CRM/Utils/Color.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | CiviCRM version 5                                                  |
   5  +--------------------------------------------------------------------+
   6  | Copyright CiviCRM LLC (c) 2004-2019                                |
   7  +--------------------------------------------------------------------+
   8  | This file is a part of CiviCRM.                                    |
   9  |                                                                    |
  10  | CiviCRM is free software; you can copy, modify, and distribute it  |
  11  | under the terms of the GNU Affero General Public License           |
  12  | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
  13  |                                                                    |
  14  | CiviCRM is distributed in the hope that it will be useful, but     |
  15  | WITHOUT ANY WARRANTY; without even the implied warranty of         |
  16  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               |
  17  | See the GNU Affero General Public License for more details.        |
  18  |                                                                    |
  19  | You should have received a copy of the GNU Affero General Public   |
  20  | License and the CiviCRM Licensing Exception along                  |
  21  | with this program; if not, contact CiviCRM LLC                     |
  22  | at info[AT]civicrm[DOT]org. If you have questions about the        |
  23  | GNU Affero General Public License or the licensing of CiviCRM,     |
  24  | see the CiviCRM license FAQ at http://civicrm.org/licensing        |
  25  +--------------------------------------------------------------------+
  26  */
  27
  28 /**
  29  *
  30  * @package CRM
  31  * @copyright CiviCRM LLC (c) 2004-2019
  32  */
  33
  34 /**
  35  * Static utility functions for working with colors
  36  */
  37 class CRM_Utils_Color {
  38
  39   const COLOR_FILE = '[civicrm.root]/bower_components/css-color-names/css-color-names.json';
  40
  41   /**
  42    * Determine the appropriate text color for a given background.
  43    *
  44    * Based on YIQ value.
  45    *
  46    * @param string $color
  47    * @param string $black
  48    * @param string $white
  49    * @return string
  50    */
  51   public static function getContrast($color, $black = 'black', $white = 'white') {
  52     list($r, $g, $b) = self::getRgb($color);
  53     $yiq = (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
  54     return ($yiq >= 128) ? $black : $white;
  55   }
  56
  57   /**
  58    * Parse any color string into rgb decimal values
  59    *
  60    * Accepted formats:
  61    *   Full hex:     "#ffffff"
  62    *   Short hex:    "#fff"
  63    *   Color name    "white"
  64    *   RGB notation: "rgb(255, 255, 255)"
  65    *
  66    * @param string $color
  67    * @return int[]|null
  68    *   [red, green, blue]
  69    */
  70   public static function getRgb($color) {
  71     $color = str_replace(' ', '', $color);
  72     $color = self::nameToHex($color) ?? $color;
  73     if (strpos($color, 'rgb(') === 0) {
  74       return explode(',', substr($color, 4, strpos($color, ')') - 4));
  75     }
  76     $color = ltrim($color, '#');
  77     if (strlen($color) === 3) {
  78       $color = $color[0] . $color[0] . $color[1] . $color[1] . $color[2] . $color[2];
  79     }
  80     if (!CRM_Utils_Rule::color('#' . $color)) {
  81       return NULL;
  82     }
  83     return [
  84       hexdec(substr($color, 0, 2)),
  85       hexdec(substr($color, 2, 2)),
  86       hexdec(substr($color, 4, 2)),
  87     ];
  88   }
  89
  90   /**
  91    * Calculate a highlight color from a base color
  92    *
  93    * @param $color
  94    * @return string
  95    */
  96   public static function getHighlight($color) {
  97     $rgb = self::getRgb($color);
  98     $avg = array_sum($rgb) / 3;
  99     foreach ($rgb as &$v) {
 100       if ($avg > 242) {
 101         // For very bright values, lower the brightness
 102         $v -= 50;
 103       }
 104       else {
 105         // Bump up brightness on a nonlinear curve - darker colors get more of a boost
 106         $v = min(255, intval((-.0035 * ($v - 242) ** 2) + 260));
 107       }
 108     }
 109     return self::rgbToHex($rgb);
 110   }
 111
 112   /**
 113    * Convert named color (e.g. springgreen) to hex
 114    *
 115    * @param $colorName
 116    * @return string|null
 117    */
 118   public static function nameToHex($colorName) {
 119     if (strpos($colorName, '#') !== FALSE || strpos($colorName, '(') !== FALSE) {
 120       return NULL;
 121     }
 122     if (empty(Civi::$statics[__CLASS__]['names'])) {
 123       Civi::$statics[__CLASS__]['names'] = json_decode(file_get_contents(Civi::paths()->getPath(self::COLOR_FILE)), TRUE);
 124     }
 125     return Civi::$statics[__CLASS__]['names'][strtolower($colorName)] ?? NULL;
 126   }
 127
 128   /**
 129    * Converts rgb array to hex string
 130    *
 131    * @param int[] $rgb
 132    * @return string
 133    */
 134   public static function rgbToHex($rgb) {
 135     $ret = '#';
 136     foreach ($rgb as $dec) {
 137       $ret .= str_pad(dechex($dec), 2, '0', STR_PAD_LEFT);
 138     }
 139     return $ret;
 140   }
 141
 142   /**
 143    * Validate color input and convert it to standard hex notation
 144    *
 145    * @param string $color
 146    * @return bool
 147    */
 148   public static function normalize(&$color) {
 149     $rgb = self::getRgb($color);
 150     if ($rgb) {
 151       $color = self::rgbToHex($rgb);
 152       return TRUE;
 153     }
 154     return FALSE;
 155   }
 156
 157 }