CRM/Utils/Color.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | Copyright CiviCRM LLC. All rights reserved.                        |
   5  |                                                                    |
   6  | This work is published under the GNU AGPLv3 license with some      |
   7  | permitted exceptions and without any warranty. For full license    |
   8  | and copyright information, see https://civicrm.org/licensing       |
   9  +--------------------------------------------------------------------+
  10  */
  11
  12 /**
  13  *
  14  * @package CRM
  15  * @copyright CiviCRM LLC https://civicrm.org/licensing
  16  */
  17
  18 /**
  19  * Static utility functions for working with colors
  20  */
  21 class CRM_Utils_Color {
  22
  23   const COLOR_FILE = '[civicrm.root]/bower_components/css-color-names/css-color-names.json';
  24
  25   /**
  26    * Determine the appropriate text color for a given background.
  27    *
  28    * Based on YIQ value.
  29    *
  30    * @param string $color
  31    * @param string $black
  32    * @param string $white
  33    * @return string
  34    */
  35   public static function getContrast($color, $black = 'black', $white = 'white') {
  36     list($r, $g, $b) = self::getRgb($color);
  37     $yiq = (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
  38     return ($yiq >= 128) ? $black : $white;
  39   }
  40
  41   /**
  42    * Parse any color string into rgb decimal values
  43    *
  44    * Accepted formats:
  45    *   Full hex:     "#ffffff"
  46    *   Short hex:    "#fff"
  47    *   Color name    "white"
  48    *   RGB notation: "rgb(255, 255, 255)"
  49    *
  50    * @param string $color
  51    * @return int[]|null
  52    *   [red, green, blue]
  53    */
  54   public static function getRgb($color) {
  55     $color = str_replace(' ', '', $color);
  56     $color = self::nameToHex($color) ?? $color;
  57     if (strpos($color, 'rgb(') === 0) {
  58       return explode(',', substr($color, 4, strpos($color, ')') - 4));
  59     }
  60     $color = ltrim($color, '#');
  61     if (strlen($color) === 3) {
  62       $color = $color[0] . $color[0] . $color[1] . $color[1] . $color[2] . $color[2];
  63     }
  64     if (!CRM_Utils_Rule::color('#' . $color)) {
  65       return NULL;
  66     }
  67     return [
  68       hexdec(substr($color, 0, 2)),
  69       hexdec(substr($color, 2, 2)),
  70       hexdec(substr($color, 4, 2)),
  71     ];
  72   }
  73
  74   /**
  75    * Calculate a highlight color from a base color
  76    *
  77    * @param $color
  78    * @return string
  79    */
  80   public static function getHighlight($color) {
  81     $rgb = self::getRgb($color);
  82     $avg = array_sum($rgb) / 3;
  83     foreach ($rgb as &$v) {
  84       if ($avg > 242) {
  85         // For very bright values, lower the brightness
  86         $v -= 50;
  87       }
  88       else {
  89         // Bump up brightness on a nonlinear curve - darker colors get more of a boost
  90         $v = min(255, intval((-.0035 * ($v - 242) ** 2) + 260));
  91       }
  92     }
  93     return self::rgbToHex($rgb);
  94   }
  95
  96   /**
  97    * Convert named color (e.g. springgreen) to hex
  98    *
  99    * @param $colorName
 100    * @return string|null
 101    */
 102   public static function nameToHex($colorName) {
 103     if (strpos($colorName, '#') !== FALSE || strpos($colorName, '(') !== FALSE) {
 104       return NULL;
 105     }
 106     if (empty(Civi::$statics[__CLASS__]['names'])) {
 107       Civi::$statics[__CLASS__]['names'] = json_decode(file_get_contents(Civi::paths()->getPath(self::COLOR_FILE)), TRUE);
 108     }
 109     return Civi::$statics[__CLASS__]['names'][strtolower($colorName)] ?? NULL;
 110   }
 111
 112   /**
 113    * Converts rgb array to hex string
 114    *
 115    * @param int[] $rgb
 116    * @return string
 117    */
 118   public static function rgbToHex($rgb) {
 119     $ret = '#';
 120     foreach ($rgb as $dec) {
 121       $ret .= str_pad(dechex($dec), 2, '0', STR_PAD_LEFT);
 122     }
 123     return $ret;
 124   }
 125
 126   /**
 127    * Validate color input and convert it to standard hex notation
 128    *
 129    * @param string $color
 130    * @return bool
 131    */
 132   public static function normalize(&$color) {
 133     $rgb = self::getRgb($color);
 134     if ($rgb) {
 135       $color = self::rgbToHex($rgb);
 136       return TRUE;
 137     }
 138     return FALSE;
 139   }
 140
 141 }