Show part mass in part info page.

src/Services/SIFormatter.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ *
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ *
+ */
+
+namespace App\Services;
+
+/**
+ * A service that helps you to format values using the SI prefixes.
+ * @package App\Services
+ */
+class SIFormatter
+{
+    /**
+     * Returns the magnitude of a value (the count of decimal place of the highest decimal place).
+     * For example, for 100 (=10^2) this function returns 2. For -2500 (=-2.5*10^3) this function returns 3.
+     * @param float $value The value of which the magnitude should be determined.
+     * @return int The magnitude of the value
+     */
+    public function getMagnitude(float $value) : int
+    {
+        return (int) floor(log10(abs($value)));
+    }
+
+    /**
+     * Returns the best SI prefix (and its corresponding divisor) for the given magnitude.
+     * @param int $magnitude The magnitude for which the prefix should be determined.
+     * @return array A array, containing the divisor in first element, and the prefix symbol in second. For example, [1000, "k"].
+     */
+    public function getPrefixByMagnitude(int $magnitude) : array
+    {
+        $prefixes_pos = ['' ,'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'];
+        $prefixes_neg = ['' ,'m', 'μ', 'n', 'p', 'f', 'a', 'z', 'y'];
+
+        //Determine nearest prefix index.
+        $nearest = (int) round(abs($magnitude) / 3);
+
+        if ($magnitude >= 0) {
+            $symbol = $prefixes_pos[$nearest];
+        } else {
+            $symbol = $prefixes_neg[$nearest];
+        }
+
+        if ($magnitude < 0) {
+            $nearest *= -1;
+        }
+
+        return [10 ** (3 * $nearest), $symbol];
+    }
+
+    /**
+     * @param float $value
+     * @param string $unit
+     * @param int $decimals
+     * @return string
+     */
+    public function format(float $value, string $unit = '', int $decimals = 2)
+    {
+        [$divisor, $symbol] = $this->getPrefixByMagnitude($this->getMagnitude($value));
+        $value /= $divisor;
+        //Build the format string, e.g.: %.2d km
+        $format_string = '%.' . $decimals . 'f ' . $symbol . $unit;
+
+        return sprintf($format_string, $value);
+    }
+
+}