58 lines
1.5 KiB
PHP
58 lines
1.5 KiB
PHP
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<?php
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/**
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* @copyright Copyright (c) 2016 Julius Härtl <jus@bitgrid.net>
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*
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* @license GNU AGPL version 3 or any later version
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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namespace OCA\Theming;
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class Util {
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/**
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* @param string $color rgb color value
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* @return bool
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*/
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public static function invertTextColor($color) {
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$l = self::calculateLuminance($color);
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if($l>0.5) {
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return true;
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} else {
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return false;
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}
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}
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/**
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* @param string $color rgb color value
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* @return float
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*/
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public static function calculateLuminance($color) {
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$hex = preg_replace("/[^0-9A-Fa-f]/", '', $color);
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if (strlen($hex) === 3) {
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$hex = $hex{0} . $hex{0} . $hex{1} . $hex{1} . $hex{2} . $hex{2};
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}
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if (strlen($hex) !== 6) {
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return 0;
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}
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$r = hexdec(substr($hex, 0, 2));
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$g = hexdec(substr($hex, 2, 2));
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$b = hexdec(substr($hex, 4, 2));
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return (0.299 * $r + 0.587 * $g + 0.114 * $b)/255;
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}
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}
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