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   1  <?php
   2  
   3  namespace LesserPHP\Functions;
   4  
   5  use Exception;
   6  use LesserPHP\Utils\Asserts;
   7  use LesserPHP\Utils\Color;
   8  
   9  /**
  10   * Implementation of the Color Channel functions for LESS
  11   *
  12   * @link https://lesscss.org/functions/#color-channels
  13   */
  14  class ColorChannels extends AbstractFunctionCollection
  15  {
  16      /** @inheritdoc */
  17      public function getFunctions(): array
  18      {
  19          return [
  20              'hue' => [$this, 'hue'],
  21              'saturation' => [$this, 'saturation'],
  22              'lightness' => [$this, 'lightness'],
  23              //'hsvhue' => [$this, 'hsvhue'],
  24              //'hsvsaturation' => [$this, 'hsvsaturation'],
  25              //'hsvvalue' => [$this, 'hsvvalue'],
  26              'red' => [$this, 'red'],
  27              'green' => [$this, 'green'],
  28              'blue' => [$this, 'blue'],
  29              'alpha' => [$this, 'alpha'],
  30              'luma' => [$this, 'luma'],
  31              //'luminance' => [$this, 'luminance'],
  32          ];
  33      }
  34  
  35      /**
  36       * Extracts the hue channel of a color object in the HSL color space
  37       *
  38       * @link https://lesscss.org/functions/#color-channel-hue
  39       * @throws Exception
  40       */
  41      public function hue(array $color): int
  42      {
  43          $hsl = Color::toHSL(Asserts::assertColor($color));
  44          return round($hsl[1]);
  45      }
  46  
  47      /**
  48       * Extracts the saturation channel of a color object in the HSL color space
  49       *
  50       * @link https://lesscss.org/functions/#color-channel-saturation
  51       * @throws Exception
  52       */
  53      public function saturation(array $color): int
  54      {
  55          $hsl = Color::toHSL(Asserts::assertColor($color));
  56          return round($hsl[2]);
  57      }
  58  
  59      /**
  60       * Extracts the lightness channel of a color object in the HSL color space
  61       *
  62       * @link https://lesscss.org/functions/#color-channel-lightness
  63       * @throws Exception
  64       */
  65      public function lightness(array $color): int
  66      {
  67          $hsl = Color::toHSL(Asserts::assertColor($color));
  68          return round($hsl[3]);
  69      }
  70  
  71      // hsvhue is missing
  72  
  73      // hsvsaturation is missing
  74  
  75      // hsvvalue is missing
  76  
  77      /**
  78       * @throws Exception
  79       */
  80      public function red($color)
  81      {
  82          $color = Asserts::assertColor($color);
  83          return $color[1];
  84      }
  85  
  86      /**
  87       * @throws Exception
  88       */
  89      public function green($color)
  90      {
  91          $color = Asserts::assertColor($color);
  92          return $color[2];
  93      }
  94  
  95      /**
  96       * @throws Exception
  97       */
  98      public function blue($color)
  99      {
 100          $color = Asserts::assertColor($color);
 101          return $color[3];
 102      }
 103  
 104      /**
 105       * Extracts the alpha channel of a color object
 106       *
 107       * defaults to 1 for colors without an alpha
 108       * @fixme non-colors return null - should they?
 109       * @link https://lesscss.org/functions/#color-channel-alpha
 110       */
 111      public function alpha(array $value): ?float
 112      {
 113          if (!is_null($color = Color::coerceColor($value))) {
 114              return $color[4] ?? 1;
 115          }
 116          return null;
 117      }
 118  
 119      /**
 120       * Calculates the luma (perceptual brightness) of a color object
 121       *
 122       * @link https://lesscss.org/functions/#color-channel-luma
 123       * @throws Exception
 124       */
 125      public function luma(array $color): array
 126      {
 127          $color = Asserts::assertColor($color);
 128          return ['number', round(Color::toLuma($color) * 100, 8), '%'];
 129      }
 130  
 131      // luminance is missing
 132  }