Auto generate colors

Author: yakatz

src/InitialAvatar.php

@@ -207,6 +207,27 @@ public function color( $color ) {
 		return $this;
 	}
 
+	/**
+	 * Automatically set a font and/or background color based on the supplied name
+	 * 
+	 * @param bool $foreground
+	 * @param bool $background
+	 * 
+	 * @return $this
+	 */
+	public function autoColor(bool $foreground = true, bool $background = true, int $saturation = 85, int $luminance = 60)
+	{
+
+		$hue = (crc32($this->name) % 360) / 360;
+		$saturation /= 100;
+		$luminance /= 100;
+
+		$this->bgColor = $this->convertHSLtoRGB($hue, $saturation, $luminance);
+		$this->fontColor = $this->getContrastColor($this->bgColor);
+
+		return $this;
+	}
+
 	/**
 	 * Set the font file by path or int (1-5).
 	 *
@@ -738,4 +759,116 @@ protected function getFontByScript() {
 
 		return $this->getFontFile();
 	}
+
+	/**
+	 * Convert HSL color value produced by autoColor() to RGB value expected by image driver
+	 */
+	protected function convertHSLtoRGB($h, $s, $l, $toHex = true)
+	{
+		assert((0 <= $h) && ($h <= 1));
+
+		$red = $l;
+		$green = $l;
+		$blue = $l;
+
+		$v = ($l <= 0.5) ? ($l * (1.0 + $s)) : ($l + $s - $l * $s);
+		if ($v > 0) {
+			$m = $l + $l - $v;
+			$sv = ($v - $m) / $v;
+			$h *= 6.0;
+			$sextant = floor($h);
+			$fract = $h - $sextant;
+			$vsf = $v * $sv * $fract;
+			$mid1 = $m + $vsf;
+			$mid2 = $v - $vsf;
+
+			switch ($sextant) {
+				case 0:
+					$red = $v;
+					$green = $mid1;
+					$blue = $m;
+					break;
+				case 1:
+					$red = $mid2;
+					$green = $v;
+					$blue = $m;
+					break;
+				case 2:
+					$red = $m;
+					$green = $v;
+					$blue = $mid1;
+					break;
+				case 3:
+					$red = $m;
+					$green = $mid2;
+					$blue = $v;
+					break;
+				case 4:
+					$red = $mid1;
+					$green = $m;
+					$blue = $v;
+					break;
+				case 5:
+					$red = $v;
+					$green = $m;
+					$blue = $mid2;
+					break;
+			}
+		}
+
+		$red = round($red * 255, 0);
+		$green = round($green * 255, 0);
+		$blue = round($blue * 255, 0);
+
+		if ($toHex) {
+			$red = ($red < 15) ? '0' . dechex($red) : dechex($red);
+			$green = ($green < 15) ? '0' . dechex($green) : dechex($green);
+			$blue = ($blue < 15) ? '0' . dechex($blue) : dechex($blue);
+			return "#{$red}{$green}{$blue}";
+		} else {
+			return ['red' => $red, 'green' => $green, 'blue' => $blue];
+		}
+	}
+
+	/**
+	 * Get contrasting foreground color for autoColor background
+	 */
+	protected function getContrastColor($hexColor)
+	{
+
+		// hexColor RGB
+		$R1 = hexdec(substr($hexColor, 1, 2));
+		$G1 = hexdec(substr($hexColor, 3, 2));
+		$B1 = hexdec(substr($hexColor, 5, 2));
+
+		// Black RGB
+		$blackColor = "#000000";
+		$R2BlackColor = hexdec(substr($blackColor, 1, 2));
+		$G2BlackColor = hexdec(substr($blackColor, 3, 2));
+		$B2BlackColor = hexdec(substr($blackColor, 5, 2));
+
+		// Calc contrast ratio
+		$L1 = 0.2126 * pow($R1 / 255, 2.2) +
+			0.7152 * pow($G1 / 255, 2.2) +
+			0.0722 * pow($B1 / 255, 2.2);
+
+		$L2 = 0.2126 * pow($R2BlackColor / 255, 2.2) +
+			0.7152 * pow($G2BlackColor / 255, 2.2) +
+			0.0722 * pow($B2BlackColor / 255, 2.2);
+
+		$contrastRatio = 0;
+		if ($L1 > $L2) {
+			$contrastRatio = (int)(($L1 + 0.05) / ($L2 + 0.05));
+		} else {
+			$contrastRatio = (int)(($L2 + 0.05) / ($L1 + 0.05));
+		}
+
+		// If contrast is more than 5, return black color
+		if ($contrastRatio > 5) {
+			return '#000000';
+		} else {
+			// if not, return white color.
+			return '#FFFFFF';
+		}
+	}
 }