Generate a pseudorandom color based on the user's name

README.md

@@ -111,6 +111,12 @@ $image = $avatar->background('#ff0000')->generate();
 $image = $avatar->color('#ff0000')->generate();
 ````
 
+### Auto Color
+````php
+// Will choose a background color based on `name` and a contrasting font color. The color for a specific name will always be the same.
+$image = $avatar->autoColor()->generate();
+````
+
 ### Font file - default: /fonts/OpenSans-Regular.ttf
 Two fonts with two variants are included:
 * /fonts/OpenSans-Regular.ttf

src/InitialAvatar.php

@@ -219,6 +219,26 @@ 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).
      *
@@ -782,4 +802,116 @@ 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';
+        }
+    }
 }

tests/AutoColorUtilsTest.php

@@ -0,0 +1,29 @@
+<?php
+
+use LasseRafn\InitialAvatarGenerator\InitialAvatar;
+use PHPUnit\Framework\TestCase;
+
+class AutoColorUtilsTest extends TestCase
+{
+    /** @test */
+    public function can_create_all_colors()
+    {
+        $avatar = new InitialAvatar();
+
+        $avatar->name('A')->autoColor();
+        $this->assertEquals('#f0a742', $avatar->getBackgroundColor());
+        $this->assertEquals('#000000', $avatar->getColor());
+
+        $avatar->name('B')->autoColor();
+        $this->assertEquals('#42caf0', $avatar->getBackgroundColor());
+        $this->assertEquals('#000000', $avatar->getColor());
+
+        $avatar->name('C')->autoColor();
+        $this->assertEquals('#42f085', $avatar->getBackgroundColor());
+        $this->assertEquals('#000000', $avatar->getColor());
+
+        $avatar->name('D')->autoColor();
+        $this->assertEquals('#f04293', $avatar->getBackgroundColor());
+        $this->assertEquals('#FFFFFF', $avatar->getColor());
+    }
+}

tests/ParameterTest.php

@@ -98,4 +98,16 @@ public function can_set_auto_font()
 
         $this->assertNotTrue($avatar->getAutoFont());
     }
+
+    /** @test */
+    public function can_set_auto_color()
+    {
+        $avatar = new InitialAvatar();
+
+        $avatar->autoColor();
+
+        $this->assertEquals('#eaf042', $avatar->getBackgroundColor());
+
+        $this->assertEquals('#000000', $avatar->getColor());
+    }
 }