminance * (1.0 + $saturation);
} else {
$m2 = $luminance + $saturation - ($luminance * $saturation);
}
$m1 = 2.0 * $luminance - $m2;
return [
self::vFunction($m1, $m2, $hue + self::ONE_THIRD),
self::vFunction($m1, $m2, $hue),
self::vFunction($m1, $m2, $hue - self::ONE_THIRD),
];
}
private static function vFunction(float $m1, float $m2, float $hue): float
{
$hue = self::positiveDecimalPart($hue);
if ($hue < self::ONE_SIXTH) {
return $m1 + ($m2 - $m1) * $hue * 6.0;
}
if ($hue < 0.5) {
return $m2;
}
if ($hue < self::TWO_THIRD) {
return $m1 + ($m2 - $m1) * (self::TWO_THIRD - $hue) * 6.0;
}
return $m1;
}
private static function positiveDecimalPart(float $hue): float
{
$hue = fmod($hue, 1.0);
return ($hue >= 0.0) ? $hue : (1.0 + $hue);
}
/**
* Convert red/green/blue to HLSMAX-based hue/luminance/saturation.
*
* @return int[]
*/
private static function rgbToMsHls(int $red, int $green, int $blue): array
{
$red01 = $red / self::RGBMAX;
$green01 = $green / self::RGBMAX;
$blue01 = $blue / self::RGBMAX;
[$hue, $luminance, $saturation] = self::rgbToHls($red01, $green01, $blue01);
return [
(int) round($hue * self::HLSMAX),
(int) round($luminance * self::HLSMAX),
(int) round($saturation * self::HLSMAX),
];
}
/**
* Converts HLSMAX based HLS values to rgb values in the range (0,1).
*
* @return float[]
*/
private static function msHlsToRgb(int $hue, int $lightness, int $saturation): array
{
return self::hlsToRgb($hue / self::HLSMAX, $lightness / self::HLSMAX, $saturation / self::HLSMAX);
}
/**
* Tints HLSMAX based luminance.
*
* @see http://ciintelligence.blogspot.co.uk/2012/02/converting-excel-theme-color-and-tint.html
*/
private static function tintLuminance(float $tint, float $luminance): int
{
if ($tint < 0) {
return (int) round($luminance * (1.0 + $tint));
}
return (int) round($luminance * (1.0 - $tint) + (self::HLSMAX - self::HLSMAX * (1.0 - $tint)));
}
/**
* Return result of tinting supplied rgb as 6 hex digits.
*/
public static function rgbAndTintToRgb(int $red, int $green, int $blue, float $tint): string
{
[$hue, $luminance, $saturation] = self::rgbToMsHls($red, $green, $blue);
[$red, $green, $blue] = self::msHlsToRgb($hue, self::tintLuminance($tint, $luminance), $saturation);
return sprintf(
'%02X%02X%02X',
(int) round($red * self::RGBMAX),
(int) round($green * self::RGBMAX),
(int) round($blue * self::RGBMAX)
);
}
}
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